CA2606505A1 - Method for producing foamed aluminum products by use of selected carbonate decomposition products - Google Patents
Method for producing foamed aluminum products by use of selected carbonate decomposition products Download PDFInfo
- Publication number
- CA2606505A1 CA2606505A1 CA002606505A CA2606505A CA2606505A1 CA 2606505 A1 CA2606505 A1 CA 2606505A1 CA 002606505 A CA002606505 A CA 002606505A CA 2606505 A CA2606505 A CA 2606505A CA 2606505 A1 CA2606505 A1 CA 2606505A1
- Authority
- CA
- Canada
- Prior art keywords
- aluminum
- reactive gas
- molten metal
- producing particles
- gas producing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 129
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 129
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 238000000354 decomposition reaction Methods 0.000 title claims description 61
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 title description 23
- 239000002245 particle Substances 0.000 claims abstract description 151
- 239000006260 foam Substances 0.000 claims abstract description 66
- 238000000034 method Methods 0.000 claims abstract description 49
- 239000000047 product Substances 0.000 claims abstract description 48
- 229910000838 Al alloy Inorganic materials 0.000 claims abstract description 29
- 229910044991 metal oxide Inorganic materials 0.000 claims abstract description 27
- 239000006262 metallic foam Substances 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 16
- 150000004706 metal oxides Chemical class 0.000 claims abstract description 13
- 239000007787 solid Substances 0.000 claims abstract description 9
- 239000006227 byproduct Substances 0.000 claims abstract description 8
- 239000000919 ceramic Substances 0.000 claims abstract description 8
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 117
- 239000000725 suspension Substances 0.000 claims description 72
- 229910001092 metal group alloy Inorganic materials 0.000 claims description 70
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 59
- 239000004088 foaming agent Substances 0.000 claims description 54
- 239000011777 magnesium Substances 0.000 claims description 40
- 229910052751 metal Inorganic materials 0.000 claims description 35
- 239000002184 metal Substances 0.000 claims description 35
- 229910052749 magnesium Inorganic materials 0.000 claims description 34
- 238000002156 mixing Methods 0.000 claims description 34
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 29
- 238000005187 foaming Methods 0.000 claims description 27
- 238000009826 distribution Methods 0.000 claims description 24
- 239000000126 substance Substances 0.000 claims description 23
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 22
- 239000006185 dispersion Substances 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 18
- 229910001338 liquidmetal Inorganic materials 0.000 claims description 17
- 239000011159 matrix material Substances 0.000 claims description 17
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 16
- 229910000514 dolomite Inorganic materials 0.000 claims description 16
- 239000011148 porous material Substances 0.000 claims description 16
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims description 15
- 239000010459 dolomite Substances 0.000 claims description 14
- 239000006261 foam material Substances 0.000 claims description 14
- 239000001095 magnesium carbonate Substances 0.000 claims description 13
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims description 13
- 238000006073 displacement reaction Methods 0.000 claims description 11
- 239000000292 calcium oxide Substances 0.000 claims description 9
- 238000004891 communication Methods 0.000 claims description 9
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 9
- 239000000395 magnesium oxide Substances 0.000 claims description 8
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 8
- 238000012546 transfer Methods 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 6
- 238000010276 construction Methods 0.000 claims description 5
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 229910001111 Fine metal Inorganic materials 0.000 claims description 2
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 2
- -1 titanium hydride Chemical compound 0.000 claims description 2
- 229910000048 titanium hydride Inorganic materials 0.000 claims description 2
- QSGNKXDSTRDWKA-UHFFFAOYSA-N zirconium dihydride Chemical compound [ZrH2] QSGNKXDSTRDWKA-UHFFFAOYSA-N 0.000 claims description 2
- 229910000568 zirconium hydride Inorganic materials 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims 2
- 239000007789 gas Substances 0.000 abstract description 143
- 238000007792 addition Methods 0.000 abstract description 30
- 238000013019 agitation Methods 0.000 abstract description 20
- 230000000087 stabilizing effect Effects 0.000 abstract description 17
- 239000002243 precursor Substances 0.000 abstract description 4
- 239000000155 melt Substances 0.000 description 27
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 24
- 206010001497 Agitation Diseases 0.000 description 20
- 230000000694 effects Effects 0.000 description 16
- 229910002092 carbon dioxide Inorganic materials 0.000 description 14
- 230000001965 increasing effect Effects 0.000 description 14
- 229910045601 alloy Inorganic materials 0.000 description 11
- 239000000956 alloy Substances 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 9
- 230000006641 stabilisation Effects 0.000 description 9
- 238000011105 stabilization Methods 0.000 description 9
- 230000008569 process Effects 0.000 description 7
- 239000000654 additive Substances 0.000 description 6
- 230000000996 additive effect Effects 0.000 description 6
- 210000004027 cell Anatomy 0.000 description 6
- 229910000861 Mg alloy Inorganic materials 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 239000008258 liquid foam Substances 0.000 description 5
- 150000002739 metals Chemical class 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 229910003455 mixed metal oxide Inorganic materials 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000004581 coalescence Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Al+3].[Al+3].[O-]C([O-])=O GDVKFRBCXAPAQJ-UHFFFAOYSA-A 0.000 description 3
- 229960001545 hydrotalcite Drugs 0.000 description 3
- 229910001701 hydrotalcite Inorganic materials 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000003381 stabilizer Substances 0.000 description 3
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 210000002421 cell wall Anatomy 0.000 description 2
- 230000001413 cellular effect Effects 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000011162 core material Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000000977 initiatory effect Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 238000011081 inoculation Methods 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000001757 thermogravimetry curve Methods 0.000 description 2
- 238000003260 vortexing Methods 0.000 description 2
- 229910018134 Al-Mg Inorganic materials 0.000 description 1
- 229910018467 Al—Mg Inorganic materials 0.000 description 1
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 229910001369 Brass Inorganic materials 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000978 Pb alloy Inorganic materials 0.000 description 1
- 229910001128 Sn alloy Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 238000010923 batch production Methods 0.000 description 1
- 239000010951 brass Substances 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- 229910000011 cadmium carbonate Inorganic materials 0.000 description 1
- KOHRTFCSIQIYAE-UHFFFAOYSA-N cadmium;carbonic acid Chemical compound [Cd].OC(O)=O KOHRTFCSIQIYAE-UHFFFAOYSA-N 0.000 description 1
- HHSPVTKDOHQBKF-UHFFFAOYSA-J calcium;magnesium;dicarbonate Chemical compound [Mg+2].[Ca+2].[O-]C([O-])=O.[O-]C([O-])=O HHSPVTKDOHQBKF-UHFFFAOYSA-J 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 125000005587 carbonate group Chemical group 0.000 description 1
- WIKQEUJFZPCFNJ-UHFFFAOYSA-N carbonic acid;silver Chemical compound [Ag].[Ag].OC(O)=O WIKQEUJFZPCFNJ-UHFFFAOYSA-N 0.000 description 1
- ONIOAEVPMYCHKX-UHFFFAOYSA-N carbonic acid;zinc Chemical compound [Zn].OC(O)=O ONIOAEVPMYCHKX-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 210000003850 cellular structure Anatomy 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 238000010961 commercial manufacture process Methods 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 238000009408 flooring Methods 0.000 description 1
- 210000000497 foam cell Anatomy 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 1
- 229910052808 lithium carbonate Inorganic materials 0.000 description 1
- 150000002680 magnesium Chemical class 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011656 manganese carbonate Substances 0.000 description 1
- 235000006748 manganese carbonate Nutrition 0.000 description 1
- 229910000016 manganese(II) carbonate Inorganic materials 0.000 description 1
- 229910052987 metal hydride Inorganic materials 0.000 description 1
- 150000004681 metal hydrides Chemical class 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000000518 rheometry Methods 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- LKZMBDSASOBTPN-UHFFFAOYSA-L silver carbonate Substances [Ag].[O-]C([O-])=O LKZMBDSASOBTPN-UHFFFAOYSA-L 0.000 description 1
- KQTXIZHBFFWWFW-UHFFFAOYSA-L silver(I) carbonate Inorganic materials [Ag]OC(=O)O[Ag] KQTXIZHBFFWWFW-UHFFFAOYSA-L 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 229910052566 spinel group Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- LEDMRZGFZIAGGB-UHFFFAOYSA-L strontium carbonate Chemical compound [Sr+2].[O-]C([O-])=O LEDMRZGFZIAGGB-UHFFFAOYSA-L 0.000 description 1
- 229910000018 strontium carbonate Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011667 zinc carbonate Substances 0.000 description 1
- 235000004416 zinc carbonate Nutrition 0.000 description 1
- 229910000010 zinc carbonate Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/08—Alloys with open or closed pores
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B21/00—Obtaining aluminium
- C22B21/0084—Obtaining aluminium melting and handling molten aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B21/00—Obtaining aluminium
- C22B21/06—Obtaining aluminium refining
- C22B21/064—Obtaining aluminium refining using inert or reactive gases
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/10—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals with refining or fluxing agents; Use of materials therefor, e.g. slagging or scorifying agents
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/08—Alloys with open or closed pores
- C22C1/083—Foaming process in molten metal other than by powder metallurgy
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
- C22C21/10—Alloys based on aluminium with zinc as the next major constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/11—Making porous workpieces or articles
- B22F3/1103—Making porous workpieces or articles with particular physical characteristics
- B22F2003/1106—Product comprising closed porosity
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Manufacture Of Alloys Or Alloy Compounds (AREA)
Abstract
A method for producing an aluminum foam product wherein reactive gas producing particles are introduced into an aluminum alloy melt under controlled conditions and subjected to agitation to induce the production of foam-stabilizing by-products (20), and, under certain conditions, the production of gases (15) used to produce the molten metal foam itself. Foam products produced through this method have intrinsically formed metal oxides (20) and other solid particles dispersed therein and are devoid of the large extrinsically added stabilizing ceramic additions traditionally used in the production of aluminum foams. The invention claims a rapid, single step method for producing an inoculated, foamable melt using low cost precursor materials.
Description
METHOD FOR PRODUCING FOAMED ALUMINUM PRODUCTS BY USE OF
SELECTED CARBONATE DECOMPOSITION PRODUCTS
Cross Reference to Related Applications [0001] This application is a contiiluation-in-part and claims the benefit of U.S. Patent Application Serial No. 11/119,002, filed on April 29, 2005, the disclosure of which is fully incorporated by reference herein.
Field of the Invention [0002] The present invention relates generally to foamable metals, and more particularly, to a method for forming metal foam products in which reactive particles decompose within a metal melt to produce foam stabilizing by-products and gases suitable for foaming metal.
Background Information [0003] Low-density porous products offer unique mechanical and physical properties.
The high specific strength, structural rigidity and insulating properties of foamed products produced in a polymer type matrix are well known. Such closed cell polymeric foams are used extensively in a wide range of applications, including construction, packaging and transportation.
SELECTED CARBONATE DECOMPOSITION PRODUCTS
Cross Reference to Related Applications [0001] This application is a contiiluation-in-part and claims the benefit of U.S. Patent Application Serial No. 11/119,002, filed on April 29, 2005, the disclosure of which is fully incorporated by reference herein.
