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WO2024177636A1 - Compositions de revêtement de protection d'acier améliorées, leurs procédés de fabrication et leurs procédés d'utilisation - Google Patents

Compositions de revêtement de protection d'acier améliorées, leurs procédés de fabrication et leurs procédés d'utilisation Download PDF

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Publication number
WO2024177636A1
WO2024177636A1 PCT/US2023/013751 US2023013751W WO2024177636A1 WO 2024177636 A1 WO2024177636 A1 WO 2024177636A1 US 2023013751 W US2023013751 W US 2023013751W WO 2024177636 A1 WO2024177636 A1 WO 2024177636A1
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composition
aluminum
coating
present
concentration
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PCT/US2023/013751
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English (en)
Inventor
Jonathan Kerry WINTERS
James Epstein
Original Assignee
Thor Custom Steel Coatings LLC
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Priority to PCT/US2023/013751 priority Critical patent/WO2024177636A1/fr
Publication of WO2024177636A1 publication Critical patent/WO2024177636A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08—Anti-corrosive paints
    • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
    • C09D5/084—Inorganic compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/10—Metal compounds
    • C08K3/105—Compounds containing metals of Groups 1 to 3 or of Groups 11 to 13 of the Periodic Table
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/10—Metal compounds
    • C08K3/11—Compounds containing metals of Groups 4 to 10 or of Groups 14 to 16 of the Periodic Table
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/20—Diluents or solvents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
    • B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/01—Hydrocarbons

Definitions

  • the present invention relates generally to steel sheets provided with aluminized, i.e., aluminum-based, coating compositions for protecting the steel sheet from unwanted oxidation and oxide formation that occurs during the metallurgical process of heat-stamping.
  • the compositions of the invention relate to the scientific, engineering, and technical fields and subjects of inorganic chemistry, organic chemistry, metallurgy, ceramics, steel, coil steel fabrication, and coil steel coating. Background of the Invention The steel industry continually searches for novel methods and technologies to lower the costs of producing steel.
  • Such requirements for steel sheet are not limited to the automaking industry but also apply similarly to various other manufacturing sectors, for example appliances.
  • Research and development has therefore been conducted with regard to steel sheet that, by enhancing the mechanical strength of the steel sheet, is capable of maintaining or increasing such mechanical strength even when the sheet steel is made thinner than the steel sheet used previously.
  • a steel material having high mechanical strength generally tends to decline in shape flexibility performance and formability performance during bending and other forming movements due to metal fatigue, so that the metalworking itself becomes more and more challenging when the desired final shape becomes more complex.
  • An important case in point is when the steel sheet piece is to take on some variation of an accordian-like corrugated article.
  • hot stamping is the so called “hot stamping” method (variously also referred to as heat-stamping, hot-pressing, hot press forming, high- temperature stamping, or die-quenching, etc.).
  • This product is commonly known in the industry as Press Hardened Steel (PHS).
  • PHS Press Hardened Steel
  • a typical tensile strength for PHS is about 1,500 Mega Pascals (MPas).
  • MPas Mega Pascals
  • the hot stamping method softens the steel material by initially heating it to a high temperature, the material can be readily stamped and thus strength hardened, and additionally the mechanical strength of the material can be increased by the quenching effect of rapid cooling subsequent to the stamp- forming.
  • the hot stamping method therefore makes it possible to obtain a formed article that simultaneously achieves good shape-ability and high mechanical strength.
  • U.K. Patent 1,490,535 the disclosure of which is incorporated herein by reference, according to the technology of hot press forming, it is possible to form a steel sheet into a complicated shape with good dimensional accuracy since the steel sheet is softer and more ductile at high temperature.
  • PHS parts commonly used in the automobile industry include front and rear bumper beams, door reinforcements, windscreen pillar reinforcements, B-pillar reinforcements, floor and roof reinforcements, roof and dash panel cross members, and racking for the batteries of electric and hybrid vehicles.
  • Another advantage of hot press forming is that of strengthening of the steel sheet, due to the phenomenon of martensite crystal structure transformation (so-called work hardening in the field of metallurgy) which can be simultaneously achieved, in parallel, by heating the steel sheet to the austenite crystal structure region (region where austenite exists on a y-axis temperature versus x-axis time cartesian chart) and then performing rapid quenching at the same time as press forming in the die.
  • hot press forming is a method in which a heated steel sheet is subjected to working or work hardening, the surface of the steel sheet to be worked is unavoidably oxidized. Even if the steel sheet is heated in a non-oxidizing atmosphere in a heating furnace, the sheet retains the possibility of contacting the atmosphere, for example, when it is removed from the furnace before press forming, resulting in the oxidation formation of iron oxides on the surface of the steel sheet.
  • These iron oxides have the cost disadvantage that they may fall off during press forming and adhere to stamping or forming dies, thereby decreasing productivity and increasing cost and expense due to the need for extra cleaning and the cost of reduced lifetime of the die.
  • an oxide film i.e.
  • steel sheet having a zinc-based coating that provides the steel sheet with a sacrificial corrosion protection effect is widely used for automotive steel sheet and the like.
  • the heating temperature in hot stamping 700 to 1000° C.
  • the decomposition temperatures of organic materials and the boiling points of Zn- based and other metallic materials so that the effect of heating to such temperatures during hot stamping may sometimes evaporate an applied surface-coating layer and then cause marked degradation of the sheet steel surface properties.
  • a steel sheet having an Al-based metal coating which has a higher boiling point than an organic material coating or a Zn-based metal coating, referred to in the industry as aluminum plated steel sheet.
  • Providing an Al-based metal coating prevents scale from adhering to the steel sheet surface and improves productivity by making descaling or other such scale removal processes unnecessary.
  • corrosion resistance after painting the sheet improves because the Al-based metal coating has a corrosion-proofing effect.
  • the prior art describes a method which performs hot stamping using an aluminum-plated steel sheet obtained by coating a steel having a predetermined steel composition with an Al-based metal coating.
  • the Al coating first melts and is then changed to an Al-Fe alloy layer by the process of Fe diffusion from the steel sheet, whereby such newly formed Al-Fe alloy comes to extend itself to the steel sheet surface through the growth of the Al-Fe alloy.
  • This compound layer is called the alloy layer. Since this alloy layer has the property of being extremely hard, processing scratches are formed by contact with the die during stamping.
