JP4402213B2 - Plate-like Al2O3 grains and method for producing the same - Google Patents
Plate-like Al2O3 grains and method for producing the same Download PDFInfo
- Publication number
- JP4402213B2 JP4402213B2 JP23548099A JP23548099A JP4402213B2 JP 4402213 B2 JP4402213 B2 JP 4402213B2 JP 23548099 A JP23548099 A JP 23548099A JP 23548099 A JP23548099 A JP 23548099A JP 4402213 B2 JP4402213 B2 JP 4402213B2
- Authority
- JP
- Japan
- Prior art keywords
- plate
- grains
- producing
- heat treatment
- heat
- 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.)
- Expired - Fee Related
Links
Images
Landscapes
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Manufacture And Refinement Of Metals (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、板状Ａｌ2 Ｏ3 粒の製造方法に関するものである。
【０００２】
【従来の技術及び発明が解決しようとする課題】
板状Ａｌ2 Ｏ3 粒は、セラミックス材料、金属材料の添加強化材として注目されており、無添加材料と比較して強度特性の改善が報告されている。このような板状Ａｌ2 Ｏ3 粒の合成法としては、ＡｌＦ3 を用いたフラックス法、溶液法あるいは水熱合成法等が知られている。しかしながら、これまでに微細均一で形状の整った六角板状のＡｌ2 Ｏ3 粒は得られていなかった。
【０００３】
本発明の目的は、板状Ａｌ2 Ｏ3 粒、特に均一な形状を有する六角板状のＡｌ2 Ｏ3 粒を製造することができる新規な製造方法を提供することにある。
【０００４】
【課題を解決するための手段】
【０００５】
本発明の板状Ａｌ2 Ｏ3 粒の製造方法は、Ｎａ2 ＳＯ4 （硫酸ナトリウム）をフラックスとして用いγ−Ａｌ2 Ｏ3 （γ−アルミナ）を加熱処理してα−Ａｌ2 Ｏ3 （α−アルミナ）とすることを特徴としている。
【０００６】
本発明において、γ−Ａｌ2 Ｏ3 を加熱処理するときの温度は、９００℃以上であることが好ましく、さらに好ましくは、１０００℃以上である。加熱処理の温度が９００℃未満であると、γ−Ａｌ2 Ｏ3 の結晶構造をα−Ａｌ2 Ｏ3 の結晶構造に変換することができない場合がある。
【０００７】
本発明によれば、γ−Ａｌ2 Ｏ3 を加熱して板状のα−Ａｌ2 Ｏ3 を製造することができる。
本発明において、フラックスとして用いるＮａ2 ＳＯ4 の混合割合は特に限定されるものではないが、Ｎａ2 ＳＯ4 の混合割合を調整することにより、得られる板状Ａｌ2 Ｏ3 粒の粒子径を制御することができる。すなわち、Ｎａ2 ＳＯ4 の混合割合を増加させることにより、得られる板状Ａｌ2 Ｏ3 粒の粒子径を大きくすることができる。例えば、γ−Ａｌ2 Ｏ3 ：Ｎａ2 ＳＯ4 のモル比で１：１〜６の範囲で変化させることにより、板状Ａｌ2 Ｏ3 粒の平均粒子径を３〜５μｍの範囲で制御することができる。
【０００８】
本発明において原料として用いられるγ−Ａｌ2 Ｏ3 は、例えばＡｌ2 （ＳＯ4 ）3 を加熱処理して得ることができる。また、Ａｌ2 （ＳＯ4 ）3 は、例えばＡｌ2 （ＳＯ4 ）3 ・１４〜１８Ｈ2 Ｏを加熱処理して得ることができる。
【０００９】
【実施例】
［六角板状Ａｌ2 Ｏ3 粒の合成］
出発原料として、特級試薬のＡｌ2 （ＳＯ4 ）3 ・１４〜１８Ｈ2 Ｏ及びＮａ2 ＳＯ4 を用いた。Ａｌ2 （ＳＯ4 ）3 ・１４〜１８Ｈ2 Ｏを、３００℃で１２時間以上加熱保持することにより、Ａｌ2 （ＳＯ4 ）3 （硫酸アルミニウム無水塩）とした後、さらに９００℃で３時間加熱することによりγ−Ａｌ2 Ｏ3 とした。得られたγ−Ａｌ2 Ｏ3 と、モル比で２倍量のＮａ2 ＳＯ4 を混合し、混合物をアルミナ坩堝に入れ、電気炉中１１００℃で１時間加熱処理した。
【００１０】
冷却後、０．１ＮのＨＣｌを注ぎ、７０〜８０℃に０．５〜１時間保って溶出成分を除去した。得られた残留白色粉末について、ＸＲＤ（Ｘ線回折分析）により同定したところ、α−Ａｌ2 Ｏ3 であった。また、走査型電子顕微鏡（ＳＥＭ）により、得られた白色粉末を観察した。図１に、得られた白色粉末の走査型電子顕微鏡写真を示す。
図１から明らかなように、得られた白色粉末は、六角板状であり、平均粒子径３．７μｍ、平均厚さ０．３μｍであった。
【００１１】
［加熱処理温度の検討］
加熱処理温度を８００℃、９００℃、及び１０００℃とし、加熱時間を１時間とする以外は、上記実験と同様にしてγ−Ａｌ2 Ｏ3 とＮａ2 ＳＯ4 の混合物を加熱処理し、得られた白色粉末についてＸＲＤで分析した。ＸＲＤチャートを図２に示す。
【００１２】