Field of the Invention [0002] The present invention relates generally to foamable metals, and more particularly, to a method for forming metal foam products in which reactive particles decompose within a metal melt to produce foam stabilizing by-products and gases suitable for foaming metal.
Background Information [0003] Low-density porous products offer unique mechanical and physical properties.
The high specific strength, structural rigidity and insulating properties of foamed products produced in a polymer type matrix are well known. Such closed cell polymeric foams are used extensively in a wide range of applications, including construction, packaging and transportation.
[0004] While polymeric type foams have enjoyed wide market success, foamed metal products have seen only limited applications. Closed cell metallic foams offer many of the attractive attributes of polymeric foam with respect to many light weight applications. In addition, the inherently higher bulk modulus of metals, as compared to polymers, provides higher specific rigidity. This higher bulk modulus makes metal foams an attractive candidate for core materials in laminate panels, in which rigidity and resistance to deflection are important performance measures. Additionally, panels produced from foamed metal are fire and smoke resistant and are well suited for construction applications.
Aluminum foam core sandwich composite products offer the additional environmeiztal benefit of being recyclable;
an issue that has restricted the use of metal clad polymer foams.
Aluminum foam core sandwich composite products offer the additional environmeiztal benefit of being recyclable;
an issue that has restricted the use of metal clad polymer foams.
[0005] While methods of producing foamed metals have been described in the scientific and patent literature, such materials suffer from problems such as high cost, large cell sizes, cell size variability and insufficient structural integrity. Many of these problems are associated with the rheology of the molten metal. In substantially all casting metallurgy methods of producing metallic foams some stabilization is required in the metallic melt.
Foams are meta-stable and therefore prone to both cellular coalescence and cell wall drainage.
Foams are meta-stable and therefore prone to both cellular coalescence and cell wall drainage.
[0006] Conventionally, in order to achieve the required stabilization for producing metal foams, particulates, such as ceramic particles, are introduced into the melt. These particulates effectively change the nature of the melt by increasing the effective viscosity of the melt and/or decreasing the effective surface tension of the liquid. These particulates must be sinall relative to the desired cell wall thickness of the foam.
Incorporating small particulates into the inelt is traditionally achieved using either intrinsic or extrinsic methods, wherein each method has disadvantages limiting their usefulness.
Incorporating small particulates into the inelt is traditionally achieved using either intrinsic or extrinsic methods, wherein each method has disadvantages limiting their usefulness.
[0007] In intrinsic particle formation a gas is stirred into the molten metal, either by vortexing mechanical mixers and/or bubbling of gas (direct gas injection) through the melt.
The gas reacts with the melt to form small particles including oxides, spinels and/or other unique particles. Controlling the size, geometry and volume fraction of the particles formed to create a stable, foamable matrix is particularly difficult.
The gas reacts with the melt to form small particles including oxides, spinels and/or other unique particles. Controlling the size, geometry and volume fraction of the particles formed to create a stable, foamable matrix is particularly difficult.
[0008] The size of the particles formed is affected by the size of the gas bubbles injected or entrained. Producing small gas bubbles in liquid metal is notoriously difficult.
Additionally, melt temperature, time at melt temperature, gas composition, stirring rate and melt composition all affect the rate, amount and characteristics of the particles and their distribution. Further, in aluminum melts, it is often necessary to add highly reactive alkali metals to promote such oxidation reactions.
Additionally, melt temperature, time at melt temperature, gas composition, stirring rate and melt composition all affect the rate, amount and characteristics of the particles and their distribution. Further, in aluminum melts, it is often necessary to add highly reactive alkali metals to promote such oxidation reactions.
[0009] One disadvantage of direct gas injection and/or stirring in providing foamed metals is the time required to create a stable foamable matrix. Time scales on the order of 20 minutes to several hours are often required even for small quantities of molten metal and larger quantities of molten metal often require much longer times to achieve the rheological character required to create a stable metal foam.
[0010] Extrinsic particle addition also suffers from a number of disadvantages which limit its usefulness as a method of stabilizing metal for foaming. In extrinsic particle addition small, inert particles are directly added and mixed into the melt. One disadvantage of extrinsic particle addition is that the extrinsically added particulates must be wetted so they remain suspended in the melt.
[0011] In an effort to wet extrinsically added particles, prior methods have utilized special alloying of the melt and/or particle coatings; sequencing of the melt alloy concentration and/or particulate addition; tight requirements on particle quality/surface composition; and elaborate equipment to control and enhance the wetting process between the particulates and the molten metal by imposing high shear in a vacuum or inert environment.
These technical challenges translate into exotic processing equipment and limitations on the size and purity of the extrinsic particles used. These barriers have prevented the economical production of metal foams produced through extrinsically stabilized melts.
These technical challenges translate into exotic processing equipment and limitations on the size and purity of the extrinsic particles used. These barriers have prevented the economical production of metal foams produced through extrinsically stabilized melts.
[0012] U.S. Patent No. 3,297,431 to Ridgeway Jr. ("Ridgeway Jr.") requires the use of stabilizer powders to maintain and preserve the cellular structure of aluminum foam upon cooling. As described in Ridgeway Jr., such stabilizing particles are finely divided inert powders which are wetted by the molten metal and are stable in the molten metal. The use of stabilizer particles is also described'in U.S. Patent No. 5,112,697 to Jin et al. ("Jin et al."), in which Jin et al. defines precise limits on the size and volume fractions of such "finely divided stabilizer particles". Additionally, U.S. Patent Application Publications 2004/0163492A1 and 2004/0079198A1 (Crowley et al. and Bryant et al. respectively) disclose the use of surface coatings on such viscosity control agents in foaming aluminum. All of these disclosures have their own disadvantages.
[0013] In light of the above-described obstacles and disadvantages, there is a need to provide a more commercially attractive means of metal foam production.
Summary of the Invention [0014] The present invention provides an economical metal foaming process using a minimum of precursor, a minimum number of process steps, and being workable at temperatures and pressures suitable for aluminum processing. Broadly, the present invention provides a method of making foamed aluminum comprising the steps of:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350 C to about 850 C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing said reactive gas producing particles to decompose a first portion of the reactive gas producing particles into a reactive gas and retain a second portion of the reactive gas producing particles in an unreacted state, wherein the reactive gas vigorously combines with the molten metal alloy to produce a suspension of metallic oxide phases and gas bubbles, and the second portion of the reactive gas producing particles in the unreacted state are chemical foaming agents in an inoculated foamable melt;
foaming the inoculated foamable to produce a liquid metal foam; and solidifying the liquid metal foam to create a foamed aluminum product.
Summary of the Invention [0014] The present invention provides an economical metal foaming process using a minimum of precursor, a minimum number of process steps, and being workable at temperatures and pressures suitable for aluminum processing. Broadly, the present invention provides a method of making foamed aluminum comprising the steps of:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350 C to about 850 C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing said reactive gas producing particles to decompose a first portion of the reactive gas producing particles into a reactive gas and retain a second portion of the reactive gas producing particles in an unreacted state, wherein the reactive gas vigorously combines with the molten metal alloy to produce a suspension of metallic oxide phases and gas bubbles, and the second portion of the reactive gas producing particles in the unreacted state are chemical foaming agents in an inoculated foamable melt;
foaming the inoculated foamable to produce a liquid metal foam; and solidifying the liquid metal foam to create a foamed aluminum product.
[0015] The molten metal alloy comprising aluminum may be commercial grade purity aluminum; scrap aluminum; aluminum containing silicon and magnesium; and mixtures thereof. In some embodiments, magnesium may be in solution in the molten metal alloy in the range of about 0.5 wt. % to about 8 wt. %.
[0016] The reactive gas producing particle may be selected from calcium carbonate, magnesium carbonate, magnesium-calcium carbonate (dolomite) or mixtures thereof.
Calcium carbonate is particularly effective as a reactive gas producing particle and/or as a foaming agent. In this process, with calcium carbonate, the carbonate decomposes within the molten metal and forms CaO solids and the reactive gas CO2. Under conditions of aggressive agitation, the gas bubbles formed within the molten metal are ruptured and fragmented, exposing more of the reactive gas to the molten metal. This gas reacts vigorously with the molten aluminum forming CO gas and in-situ formed A1203. The CO and CO2 gas bubbles, as well as A1203, CaO and other metallic oxide phases, stabilize the liquid metal suspension by modifying the viscosity and surface energy of the molten metal. The term "vigorous" denotes the exothermic nature of the reaction and the production of flammable gas.
Calcium carbonate is particularly effective as a reactive gas producing particle and/or as a foaming agent. In this process, with calcium carbonate, the carbonate decomposes within the molten metal and forms CaO solids and the reactive gas CO2. Under conditions of aggressive agitation, the gas bubbles formed within the molten metal are ruptured and fragmented, exposing more of the reactive gas to the molten metal. This gas reacts vigorously with the molten aluminum forming CO gas and in-situ formed A1203. The CO and CO2 gas bubbles, as well as A1203, CaO and other metallic oxide phases, stabilize the liquid metal suspension by modifying the viscosity and surface energy of the molten metal. The term "vigorous" denotes the exothermic nature of the reaction and the production of flammable gas.
[0017] In aluminum alloy melts, other metal oxides may also be formed as by-products of the decomposition of the reactive gas. For example, in Al-Mg alloys, the reactive gas CO2 decomposes to form CO and the metal oxide MgO along with A12O3 and various mixed metal oxides. Other traditional aluminum alloying elements form similar finely dispersed metal oxides within the agitated melt. Similar to A1203 and CaO, MgO is an example of a metal oxide phase, which when incorporated into the molten metal along with the small gas bubbles, modifies the viscosity and surface energy of the molten metal to create a foamable liquid metal suspension. The term "foamable" is defined as having the capability of stabilizing a liquid foam so that it resists coalescence and drainage. Coalescence is the disappearance of the boundary between two gas bubbles in contact, resulting in a coarsening of the liquid foam structure. Drainage is an increased density gradient within the liquid foam due to gravitational forces, resulting in a loss of structural uniformity in the liquid foam.
[0018] The generation of fine gas bubbles and mixed metal oxide phases from the decomposition of the reactive gas producing particles is very rapid, and is complete within 2 to 8 minutes under optimum conditions. Alloy composition, particle size distribution, temperature and degree of agitation all impact the decomposition kinetics.
Surprisingly, the decomposition rate of the reactive gas producing particles is greatly accelerated by the presence of sufficient amounts of magnesium within the aluminum melt. The addition of 0.5 wt. % to 8 wt. % Mg significantly reduces the time required to decompose the reactive gas producing particles in the agitated melt. This magnesium addition has been shown to not only more the double the decomposition rate of the reactive gas producing carbonate, affording higher processing speeds, but to significantly impact the structure of the foam products produced by changing the cell size, drainage rate and wall thickness.