  • the surface of the Al-Fe alloy layer by its nature is relatively resistant to slipping and is poor in lubricity, a desirable property in stamping and rolling operations.
  • the Al-Fe alloy layer is not only hard but is relatively friable and is thus susceptible to cracking, so that formability is liable to decrease owing to cracking, flaking, and powdering of the plating layer.
  • the quality of the stamped product is degraded by adhesion to the die of exfoliated Al-Fe alloy layer particles and of the strongly scored surface of the Al-Fe alloy. This makes it necessary to remove the Al-Fe alloy powder that has adhered to the die during repair, which again lowers productivity and increases cost.
  • the Al-Fe alloy allow is relatively low in reactivity in situ with conventional phosphate metal treatment, which hinders the formation of the sought-after phosphate film that is ordinarily produced by a chemical conversion reaction that is part of electrocoating pretreatment.
  • the prior art most prevalent sheet steel coating product is known as Usibor ® , made and/or distributed by the ArcelorMittal company, also called Ultralume ® PHS.
  • compositions of the invention meet these needs, enable a method of their manufacture, and enable a method of their use, resulting in steel coated products that are made by these methods and that will themselves have novel and advantageous properties over coatings of prior art compositions or manufacturing processes.
  • This background information is provided to present and disclose information believed by the applicants to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.
  • Summary of the Invention In summary of a most preferred embodiment of the invention, it is a type of aluminum ceramic, and more specifically, an oxidation-protective coating composition for steel sheets comprising an aromatic organic solvent, at least one source of aluminum, a silazane and, an organic synthesis catalyst.
  • the aromatic organic solvent may advantageously be selected from one or more compounds of the group consisting of 1,2-diethylbenzene, 1,3-diethylbenzene, 1,4-diethylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, polyethylbenzene, bicyclo[4.4.0]deca-1,3,5,7,9-pentaene, 2-methylindole, and 2-phenylpropane.
  • a source of aluminum is present in the form of an aluminum pigment, which may be present in the form of a coordination complex of aluminum, and is preferably strongly anhydrous, by which is meant that there is substantially little to no water nor any organic alcohol in the aluminum preparation, nor any other source of hydroxyl or hydroxy functional groups, nor other organic functional groups that can form water in situ, directly or through an intermediate(s) e.g. carboxyls, ethers, thiols, amines, aldehydes, nor carbonyls or other acyls.
  • a preferred silazane is a polysilazane polymer resin comprising silicon and nitrogen, and an alternative preferred embodiment uses a polysilazane that is an organic polysilazane.
  • an inorganic polysilazane may comprise an inorganic polysilazane, or admixtures of organic and inorganic polysilazines.
  • the organic synthesis catalyst may be an organohetercyclic compound, preferably an azepane, and more preferably 1,8- diazabicyclo[5.4.0]undec-7-ene.
  • the composition may additionally comprise an organophosphorus compound, preferably a phosphazene, and more preferably for example 2-tert- Butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diaza phosphorine.
  • the aromatic organic solvent is preferably present in a w/w concentration of from about 30% to 60%; the aluminum is preferably present in a w/w concentration of from about 5% to 25%; the silazane is preferably present in a w/w concentration of from about 20% to 60%; and the organic synthesis catalyst is preferably present in a concentration of from about 0.5% to 5%.
  • the aromatic organic solvent is more preferably present in a w/w concentration of from about 40% to 50%; the aluminum is more preferably present in a w/w concentration of from about 10% to 20%; the silazane is more preferably present in a w/w concentration of from about 30% to 50%; and the organic synthesis catalyst is more preferably present in a concentration of from about 1% to 4%.
  • the aromatic organic solvent is most preferably present in a w/w concentration of about 44 to 45%; the aluminum is most preferably present in a w/w concentration of from about 12% to14%; the silazane is most preferably present in a w/w concentration of from about 38% to 42%; and the organic synthesis catalyst is most preferably present in a w/w concentration of approximately about 2%.
  • a preferred method of protecting surfaces of carbon steel during high temperature stamping comprises roller-coating the surfaces of the steel to be stamped with a coating comprised of any of the above described compositions.
  • the invention further comprises a method of making or furthermore applying the steel oxidative-protective coating compositions of those as described above, comprising the steps of admixing the aromatic organic solvent, the aluminum, the silazane, and the catalyst to a homogeneous consistency admixture; calculating an amount of time needed to achieve an optimized drying time or cure rate of this admixture; adding the selected organophosphorous compound to the admixture product in an amount sufficient to obtain the optimized drying or cure rate; and applying the optimized admixture to a steel article in need of protection from oxidation, by applying the dry-time or cure rate- optimized admixture to the steel article prior to heat-stamping that steel article.
  • the invention further comprises a coated steel sheet that has been prepared for heat-stamping, in accordance with the method as described above.
  • the invention preferably comprises an aluminum-plated steel sheet for hot- stamping, comprising said steel sheet having at least one surface coated by a composition comprising an aromatic organic solvent, a source of aluminum, a silazane; and an organic synthesis catalyst, where each component may be present in any of the preferred alternative concentrations described above, and in any of the ranges of concentrations described above.
  • another preferred embodiment of the invention comprises an oxidation- protective coating composition for steel sheets comprising the chemical components of: an aromatic organic solvent; at least one source of aluminum; a silazane; an organic synthesis catalyst; or alternatively comprising additionally an organophosphorus compound.
  • these coating compositions of the invention have an aromatic organic solvent present during the admixture process of making the compositions, where the aromatic organic solvent is preferably selected from one or more solvents such as 1,2-diethylbenzene, 1,3- diethylbenzene, 1,4-diethylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5- trimethylbenzene, polyethylbenzene, bicyclo[4.4.0]deca-1,3,5,7,9-pentaene, 2-methylindole, or 2- phenylpropane.
  • solvents such as 1,2-diethylbenzene, 1,3- diethylbenzene, 1,4-diethylbenzene, 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5- trimethylbenzene, polyethylbenzene, bicyclo[4.4.0]deca-1,3,5,7,9-pentaene,
  • the coating compositions of the invention utilize at least one source of aluminum, most preferably sourced as an aluminum pigment, while another source or an additional source of aluminum may be a coordination complex of aluminum.
  • a preferred coordination complex of aluminum is aluminum acetylacetonate.
  • the coating compositions of the present invention utilize a silazane.
  • the silazane component is a polysilazane, which may be a polymer resin comprised of silicon and nitrogen, and the polysilazane furthermore may be an organic silazane or an inorganic polysilazane.
