Birchwood Laboratories, Inc.

Economics Laboratory, Inc.

Fremont Industries, Inc.

William V Block

Bryce D Devine

Keith N Ravenscroft

Dennis F Mahoney

David J Halverson

Edward H Chang

John T Nguyen

John Thanh Ngoc Nguyen

Mark L Gruss

The present invention relates to methods and compositions for coating aluminum substrates. In an embodiment, the invention includes a method of applying a coating on an aluminum substrate including contacting the aluminum substrate with a first solution. The first solution can include a zinc metal salt, a sugar acid or alkali metal salt thereof, and an alkali metal hydroxide. The method can also include contacting the aluminum substrate with a second solution. The second solution can include a molybdate salt, an alkanolamine, and a fluorine acid. Other embodiments are also included herein.

Methods and compositions for coating aluminum substrates

A process for forming a magnetite coating on a ferrous metal surface and for chemical reagents used to implement the coating process. The process comprises the step of making the ferrous metal surface more reactive by contacting the surface with an activating reagent and then contacting the activated surface with an oxidizing reagent to form the coating at a relatively low temperature range. The surface is activated by contact with an acid solution to form a surface rich in reactive iron. The activated surface is then oxidized by contact with an aqueous reagent of alkali metal hydroxide, alkali metal nitrate, alkali metal nitrite, and mixtures thereof.

Ferrous metal magnetite coating processes and reagents

The ferrous metal chemical conversion coating is comprised of mixed oxides and organometallic compounds of aluminum and iron. A ferrous metal substrate is immersed for a period of time in a bath composition, at a temperature, at a pH, and at a concentration for each constituent of the bath composition, that will form a coating with the desired characteristics. The bath composition comprises water, aluminum salt, oxalic acid, and an oxidizer. The conversion coating is amorphous in nature and can be formed as thin as 1 micron with a coating weight in the range of about 40-250 milligrams per square foot. When sealed with an appropriate rust preventive material, the coating enhances corrosion resistance of the ferrous metal substrate. It is an effective absorbent base for paint finishes. When top coated with a lubricant, the conversion coating aids (a) assembly of parts, (b) break-in of sliding surfaces, and (c) anti-galling.

Bath composition for converting surface of ferrous metal to mixed oxides and organometallic compounds of aluminum and iron

Process for making bath composition for converting surface of ferrous metal to mixed oxides and organometallic compounds of aluminum and iron

The ferrous metal chemical conversion coating is comprised of mixed oxides and organometallic compounds of aluminum and iron. A ferrous metal substrate is immersed for a period of time in a bath composition, at a temperature, at a pH, and at a concentration for each constituent of the bath composition, that will form a coating with the desired characteristics. The bath composition comprises water, aluminum salt, oxalic acid, and an oxidizer. The conversion coating is amorphous in nature and can be formed as thin as 1 micron with a coating weight in the range of about 40&#x2013;250 milligrams per square foot. When sealed with an appropriate rust preventive material, the coating enhances corrosion resistance of the ferrous metal substrate. It is an effective absorbent base for paint finishes. When top coated with a lubricant, the conversion coating aids (a) assembly of parts, (b) break-in of sliding surfaces, and (c) anti-galling.

Hybrid metal oxide/organometallic conversion coating for ferrous metals

This invention is a method for forming a chemical conversion coating on ferrous metal substrates, the chemical solutions used in the coating and the articles coated thereby. By modifying and combining the features of two existing, but heretofore unrelated, coating technologies, a hybrid conversion coating is formed. Specifically, a molecular iron/oxygen-enriched intermediate coating, such as a dicarboxylate or phosphate, is applied to a ferrous substrate by a first oxidation. The intermediate coating pre-conditions the substrate to form a surface rich in molecular iron and oxygen in a form easily accessible for further reaction. This oxidation procedure is followed by a coloring procedure using a heated (about 120-220 F) oxidizing solution containing alkali metal hydroxide, alkali metal nitrate, alkali metal nitrite or mixtures thereof, which reacts with the iron and oxygen enriched intermediate coating to form magnetite (FeO). The result is the formation of a brown or black finish under much more favorable, milder and safer conditions than previously seen with conventional caustic blackening processes, by virtue of the chemical reaction between the intermediate coating and the second oxidation solution. When sealed with an appropriate rust preventative topcoat, the final result is an ultra-thin, attractive and protective finish applied through simple immersion techniques. The finish is a final protective coating on a fabricated metal article and also affords a degree of lubricity to aid assembly, break-in of sliding surfaces or provide anti-galling protection. The finish also provides an adherent base for paint finishes.