Surprisingly, the decomposition rate of the reactive gas producing particles is greatly accelerated by the presence of sufficient amounts of magnesium within the aluminum melt. The addition of 0.5 wt. % to 8 wt. % Mg significantly reduces the time required to decompose the reactive gas producing particles in the agitated melt. This magnesium addition has been shown to not only more the double the decomposition rate of the reactive gas producing carbonate, affording higher processing speeds, but to significantly impact the structure of the foam products produced by changing the cell size, drainage rate and wall thickness.
[0019] In one embodiment of the present invention, the reactive gases produced by the decomposition of the reactive gas producing particles, along with the gaseous products of their decomposition, are used to create the bubbles within the liquid foam. More specifically, in this embodiment of the present invention the agitation of the molten metal alloy is purposefully ceased after a portion of the reactive gas producing particles decomposes to leave an unreacted portion of the reactive gas producing particles within the molten metal alloy.
Thereafter, the unreacted portion of the reactive gas producing particles functions as a foaming agent to create the liquid metal foam, wherein the dispersion of fine gas bubbles, along with the metal oxide phases produced by the vigorous combination of the reactive gas and the molten metal alloy, stabilize the foam. In one embodiment, a single addition of calcium carbonate into the molten metal alloy in an amount ranging from about 2.0 wt %
to about 16.0 wt %, is sufficient to provide both the dispersion of fine gas bubbles and metal oxide phases required to produce a foamable suspension as well as the chemical foaming agent required to inoculate this suspension to yield an inoculated foamable suspension. In one embodiment of the present invention, the above described method may further include the steps of solidifying the inoculated foamable suspension and then remelting the inoculated foamable suspension prior to foaming.
Thereafter, the unreacted portion of the reactive gas producing particles functions as a foaming agent to create the liquid metal foam, wherein the dispersion of fine gas bubbles, along with the metal oxide phases produced by the vigorous combination of the reactive gas and the molten metal alloy, stabilize the foam. In one embodiment, a single addition of calcium carbonate into the molten metal alloy in an amount ranging from about 2.0 wt %
to about 16.0 wt %, is sufficient to provide both the dispersion of fine gas bubbles and metal oxide phases required to produce a foamable suspension as well as the chemical foaming agent required to inoculate this suspension to yield an inoculated foamable suspension. In one embodiment of the present invention, the above described method may further include the steps of solidifying the inoculated foamable suspension and then remelting the inoculated foamable suspension prior to foaming.
[0020] In another aspect of the present invention an apparatus is provided for practicing the above-described method. In its simplest implementation, the inventive apparatus requires only one vessel chamber for batch or continuous production of an inoculated foamable suspension that functions as a foamable charge. In broad terms, the inventive apparatus for forming foamed aluminum product comprises:
a feeding system for providing reactive gas producing particles and molten inetal alloy, wherein the molten metal alloy is provided at a preselected flow rate;
a reactor unit in communication witli the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into an inoculated foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit suitable for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the preselected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit; and a tip in communication with the reactor unit.
a feeding system for providing reactive gas producing particles and molten inetal alloy, wherein the molten metal alloy is provided at a preselected flow rate;
a reactor unit in communication witli the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into an inoculated foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit suitable for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the preselected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit; and a tip in communication with the reactor unit.
[0021] The transit time of the molten metal alloy containing the gas producing particles through the mixing unit is selected to provide an inoculated foamable suspension upon exiting the reactor unit. The transit time may be modified by adjusting the flow rate into the reactor unit and the effective volume of the mixing unit in view of the reactive gas producing particles. More specifically, the reactive gas producing particles composition, decomposition temperature, and particle size must all be considered in adjusting the reactor unit. Finally, the degree of agitation provided by the stirrer must also be considered. In one embodiment, a transport system, such as a pump or a passage, is configured to transfer the inoculated foamable suspension from the reactor unit to the tip. In one embodiment, a positive displacement pump, such as a rotary gear pump or a rotary lobe pump, delivers the inoculated foamable suspension from the reactor unit to the tip. In one embodiment, the tip is heated to a temperature above that of the incoming inoculated foamable suspension so as to increase the rate of decomposition of the foaming agent. Preferably, the tip may be electrically or gas fire heated to a temperature ranging from 670 C to 740 C.
[0022] In another embodiment of the invention, the decomposition of the reactive gas producing particles is allowed to proceed under agitation to completion. In this case, the chemical foaming agent is provided through a separate addition of a chemical foaming agent, which may or may not be chemically identical to the reactive gas producing particles.
Broadly, the present invention provides method of forming aluminum foam comprises:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350 C to about 850 C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of fine gas bubbles and metallic oxide phases;
dispersing chemical foaming agents into the foamable suspension to produce an inoculated foamable melt;
foaming the inoculated foamable suspension to produce a liquid metal foam; and solidifying the liquid metal foam to create a foamed aluminum product.
Broadly, the present invention provides method of forming aluminum foam comprises:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350 C to about 850 C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of fine gas bubbles and metallic oxide phases;
dispersing chemical foaming agents into the foamable suspension to produce an inoculated foamable melt;
foaming the inoculated foamable suspension to produce a liquid metal foam; and solidifying the liquid metal foam to create a foamed aluminum product.
[0023] In this embodiment of the present invention, the addition of calcium carbonate into the molten metal alloy in an amount ranging from about 0.5 wt. % to about 4.0 wt. % is sufficient to provide a sufficient suspension of fine gas bubbles and metal oxide phases to stabilize a liquid metal foam. This suspension of fine gas bubbles and metal oxides results in a volumetric expansion of the melt, wherein the initial volumetric expansion, following agitation, is within the range of 5% to 50%. In another embodiment, calcium carbonate may dispersed into the foamable suspension as a foaming agent in a weight percent ranging from about 0.5 wt. % to about 4.0 wt. % to produce an inoculated foamable suspension. In one embodiment of the present invention, the above described method may further include the steps of solidifying the inoculated foamable melt and then remelting the inoculated foamable melt prior to foaming.
[0024] In another aspect of the present invention, an apparatus is provided for practicing the above-described method, in which a chemical foaming agent is separately dispersed into the foamable suspension after the foamable suspension has been produced. In its simplest implementation, the apparatus requires at least two stages, in which a first stage introduces the reactive gas producing particles into the molten alloy and a second stage disperses the chemical foaming agent. The first stage may be similar in structure to above-described reactor unit in which the foaming agent is provided by the unreacted portion of the reactive gas producing particles. The second stage for dispersing the chemical foaming agent and is in communication with the first stage. Broadly, the apparatus for making foamed aluminum comprises:
a feeding system for providing reactive gas producing particles and molten metal alloy, wherein the molten metal alloy is provided at a pre-selected flow rate;
a reactor unit in communication with the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into a foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit suitable for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the pre-selected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit;
a dispersion unit in communication with the reactor unit comprising:
a foaming agent mixing chamber for receiving the foamable suspension;
a feeding system positioned to provide chemical foaming agent into the foamable suspension within the foaming agent mixing chamber;
a stirrer positioned in the foaming agent mixing chamber to disperse the chemical foaming agent to produce an inoculated foamable suspension; and a transport system to transfer the inoculated foamable suspension from the dispersion unit to a tip.
a feeding system for providing reactive gas producing particles and molten metal alloy, wherein the molten metal alloy is provided at a pre-selected flow rate;
a reactor unit in communication with the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into a foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit suitable for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the pre-selected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit;
a dispersion unit in communication with the reactor unit comprising:
a foaming agent mixing chamber for receiving the foamable suspension;
a feeding system positioned to provide chemical foaming agent into the foamable suspension within the foaming agent mixing chamber;
a stirrer positioned in the foaming agent mixing chamber to disperse the chemical foaming agent to produce an inoculated foamable suspension; and a transport system to transfer the inoculated foamable suspension from the dispersion unit to a tip.
[0025] In one embodiment, the transport system may include a positive displacement pump, such as a rotary gear pump or rotary lobe pump. Alternatively, the transport system may be a passage configured to transfer the inoculated foamable suspension from the reactor unit to the tip.
[0026] In another aspect of the present invention, a method of making a foamable liquid+gas+solid suspension is provided. Broadly, the method includes the steps of:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350 C to about 850 C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of gas bubbles and metallic oxide phases within the molten aluminum.
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350 C to about 850 C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of gas bubbles and metallic oxide phases within the molten aluminum.
[0027] It is further noted, the reactive gas producing particles used to create the reactive gas produce an even distribution of fine gas bubbles and mixed metal oxides far superior to that which could be formed by either bubbling gasses directly into the melt or through other coarse methods such as vortexing. The distribution of fine gas bubbles and mixed metal oxides formed by the decomposition of the reactive gas producing particles also appear to be more effective than conventional methods that introduce stabilizing particles into aluminum melts by extrinsic addition. The creation of such a liquid+gas+solid suspension in the invented method is greatly superior to the incumbent method which relies solely on a liquid+solid suspension. As the foamable suspension is stabilized by a fine distribution of gas bubbles as well as metallic oxides, and the volumetric expansion due to reactive gas forming particles is many times greater than the volume of the particles themselves.
The invention allows for melt stabilization at substantially lower volume fractions of solid than heretofore have been required in extrinsically stabilized metallic foams. In one embodiment, the foamable suspension undergoes a volumetric expansion of between about 5% and 50%
following agitation.
The invention allows for melt stabilization at substantially lower volume fractions of solid than heretofore have been required in extrinsically stabilized metallic foams. In one embodiment, the foamable suspension undergoes a volumetric expansion of between about 5% and 50%
following agitation.
[0028] As described inLT.S. Patent No. 5,112,697 to Jin et al. ("Jin et al."), the prior art teaches that a minimum effective volume fraction of stabilizing particles of 5% is required when usiiig the finest particulate, with much emphasis placed on the difficulty of dispersing such fine particles within the molten metal. In the present invention, surprisingly and unexpectedly, reactive gas producing particles have been shown to be effective at far lower volume fractions, as low as 0.5%, less than 1/10t' of that previously thought to be required for when using stable, extrinsically added stabilizing particles.
[0029] While the minimum level of carbonate is at or near 0.5 wt. % to effectively create an aluminum melt capable of sustaining a foam in a reasonable time period, higher weight fractions of carbonate result in even more rapid attainment of the required melt stability. Low density aluminum foams have been produced with carbonate levels up to 16 wt.
%. Such high levels of viscosity enhancing carbonate significantly reduce the time required to reach effective stability levels.
%. Such high levels of viscosity enhancing carbonate significantly reduce the time required to reach effective stability levels.
[0030] In another aspect of the present invention, a foamed aluminum product is provided. In one embodiment, the foamed aluminum product includes an aluminum alloy matrix including magnesium in a percentage ranging from about 0.5% to 8% by weight percent and a distribution of fine metallic oxides in a percentage ranging from 0.5% to about 16% by weight percent; wherein the average size of the fine metal oxides is less than 1.0 micron; and a distribution of pores within said aluminum alloy matrix including a majority of closed pores with an average diameter ranging from about 200 microns to about 1500 microns;
wherein said distribution of pores within said aluminum alloy matrix provides a product density between 0.30 g/cm3 and 0.70 g/cm3.
wherein said distribution of pores within said aluminum alloy matrix provides a product density between 0.30 g/cm3 and 0.70 g/cm3.
