Wear-resistant, nonabrading tic article and process for making
AssigneeMinnesota Mining and Manufacturing Company
InventorAlan R. Berry
Life of this patent
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Abstract
A wear-resistant, nonabrasive metal article, such as a thread guide, comprising a plain carbon steel substrate with a thin, dense, continuous coating of titanium nitride, having a thickness of about 1 to 5 microns, chemically vapor deposited at reduced pressure on said steel substrate, and preferably a thin, continuous, smooth, titanium carbide coating, having a thickness of about 5 to 25 microns, chemically vapor deposited at reduced pressure on said nitride coating, the carbide coating having HK.sub.50 hardness of 3600 to 3900 and a surface finish of 0.2 to 0.5 micron.
Claims13
A process for forming a chemically vapor coated finished metal article having a wear-resistant working surface, comprising the steps of:
- exposing the reduced working surface of a plain carbon steel article at a pressure of 50 to 250 Torr and elevated temperature of 600.degree. to 1100.degree.C to a gaseous mixture containing hydrogen and stoichiometric quantites of titanium (IV) halide gas and nitrogen sufficient to form a chemically vapor deposited continuous layer of titanium nitride on said reduced surface, said plain carbon steel article being essentially free of carbide forming elements;
- and
- cooling the coated article to room temperature in an inert atmosphere to prevent reaction of the nitride layer with the atmosphere.
A process for forming a chemically vapor coated finished metal article having a wear-resistant working surface, comprising the steps of:
- exposing the reduced working surface of a plain carbon steel article at a pressure of 50 to 250 Torr and elevated temperature of 600.degree. - 1100.degree.C to a gaseous mixture containing stoichiometric quantities of titanium (IV) halide gas and nitrogen in hydrogen sufficient to form a chemically vapor deposited continuous layer of titanium nitride on said reduced surface, said plain carbon steel article being essentially free of carbide forming elements;
- exposing the resulting nitrided surface at a pressure of 50 to 250 Torr and elevated temperature of 950.degree. - 1200.degree.C to a mixture of gases containing stoichiometric amounts of titanium (IV) halide gas and hydrocarbon gas in hydrogen sufficient to form a chemical vapor deposited, continuous wear-resistant layer of titanium carbide on said nitrided surface and metallurgically bonded thereto;
- exposing the deposited carbide layer to a mixture of the titanium halide and hydrogen for a sufficient period of time to increase the hardness and smoothness of said deposited carbide;
- and
- cooling the resulting coated article to room temperature in an inert atmosphere to prevent reaction of the carbide layer with the atmosphere.
A laminated wear-resistant article comprising:
- a plain carbon steel substrate having no more than 0.8 weight percent carbon and essentially free of carbide forming elements;
- and
- a thin, dense, continuous coating of titanium nitride having a thickness of about 1 to 5 microns and a Knoop hardness of about 2000 HK.sub.50 deposited on and metallurgically bonded to said substrate.
A laminated wear-resistant article comprising:
- a plain carbon steel substrate having no more than 0.8 weight percent carbon and essentially free of carbide forming elements;
- a thin, dense, continuous coating of titanium nitride having a thickness of about 1 to 5 microns deposited on and metallurgically bonded to said substrate;
- and
- a thin, continuous, smooth titanium carbide coating, having a thickness of 5 to 25 microns deposited on and metallurgically bonded to said thin titanium nitride coating, said carbide coating having a Knoop hardness of 3600 to 3900 HK.sub.50 and a surface finish of 0.2 to 0.5 micron.
A laminated wear-resistant article comprising:
- a plain carbon steel substrate having no more than 0.8 weight percent carbon and essentially free of carbide forming elements;
- a thin, dense, fine grained, nonporous continuous coating of titanium nitride having a thickness of about 1 to 5 microns deposited on said substrate;
- and
- a thin, continuous, smooth, fine grained titanium carbide coating having a thickness of 5 to 25 microns deposited on and metallurgically bonded to said titanium nitride coating, a substantial portion of the grains of said carbide being less than 0.5 micron in diameter, said carbide coating having a Knoop hardness of 3600 to 3900 HK.sub.50 and a surface finish of 0.20 to 0.5 micron.
A laminated wear-resistant article comprising:
- a plain carbon steel substrate having no more than 0.8 weight percent carbon and essentially free of carbide forming elements;
- a thin, dense, continuous coating of titanium nitride having a thickness of about 1 to 5 microns deposited on and metallurgically bonded to said substrate;
- and
- a thin, continuous, smooth titanium carbide coating, having a thickness of 5 to 25 microns deposited on and metallurgically bonded to said thin titanium nitride coating.
Dependencies are inferred from the claim text.