図２に示す結果から明らかなように、８００℃ではγ−Ａｌ2 Ｏ3 の結晶ピークのみが観察され、α−Ａｌ2 Ｏ3 の結晶ピークは観察されなかった。９００℃の加熱処理温度では、α−Ａｌ2 Ｏ3 の結晶ピークが観察され、γ−Ａｌ2 Ｏ3 の弱いピークが観察された。１０００℃の加熱処理温度では、γ−Ａｌ2 Ｏ3 の結晶ピークが観察されなくなり、α−Ａｌ2 Ｏ3 の結晶ピークのみが観察された。このことから、加熱処理温度としては、９００℃以上が好ましく、さらに好ましくは１０００℃以上であることがわかる。
【００１３】
［Ｎａ2 ＳＯ4 フラックス量の検討］
Ｎａ2 ＳＯ4 を、γ−Ａｌ2 Ｏ3 に対し、モル比で１、１．５、２、３、４、５及び６と変化させる以外は、上記実験と同様に１１００℃で１時間加熱処理し、上記実験と同様に溶出成分を除去して、白色粉末を得た。得られた各白色粉末について、ＳＥＭにより観察し、平均粒子径を測定した。得られた結果を図３に示す。
【００１４】
図３に示す結果から明らかなように、Ｎａ2 ＳＯ4 フラックス量をモル比で１倍から６倍まで変化させると、平均粒子径が３μｍから５μｍに大きくなる傾向が認められた。従って、Ｎａ2 ＳＯ4 フラックス量を調整することにより、板状Ａｌ2 Ｏ3 粒の粒子径を制御できることがわかる。
【００１５】
【発明の効果】
本発明によれば、六角板状などの板状Ａｌ2 Ｏ3 粒を、良好な分散状態で製造することができる。従って、本発明に係る板状Ａｌ2 Ｏ3 粒は、セラミックス材料、金属材料、プラスチック材料などの添加強化材や、その他の目的の添加材等として有用なものである。
【図面の簡単な説明】
【図１】本発明の実施例で得られた六角板状Ａｌ2 Ｏ3 粒を示す走査型電子顕微鏡写真。
【図２】加熱処理温度を変化させて得られるＡｌ2 Ｏ3 粒のＸＲＤチャート。
【図３】本発明の実施例におけるＡｌ2 ＳＯ4 フラックス量と板状Ａｌ2 Ｏ3 粒の平均粒子径との関係を示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing plate-like Al 2 O 3 grains.
[0002]
[Prior art and problems to be solved by the invention]
Plate-like Al 2 O 3 grains are attracting attention as additive reinforcing materials for ceramic materials and metal materials, and improved strength characteristics have been reported compared to additive-free materials. As a method for synthesizing such plate-like Al 2 O 3 grains, a flux method using AlF 3 , a solution method, a hydrothermal synthesis method, or the like is known. However, hexagonal plate-like Al 2 O 3 grains that have been finely uniform and well-shaped have not been obtained so far.
[0003]
An object of the present invention is to provide a novel production method capable of producing plate-like Al 2 O 3 grains, particularly hexagonal plate-like Al 2 O 3 grains having a uniform shape.
[0004]
[Means for Solving the Problems]
[0005]
In the method for producing plate-like Al 2 O 3 grains of the present invention, γ-Al 2 O 3 (γ-alumina) is heat-treated using Na 2 SO 4 (sodium sulfate) as a flux and α-Al 2 O 3 ( α-alumina).
[0006]
In the present invention, the temperature at which heat treatment of γ-Al 2 O 3 is preferably 900 ° C. or higher, more preferably is 1000 ° C. or higher. If the temperature of the heat treatment is less than 900 ° C., the crystal structure of γ-Al 2 O 3 may not be converted to the crystal structure of α-Al 2 O 3 in some cases.
[0007]
According to the present invention, γ-Al 2 O 3 can be heated to produce plate-like α-Al 2 O 3 .