[0031] The metallic oxides may include aluminum oxide, magnesium oxide and calcium oxide and mixed oxides of the same. Further, the above aluminum foam may be substantially free of stable ceramic particles greater than 5 microns. The aluminum alloy matrix may have a mean wall thickness ranging from about 5 microns to about 100 microns and the distribution of pores within the aluminum alloy matrix constituting between 70% and 90% of the aluminum foam material by volume.
[0032] The foamed aluminum products made by the process of this invention exhibit improved properties such as low density and high rigidity, decreased thermal conductivity, and good tensile strength, iinpact resistance, energy absorption and sound deadening properties.
[0033] The foamed aluminum products may be used in various applications sucll as high performance lightweight automotive technology, thin sheet materials, architectural construction materials, buoyatit applications, and any field where effective utilization of energy absorption, high specific stiffness, and low density are required.
[0034] In another embodiment of the present invention, an aluminum foam material is provided including an aluminum alloy matrix comprising an effective amount of magnesium;
a distribution of fine metallic carbonates; a distribution of pores within said aluminum alloy;
and substantially free of stable ceramic particles greater than 5 microns in size. The average pore diameter may be less than about 1000 microns.
a distribution of fine metallic carbonates; a distribution of pores within said aluminum alloy;
and substantially free of stable ceramic particles greater than 5 microns in size. The average pore diameter may be less than about 1000 microns.
[0035] For the purposes of this disclosure, the term "effective amount of magnesium"
is the magnesium concentration suitable to provide a stable metal foam. The fine metallic carbonates may include calcium carbonate, magnesium carbonate or combinations thereof.
is the magnesium concentration suitable to provide a stable metal foam. The fine metallic carbonates may include calcium carbonate, magnesium carbonate or combinations thereof.
[0036] In one embodiment, the fine metallic carbonates have a diameter or less than 100 microns. In one embodiment, the term stable ceramic particles denotes ceramic species that are largely inert and unreactive to molten aluminum at teinperatures less than 750 C.
Brief Description of the Drawings [0037] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
Brief Description of the Drawings [0037] A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
[0038] Figure 1 is a graph of the weight % change as temperature is monotonically increased over time for calcium carbonate (CaCO3), the most preferred additive of this invention, showing a decomposition temperature at ambient pressure in air of about 600 C to 650 C.
[0039] Figure 2 is a graph of the weight percent change as temperature is monotonically increased over time for dolomite (CaMg(C03)2), a preferred additive of this invention, showing a decomposition temperature at ambient in air of about 600 C to 700 C.
[0040] Figure 3 is a graph of the weight % change as temperature is monotonically increased over time for magnesium carbonate (MgCO3), showing a decomposition temperature at ambient in air of about 350 C to 450 C.
[0041] Figure 4 is a graph of the weight percent change as temperature is monotonically increased over time for hydrotalcite (Mg~A12(OH)12CO3H20), showing a decomposition temperature at ambient in air of about 175 C to 200 C.
[0042] Figure 5 illustrates the chemical reactions in the evolution of the reactions for vigorous decomposition of calcium carbonate in a molten metal comprising aluminum and magnesium and the formation of metallic oxides and gas products.
[0043] Figure 6 is a pictorial representation showing the evolution of the reactions for decomposition of calcium carbonate in a molten metal comprising aluminum and magnesium and the formation of metallic oxides.
[0044] Figure 7 (cross-sectional view) depicts an apparatus for producing aluminum foam, in which a viscosity agent and foaming agent are provided by the single addition of reactive gas producing particles.
[0045] Figure 8(cross-sectional view) depicts a chemical foaming agent dispersion apparatus compatible with the apparatus depicted in Figure 7.
[0046] Figure 9a (exploded view) depicts a positive displacement lobe pump.
[0047] Figure 9b (perspective view) depicts the positive displacement lobe pump depicted in Figure 9a.
[0048] Figure 9c (cross-sectional side view) depicts a positive displacement gear pump.
[0049] Figure 10 depicts a chart illustrating the effects of reactive gas producing particles on the stability of aluminum alloy foams.
[0050] Figure 11 depicts a chart illustrating the effects of calcium carbonate particle size on the structure of aluminum alloy foams.
[0051] Figure 12 depicts a chart illustrating the effects of magnesium addition to molten metal alloys for producing aluminum foams.
[0052] Figure 13 depicts a chart illustrating the effects of mixing time on a single addition of reactive gas producing particles for a stabilizing additive and as a foaming agent.
[0053] Figure 14 depicts a chart illustrating the effects of increasing wt. %
of reactive gas producing particles with a single addition of reactive gas producing particles for a stabilizing additive and as a foaming agent.
Detailed Description of the Invention [0054] The present invention provides an aluminum foam and a method for producing a foamed aluminum product, in which the method incorporates reactive gas producing particles having a decoinposition temperature ranging from about 350 C to about 850 C into a molten metal alloy, wherein at least a portion of the reactive gas producing particles decomposes to provide a foamable suspension of metal oxide phases and gas bubbles with minimal changes in pressure and teinperature to the molten metal alloy. The present invention also provides an apparatus for practicing the method of the present invention comprising a reactor unit having a flow rate and volume configured to provide a sufficient transit time to decompose at least a portion of reactive gas producing particles in producing a foamable suspension, the inoculation of the foamable suspension with foaming agents, the transfer of the inoculated foamable suspension to a mold, the foaming of the inoculated foamable suspension to produce a liquid metal foam and the solidification of the liquid metal foam to produce a foam metal product. The present invention is now discussed in more detail referring to the drawings that accompany the present application. In the accoinpanying drawings, like and/or corresponding elements are referred to by like reference numbers.
of reactive gas producing particles with a single addition of reactive gas producing particles for a stabilizing additive and as a foaming agent.
Detailed Description of the Invention [0054] The present invention provides an aluminum foam and a method for producing a foamed aluminum product, in which the method incorporates reactive gas producing particles having a decoinposition temperature ranging from about 350 C to about 850 C into a molten metal alloy, wherein at least a portion of the reactive gas producing particles decomposes to provide a foamable suspension of metal oxide phases and gas bubbles with minimal changes in pressure and teinperature to the molten metal alloy. The present invention also provides an apparatus for practicing the method of the present invention comprising a reactor unit having a flow rate and volume configured to provide a sufficient transit time to decompose at least a portion of reactive gas producing particles in producing a foamable suspension, the inoculation of the foamable suspension with foaming agents, the transfer of the inoculated foamable suspension to a mold, the foaming of the inoculated foamable suspension to produce a liquid metal foam and the solidification of the liquid metal foam to produce a foam metal product. The present invention is now discussed in more detail referring to the drawings that accompany the present application. In the accoinpanying drawings, like and/or corresponding elements are referred to by like reference numbers.
[0055] Figures 1-4 show TGA (Thermal Gravometric Analysis) graphs for a variety of materials to illustrate the range of decomposition of the reactive gas producing particles in terms of mass loss (wt % loss) over time as the sample decomposes under specific process conditions (temperature history, particle size, ambient environment, etc.) controlling the decomposition initiation and kinetics (rate). In Figures 1-4, the decomposition curve 10 is shown along with the preferred decomposition range 14 and the thermally stable range 12.
[0056] The readtive gas producing particles found to be practical and useful in foamed aluminum production are carbonates, which are both effective and inexpensive, having a decomposition temperature as illustrated in the TGA (Thermal Gravometric Analysis) graphs plotted in Figures 1, 2 and 3. More specifically, the reactive gas producing particles are preferably carbonates having a decomposition temperature ranging from about 350 C to about 850 C, even more preferably having a decomposition temperature ranging from about 550 C
to 850 C.
to 850 C.
[0057] The preferred carbonates are calcium carbonate (CaCO3) and/or dolomite (CaMg(C03)2), wherein Figure 1 illustrates the decomposition range for calcium carbonate and Figure 2 illustrates the decomposition range for dolomite. These reactive gas producing particles undergo decomposition to form metallic oxide phases and carbon dioxide at .
temperatures which do not require that the temperature or pressure of the molten aluminum alloy be elevated to temperatures or pressures that are inconsistent with conventional aluminum processing. In one preferred embodiment, calcium carbonate has an average diameter of less than about 40 microns.
temperatures which do not require that the temperature or pressure of the molten aluminum alloy be elevated to temperatures or pressures that are inconsistent with conventional aluminum processing. In one preferred embodiment, calcium carbonate has an average diameter of less than about 40 microns.
[0058] Pure aluminum melts at approximately 660 C. Coinmercial aluminum alloys typically melt at lower temperatures than pure aluminum. More specifically, commercial aluminum alloys melt at temperatures ranging from approximately 560 C to approximately 650 C, wherein the melting temperature of commercial aluminum alloy may vary depending on elemental additions within the alloy. The molten metal alloy utilized in the present invention can be, for example, at least one of commercial grade/purity molten aluminum, scrap aluminum, or aluminum containing Si and/or Mg, or the like.
[0059] Calcium carbonate begins to decompose at temperatures greater than 550 C, as depicted in Figure 1, and dolomite decomposes at a slightly higher temperature than calcium carbonate, in which the decomposition temperature of dolomite begins at a temperature on the order of approximately 575 C. These compounds when utilized as the reactive gas producing particles, botll having decomposition temperatures ranging from about 550 C to about 650 C, demonstrate vigorous but not excessively energetic decomposition, allowing for adequate dispersion of the aluminum oxide phases produced by the interaction of the reactive gas producing particles and the molten alloy melt before the reactive gas producing particles exhaust their gassing ability.
[0060] The decomposition of calcium carbonate within the molten metal alloy is best described with reference to Figures 5 and 6. The decomposition of calcium carbonate within a molten metal alloy comprising aluminum and magnesium includes the following reactions:
CaCO3 ~ CaO+CO2 (1) C02+Al A1203+CO (2) CaO+AI ~ AlCaOX (3) C02+Mg -~ MgO+CO (4) [0061] Figure 5 depicts the decomposition reactions of calcium carbonate in molten metal alloy and the interaction of decomposition products with the aluminum and magnesium that is present in the molten metal alloy to produce a fine dispersion of gas products (also referred to as gas bubbles) and stabilizing products. The fine dispersion of gas products is provided by a reactive gas that vigorously combines with the aluminum and magnesium of the molten metal alloy to produce alumiiium oxide phases, such as alumina (A1203) and magnesium oxide (MgO), in which the fine dispersion of gas bubbles in conjunction with the aluminum oxide phases are stabilizing products that contribute to forming a foamable suspension. Without wishing to be bound, but in the interest of further describing certain aspects of the present invention, it is believed that the self stabilizing nature of the molten metal alloy is primarily provided by the generation of the fine dispersion of gas products.