  • the coating compositions of the invention preferably use an organic synthesis catalyst, more preferably an organohetercyclic compound, and most preferably an azepane.
  • a particularly advantageous organic synthesis catalyst is 1,8-diazabicyclo[5.4.0]undec-7-ene.
  • the coating compositions may optioanally alternatively or additionally comprise an organophosphorus compound, preferably a phosphazene.
  • a particularly prepferred phosphazene is 2- tert-Butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diaza phosphorine.
  • compositions of the invention are typically present as the aromatic organic solvent in a w/w concentration of from about 30% to 60%; the aluminum sources present in a w/w concentration of from about 5% to 25%; the silazane present in a w/w concentration of from about 20% to 60%; the organophosphorus, when it is additionally used, being present in a w/w concentration of from about about 5% to 25%; and the organic synthesis catalyst present in a w/w concentration of from about 0.5% to 5%.
  • More preferable ranges of components of the compositions of the invention are: aromatic organic solvent present in a w/w concentration of from about 40% to 50%; aluminum sources present in a w/w concentration of from about 10% to 20%; silazane present in a w/w concentration of from about 30% to 50%; organophosphorus, when it is additionally used, present in a w/w concentration of from about 10% to 20%; and organic synthesis catalyst present in a concentration of from about 1% to 4%.
  • the aromatic organic solvent is present in a w/w concentration of about 44% to 45%; the aluminum sources are present in a w/w concentration of from about 12% to14%; the silazane is present in a w/w concentration of from about 38% to 42%; the organophosphorus, when it is additionally used, is present in a w/w concentration of approximately about 20%; and the organic synthesis catalyst is present in a w/w concentration of approximately about 2%.
  • Alternative metals that can form alternative embodiments of the invention are Boron, Gallium, Indium, Thallium, Tungstun, Molybdenum, Chromium, Cobalt, Ruthenium, Iridium, Nickel, Platinum, Palladium, Silver, Gold, Copper, and the nitrides, sulfides, or nanocatalysts thereof any of these metals.
  • the present invention also covers a method of protecting surfaces of steel, preferably carbon steel during high temperature stamping, comprising coating the surfaces of the steel to be stamped with a coating composition made up of an aromatic organic solvent; at least one source of aluminum; a silazane; an organic synthesis catalyst; and optionally additionally an organophosphorus compound, each chemical component present in the w/w ranges described above.
  • the protective coating compositions of the invention are made by a method comprising the steps of admixing the aromatic organic solvent, at least one aluminum source, the silazane, and the catalyst, in an amount calculated to achieve desired drying time or cure time, to a homogeneous consistency; achieving an optimally desired coating admixture drying time or cure time by selectively adding sufficient amounts of aluminum and optionally an organophosphorus compound to the admixture product; and applying the optimized dry-time or cure-time admixture product to a steel article in need of protection from oxidation, by applying the admixture to such a steel article prior to heat-stamping it.
  • composition preparation method there will be produced a coated steel sheet, having a chemical surface layer composition that is novel and unique, and that is now prepared for heat-stamping, which will be protected against oxidation that tends to otherwise take place during a heat-stamping process.
  • the compositions of the invention are intended to be used in the preparation of sheet steel generally, and carbon steel in particular, to produce a sheet of steel that can withstand the oxidative effects of oxygen present in the steel production factory or mill, whose oxidative effects are otherwise made more corrosive by the high temperatures and high stamping forces typically utilized in steel heat-stamping manufacturing.
  • the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art on how to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure of the invention, which is defined solely by the claims. Furthermore, in this detailed description, a person skilled in the art should note that quantitative qualifying terms such as “generally,” “substantially,” “mostly,” and other terms are used, in general, to mean that the referred-to object, characteristic, or quality constitutes a majority of the subject of the reference.
  • compositions of the present invention can be prepared readily according to the following examples or modifications thereof using readily available starting materials, reagents and conventional synthesis procedures.
  • compositions and their constituent compounds of the invention are any or all of those specifically set forth in these examples. These compositions are not, however, to be construed as forming the only genus that is considered as the invention, and any combination of the compositions and constituent compounds or their moieties may itself form a genus.
  • the following examples further illustrate details for the preparation and the quantitative and qualitative analysis of the compounds of the present invention. Those skilled in the art will readily understand that known variations of the conditions and processes of the following preparative procedures can be used to prepare these compounds. All temperatures are degrees Celsius unless noted otherwise. Silazanes.
  • silazanes Silicon-nitrogen compounds with alternating silicon- (“sila”) and nitrogen atoms (“aza”) are designated as silazanes.
  • Simple examples of silazanes are disilazane H 3 Si–NH–SiH 3 and hexamethyldisazane (H 3 C) 3 Si–NH–Si(CH 3 ) 3 . If only one silicon atom is bound to the nitrogen atom, the materials are known as silylamines or aminosilanes (for example triethylsilylamine (H 5 C 2 ) 3 Si–NH 2 ). If three silicon atoms are bound to each nitrogen atom, the materials are called silsesquiazanes.
  • cyclosilazanes Small ring-shaped molecules with a basic network of Si-N are named cyclosilazanes (for example cyclotrisilazane [H2Si–NH] 3).
  • Polysilazanes Polysilazanes are silazane polymers consisting of both large chains and rings showing a range of molecular masses. Polysilazanes are a class of polymers in which silicon and nitrogen atoms alternate to form the basic backbone. Polysilazanes are a preferred category of silazanes utilized in the present invention.
  • a polymer with the general formula (CH3)3Si–NH– [(CH3)2Si-NH] n–Si(CH3)3 is designated as poly(dimethylsilazane).
  • polysilazane any oligomeric or polymeric composition comprising a plurality of Si—N repeat units.
  • oligomer is meant any molecule or chemical compound which comprises several repeat units, generally from about 2 to 10 repeat units.
  • Polymer as used herein, means a molecule or compound which comprises a large number of repeat units, generally greater than about 10 repeat units.
  • each silicon atom is bound to two separate nitrogen atoms and each nitrogen atom to two silicon atoms, both chains and rings of the formula [R 1 R 2 Si-NR 3 ] may occur, where R 1 -R 2 can be hydrogen atoms or organic substituents. If all substituents R are H atoms, then the polymer is designated as perhydropolysilazane, polyperhydridosilazane, or inorganic polysilazane ([H2Si–NH]n). If hydrocarbon substituents are bound to the silicon atoms, the polymers are designated as organopolysilazanes. The synthesis of polyorganosilazanes was first described in 1964 by Krüger and Rochow. C. R. Krüger, E.
