Surface-coated blade member of super hard alloy for cutting tools and process for producing same

Claim 1

In a surface-coated blade member for cutting tools which comprises: a substrate, and a coating on at least one surface of said substrate, said coating being composed of (1) a layer of vapor deposited titanium metal on the surface of said substrate, and (2) at least one layer of vapor deposited titanium compound on said layer of titanium metal, said layer of titanium compound being selected from the group consisting of titanium carbide, titanium nitride, titanium carbo-nitride, titanium oxy-carbide and titanium oxy-carbo-nitride, said layer of titanium metal being no larger than 2 μm thick and said layer of titanium compound being from 0.5 to 10 μm thick, the improvement wherein said substrate is a cemented carbide containing 2 to 30% by weight of at least one metal selected from the iron family, and a major proportion of at least one compound selected from the group consisting of carbides, nitrides and carbo-nitrides of metals in Groups IV A , V A and VI A of the Periodic Table said surface-coated blade member produced by the process comprising the steps of: (a) placing a cemented carbide substrate in a vacuum chamber; (b) vapor depositing a layer of titanium metal no larger than 2 μm thick on at least one surface of said substrate; and (c) subsequently vapor depositing at least one layer of titanium compound on said layer of titanium metal to form a coating on said substrate, said layer of titanium compound being 0.5 to 10 μm thick, and said titanium compound being selected from the group consisting of titanium carbide, titanium nitride, titanium carbo-nitride, titanium oxy-carbide and titanium oxy-carbo-nitride; provided that during steps (b) and (c) said substrate is maintained at a temperature between about 700° C. to 800° C.