CaCO3 ~ CaO+CO2 (1) C02+Al A1203+CO (2) CaO+AI ~ AlCaOX (3) C02+Mg -~ MgO+CO (4) [0061] Figure 5 depicts the decomposition reactions of calcium carbonate in molten metal alloy and the interaction of decomposition products with the aluminum and magnesium that is present in the molten metal alloy to produce a fine dispersion of gas products (also referred to as gas bubbles) and stabilizing products. The fine dispersion of gas products is provided by a reactive gas that vigorously combines with the aluminum and magnesium of the molten metal alloy to produce alumiiium oxide phases, such as alumina (A1203) and magnesium oxide (MgO), in which the fine dispersion of gas bubbles in conjunction with the aluminum oxide phases are stabilizing products that contribute to forming a foamable suspension. Without wishing to be bound, but in the interest of further describing certain aspects of the present invention, it is believed that the self stabilizing nature of the molten metal alloy is primarily provided by the generation of the fine dispersion of gas products.
[0062] Figure 6 is a pictorial representation of decomposition of the reactive gas producing product within the molten metal alloy to produce the fine dispersion of gas bubbles 15 and the metallic oxide phases 20. Without limiting the invention, but in the interest of further describing some aspects of the present invention, it is believed that based on the rate of coiiapse ot the tbamable suspension, the bulk viscosity of aluminum, buoyancy forces and Stoke's law that the average diameter of the gas bubbles is on the order of less than 100 microns. It is noted that although magnesium is included in the above example, the present invention may be practiced without the incorporation of magnesium within the molten metal alloy. It is further noted, that in a preferred embodiment magnesium advantageously provides stabilization when supplied in an effective amount. In one embodiment, the term effective amount of magnesium denotes that the magnesium content is sufficient to provide a stable foam. In one embodiment, an effective amount of magnesium is greater than 0.5 wt. %, preferable ranging from about 0.5 wt. % to about 8.0 wt. %, preferably ranging from about 1 wt. % to about 2 wt. %. Additionally, the molten metal alloy can be, for example, at least one of commercial grade/purity molten aluminum, scrap aluminum, or aluminum containing Si and/or Mg, or the like.
[0063] The decoinposition reactions in which dolomite are included into the molten metal alloy as the reactive gas producing particles comprise:
2CaMg(CO3)2 - CaCO3+CaO+2MgO+3CO2 3 CO2+Al --~ A1203+3 CO
CaO+Al --> AlCaOX
C02+Mg --~ MgO+CO
2CaMg(CO3)2 - CaCO3+CaO+2MgO+3CO2 3 CO2+Al --~ A1203+3 CO
CaO+Al --> AlCaOX
C02+Mg --~ MgO+CO
[0064] Although calcium carbonate and dolomite are highly preferred embodiments of the present invention, other carbonates have been contemplated and are therefore within the scope of the present invention.
[0065] For example, referring to Figure 3 depicting a TGA plot for magnesium carbonate (MgCO3), magnesium carbonate has been considered for application as a reactive gas producing particle. As a result of the low decomposition temperature for magnesium carbonate, magnesium carbonate is more difficult to disperse prior to the onset of decomposition than calcium carbonate and dolomite, and while magnesium carbonate is useful, it is not preferred alone.
[0066] Referring now to Figure 4, depicting a TGA plot for hydrotalcite (Mg4Al2(OH)12CO3H2O) having a decomposition temperature at ambient in air of about 175 C
to 200 C, hydrotalcite is insufficient as a reactive gas producing particle as resulting in premature decomposition when incorporated into a molten metal alloy comprising aluminum.
to 200 C, hydrotalcite is insufficient as a reactive gas producing particle as resulting in premature decomposition when incorporated into a molten metal alloy comprising aluminum.
[0067] The selection of carbonates with higher decomposition temperatures than CaCO3 and dolomite, while inappropriate for the production of aluminum foams, may be ideally suited for metals with higher melting teinperatures, such as copper, titanium, steel or brass. Similarly, the carbonates with substantially lower decomposition temperatures than those selected for aluminum may be ideally suited for low inelting metallic systems, such as lead, tin and magnesium alloys.
[0068] Table 1 shows carbonate thermodynamic equilibrium temperatures of carbonates abundant in nature at approximately 0.01 atmosphere of partial pressure of CO2 (which is approximately the partial pressure of CO2 in the ambient atmosphere). This is a thermodynamic equilibrium summary, not a kinetic summary, but it helps to show the relative decomposition order of the carbonates and provides an estimate of decomposition temperatures in the molten metal. These suggest examples of carbonates that would be ineffective for use in aluminum as their decomposition temperatures lie outside of the 350 C
to 850 C range.
TABLE 1 - Thermodynamic Equilibrium Temperatures for Assorted Carbonates at 0.01atm Partial Pressure CO2 Carbonate C
NaHCO3 52 ZnCO3 61 Ag2CO3 122 CdCO3 231 MnCO3 249 MgCO3 283 CaCO3 656 SrCO3 865 Li2CO3 1016 Ba2CO3 1088 [0069] Thus, using Table 1 only to screen out likely ineffective carbonates, it's evident that carbonates of Na, Zn, Ag, Cd and Mn would have too low a decomposition temperature for commercial manufacture of aluminum foam because they would be far too rapid in their decomposition to allow for adequate dispersion. Alternately, Sr, Li and Ba carbonates would have too high a decomposition temperature and would not decompose or would decompose at a very slow rate not appropriate for a viable commercial process. Note that at these partial pressures, the equilibrium temperature of CaCO3 and MgCO3 are not that different from their respective TGA decomposition temperatures.
to 850 C range.
TABLE 1 - Thermodynamic Equilibrium Temperatures for Assorted Carbonates at 0.01atm Partial Pressure CO2 Carbonate C
NaHCO3 52 ZnCO3 61 Ag2CO3 122 CdCO3 231 MnCO3 249 MgCO3 283 CaCO3 656 SrCO3 865 Li2CO3 1016 Ba2CO3 1088 [0069] Thus, using Table 1 only to screen out likely ineffective carbonates, it's evident that carbonates of Na, Zn, Ag, Cd and Mn would have too low a decomposition temperature for commercial manufacture of aluminum foam because they would be far too rapid in their decomposition to allow for adequate dispersion. Alternately, Sr, Li and Ba carbonates would have too high a decomposition temperature and would not decompose or would decompose at a very slow rate not appropriate for a viable commercial process. Note that at these partial pressures, the equilibrium temperature of CaCO3 and MgCO3 are not that different from their respective TGA decomposition temperatures.
[0070] Turning back to the embodiments of the present invention in which calcium carbonate is selected for the reactive gas producing particles, when added to prepare the molten aluminum for viscosity enhancement, the calcium carbonate particle size can be from about 0.5 micrometer to 40 micrometer. The amount added is in the range of from 0.5 wt. %
to 16 wt. % of the total aluminum melt mass and preferably 0.5 wt. % to 2 wt.
%. It has been determined that small volume fractions of calcium carbonate are highly effective to control melt viscosity and/or surface energy to maintain a stable foam.
to 16 wt. % of the total aluminum melt mass and preferably 0.5 wt. % to 2 wt.
%. It has been determined that small volume fractions of calcium carbonate are highly effective to control melt viscosity and/or surface energy to maintain a stable foam.
[0071] Alternatively, the calcium carbonate particle sizes can be as large as micrometer to 150 micrometer. At this size the reaction rates are markedly slower, and there will be incomplete decomposition of the carbonate after 10 minutes.
Nevertheless, a sufficient fine dispersion of gas bubbles will be generated to stabilize the aluminum melt. The residual unreacted carbonate can then be used as a foaming agent in the melt. Thus, depending on the product and process requirements, carbonate can be added in multiple steps, with multiple particle size distributions to achieve various levels of viscosity enhancement and various levels of foaming.
Nevertheless, a sufficient fine dispersion of gas bubbles will be generated to stabilize the aluminum melt. The residual unreacted carbonate can then be used as a foaming agent in the melt. Thus, depending on the product and process requirements, carbonate can be added in multiple steps, with multiple particle size distributions to achieve various levels of viscosity enhancement and various levels of foaming.
[0072] If added to both stabilize and foam the melt in a single addition, then the particle sizes can be from about 0.5 micrometer to 150 micrometer. The optimal mixture of particle sizes is dependent on the desired mixing time as smaller particles decompose first and are more effective at increasing the viscosity leaving the larger particles to provide the gas for the final foaming.
[0073] Foaming agents must be selected to have good stability at low temperatures and decompose to produce foaming gas at temperatures at or above the melting point of the metal alloy. The size of the foaming agents introduced into the molten metal or alloy can be selected based on the desired rate of foam geiieration and on the structure of the foam desired. In casting foamed aluminum, the size and composition of the foaming agents introduced into the melt affects the size and number density of the bubbles produced. By controlling the size of the bubbles produced in a foamed aluminum mass, the net density can be targeted so that properties such as thermal conductivity, strength or crush energy absorption can be controlled.
[0074] Examples of suitable practical chemical foaming agents for use in aluminum foain production include magnesium carbonate, calcium carbonate, dolomite, and metal hydrides such as titanium hydride and zirconium hydride, and mixtures thereof.
The foaming agents may have any desired morphology. They can be added in one or more stages in the process. In one embodiment, the foaming agents have particle sizes between about 0.5 micrometer to about 40 micrometer. In another embodiment, the foaming agents have an average size of from about 40 micrometers to about 150 micrometer.
The foaming agents may have any desired morphology. They can be added in one or more stages in the process. In one embodiment, the foaming agents have particle sizes between about 0.5 micrometer to about 40 micrometer. In another embodiment, the foaming agents have an average size of from about 40 micrometers to about 150 micrometer.
[0075] Referring now to FIG. 7, in another aspect of the present invention an apparatus 25 is provided that produces a foamed aluminum product using the above-described reactive gas producing particles. The apparatus includes a means for introducing a molten metal alloy 28 and a feed system 35 for introducing reactive gas producing particles 33 into a reactor unit v, wnerein tne reactive gas producing particles 33 vigorously decomposes within the molten metal alloy 31 to provide a foamable suspension. The means for introducing the molten metal alloy 28 provides the molten metal alloy 31 at a pre-selected flow rate.
[0076] The reactor unit 30 comprises a mixing unit with a stirrer 32 contained, wherein the mixing unit is housed by a furnace 34. The mixing unit and the stirrer 32 combine reactive gas producing particles 33 with the molten metal alloy 31 to increase the viscosity/modify the surface energy of the alumitlum melt. The dimensions and the geometry of the mixing unit and the stirrer 32 are selected to provide an effective volume that when utilized in conjunction with the pre-selected flow rate provides a transit time of the molten metal alloy containing the reactive gas producing particles sufficient to provide that at least a portion of the reactive gas producing particles decompose within the mixing unit to" provide a foamable suspension. Further, the agitation provided by the stirrer, the composition and/or particle size of the reactive gas producing particles, and the composition of the molten metal alloy may be configured to modify the transit time.
