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US 2022/0064778 A1Published application
Chemical activation of self-passivating metals
AssigneeSwagelok Company
InventorsCyprian A.W. Illing, Peter C. Williams, Christina Semkow
Life of this patent
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Abstract
A workpiece made from a self-passivating metal and having one or more surface regions defining a Beilby layer as a result of a previous metal shaping operation is activated for subsequent low temperature gas hardening by exposing the workpiece to the vapors produced by heating a non-polymeric N/C/H compound.
Claims20
A process for treating a metal workpiece made from a self-passivating metal comprising a nickel-based alloy and having one or more surface regions comprising a Beilby layer, the process comprising:
- heating a non-polymeric, halogen-free N/C/H compound to a processing temperature below a temperature at which nitride and/or carbide precipitates form to produce vapors, wherein the non-polymeric, halogen-free N/C/H compound:
- (a) comprises at least one of melamine;
- aminobenzimidazole;
- adenine;
- benzimidazole;
- guanidine;
- cyanamide;
- dicyandiamide;
- 2,4-diamino-6-phenyl-1,3,5-triazine;
- 6-methyl-1,3,5-triazine-2,4-diamine;
- 2-(aminomethyl)pyridine;
- 4-(aminomethyl)pyridine;
- 2-amino-6-methylpyridine;
- 1,10-phenanthroline;
- 2,2′-bipyridine;
- (2-(pyridyl)benzimidazole);
- 4-methylbenzeneamine;
- 2- methylaniline;
- 3-methylaniline;
- 2-aminobiphenyl;
- 3-aminobiphenyl;
- 4-aminobiphenyl;
- 1-naphthylamine;
- 2-naphthylamine;
- 2-aminoimidazole;
- 5-aminoimidazole-4-carbonitrile;
- 4,4′-methylene-bis(2-methylaniline);
- benzidine;
- 4,4′-diaminodiphenylmethane;
- 1,5-diaminonaphthalene;
- 1,8-diaminonaphthalene;
- 2,3 -diaminonaphthalene;
- hexamethylenetetramine;
- and ethylene diamine,
- (b) is solid or liquid at 25° C. and atmospheric pressure, and
- (c) has a molecular weight of ≤5,000 Daltons, and
- exposing the workpiece to the vapors.
34 more elements
A process for treating a workpiece, wherein:
- the workpiece:
- is a corrosion-resistant, self-passivating metal comprising a nickel-based alloy;
- has one or more surface regions with a Beilby layer,
- has a protective coating of at least one of chromium oxide or titanium oxide;
- and the process comprises:
- heating a non-polymeric, halogen-free N/C/H compound to a processing temperature high enough to convert the non-polymeric, halogen-free N/C/H compound to vapors, less than 500° C., and below a temperature at which nitride and/or carbide precipitates form, wherein the non-polymeric, halogen-free N/C/H compound:
- (a) comprises at least one of melamine;
- aminobenzimidazole;
- adenine;
- benzimidazole;
- guanidine;
- cyanamide;
- dicyandiamide;
- 2,4-diamino-6-phenyl-1,3,5-triazine;
- 6-methyl-1,3,5-triazine-2,4-diamine;
- 2-(aminomethyl)pyridine;
- 4-(aminomethyl)pyridine;
- 2-amino-6-methylpyridine;
- 1,10-phenanthroline;
- 2,2′-bipyridine;
- (2-(pyridyl)benzimidazole);
- 4-methylbenzeneamine;
- 2- methylaniline;
- 3-methylaniline;
- 2-aminobiphenyl;
- 3-aminobiphenyl;
- 4-aminobiphenyl;
- 1-naphthylamine;
- 2-naphthylamine;
- 2-aminoimidazole;
- 5-aminoimidazole-4-carbonitrile;
- 4,4′-methylene-bis(2-methylaniline);
- benzidine;
- 4,4′-diaminodiphenylmethane;
- 1,5-diaminonaphthalene;
- 1,8-diaminonaphthalene;
- 2,3 -diaminonaphthalene;
- hexamethylenetetramine;
- and ethylene diamine,
- (b) is solid or liquid at 25° C. and atmospheric pressure, and
- (c) has a molecular weight of ≤5,000 Daltons,
- contacting the workpiece with the vapors to:
- depassivate the workpiece;
- and
- simultaneously surface harden the workpiece by causing at least one of carbon and nitrogen atoms to diffuse into the surface of the workpiece without formation of carbide and nitride precipitates.
42 more elements
Dependencies are inferred from the claim text.