In the present invention, the mixing ratio of Na 2 SO 4 used as the flux is not particularly limited, but by adjusting the mixing ratio of Na 2 SO 4 , the particle diameter of the obtained plate-like Al 2 O 3 grains can be adjusted. Can be controlled. That is, by increasing the mixing ratio of Na 2 SO 4 , the particle size of the obtained plate-like Al 2 O 3 grains can be increased. For example, by changing the molar ratio of γ-Al 2 O 3 : Na 2 SO 4 in the range of 1: 1 to 6, the average particle diameter of the plate-like Al 2 O 3 grains is controlled in the range of 3 to 5 μm. be able to.
[0008]
Γ-Al 2 O 3 used as a raw material in the present invention can be obtained, for example, by heat-treating Al 2 (SO 4 ) 3 . Further, Al 2 (SO 4) 3 may be for example Al 2 (SO 4) 3 · 14~18H 2 O and obtained by heat treatment.
[0009]
【Example】
[Synthesis of hexagonal plate-like Al 2 O 3 grains]
As starting materials, Al 2 (SO 4 ) 3 · 14-18H 2 O and Na 2 SO 4 as special grade reagents were used. Al 2 (SO 4 ) 3 · 14-18H 2 O was heated and held at 300 ° C. for 12 hours or longer to obtain Al 2 (SO 4 ) 3 (anhydrous aluminum sulfate), and then at 900 ° C. for 3 hours. By heating, γ-Al 2 O 3 was obtained. The obtained γ-Al 2 O 3 and Na 2 SO 4 having a molar amount of 2 times were mixed, and the mixture was put in an alumina crucible and heat-treated at 1100 ° C. for 1 hour in an electric furnace.
[0010]
After cooling, 0.1N HCl was poured, and the eluate was removed by maintaining at 70-80 ° C. for 0.5-1 hour. The obtained residual white powder was identified by XRD (X-ray diffraction analysis) and found to be α-Al 2 O 3 . The obtained white powder was observed with a scanning electron microscope (SEM). FIG. 1 shows a scanning electron micrograph of the obtained white powder.
As is clear from FIG. 1, the obtained white powder was hexagonal plate-shaped, having an average particle diameter of 3.7 μm and an average thickness of 0.3 μm.
[0011]
[Examination of heat treatment temperature]
A mixture of γ-Al 2 O 3 and Na 2 SO 4 was heat-treated in the same manner as in the above experiment except that the heat treatment temperatures were 800 ° C., 900 ° C., and 1000 ° C., and the heating time was 1 hour. The resulting white powder was analyzed by XRD. An XRD chart is shown in FIG.
[0012]
As is clear from the results shown in FIG. 2, only the crystal peak of γ-Al 2 O 3 was observed at 800 ° C., and the crystal peak of α-Al 2 O 3 was not observed. At a heat treatment temperature of 900 ° C., a crystal peak of α-Al 2 O 3 was observed, and a weak peak of γ-Al 2 O 3 was observed. At the heat treatment temperature of 1000 ° C., the crystal peak of γ-Al 2 O 3 was not observed, and only the crystal peak of α-Al 2 O 3 was observed. From this, it can be seen that the heat treatment temperature is preferably 900 ° C. or higher, more preferably 1000 ° C. or higher.
[0013]
[Examination of Na 2 SO 4 flux amount]
Heated at 1100 ° C. for 1 hour as in the above experiment except that Na 2 SO 4 was changed to 1, 1.5, 2, 3 , 4 , 5, and 6 in molar ratio with respect to γ-Al 2 O 3. The elution component was removed in the same manner as in the above experiment to obtain a white powder. About each obtained white powder, it observed by SEM and measured the average particle diameter. The obtained results are shown in FIG.
[0014]
As is apparent from the results shown in FIG. 3, when the Na 2 SO 4 flux amount was changed from 1 to 6 times in molar ratio, the average particle size tended to increase from 3 μm to 5 μm. Therefore, it can be seen that the particle diameter of the plate-like Al 2 O 3 grains can be controlled by adjusting the amount of Na 2 SO 4 flux.
[0015]
【The invention's effect】
According to the present invention, plate-like Al 2 O 3 grains such as hexagonal plates can be produced in a good dispersion state. Accordingly, the plate-like Al 2 O 3 grains according to the present invention are useful as additive reinforcing materials such as ceramic materials, metal materials, plastic materials, and other purposes.
[Brief description of the drawings]
FIG. 1 is a scanning electron micrograph showing hexagonal plate-like Al 2 O 3 grains obtained in an example of the present invention.
FIG. 2 is an XRD chart of Al 2 O 3 grains obtained by changing the heat treatment temperature.