[0077] The reactor unit 30 may further comprise at least one vent for releasing the unreacted portions of the gaseous product of the decomposition of the reactive gas producing particles, as well as the gaseous products of the reaction itself. In the preferred case in which the reactive gas producing particle is calcium carbonate, the unreacted portion of the CO2 gas may be vented along with the CO reaction product produced through the reaction of CO2 with the aluminum alloy melt. As CO is a flammable gas, this by-product can be safely flamed off at the surface of the reactor unit 30.
[0078] In one embodiment of the present invention, the transit time and mixing unit geometry is selected to decompose only a portion of the reactive gas producing particles 33 leaving a remaining portion of the reactive gas producing particles uiireacted. In this embodiment of the present invention, the unreacted portions of the reactive gas producing particles function as a foaming agent in a foamable suspension 47.
[0079] In another embodiment of the present invention, the transit tiine and the mixing unit geometry are selected to fully decompose the reactive gas producing particles 33. As shown in Figure 8, the viscosity enhanced alloy melt may then flow into the foaming agent dispersion unit 42 with stirrers 44, where the foaming agents 46 would be added to produce an inoculated foamable molten aluminum feedstock 48. Although not depicted in the supplied figures, in another embodiment of the present invention the inoculated foamable molten aluminum feedstock may be passed to optional caster-type device to form ingots which could later be remelted in a furnace prior to the addition of the foaming agent.
Another gas vent 37 can optionally exhaust excess gas from the foaming agent dispersion unit 42.
Another gas vent 37 can optionally exhaust excess gas from the foaming agent dispersion unit 42.
[0080] The inoculated foamable molten aluminum feedstock 48 can then be passed to a foaming unit to form continuous products (plates, sheets, bars, extrusions, etc.) or to be processed, for example, by a continuous belt caster, roll caster, vertical caster or the like (not shown) to provide liquid foamed/cellular sheet which upon cooling can be used itself or laminated to other materials.
[0081] Referring to Figures 9a-9c, another aspect of the apparatus 25 is a rotary positive displacement pump that provides for the transfer of aluminum from the reactor unit or dispersion unit to the tip. Prior molten metal pumps typically rely on centrifugal or reciprocating designs and require tight tolerances to reduce metal leakage.
Contrary to prior molten metal applications, the increased sessile viscosity (approximately 700 cp) of the aluminum melt due to the inoculation and initiation of foaming allows for the application of positive displacement pump designs. In one embodiment, the pump may be a lobe pump, as depicted in Figures 9a and 9b, or a gear pump, as depicted in Figure 9c, which allows for accurate metering of the foamable melt onto the belt or into the tip.
Contrary to prior molten metal applications, the increased sessile viscosity (approximately 700 cp) of the aluminum melt due to the inoculation and initiation of foaming allows for the application of positive displacement pump designs. In one embodiment, the pump may be a lobe pump, as depicted in Figures 9a and 9b, or a gear pump, as depicted in Figure 9c, which allows for accurate metering of the foamable melt onto the belt or into the tip.
[0082] Referring to Figures 9a and 9b, in a preferred embodiment, a lobe pump in which the lobes 50, as well as the pump housing 51 are formed of a high teinperature material.
In one embodiment, the pump housing 51 includes an entry surface 52, and exit surface 32, a first sidewall 54, second sidewall 55, and an intermediate pump surface 56.
The intermediate pump surface 56 has a geometry corresponding with the lobes 50 to provide a pump chamber.
The first sidewall, the intermediate pump surface, and the second sidewall and connected through a plurality of studs and bolts, in which the bolts are designed to accommodate thermal expansion resulting from aluminum foam processing temperatures. The lobes 50 have a geometry that provides a pumping action when rotated within the pump chamber.
In a preferred embodiment, the pump housing 51 and lobes 50 are formed from a machineable ceramic comprising boron nitride. It is noted that alternative materials have also been contemplated, so long as the material of the pump housing 51 and lobes 50 has a thermal expansion that avoids leakage and that the material can be subjected to temperatures consistent with aluminum foam manufacturing without significant degradation of the materials physical properties.
In one embodiment, the pump housing 51 includes an entry surface 52, and exit surface 32, a first sidewall 54, second sidewall 55, and an intermediate pump surface 56.
The intermediate pump surface 56 has a geometry corresponding with the lobes 50 to provide a pump chamber.
The first sidewall, the intermediate pump surface, and the second sidewall and connected through a plurality of studs and bolts, in which the bolts are designed to accommodate thermal expansion resulting from aluminum foam processing temperatures. The lobes 50 have a geometry that provides a pumping action when rotated within the pump chamber.
In a preferred embodiment, the pump housing 51 and lobes 50 are formed from a machineable ceramic comprising boron nitride. It is noted that alternative materials have also been contemplated, so long as the material of the pump housing 51 and lobes 50 has a thermal expansion that avoids leakage and that the material can be subjected to temperatures consistent with aluminum foam manufacturing without significant degradation of the materials physical properties.
[0083] One aspect of the present invention is the ability of the apparatus to pump an inoculated foamable molten aluminum prior to extensive onset of foaming. In one example, the foamable molten aluminum may be pumped, so long as expansion is no greater than 250%, preferably less than 200%. It is noted that greater and lesser degrees of expansion have been contemplated and are within the scope of the invention, so long as the degree of expansion of the aluminum foam does not deform the structure in a manner that is not repairable.
[0084] In one embodiment, the apparatus 25 may further include a heated mold or tip.
In one embodiment, the tip is heated to a temperature above that of incoming inoculated foamable suspension so as to increase the rate of decomposition of the foaming agent.
Preferably, the tip is heated to a temperature between 670 C and 740 C. In one example, the rate of foaming may be reduced from 6 minutes down to 30 seconds by increasing the temperature of the inoculated foamable aluminum alloy.
In one embodiment, the tip is heated to a temperature above that of incoming inoculated foamable suspension so as to increase the rate of decomposition of the foaming agent.
Preferably, the tip is heated to a temperature between 670 C and 740 C. In one example, the rate of foaming may be reduced from 6 minutes down to 30 seconds by increasing the temperature of the inoculated foamable aluminum alloy.
[0085] In another embodiment, inoculated foamable molten aluminum feedstock 48 could be very quickly passed to the freezing unit before significant foaming occurs to produce a foamable solid precursor for other product applications. Surprisingly, aluminum foams produced from remelted foamable solid precursors result in a coarsening of foam cell sizes.
This process can be used to create metal foams at a larger cell size, which may be appropriate for many final applications.
This process can be used to create metal foams at a larger cell size, which may be appropriate for many final applications.
[0086] The aluminum foam of the present invention may be processed to provide a structural materials for construction, automotive, or aerospace applications.
In some embodiments, the aluminum foam may be processed to provide a flat panel, wherein the flat panel may be applicable for flooring, roofing, and walling utilized in construction.
In some embodiments, the aluminum foam may be processed to provide a flat panel, wherein the flat panel may be applicable for flooring, roofing, and walling utilized in construction.
[0087] Optionally, the inoculated foamable molten aluminum feedstock 48 can be passed to a mold or hollow part where it can be foamed and cooled to form a molded product, or interior or exterior of a part.
[0088] The following examples are provided to further illustrate the present invention and demonstrate some advantages that arise therefrom. It is not intended that the invention be limited to the specific examples disclosed.
Example 1: Effect of Reactive Gas Producing Particles on Stability in Aluminum Alloy Foams [0089] A series of aluminum alloy melts were prepared to determine the effect of calcium carbonate on the stability of the aluminum foam and the propensity for gravitational drainage in the foamed structure. Specimens comprising 100 gm of an aluminum-2 wt. %
magnesium alloy were melted and stirred vigorously for different times while adding various weight fractions of calcium carbonate powders. Following agitation, a separate chemical foaming agent was added and dispersed for 30 seconds. In these tests that chemical foaming agent was calcium carbonate. The various specimens were then foamed and the rise of the aluminum foam monitored.
Example 1: Effect of Reactive Gas Producing Particles on Stability in Aluminum Alloy Foams [0089] A series of aluminum alloy melts were prepared to determine the effect of calcium carbonate on the stability of the aluminum foam and the propensity for gravitational drainage in the foamed structure. Specimens comprising 100 gm of an aluminum-2 wt. %
magnesium alloy were melted and stirred vigorously for different times while adding various weight fractions of calcium carbonate powders. Following agitation, a separate chemical foaming agent was added and dispersed for 30 seconds. In these tests that chemical foaming agent was calcium carbonate. The various specimens were then foamed and the rise of the aluminum foam monitored.
[0090] Following foaming, the specimens were rapidly cooled and foam specimens sectioned, weighed, photographed, and the density calculated. The results of these tests are shown in Figure 10. The results clearly show the role of calcium carbonate in creating a stabilized aluminum melt and the impact of the carbonate decoinposition products on the structure.
[0091] In specimen S-787295, wherein no reactive gas producing particles (CaCO3) were added and the melt was simply agitated in air for 6 minutes, the subsequent dispersion of chemical foaming agent and foaming operations resulted in a foam of exceptionally poor quality. Relative density (compared to aluminum) was 77% of the base metal.
Standard deviation, taken from the set of specimens sectioned from top to bottom of the foamed product, was at this same level, indicating that the specimen suffered substantial gravitational drainage. These data clearly show the ineffectiveness of simple agitation in air (the incumbent method) in stabilizing aluminum melts for foaming.
Standard deviation, taken from the set of specimens sectioned from top to bottom of the foamed product, was at this same level, indicating that the specimen suffered substantial gravitational drainage. These data clearly show the ineffectiveness of simple agitation in air (the incumbent method) in stabilizing aluminum melts for foaming.
[0092] In specimen S-787293 (again shown in Figure 9), wherein 2 wt. % calcium carbonate is added to the inelt, but only agitated for 2 minutes, the specimen shows the ineffectiveness of insufficient decomposition of the reactive gas producing particles in stabilizing the aluminum foam. Here, the abbreviated agitation period (2 minutes stirring) results in the creation of an aluminum matrix with insufficient levels metallic oxide phases.
Subsequent addition and dispersion of chemical foaming agent, followed by foaming, and subsequent cooling, results in a foam product with a relative density of 54%, far too high to be considered an attractive foam product. With a standard deviation between different sections of the foam equal to approximately 34%, it is clear that the foamed product suffers from severe gravitational drainage. This result can be compared to that of specimen S-787296, where all experimental parameters were identical with the exception of extending the stirring time to 6 minutes. Here attractive relative densities of 24% were achieved, and significantly, standard deviation between foam sections dropped to 7%, indicative of a highly uniform density in the foamed product.
Subsequent addition and dispersion of chemical foaming agent, followed by foaming, and subsequent cooling, results in a foam product with a relative density of 54%, far too high to be considered an attractive foam product. With a standard deviation between different sections of the foam equal to approximately 34%, it is clear that the foamed product suffers from severe gravitational drainage. This result can be compared to that of specimen S-787296, where all experimental parameters were identical with the exception of extending the stirring time to 6 minutes. Here attractive relative densities of 24% were achieved, and significantly, standard deviation between foam sections dropped to 7%, indicative of a highly uniform density in the foamed product.