  • pre-ceramic (“pre-ceramic”) polymers heated to 1000 °C or higher were shown to split off organic groups and hydrogen and, in the process, the molecular network is rearranged to form amorphous inorganic materials.
  • PDCs polymer derived ceramics
  • the most important pre-ceramic polymers in the production of PDCs are polysilanes [R 1 R 2 Si-R 1 R 2 Si] n , polycarbosilanes [R 1 R 2 Si-CH 2 ] , polysiloxanes [R 1 R 2 Si-O] n and polysilazanes [R1R2Si-NR3] n . ).
  • polysiloxanes each silicon atom is bound to two oxygen atoms and each oxygen atom to at least two silicon atoms.
  • polysilazanes however, each silicon atom is bound to two nitrogen atoms and each nitrogen atom to at least two silicon atoms (three bonds to silicon atoms are also possible.
  • organopolysilazanes In organopolysilazanes, at least one organic substituent is bound to the silicon atom. The amount and type of organic substituents have a predominant influence on the macro-molecular structure of polysilazanes. Polysilazanes are colorless to pale yellow liquids or solid materials. Conditional of manufacturing, the liquids often contain dissolved ammonia that can be detected by smell, though this is not a preferred embodiment of the present invention and ammonia-free or lowered ammonia preparations are preferred. The average molecular weight can range from a few thousand to approximately 100,000 g/mol while the density normally lies around 1 g/cm 3 .
  • Solid polysilazanes are produced by chemical conversion of the liquid materials (crosslinking of smaller molecules).
  • the solid materials can be fusible or unmeltable and can be soluble or insoluble in organic solvents.
  • polysilazane solids behave as thermosetting polymers, but in some cases, thermoplastic processing is possible. After the synthesis, an aging process frequently takes place in which dissolved ammonia plays an important role.
  • the R3Si– NH2 groups resulting from the ammonolysis reaction form silazane units by splitting off ammonia. If ammonia cannot escape, the silazane units can be split again into R3Si–NH2 groups.
  • polysilzanes used in the invention are of reduced ammonia content or ammonia free.
  • functional groups that are not bound directly into the polymer backbone can react under suitable conditions (for example Si–H with N–H groups) and increase crosslinking of the rings and chains.
  • An increase in molecular weight can also be observed during storage at higher temperatures or in sunlight.
  • polysilazanes With contact to water or moisture, polysilazanes decompose more or less quickly. Water molecules attack the silicon atom and the Si–N bond is cleaved.
  • the R 3 Si–NH–SiR 3 forms R 3 Si– NH 2 and HO–SiR 3 which can further react (condensation) to form R 3 Si–O–SiR 3 (siloxanes).
  • the rate of the reaction with water (or other OH containing materials like alcohols) depends on the molecular structure of the polysilazanes and the substituents. Perhydropolysilazane [H 2 Si–NH] n will decompose very quickly and exothermically with contact to water while polysilazanes with large substituents react very slowly. Polysilazanes are not vaporizable because of strong intermolecular forces. Heating polysilazanes results in crosslinking to form higher molecular weight polymers.
  • a further temperature increase can result in crystallization of the amorphous material and the formation of silicon nitride, silicon carbide and carbon.
  • This so-called pyrolysis of the polysilazanes produces preferred ceramic materials from low-viscosity liquids with very high yield (up to 90%). Due to the organic groups that are often used to give good polymer processability, preferred ceramic yield is normally in the range of 60-80%.
  • polysilazanes have been synthesized and characterized, and their great potential for many applications was acknowledged. However, up to now, very few products have been developed into a marketable commodity.
  • the most preferred polysilazane used in a most preferred embodiment of the invention is a commercially available product called Durazane® 1800, available from Merck KGaA of Darmstadt, Germany.
  • This polysilazane is a liquid phase, low-viscosity, solvent-free organic polysilazane resin having the industrial properties of being a coating binder and a polymeric ceramic precursor.
  • Durazane® 1800 exhibits good adhesion, good hardness, hydrophobicity, and good barrier properties. When used as a polymeric ceramic precursor, it yields a preferred pyrolyzed ceramic material that shows excellent high temperature stability, being able to endure peak temperatures of up to 1000 ° C, which is well within the range of temperatures encountered in the hot-stamping process.
  • Durazane 1800 exhibits the following properties in approximately or about the quantities and ranges expressed here: Dry film thickness: 8 – 10 ⁇ m.
  • Conditions of use Pretreatment: Grease and dust/particle free surface of substrates are required. Sandblasting of metal substrates is preferred.
  • Curing conditions Optimally cured with radical initiators, which allows a reduction of the curing temperature or time (for example 2h/150°C with addition of 0.5 – 2 wt.-% dicumylperoxide [DCP] or 2h/130°C with addition of 0.5 – 2 wt.-% Luperox531M80 [LP]).
  • Non catalytic curing 250°C for 0.5 h; 180°C for 3 – 4 h.
  • Pyrolysis Pyrolysis takes place at temperatures >500°C.
  • Dilution/Formulation Dilution is possible with organic solvents such as alkanes (e.g. heptane, isoalkanes), esters (e.g. ethyl acetate, butyl acetate, propylene glycol, methyl ether acetate), ethers (e.g. THF, di-n butyl ether), aromates (e.g. toluene, xylene) or ketones (e.g. methyl ethyl ketone).
  • alkanes e.g. heptane, isoalkanes
  • esters e.g. ethyl acetate, butyl acetate, propylene glycol, methyl ether acetate
  • ethers e.g. THF, di-n butyl ether
  • aromates e.g. toluene, xylene
  • ketones e.g. methyl ethyl ketone
  • Durazane® 1800 may be blended with multiple alternative embodiment coating components, including organic pigments, pigment preparations, metal powders (zinc, aluminum), ceramic powders to increase the ceramic properties of the final admixture (e.g. silicon nitride, boron carbide, aluminum oxide, boron nitride, or silicon nitride) and many alternative co-binders and additives.
  • organic pigments e.g. silicon nitride, boron carbide, aluminum oxide, boron nitride, or silicon nitride
  • ceramic powders e.g. silicon nitride, boron carbide, aluminum oxide, boron nitride, or silicon nitride
  • Aluminum Aluminum Pigment as a Source.