FIG. 3 is a graph showing the relationship between the amount of Al 2 SO 4 flux and the average particle diameter of plate-like Al 2 O 3 grains in an example of the present invention.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23548099A JP4402213B2 (en) | 1999-08-23 | 1999-08-23 | Plate-like Al2O3 grains and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23548099A JP4402213B2 (en) | 1999-08-23 | 1999-08-23 | Plate-like Al2O3 grains and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001058818A JP2001058818A (en) | 2001-03-06 |
| JP4402213B2 true JP4402213B2 (en) | 2010-01-20 |
Family
ID=16986699
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23548099A Expired - Fee Related JP4402213B2 (en) | 1999-08-23 | 1999-08-23 | Plate-like Al2O3 grains and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4402213B2 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20050124745A1 (en) | 2002-04-19 | 2005-06-09 | Saint-Gobain Ceramics & Plastics, Inc. | Flame retardant composites |
| AU2003900030A0 (en) * | 2003-01-07 | 2003-01-23 | Advanced Nano Technologies Pty Ltd | Process for the production of ultrafine plate-like alumina particles |
| CN1313374C (en) * | 2004-10-29 | 2007-05-02 | 中国石油化工股份有限公司 | Gama-Al2O3 preparation method |
| US20060104895A1 (en) | 2004-11-18 | 2006-05-18 | Saint-Gobain Ceramics & Plastics, Inc. | Transitional alumina particulate materials having controlled morphology and processing for forming same |
| JP4841851B2 (en) * | 2005-03-02 | 2011-12-21 | 電気化学工業株式会社 | Alumina and production method thereof |
| JP5058475B2 (en) * | 2005-10-11 | 2012-10-24 | 電気化学工業株式会社 | Alumina and production method thereof |
| US7479324B2 (en) | 2005-11-08 | 2009-01-20 | Saint-Gobain Ceramics & Plastics, Inc. | Pigments comprising alumina hydrate and a dye, and polymer composites formed thereof |
| KR100803049B1 (en) | 2007-08-31 | 2008-02-22 | (주)제이피에스 마이크로텍 | Manufacture method of flake aluminum oxide using microwave |
| US8173099B2 (en) | 2007-12-19 | 2012-05-08 | Saint-Gobain Ceramics & Plastics, Inc. | Method of forming a porous aluminous material |
| US8460768B2 (en) | 2008-12-17 | 2013-06-11 | Saint-Gobain Ceramics & Plastics, Inc. | Applications of shaped nano alumina hydrate in inkjet paper |
-
1999
- 1999-08-23 JP JP23548099A patent/JP4402213B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2001058818A (en) | 2001-03-06 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4402213B2 (en) | Plate-like Al2O3 grains and method for producing the same | |
| JPH03504848A (en) | Hard mullite - manufacturing method of whisker felt | |
| JP2010090021A (en) | Method for producing sintered compact of compound with perovskite structure | |
| CN110483029A (en) | Low thermal coefficient of expansion monocline baryta fledspar matter ceramics and preparation method | |
| EP3088574B1 (en) | Ternary inorganic compound crystal and preparation method and application thereof | |
| Ren et al. | Effects of pyrolusite and dolomite co-additives on the structure and properties of bauxite-based ceramics | |
| US6548436B2 (en) | Cristobalite-free mullite grain having reduced reactivity to molten aluminum and method of producing the same | |
| JPS62223009A (en) | Production of alpha-sialon powder | |
| JP6254913B2 (en) | Method for producing α-lithium aluminate | |
| JPH0372572B2 (en) | ||
| Kohoutkova et al. | Preparation and characterization of analcime powders by X-ray and SEM analyses | |
| Su et al. | Effect of potassium sulfate on the low‐temperature formation of alpha alumina platelets from bayerite | |
| KR101893144B1 (en) | Friction material comprising potassium titanate and method for preparing the same by melting method | |
| JPH0130766B2 (en) | ||
| Guo et al. | Synthesis and characterization of Celsian by solid‐state reaction process from mullite | |
| CN113636581A (en) | Method for synthesizing calcium aluminate composite powder by microwave induction heating | |
| CN101780959A (en) | Preparation method of Bi4Si3O12 nanocrystals | |
| HASHIMOTO et al. | Synthesis of needlelike leucite crystals using potassium sulfate flux | |
| JP6989722B1 (en) | Mullite sintered body with excellent heat resistance and durability and its manufacturing method | |
| HASHIMOTO et al. | Synthesis of spherical leucite crystals | |
| JPH11246280A (en) | Monoclinic celsian porous body and its production | |
| JPH0421605B2 (en) | ||
| JPH07330499A (en) | Granular aggregate of aluminum borate whisker | |
| KR20230144922A (en) | Lightweight aggregate for the application of insulation in steelmaking facilities and the manufacturing method thereof | |
| JP2691301B2 (en) | Method for producing acicular aluminum oxide |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20060804 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20081209 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20090804 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20090928 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20091027 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20091029 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121106 Year of fee payment: 3 |
|
| LAPS | Cancellation because of no payment of annual fees |