[0093] Higher levels of gas producing particles, such as 4 wt.%, 8 wt. % and 10 wt. %
calcium carbonate for specimens S-787291, S-787294, S-787299, respectively, show modest changes in foam density and resistance to gravitational drainage. For this particular alloy composition and particle size distribution of calcium carbonate, a miniinum of a 2 wt. %
addition and a 6 minute agitation period is required to stabilize the melt.
Example 2: Effect of CaCO3 Particle Size Distribution on Foam Structure:
calcium carbonate for specimens S-787291, S-787294, S-787299, respectively, show modest changes in foam density and resistance to gravitational drainage. For this particular alloy composition and particle size distribution of calcium carbonate, a miniinum of a 2 wt. %
addition and a 6 minute agitation period is required to stabilize the melt.
Example 2: Effect of CaCO3 Particle Size Distribution on Foam Structure:
[0094] A series of aluminum alloy melts were prepared to determine the effect of size and weight fraction of calcium carbonate (reactive gas producing particles) on the stability of the aluminum foam and the propensity for gravitational drainage in the foamed structure.
Specimens comprising 100 gm of an aluminum-2wt. % magnesium alloy were melted and stirred vigorously for 6 minutes after adding various weight fractions of calcium carbonate powders. The results of this experimentation are shown in Figure 11, in which particles labeled "coarse" correspond to volume average diameters of 150 microns, while those labeled as "fine" correspond to volume average diameters of 40 microns. The finer carbonates clearly show greater efficacy in stabilizing the aluminum melt. At a 2 wt. % carbonate addition, the "coarse" addition resulted in an average foam density of 25%, while the "fine"
particles resulted in a density of 17%. This finer carbonate addition allows for the effective weight fraction of the viscosity enhancement to be brought down to 1%, as shown in Figure 10.
These data suggest that even finer carbonate distributions will result in lower minimum levels of viscosity addition.
Example 3: Effect of Magnesium Addition on Stabilization of Aluminum Foams:
Specimens comprising 100 gm of an aluminum-2wt. % magnesium alloy were melted and stirred vigorously for 6 minutes after adding various weight fractions of calcium carbonate powders. The results of this experimentation are shown in Figure 11, in which particles labeled "coarse" correspond to volume average diameters of 150 microns, while those labeled as "fine" correspond to volume average diameters of 40 microns. The finer carbonates clearly show greater efficacy in stabilizing the aluminum melt. At a 2 wt. % carbonate addition, the "coarse" addition resulted in an average foam density of 25%, while the "fine"
particles resulted in a density of 17%. This finer carbonate addition allows for the effective weight fraction of the viscosity enhancement to be brought down to 1%, as shown in Figure 10.
These data suggest that even finer carbonate distributions will result in lower minimum levels of viscosity addition.
Example 3: Effect of Magnesium Addition on Stabilization of Aluminum Foams:
[0095] A series of alumiiium alloy melts were prepared to determine the effect of magnesium level on the stability of the aluminum foam and the propensity for gravitational drainage in the foamed structure. Specimens comprising 100 gm of an aluminum and various levels of magnesium were melted and stirred vigorously after adding 20 wt. %
calcium carbonate powders. The results are shown in Figure 12. A marked effect is seen on the addition of 2 wt. % Mg (for this particular carbonate size and weight fraction), with relative density of the foam product dropping from near full density to 25 wt. %.
Higher additions of Mg have limited effect on foam density itself.
Example 4: Single Production of Aluminum Foam using Unexpended Stabilizing Additive as Foaming Agent:
calcium carbonate powders. The results are shown in Figure 12. A marked effect is seen on the addition of 2 wt. % Mg (for this particular carbonate size and weight fraction), with relative density of the foam product dropping from near full density to 25 wt. %.
Higher additions of Mg have limited effect on foam density itself.
Example 4: Single Production of Aluminum Foam using Unexpended Stabilizing Additive as Foaming Agent:
[0096] A series of aluminum alloy melts were prepared to determine the effect of agitation time of the reactive gas producing particles on the density and stability of the aluminum foam and the possibility of producing inoculated (inoculated defined here as melt plus unreacted foaming agent) foamable charge in a single agitating step.
Figure 13 shows the results of 100 gm specimens of an aluminum-2 wt. % magnesium alloy that were melted and stirred vigorously for various times following the addition of carbonate. For these carbonate sizes, the results show an optimum agitation time of approximately 6 minutes to render the lowest foam relative density - 18%.
Figure 13 shows the results of 100 gm specimens of an aluminum-2 wt. % magnesium alloy that were melted and stirred vigorously for various times following the addition of carbonate. For these carbonate sizes, the results show an optimum agitation time of approximately 6 minutes to render the lowest foam relative density - 18%.
[0097] Shorter agitation times show the effects of insufficient levels of stabilization, expressed by increasing density from top to bottom of the foam. At 10 minutes of agitation, however, insufficient unreacted carbonate remains to drive the expansion of the foam during the foaming step, resulting in a rise in the relative density. Thus 10 minutes of agitation, while providing the highest degree of stabilization (as judged by the low standard deviation between density readings) does not provide the best balance of stabilization and residual foam efficacy.
Example 5: Sin lg e Sto Production of Aluminum Foam using Unexpended Stabil Additive as Foaming Agent:
Example 5: Sin lg e Sto Production of Aluminum Foam using Unexpended Stabil Additive as Foaming Agent:
[0098] A series of aluminum alloy melts were prepared to determine the effect of agitation time and weight fraction ofthe reactive gas producing particles on the density and stability of the aluminum foam and the possibility of producing inoculated foamable charge in a single agitating step. Figure 14 shows the results of 100 gm specimens of an aluminum-2 wt. % magnesium alloy that were melted and stirred vigorously for various times following the addition of carbonate. For these carbonate sizes, the results show increasing stabilization with either increased agitation time or increased carbonate level, again, as judged by the standard deviation of density taken from top to bottom. Single additions are calcium carbonate are increased from 8 wt. % to 14 wt. % and agitation times varied from 2 minutes to 8 minutes, with resulting densities as low as 17%.
[0099] While the present invention has been particularly shown and described with respect to the preferred embodiments thereof, it will be understood by those skilled in the art that the foregoing and other changes in forms of details may be made without departing form the spirit and scope of the present invention. It is therefore intended that the present invention not be limited to the exact forms and details described and illustrated, but fall within the scope of the appended claims.
Claims (49)
1. A method of making foamed aluminum comprising:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350°C to about 850°C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of metallic oxide phases and gas bubbles;
dispersing chemical foaming agents into the foamable suspension to produce an inoculated foamable suspension;
foaming the inoculated foamable suspension to produce a liquid metal foam;
and solidifying the liquid metal foam to create a foamed aluminum product.
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350°C to about 850°C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of metallic oxide phases and gas bubbles;
dispersing chemical foaming agents into the foamable suspension to produce an inoculated foamable suspension;
foaming the inoculated foamable suspension to produce a liquid metal foam;
and solidifying the liquid metal foam to create a foamed aluminum product.
2. The method of Claim 1, wherein the reactive gas producing particles comprise magnesium carbonate, calcium carbonate, dolomite or mixtures thereof.
3. The method of Claim 2, wherein the reactive gas producing particles are calcium carbonate.
4. The method of Claim 1, wherein the chemical foaming agents comprise magnesium carbonate, calcium carbonate, dolomite, titanium hydride, zirconium hydride or mixtures thereof.
5. The method of Claim 4, wherein the chemical foaming agents are calcium carbonate.
6. The method of Claim 1, wherein the molten metal alloy comprises commercial grade purity aluminum, scrap aluminum, aluminum containing silicon and magnesium, or mixtures thereof.
7. The method of Claim 3, wherein the calcium carbonate has an average diameter of less than 40 microns.
8. The method of Claim 3, wherein the calcium carbonate comprises between 0.5 wt. % and 4 wt. % of the molten metal alloy.
9. The method of Claim 5, wherein the calcium carbonate constitutes between 0.5 wt. % and 4 wt. % of the molten metal alloy.
10. The method of Claim 1, wherein the molten metal alloy comprises between 0.5% and 8% magnesium by weight percent.
11. The method of Claim 1, wherein the inoculated foamable suspension is solidified and remelted prior to the foaming of the inoculated foamable suspension to produce the liquid metal foam.
12. The method of Claim 1, wherein the step of foaming the inoculated foamable suspension further comprises heating the foamable inoculated suspension to increase the chemical foaming agents rate of decomposition.
13. The method of Claim 12 comprising heating the foamable inoculated suspension to a temperature ranging from about 670°C to about 740°C.
14. A method of making foamed aluminum comprising:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350°C to about 850°C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose a first portion of the reactive gas producing particles into a reactive gas and retain a second portion of the reactive gas producing particles in an unreacted state, wherein the reactive gas vigorously combines with the molten metal alloy to produce metallic oxide phases and gas bubbles and the second portion of the reactive gas producing particles in the unreacted state are chemical foaming agents in an inoculated foamable suspension;
foaming the inoculated foamable suspension to produce a liquid metal foam;
and solidifying the liquid metal foam to create a foamed aluminum product.
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350°C to about 850°C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose a first portion of the reactive gas producing particles into a reactive gas and retain a second portion of the reactive gas producing particles in an unreacted state, wherein the reactive gas vigorously combines with the molten metal alloy to produce metallic oxide phases and gas bubbles and the second portion of the reactive gas producing particles in the unreacted state are chemical foaming agents in an inoculated foamable suspension;
foaming the inoculated foamable suspension to produce a liquid metal foam;
and solidifying the liquid metal foam to create a foamed aluminum product.
15. The method of Claim 14, wherein the reactive gas producing particles comprise magnesium carbonate, calcium carbonate, dolomite or mixtures thereof.
16. The method of Claim 15, wherein the reactive gas producing particles are calcium carbonate.
17. The method of Claim 14, wherein the molten metal alloy comprises commercial grade purity aluminum, scrap aluminum, aluminum containing silicon and magnesium, or mixtures thereof.
18. The method of Claim 16, wherein the calcium carbonate has an average diameter of less than 40 microns.
19. The method of Claim 15, wherein the calcium carbonate comprises between 2% and 16% of the molten metal alloy by weight percent.
20. The method of Claim 17, wherein the molten metal alloy comprises between 0.5% and 8% magnesium by weight percent.
21. The method of Claim 14, wherein the inoculated foamable suspension is solidified and remelted prior to the foaming of the inoculated foamable suspension to provide the liquid metal foam.
22. A method of making a foamable liquid+gas+solid suspension in molten aluminum comprising:
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350°C to about 850°C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of gas bubbles and metallic oxide phases within the molten metal alloy.
providing reactive gas producing particles having a decomposition temperature at atmospheric pressure from about 350°C to about 850°C;
combining the reactive gas producing particles with molten metal alloy comprising aluminum;
agitating the molten metal alloy containing the reactive gas producing particles to decompose at least a portion of the reactive gas producing particles into reactive gas, wherein the reactive gas vigorously combines with the molten metal alloy to produce a foamable suspension of gas bubbles and metallic oxide phases within the molten metal alloy.