  • the preferred metal constituent of the invention is the metal aluminum. In a most preferred embodiment, aluminum is sourced from the use of a suitable aluminum pigment.
  • the most preferred aluminum source used in a most highly preferred embodiment of the invention, is a commercially available as a non-waterborne aluminum paste product called STAPA Metallic R 507 R Aluminium Paste, article number 057307G70, SDS number 102000030579, available from the United States Eckart America Corporation, at 830 East Erie Street, Painesville, Ohio, 44077, which is a division of Eckart GmbH & Co. KG, Kaiserstrasse 30, D-90763 Furth, a division of Altana Corporation, of Hartenstein, Germany.
  • This aluminum paste which is a silver pasty in appearance and more specifically a non-leafing aluminum pigment paste, and more specifically a pigment paste of flaky (cornflake) aluminum powder produced of pure aluminum, CAS number 7429-90-5, with an inorganic coating.
  • Properties that characterize the aluminum pigments in the HYDROLAN® line of aluminum pigments are that these silica-encapsulated pigments are very shear-stable, and that they are off- gassing resistant.
  • the specific gravity is about about 1.5 kg/l and its density may preferably be in a range of approximately 1.3 g/cm 3 to approximately 2 g/cm 3 .
  • the highly preferred solvents used are mineral spirits and hydrotreated heavy petroleum naptha, CAS number 64742-48-9, and light aromatic petroleum solvent naptha, where the ratio of the mineral spirits presence to the combined naptha presence is in a ratio of 1/1 by weight, giving the product a non-volatile content of approximately 63 to 67% and a volatile content of approximately 33 to 37%. It passes wet sieving standard DIN 53196 at 40 ⁇ m, over 99%. The particle size distribution is: D 10, approximately 7 ⁇ m, D 50 approximately 21 ⁇ m, and D90, approximately 44 ⁇ m.
  • Mineral spirits for example [CAS 8052-41-3] are a genus of a type of chemical substances that are 100% petroleum distillate liquid hydrocarbon solvent mixtures of aliphatic and alicyclic petroleum-based compounds, and have no additives. As a genus, they are for example typically a mixture of aliphatic, open chain, and alicyclic C7 to C12 aromatic hydrocarbons.
  • a typical composition for mineral spirits is > 65% C10 or higher hydrocarbons that are aliphatic, aliphatic solvent hexane, and a maximum benzene content of 0.1% by volume, a kauri-butanol value of 29, an initial boiling point of 145 °C (293 °F) to 174 °C (345 °F), and a density of 0.79 g/ml.
  • Mineral spirits are typically formed by the molecular interaction via distillation of paraffin (aliphatic) and cyclo-propane (alicyclic) with aromatic compounds.
  • Mineral spirits having an odor- quality suitable for use as a solvent particularly in the paint, varnish and resin trades are produced by a process comprising (1) treating a feed naphtha boiling between about 325 and 425 F that has been derived from hydrocarbons containing from 3 to 8 carbon atoms, which feed is characterized by being essentially free of olefins and aromatic hydrocarbons and elemental sulfur, with an effective amount of sulfuric acid having a concentration of between about 90 and 100 weight percent, (2) separating acid sludge from treated naphtha, (3) rain-washing said treated naphtha with liquid water to remove substantially all of the occluded-acids ludge particles therefrom, (4) separating rain-wash water from rain-washed naphtha, (5) intimately contacting said naphtha from step (4) with liquid water, (6) separating all water from washed naphtha, (7) contacting said washed naphtha with an aqueous alkaline solution to essentially neutralize said washed nap
  • the feed to the process of this invention is composed essentially of a mixture of paraffinic and isoparatinic hydrocarbons, i. e., is essentially free of olefins and aromatic hydrocarbons. Very small amounts of organic sulfur compounds may be present, but are very undesirable.
  • the feed must be essentially free of hydrogen sulfide and elemental sulfur.
  • a typical composition for mineral spirits is: aliphatic solvent hexane having a maximum aromatic hydrocarbon content of 0.1% by volume, a kauri-butanol value of 29, an initial boiling point of 149 °F (65 °C), a dry point of approximately 156 °F (69 °C), and a specific mass of 0.7 g/cc.
  • Silica encapsulation materials are, for example, alkaline colloidal silicas, aqueous dispersions of silica with average particle size of approximately 12nm to approximately 22nm, or acidic deionized colloidal silica of particle approximately 12nm to approximately 22nm.
  • Suitable silica materials are available commercially from, for example, LUDOX® Colliodal Silica Products through the Chempoint Company. Descriptions of such encapsulated aluminated pigments are found in the article “Encapsulated Aluminum Pigments”, Progress in Organic Coatings, Volume 37, Issues 3-4, December 1999, pages 179-183, the entire disclosure of whch is incorporated herein by reference.
  • STAPA Hydrolan 501 is a most preferred embodiment of the STAPA® Hydrolan line of non-leafing, aluminum pigments. It is used in general industrial, automotive and accessories coatings.
  • STAPA IL HYDROLAN 501 material number 005332, is an aluminum paste, more specifically a pigment paste of flaky aluminum powder produced of pure aluminum with an inorganic coating. Properties that characterize all aluminum pigments for waterborne, aqueous coating systems in the HYDROLAN® line of aluminum pigments are that these silica encapsulated pigments are very shear-stable, and that they are off-gassing resistant.
  • the specific gravity is 1.4 kg/l.
  • the solvent used is isopropanol (IL) and the preparation includes miscellaneous lubricants and additives.
  • the pigment composition is aluminum app.53%.
  • Preferred Aluminum Powder characteristics TI00004 pigment content / non volatile 58.0-62.0% TI00004 volatile content 38.0-42.0% TI00005 sieving ⁇ 63 ⁇ m 99.9-100.0% TI00009 D 10 7.0-11.0 micrometers TI00009 D 50 22.0-28.0 micrometers TI00009 D 90 44.0-52.0 micrometers Aluminum acetylacetonate.
  • Aluminum acetylacetonate (aluminum 2,4-pentanedionate), also referred to as Al(acac)3, is a preferred aluminum coordination complex with formula Al(C5H7O2)3, molecular weight 324.31 g/mol, CAS number 13963-57-0.
  • This aluminum coordination complex with three acetylacetone ligands is used as a precursor in the preparation of aluminum oxide films.
