Diamond coated tools and wear parts

A diamond coated tool comprising:

• a cermet substrate having hard grains bonded together by a metallic binder;
• wherein said cermet substrate has a substrate surface with relatively large hard grains thereat, as compared to said hard grains in the interior regions of the substrate, to provide an irregular substrate surface;
• wherein said relatively large hard grains at the substrate surface consist essentially of tungsten carbide grains;
• wherein said cermet substrate consists essentially of tungsten carbide, said metallic binder selected from the group consisting of cobalt and cobalt alloys, and less than 1 w/o total of Ti, Hf, Zr, Ta, Nb, V, Mo and Cr;
• a diamond coating deposited upon, and having a strong adherence to, said irregular substrate surface;
• wherein said diamond coating has an average thickness of 22 to 100 .mu.m;
• wherein said diamond coating adheres to the irregular substrate surface with an average adhesion strength of greater than 45 kilograms in Rockwell A indentation tests;
• and
• wherein said irregular substrate surface includes a chipbreaker structure in an as-molded condition.

A diamond coated cutting tool for chip forming machining of materials comprising:

• a cemented carbide substrate having tungsten carbide grains bonded together by a metallic binder;
• wherein said cemented carbide substrate has a substrate surface with relatively large tungsten carbide grains thereat, thereby providing an irregular substrate surface;
• a diamond coating deposited upon, and having a strong adherence to, said irregular substrate surface;
• wherein said relatively large tungsten carbide grains include grains having a size of at least 10 .mu.m;
• wherein said irregular substrate surface includes a flank surface and a rake surface and a cutting edge formed at the juncture of said flank and rake surfaces;
• wherein said diamond coating is adherently bonded to said rake surface and said flank surface.

A diamond coated tool or wear part comprising:

• a diamond coating;
• a cermet substrate;
• wherein said diamond is adherently bonded to a surface of said substrate;
• said substrate having hard grains bonded together by a metallic binder and wherein at the surface of said substrate the hard grains are large enough to provide the surface of the substrate with an irregular surface having an R.sub.a roughness greater than 25 microinches;
• wherein said hard grains consist essentially of tungsten carbide and said irregular surface consists essentially of said hard grains of tungsten carbide;
• and
• wherein said diamond coating has an average thickness of 22 to 100 .mu.m.

A diamond coated cutting tool for chip forming machining of materials comprising:

• a cemented carbide substrate consisting essentially of tungsten carbide grains bonded together by a metallic binder selected from the group consisting of cobalt and cobalt alloys, and less than 1 w/o total of Ti, Zr, Hf, Ta, Nb, V, Mo and Cr;
• wherein said cemented carbide substrate has a substrate surface consisting essentially of tungsten carbide grains with relatively large tungsten carbide grains thereat, as compared to said tungsten carbide grains in the interior regions of the substrate, to provide an irregular substrate surface with a surface roughness of at least 40 microinches R.sub.a ;
• a diamond coating deposited upon, and having a strong adherence to, said irregular substrate surface;
• wherein said diamond coating adheres to the irregular substrate surface with an average adhesion strength of greater than 45 kilograms in Rockwell A indentation tests;
• wherein said irregular substrate surface includes a flank surface and a rake surface and a cutting edge formed at the juncture of said flank and rake surfaces;
• wherein said diamond coating bonded to said rake surface has an average thickness of 22 to 100 .mu.m;
• and
• wherein said substrate is characterized by an absence of interconnected porosity in the substrate regions adjacent to said irregular substrate surface to which said diamond coating is deposited upon.