# US 8,784,994 B2 · Process for surface treating magnesium alloy and article made with same

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- Number: US 8,784,994 B2
- Document ID: US8784994B2
- Status: Granted
- Kind: B2
- Application number: 13/188,575
- Filed: 2011-07-22
- Published: 2012-07-05
- Granted: 2014-07-22
- Earliest claimed: 2010-12-30
- Assignees: HONG FU JIN PRECISION INDUSTRY (ShenZhen) CO., LTD.; Hon Hai Precision Industry Co., Ltd.
- Applicants: Hsin-Pei Chang; Wen-Rong Chen; Huann-Wu Chiang; Cheng-Shi Chen; Dun Mao
- Inventors: Hsin-Pei Chang; Wen-Rong Chen; Huann-Wu Chiang; Cheng-Shi Chen; Dun Mao
- Web page: https://patentgrep.com/patent/US8784994B2

## CPC

- C23G 1/12: Light metals
- C23C 14/024: {Deposition of sublayers, e.g. to promote adhesion of the coating (C23C14/027 takes precedence)}
- C23C 14/0641: {Nitrides (C23C14/0617 takes precedence)}
- C23C 14/0664: {Carbonitrides}
- C23C 14/0676: {Oxynitrides}
- C23C 22/57: Treatment of magnesium or alloys based thereon
- C23C 22/83: Chemical after-treatment
- C23F 1/40: for etching other metallic material
- C23G: CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- C23F: NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE (working metal by laser beams B23K26/00; desurfacing by applying flames B23K7/00; working of metal by electro-erosion B23H; producing decorative effects by removing surface material, e.g. by engraving, by etching, B44C1/22; electrolytic etching or polishing C25F); INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25

## Abstract

A process for treating the surface of magnesium alloy comprises providing a substrate made of magnesium alloy. The substrate is then treated with a chemical conversion treatment solution containing cerium nitrate and potassium permanganate as main film forming agents, to form a cerium conversion film on the substrate. A ceramic coating comprising refractory metal compound is next formed on the cerium conversion film by physical vapor deposition.

## Claims

### Claim 1

An article, comprising:
a substrate made of magnesium alloy;
a cerium conversion film directly formed on and in contact with the substrate, the cerium conversion film being formed by chemical conversion treatment with a chemical conversion treatment solution containing cerium nitrate and potassium permanganate as main film forming agents, the cerium conversion film comprising hydroxide of trivalent cerium, hydroxide of tetravalent cerium, hydroxide of divalent manganese, oxide of trivalent cerium, oxide of tetravalent cerium, and oxide of divalent manganese; and
a ceramic coating comprising refractory metal compound directly formed on and in contact with the cerium conversion film by physical vapor deposition.

### Claim 2 (depends on 1)

The article as claimed in claim 1, wherein the cerium conversion film is formed by immersing the substrate in the chemical conversion treatment solution maintained at about 25° C.-50° C., for about 15 min to 50 min; the chemical conversion treatment solution is an aqueous solution containing about 5 g/L-20 g/L Ce(NO3)3, and about 2 g/L-10 g/L KMnO4; the pH value of the chemical conversion treatment solution is in a range between about 1 and 5.

### Claim 3 (depends on 1)

The article as claimed in claim 1, wherein the refractory metal compound is selected from one or more of the group consisting of nitride of titanium, aluminum, chromium, zirconium, or cobalt; carbonitride of titanium, aluminum, chromium, zirconium, or cobalt; and oxynitride of titanium, aluminum, chromium, zirconium, or cobalt.

### Claim 4 (depends on 3)

The article as claimed in claim 3, wherein the ceramic coating orderly includes a first layer coated on the cerium conversion film and a second layer on the first layer, wherein the first layer is an aluminum-oxygen compound layer, the second layer is a oxynitride chromium layer.