Composition and method for metal coloring process

This invention includes improvements to a method for forming a chemical conversion coating on ferrous metal substrates, to the chemical solutions used in the coating and to the articles coated thereby. A first oxidation applies a molecular iron/oxygen-enriched intermediate coating, such as a dicarboxylate or phosphate, to a ferrous substrate. A coloring procedure (a second oxidation) follows the first oxidation procedure, using a heated oxidizing solution that reacts with the iron and oxygen enriched intermediate coating to form magnetite (FeO). The result is the formation of a brown or black finish. An appropriate rust preventive topcoat may seal the substrate. The finish affords protection, a degree of lubricity to aid assembly, break-in of sliding surfaces, provides anti-galling protection and an adherent base for paint finishes. Improvements to the first oxidation include a broader range of operating conditions, the addition of a hydroxylamine accelerator or a wetting agent, and operation by slurry deposition. Improvements to the second oxidation include a broader range of operating conditions, and the addition of a sequestrant or thio-based accelerator.

Metal coloring process and solutions therefor

This invention is a method for forming a chemical conversion coating on ferrous metal substrates, the chemical solutions used in the coating and the articles coated thereby. By modifying and combining the features of two existing, but heretofore unrelated, coating technologies, a hybrid conversion coating is formed. Specifically, a molecular iron/oxygen-enriched intermediate coating, such as a dicarboxylate or phosphate, is applied to a ferrous substrate by a first oxidation. The intermediate coating pre-conditions the substrate to form a surface rich in molecular iron and oxygen in a form easily accessible for further reaction. This oxidation procedure is followed by a coloring procedure using a heated (about 120-220&deg; F.) oxidizing solution containing alkali metal hydroxide, alkali metal nitrate, alkali metal nitrite or mixtures thereof, which reacts with the iron and oxygen enriched intermediate coating to form magnetite (Fe O ). The result is the formation of a brown or black finish under much more favorable, milder and safer conditions than previously seen with conventional caustic blackening processes, by virtue of the chemical reaction between the intermediate coating and the second oxidation solution. When sealed with an appropriate rust preventative topcoat, the final result is an ultra-thin, attractive and protective finish applied through simple immersion techniques. The finish is a final protective coating on a fabricated metal article and also affords a degree of lubricity to aid assembly, break-in of sliding surfaces or provide anti-galling protection. The finish also provides an adherent base for paint finishes.

This invention is a method for forming a chemical conversion coating on ferrous metal substrates, the chemical solutions used in the coating and the articles coated thereby. By modifying and combining the features of two existing, but heretofore unrelated, coating technologies, a hybrid conversion coating is formed. Specifically, a molecular iron/oxygen-enriched intermediate coating, such as a dicarboxylate or phosphate, is applied to a ferrous substrate by a first oxidation. The intermediate coating pre-conditions the substrate to form a surface rich in molecular iron and oxygen in a form easily accessible for further reaction. This oxidation procedure is followed by a coloring procedure using a heated (about 120-220 F.) oxidizing solution containing alkali metal hydroxide, alkali metal nitrate, alkali metal nitrite or mixtures thereof, which reacts with the iron and oxygen enriched intermediate coating to form magnetite (Fe O ). The result is the formation of a brown or black finish under much more favorable, milder and safer conditions than previously seen with conventional caustic blackening processes, by virtue of the chemical reaction between the intermediate coating and the second oxidation solution. When sealed with an appropriate rust preventative topcoat, the final result is an ultra-thin, attractive and protective finish applied through simple immersion techniques. The finish is a final protective coating on a fabricated metal article and also affords a degree of lubricity to aid assembly, break-in of sliding surfaces or provide anti-galling protection. The finish also provides an adherent base for paint finishes.

This invention is a method for forming a chemical conversion coating on ferrous metal substrates, the chemical solutions used in the coating and the articles coated thereby. By modifying and combining the features of two existing, but heretofore unrelated, coating technologies, a hybrid conversion coating is formed. Specifically, a molecular iron/oxygen-enriched intermediate coating, such as a dicarboxylate or phosphate, is applied to a ferrous substrate by a first oxidation. The intermediate coating pre-conditions the substrate to form a surface rich in molecular iron and oxygen in a form easily accessible for further reaction. This oxidation procedure is followed by a coloring procedure using a heated (about 120-220&deg; F.) oxidizing solution containing alkali metal hydroxide, alkali metal nitrate, alkali metal nitrite or mixtures thereof, which reacts with the iron and oxygen enriched intermediate coating to form magnetite (Fe,O,). The result is the formation of a brown or black finish under much more favorable, milder and safer conditions than previously seen with conventional caustic blackening processes, by virtue of the chemical reaction between the intermediate coating and the second oxidation solution. When sealed with an appropriate rust preventative topcoat, the final result is an ultra-thin, attractive and protective finish applied through simple immersion techniques. The finish is a final protective coating on a fabricated metal article and also affords a degree of lubricity to aid assembly, break-in of sliding surfaces or provide anti-galling protection. The finish also provides an adherent base for paint finishes.

Alkaline compositions useful to form aqueous paint stripping solutions are disclosed which comprise mixtures of an alkali metal hydroxide, a polyoxyalkylene polyamine accelerator and, optionally, a glycol or glycol ether accelerator.

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Apple Valley, MN, United States of America

William V Block