  • the molecule has D3 symmetry, being isomorphous with other octahedral tris(acetylacetonate)s.
  • Aluminum acetylacetonate may additionally be used to prepare transparent superhydrophobic boehmite and silica films by sublimation, to deposit alumunum oxide films by chemical vapor deposition, to deposit alumunum oxide films by chemical vapor deposition, and as a catalyst.
  • Acetylacetonates are coordination complexes derived from acetylacetone and metal salts, most often salts of transition metals, and most preferably aluminum. These compounds allow many metal ions to be soluble in organic solvent, in contrast to most metal salts. This allows them to be used as catalyst precursors and reagents in reactions which occur in organic phase in chemical synthesis.
  • Acetylacetonates are also frequently used as shift reagents in nuclear magnetic resonance (NMR) spectroscopy, a research and analysis technique that exploits magnetic properties of atomic nuclei to provide detailed information about a chemical substance.
  • Aluminum acetylacetonate is commercially available from Sigman-Aldrich of St. Louis, Missouri.
  • Alternative embodiments of the metal component of the coating invention comprise metal nitrides or carbides, with the metal nitride or carbide preferably comprising or consisting of nitrides and/or nitride anhydrates or carbides of silicon, titanium, zirconium, iron, aluminum, cerium, chromium and/or mixtures thereof.
  • the metallic substrates upon which the metal nitride coatings are applied may alternatively be selected from the group consisting of aluminum, copper, zinc, tin, brass (gold bronze), iron, titanium, chromium, nickel, silver, gold, steel, and also their alloys and/or mixtures.
  • Preferred in this context is steel.
  • Solvents. Preferred solvents used in admixing the compositions of the invention are organic aromatic solvents.
  • the most preferred organic aromatic solvent is commercially available as Hi Sol 15, which is itself a mixture of the organic aromatic solvents diethylbenzene,1,2-diethylbenzene, 1,3- diethylbenzene, 1,4-diethylbenzene, 1,2,3-trimethylbenzene,1,2,4-Trimethylbenzene or 1,3,5- trimethylbenzene, polyethylbenzene, aka solvent naphtha, naphthalene, 2- methylindole, and cumene. Catalysts.
  • the addition of a suitable catalyst confers the advantage of achieving a customized or preferred drying time or curing time of the coating on the selected steel article.
  • Target drying time or curing time may be achieved, reduced, or increased through selection of the catalyst and adjustment of the amount of the selected catalyst in the admixture.
  • the most preferred catalyst for use in the invention admixture is diazabicycloundecene, 1,8- Diazabicyclo[5.4.0]undec-7-ene, CAS 6674-22-2. This catalyst is commonly used in organic synthesis as a catalyst, a complexing ligand, a non-nucleophilic base, and as a protecting agent if needed during organic synthesis.
  • the most preferred amount of this catalyst is in the range of 0.5 to 5.0% by weight, with the operator having the freedom to adjust the concentration of catalyst upward or downward to optimize the drying time or the cure time of the coating composition.
  • Bases The most highly preferred base to use in the admixture of the invention is BEMP- phosphazene (2-tert-Butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diaza phosphorine), CAS 98015-45-3. This base is a member of the family of phosphazene bases.
  • Phosphazene bases are strong, uncharged bases that are non-metallic, non-ionic and low nucleophilic bases. They are stronger bases than regular amine or amidine bases. Protonation takes place at the doubly bonded nitrogen atom. Properties of phosphazene bases include the ability to generate in situ highly reactive "naked" anions, e.g.
  • ionic bases for alkylation reactions or for spectroscopic investigations; that they are applicable in reactions where ionic bases cause solubility problems; that they are useful in reactions where ionic bases are sensitive towards oxidation or acylation; and that they are useful in reactions where ionic bases result in Lewis-acid catalyzed side reactions, for example in aldol reactions, epoxide-opening, hydride shifts, elimination of alkoxide, and polyanion-formation.
  • a suitable phosphorous base compound confers the additional advantage of achieving a further customized or preferred drying time or curing time of the coating on the selected steel article.
  • Target drying time or curing time may be achieved, reduced, or increased through selection of the phosphorous base and adjustment of the amount of the selected phosphorous base in the admixture.
  • Methods of Application In the production of sheet steel in general, and in hot rolled sheet steel in particular, the process begins with heating slabs of steel to approximately 2,300 degrees Fahrenheit. The amount of heat directly affects the properties of the steel. Meaning, if the temperature is not high enough it can cause defects in the material. This is likely due to carbides (compound of carbon) and nitrates (polyatomic ion-an even more complex term) not fully dissolving. When the hot material is being transferred from the furnace, it reacts with the oxygen in the atmosphere.
  • This reaction forms a mill scale or a flaky surface of iron oxides. Since the mill scale can affect the surface quality of the hot rolled steel if left alone, such iron oxides are removed by then sending the material through a mill scale cleanse by being cleansed by spraying with extremely high pressure water. The cleansed material is then sent through a rolling mill and is rolled from a thickness of roughly nine inches to an inch. The process consists of a series of four to five stands (set of rollers) that decrease the thickness and increase the length by horizontal rolls. The material is also squeezed vertically to control the width. At this stage the material’s ends are sheared to create a transfer bar. The transfer bar is sent through another series of stands to further reduce the thickness to the desired sheet gauge.
  • the flat-rolled steel is delivered across a runout table that consists of cooling sprays.
  • the cooling rate may be modified for each strip to create the desired properties of the coiled end product.
  • the application of the curable protective coating compositions of the present invention may take place at a suitable part of the rolled sheet steel production process by using the application methods known in the prior art such as bar coating, air-knife coating, roll coating, spray coating and dip coating. In those cases in which flat substrates are to be coated, the application preferably takes place in the roller application method.
  • a pretreatment for Si-based passivation on the steel coil may be applied prior to the application of the coating composition on the substrate.
  • the curable protective coating composition can be applied by roller application onto the steel surface after the steel is manufactured in a steel manufacturing mill, or can be applied by spraying or other suitable dispersive process onto the steel surface at a hot-stamping site.
  • the post-application cured coating polymeric, pre-ceramic, or ceramic product of the invention can also provide corrosion protection to the steel during storage and transfer between two industrial sites.
  • the coating composition can be cured by flashing off at room temperature or by accelerated curing at an elevated temperature, in which case temperatures of preferably up to 300° C.