23. The method of Claim 22 further comprising a volumetric expansion of the foamable suspension ranging from about 5% to about 50% following the step of agitating the molten metal alloy containing the reactive gas producing particles.
24. The method of Claim 22, wherein the molten metal alloy comprises from 0.5 wt % Mg to 8.0 wt % Mg.
25. An apparatus for the making a foamable suspension comprising:
a feeding system for providing reactive gas producing particles and molten metal alloy, wherein the molten metal alloy is provided at a pre-selected flow rate;
a reactor unit in communication with the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into an inoculated foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the pre-selected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit; and a tip in communication with the reactor unit.
a feeding system for providing reactive gas producing particles and molten metal alloy, wherein the molten metal alloy is provided at a pre-selected flow rate;
a reactor unit in communication with the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into an inoculated foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the pre-selected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit; and a tip in communication with the reactor unit.
26. The apparatus of Claim 25, wherein the tip comprises a mold having a geometry for an aluminum foam product.
27. The apparatus of Claim 25, comprising a transport system to transfer the inoculated foamable suspension from the reactor unit to the tip.
28. The apparatus of Claim 25, further comprising a positive displacement pump for transferring the inoculated foamable suspension from the reactor unit to the tip.
29. The apparatus of Claim 26, wherein said positive displacement pump is a rotary gear pump or a rotary lobe pump.
30. The apparatus of Claim 25, wherein the tip is electrically heated or gass fired heated.
31. An apparatus for the making foamed aluminum comprising:
a feeding system for providing reactive gas producing particles and molten metal alloy, wherein the molten metal alloy is provided at a pre-selected flow rate;
a reactor unit in communication with the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into a foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit suitable for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the pre-selected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit;
a dispersion unit in communication with the reactor unit comprising:
a foaming agent mixing chamber for receiving the foamable suspension;
a feeding system positioned to provide chemical foaming agent into the foamable suspension within the foaming agent mixing chamber;
a stirrer positioned in the foaming agent mixing chamber to disperse the chemical foaming agent to produce an inoculated foamable suspension; and a transport system to transfer the inoculated foamable suspension from the dispersion unit to a tip.
a feeding system for providing reactive gas producing particles and molten metal alloy, wherein the molten metal alloy is provided at a pre-selected flow rate;
a reactor unit in communication with the feeding system comprising:
a mixing unit for combining the reactive gas producing particles and the molten metal alloy into a foamable suspension, the mixing unit having a stirrer contained therein and having a volume configured to provide a transit time through the mixing unit suitable for decomposing at least a portion of the reactive gas producing particles within the mixing unit at the pre-selected flow rate, at least one vent in the reactor unit to release gaseous byproducts, and a furnace housing the reactor unit;
a dispersion unit in communication with the reactor unit comprising:
a foaming agent mixing chamber for receiving the foamable suspension;
a feeding system positioned to provide chemical foaming agent into the foamable suspension within the foaming agent mixing chamber;
a stirrer positioned in the foaming agent mixing chamber to disperse the chemical foaming agent to produce an inoculated foamable suspension; and a transport system to transfer the inoculated foamable suspension from the dispersion unit to a tip.
32. The apparatus of Claim 31, wherein the pre-selected flow rate of the molten metal or the volume of the mixing unit is configured to fully decompose the reactive gas producing particles in producing the foamable suspension.
33. The apparatus of Claim 31, wherein the transport system is a positive displacement pump.
34. The apparatus of Claim 33, wherein the positive displacement pump is a rotary gear pump or a rotary lobe pump.
35. The apparatus of Claim 31, wherein the tip is electrically heated or gass fired heated.
36. The apparatus of Claim 31 wherein the tip comprises a mold having a geometry for an aluminum foam product.
37. An aluminum foam material comprising:
an aluminum alloy matrix comprising magnesium in a percentage ranging from about 0.5% to 8% by weight percent and a distribution of fine metallic oxides in a percentage ranging from 0.5% to about 16% by weight percent; wherein the average size of the fine metal oxides is less than 1.0 micron; and a distribution of pores within said aluminum alloy matrix comprising a majority of closed pores with an average diameter ranging from about 200 microns to about 1500 microns; wherein said distribution of pores within said aluminum alloy matrix provides a product density between 0.30 g/cm3 and 0.70 g/cm3.
an aluminum alloy matrix comprising magnesium in a percentage ranging from about 0.5% to 8% by weight percent and a distribution of fine metallic oxides in a percentage ranging from 0.5% to about 16% by weight percent; wherein the average size of the fine metal oxides is less than 1.0 micron; and a distribution of pores within said aluminum alloy matrix comprising a majority of closed pores with an average diameter ranging from about 200 microns to about 1500 microns; wherein said distribution of pores within said aluminum alloy matrix provides a product density between 0.30 g/cm3 and 0.70 g/cm3.
38. The aluminum foam material of Claim 37 wherein the metallic oxides are comprised of aluminum oxide, magnesium oxide, calcium oxide or combinations thereof.
39. An aluminum foam material comprising:
an aluminum alloy matrix comprising an effective amount of magnesium;
a distribution of fine metallic carbonates;
a distribution of pores within the aluminum alloy matrix;
and substantially free of stable ceramic particles greater than 5 microns in diameter.
an aluminum alloy matrix comprising an effective amount of magnesium;
a distribution of fine metallic carbonates;
a distribution of pores within the aluminum alloy matrix;
and substantially free of stable ceramic particles greater than 5 microns in diameter.
40. The aluminum foam material of Claim 39 wherein the effective amount of magnesium is between 0.5 wt. % and 8 wt. %.
41. The aluminum foam material of Claim 39 wherein the fine metallic carbonates comprise calcium carbonate, magnesium carbonate or combinations thereof.
42. The aluminum foam material of Claim 39 wherein the distribution of pores comprise pores having an average diameter ranging from about 200 microns to about 1500 microns.
43. The aluminum foam material of Claim 39 wherein the distribution of pores comprise between 70% and 90% of the volume of the aluminum foam material foam.
44. The aluminum foam material of Claim 39 wherein the metallic carbonates are in a percentage ranging from 0.5% to about 16% by weight percent.
45. The material of Claim 39 wherein the distribution of fine metallic carbonates comprise carbonates having an average size of less than 100 microns.
46. A structural material for construction, automotive, or aerospace applications comprising the aluminum foam material of Claim 39.
47. The structural material of Claim 44 wherein said structural material is a flat panel.
48. An aluminum foam material comprising:
an aluminum alloy matrix having a mean wall thickness ranging from about 5 microns to about 100 microns; and a distribution of pores within the aluminum alloy matrix having an average pore diameter ranging from about 200 microns to about 1500 microns and constituting between 70% and 90% of the aluminum foam material by volume.
an aluminum alloy matrix having a mean wall thickness ranging from about 5 microns to about 100 microns; and a distribution of pores within the aluminum alloy matrix having an average pore diameter ranging from about 200 microns to about 1500 microns and constituting between 70% and 90% of the aluminum foam material by volume.
49. The material of Claim 48 wherein the average pore diameter is less than 1000 microns.
Applications Claiming Priority (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US11/119,002 US7452402B2 (en) | 2005-04-29 | 2005-04-29 | Method for producing foamed aluminum products by use of selected carbonate decomposition products |
US11/119,002 | 2005-04-29 | ||
US11/413,884 US20060243095A1 (en) | 2005-04-29 | 2006-04-28 | Method for producing foamed aluminum products by use of selected carbonate decomposition products |
US11/413,884 | 2006-04-28 | ||
PCT/US2006/016714 WO2006119234A2 (en) | 2005-04-29 | 2006-05-01 | Method for producing foamed aluminum using carbonates |
Publications (1)
Publication Number | Publication Date |
---|---|
CA2606505A1 true CA2606505A1 (en) | 2006-11-09 |
Family
ID=37308600
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CA002606505A Abandoned CA2606505A1 (en) | 2005-04-29 | 2006-05-01 | Method for producing foamed aluminum products by use of selected carbonate decomposition products |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP1877591A4 (en) |
KR (1) | KR20080019599A (en) |
CA (1) | CA2606505A1 (en) |
WO (1) | WO2006119234A2 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN102373345A (en) * | 2011-08-30 | 2012-03-14 | 吴江市精工铝字制造厂 | Foaming agent for foam aluminum and preparation method thereof |
CN102296202A (en) * | 2011-08-30 | 2011-12-28 | 吴江市精工铝字制造厂 | Foaming agent and preparation method thereof |
KR101246070B1 (en) * | 2012-05-14 | 2013-03-22 | 정병일 | industrial alloy material composition and preparing method thereof |
CN103031454B (en) * | 2012-12-05 | 2015-06-03 | 安徽徽铝铝业有限公司 | Preparation method of refining agent for smelting aluminum alloy |
ES2526470B1 (en) * | 2013-06-06 | 2015-07-30 | Universidad De Valladolid | PROCEDURE FOR OBTAINING A METAL FOAM. |
CN118006982B (en) * | 2024-04-10 | 2024-06-18 | 江苏中机恒亚轻合金有限公司 | Super-hydrophobic aluminum alloy and preparation method thereof |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2983597A (en) * | 1959-06-11 | 1961-05-09 | Lor Corp | Metal foam and method for making |
US3214265A (en) * | 1963-03-11 | 1965-10-26 | Lor Corp | Method of making metal foam bodies |
JPS55138039A (en) * | 1979-04-13 | 1980-10-28 | Agency Of Ind Science & Technol | Production of foamed aluminum |
US20040163492A1 (en) * | 2001-05-17 | 2004-08-26 | Crowley Mark D | Method for producing foamed aluminum products |
JP3771488B2 (en) * | 2001-12-13 | 2006-04-26 | 本田技研工業株式会社 | Foaming agent for producing foamed / porous metal and method for producing the same |
KR100592533B1 (en) * | 2002-01-07 | 2006-06-23 | 조순형 | Method and apparatus for the continuous production of foamed metals |
US20040126583A1 (en) * | 2002-11-19 | 2004-07-01 | Takashi Nakamura | Foaming agent for manufacturing a foamed or porous metal |
JP2005344153A (en) * | 2004-06-02 | 2005-12-15 | Nissan Motor Co Ltd | Method for producing member made of foamed aluminum alloy |
-
2006
- 2006-05-01 EP EP06758888A patent/EP1877591A4/en not_active Withdrawn
- 2006-05-01 KR KR1020077027760A patent/KR20080019599A/en not_active Application Discontinuation
- 2006-05-01 CA CA002606505A patent/CA2606505A1/en not_active Abandoned
- 2006-05-01 WO PCT/US2006/016714 patent/WO2006119234A2/en active Application Filing
Also Published As
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KR20080019599A (en) | 2008-03-04 |
EP1877591A4 (en) | 2008-06-11 |
EP1877591A2 (en) | 2008-01-16 |
WO2006119234A3 (en) | 2007-06-07 |
WO2006119234A2 (en) | 2006-11-09 |
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