  • the curable protective coating composition is cured under a temperature 100° C. to 300° C for a polymeric coating or of 300 to 1000° C for a ceramic coating. Accelerated curing by means for example of IR radiation, forced- air drying, UV irradiation or electron beam curing may also be useful.
  • the coating can be applied not only to flat substrates but also to coils which are passing through a cold and/or hot forming step, or else the coating can be applied to substrates which have already undergone cold forming.
  • the coating composition according to the present invention may be applied in so called “direct” or "indirect” hot forming/stamping processes.
  • a flat substrate coated with the protective coating composition is sequentially pre-stamped, heated and then hot stamped.
  • the coated flat substrate is first heated and then hot stamped.
  • the present coating composition is suitable particularly for the surface coating of a substrate whose surface is composed at least partly of steel.
  • the coating composition is intended in particular for the surface coating of substrates made of carbon steel, and is suitable preferentially for the surface coating of a high-strength steel substrate which, following the surface coating, is subjected to a hot forming operation or hot stamping process, in particular to hot forming at temperatures between 800° C. and about 1000° C., preferably at between about 880° C. and about 970° C.
  • These types of steels are, for example, duplex steels alloyed with chromium, nickel, and manganese, and boron-manganese steels.
  • Suitable examples of coating film modifiers are cellulosic materials, such as cellulose esters and cellulose ethers; homopolymers or copolymers from styrene, vinylidene chloride, vinyl chloride, alkyl acrylate, alkyl methacrylate, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, vinyl ether, and vinyl acetate monomers; polyesters or copolyesters; polyurethanes or polyurethane acrylates; epoxy resins; polyvinylpyrrolidone; polytetrafluoromethylene, polyphenyl, polyphenylene, polyimide and polytetrafluoroethylene.
  • the compounds of the present invention can be prepared readily according to the following Examples or modifications thereof using readily available starting materials, reagents and conventional synthesis procedures.
  • EXAMPLE 1 Into a suitably sized mixing vessel were added 445 pounds of Hi Sol 15 Aromatic 150 organic solvent, 145 pounds of Hydrolan Aluminium 501 aluminum pigment, 389.45 pounds of Durazane 1800 Polysilizane, and 20.55 pounds of 1,8-diazabicycloundecene catalyst, which were then mixed under medium speed agitation until a lump free, smooth, and homogeneous mixture was achieved; estimated curing time of the admixture was adjusted by titrating the admixture with the addition of aluminum acetylacetonate and adding 2-tert-butylimino-2-diethylamino-1,3- dimethylperhydro-1,3,2-diazaphosphorine base .
  • EXAMPLE 4 Into a suitably sized mixing vessel are added 444 pounds of Hi Sol 15 Aromatic 150 organic solvent, 175 pounds of Hydrolan Aluminium 501 aluminum pigment, 300 pounds of Durazane 1800 Polysilizane, and 15 pounds of 1,8-diazabicycloundecene catalyst, which is then mixed under medium speed agitation until a lump free, smooth, and homogeneous mixture was achieved; estimated curing time of the admixture is adjusted by titrating the admixture with the addition of aluminum acetylacetonate and adding and 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2- diazaphosphorine base .
  • EXAMPLE 5 Into a suitably sized mixing vessel are added 444 pounds of Hi Sol 15 Aromatic 150 organic solvent, 175 pounds of Hydrolan Aluminium 501 aluminum pigment, 500 pounds of Durazane 1800 Polysilizane, and 15 pounds of 1,8-diazabicycloundecene catalyst, which is then mixed under medium speed agitation until a lump free, smooth, and homogeneous mixture is achieved; estimated curing time of the admixture is adjusted by titrating the admixture with the addition of aluminum acetylacetonate and adding and 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2- diazaphosphorine base .
  • the process of hot stamping for press hardening steels involves heating the steel blanks to elevated temperatures for austenitization in a furnace, followed by transferring the blanks to a stamping press for simultaneous die forming and quenching operations.
  • the press hardening boron steels utilized for hot stamping of structural parts are hot dip coated with AlSi 10 Fe 3 alloy (aluminized), aimed at avoiding the formation of scale during heating in the furnace.
  • the coating development progresses above the austenite finish temperature, where the outward diffusion of Fe and Mn from the steel substrate into the AlSi 10 Fe 3 coating results in the formation of Al-Fe-Si intermetallic phases at the coating surface, and the inward diffusion of Al and Si from the coating into the steel substrate causes the growth of the interdiffusion layer at the steel-coating interface.
  • Longer soaking times above these temperatures result in reduced performance during welding and painting operations of the hot formed parts, leading to an increase in the thickness of the interdiffusion layer and the total coating thickness.
  • Industry standards therefore, restrict the coating development during the residence time in the furnace to a maximum interdiffusion layer thickness of 12 to 16 microns and a maximum total coating thickness of 30 to 50 microns.
  • a new coating for press hardening steel is described as an alternative to the traditional aluminized AlSi 10 Fe 3 coating used in the hot stamping process.
  • the new coating is a heat-resistant paint that consists of polysilazane as a pre-ceramic polymer and aluminum powder as an active filler.
  • the heat-resistant paint coating was applied to a 22MnB5 steel substrate with a thickness of 0.9mm in coil form using an industrial roller coating pre-paint line.
  • a 22MnB5 PHS with a thickness of 0.9mm and coated with a typical hot dip aluminized coating was used as a baseline for comparison purposes.
  • the behavior and development of the new coating during heating in the furnace were analyzed using differential scanning calorimetry (DSC) and Continuum Depth Profile with Glow Digital Spectrometry (CDP-GDS).
  • DSC differential scanning calorimetry
  • CDP-GDS Continuum Depth Profile with Glow Digital Spectrometry
  • SEM-EDX energy-dispersive X-Ray spectroscopy
  • DSC Differential Scanning Calorimetry
  • the DSC signal of the aluminized coated sample exhibited a peak starting at around 580°C and ending at approximately 640°C, which corresponds to the melting point and solidification of the AlSi 10 Fe 3 as a eutectic coating.
  • a second DSC signal peak was observed, starting at around 720°C and ending at approximately 840°C, which corresponded to the phase transformation of ferrite to austenite in the 22MnB5 steel substrate.
  • the DSC signal of the paint coated 22MnB5 sample exhibited a smooth inverted peak between 485°C and 530°C, corresponding to a low energy exothermic reaction in the paint coating.
  • the absence of the melting point of the paint coating during heating was reflected in differences between DSC signals for the paint and for the aluminized coated samples.
  • the aluminized coated blanks underwent an optimized thermal cycle with a production intent, consisting of a 3-minute furnace residence time at 930°C.
  • the paint coated blanks were loaded into the furnace at a soaking temperature of 930°C and subjected to furnace residence times of 2 minutes and 5 minutes for this study. After the furnace residence time, the blanks were unloaded and transferred to the press within 10 seconds, followed by die forming and quenching with a 3-second die dwell time.
  • K-type thermocouples were welded onto the paint and aluminized coated blanks and were monitored using a data acquisition system to determine the temperature profiles of the 22MnB5 steel substrate during the furnace residence time.
  • the experimental results were plotted to show the temperature profiles of the paint and aluminized coated blanks. From this it was observed that the paint coated blank reached the furnace soaking temperature of 930C in approximately 25 seconds, with an average heating rate of 36C/s. On the other hand, the hot-dip aluminized coated blank required approximately 130 seconds to reach the furnace soaking temperature, resulting in an average heating rate of 7C/s.
  • the oxygen concentration measured near the surface displayed an increase from 7%O for 0 minutes furnace residence time to 60%O and 68%O for 5 minutes and 2 minutes of furnace residence time, respectively.
  • the carbon elemental profile of the paint coating underwent significant changes upon heating at 930°C.
  • the near-surface carbon percentage which was measured to be approximately 22% for the 0- minute condition, decreased to 3% and 1% for the 2-minute and 5-minute furnace residence time conditions, respectively.
  • the carbon elemental profiles for the 2-minute and 5-minute conditions overlapped after a depth of 1.5 microns into the coating.
  • CDP-GDS methods were utilized to determine the thickness of the paint coating on the steel substrate.
  • the nominal thickness of the paint coating wa determined by the intersection of the silicon and manganese elemental profiles, referred to as the Si-Mn intersect. Based on this method, the paint coating thickness of the 0-minute sample was measured to be 7.7 microns, while the thickness of the 2-minute and 5-minute sample conditions were measured to be 5.9 microns and 6.1 microns, respectively.
  • the difference in the coating thickness measurements between the 0-minute condition and the 2-minute and 5- minute furnace residence time conditions can be attributed to the shrinkage of the polymer during the cross-linking and pyrolysis processes.
  • the cured surface of the paint coating was composed of a continuous network of iron-silicon oxides (approximately 19% FeSiO) surrounding a matrix of silicon-aluminum oxides (approximately 60% SiAlO) and globular particles of aluminum- silicon-iron oxides (approximately 4% AlSiFeO) evenly distributed throughout the network.
  • the cured paint coating surface further evolved to consist of a matrix of silicon-aluminum oxides (approximately 34% SiAlO) with a network of iron oxide (approximately 17% FeO) and globular iron-silicon oxide (approximately 18% FeSiO), and islands of aluminum-silicon-iron oxides (approximately 9% AlSiFeO) evenly distributed throughout the network.
  • the mechanism of the paint coating development on sheet steel is believed to be that the polysilazine polymer undergoes an exothermic reaction, resulting in a reduction in the total coating thickness due to shrinkage during cross-linking and pyrolysis and the transition from an amorphous to crystalline phase.
  • the coating is subjected to inward diffusion of oxygen from the furnace atmosphere and outward diffusion of iron from the steel substrate, leading to altered phase compositions and morphologies.
  • a two-minute residence time at 930°C results in an enrichment of Si oxide islands with Fe, leading to the formation of a network of Fe-Si oxides and islands of Al-Si-Fe oxides in a Si-Al oxide matrix.
  • Further increasing the residence time to five minutes results in additional diffusion of Fe from the steel substrate, leading to a modification of the Fe-Si oxide phase morphology from a network to a globular structure, and the formation of a new Fe oxide network.
  • the mechanism of the paint coating development on sheet steel is believed to be that the polysilazine polymer undergoes an exothermic reaction, resulting in a reduction in the total coating thickness due to shrinkage during cross-linking and pyrolysis and the transition from an amorphous to crystalline phase.
  • the coating is subjected to inward diffusion of oxygen from the furnace atmosphere and outward diffusion of iron from the steel substrate, leading to altered phase compositions and morphologies.
  • a two-minute residence time at 930°C results in an enrichment of Si oxide islands with Fe, leading to the formation of a network of Fe-Si oxides and islands of Al-Si-Fe oxides in a Si-Al oxide matrix.

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Abstract

L'invention concerne des compositions de revêtement de tôle mince en acier dans lesquelles des propriétés de résine polymère ou de céramique sont produites par mélange d'un complexe coordonné d'aluminium et d'une pâte de particules d'aluminium, encapsulées, anhydres, d'un polysilazane en tant que source de silicium, d'un solvant organique, d'un catalyseur de synthèse organique, et éventuellement d'une base non métallique, non ionique, faiblement nucléophile. Le revêtement mélangé est appliqué sur une tôle mince en acier avant estampage à chaud afin d'inhiber la formation de surface d'oxydes de fer et d'améliorer les caractéristiques de surface de la tôle mince en acier.
PCT/US2023/013751 2023-02-23 2023-02-23 Compositions de revêtement de protection d'acier améliorées, leurs procédés de fabrication et leurs procédés d'utilisation WO2024177636A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006040030A1 (fr) * 2004-10-08 2006-04-20 Volkswagen Aktiengesellschaft Procede de revetement de surfaces metalliques
US20090084472A1 (en) * 2003-08-04 2009-04-02 General Electric Company Organic coating compositions for aluminizing metal substrates, and related methods and articles
WO2022182791A1 (fr) * 2021-02-23 2022-09-01 Thor Custom Steel Coatings LLC Compositions de revêtement protecteur en acier, leurs procédés de fabrication et leurs procédés d'utilisation

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090084472A1 (en) * 2003-08-04 2009-04-02 General Electric Company Organic coating compositions for aluminizing metal substrates, and related methods and articles
WO2006040030A1 (fr) * 2004-10-08 2006-04-20 Volkswagen Aktiengesellschaft Procede de revetement de surfaces metalliques
WO2022182791A1 (fr) * 2021-02-23 2022-09-01 Thor Custom Steel Coatings LLC Compositions de revêtement protecteur en acier, leurs procédés de fabrication et leurs procédés d'utilisation

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