Aluminum oxide coated titanium-containing cemented carbide product

Abstract

A high-strength, coated cemented carbide product comprising a cemented carbide substrate and a fully dense alpha aluminum oxide coating on the substrate. The coating has a thickness of from 1-20 microns and is firmly and adherently bonded to the cemented carbide substrate through a thin intermediate nonmetallic layer .[.of an iron group metal aluminate.].. The coated product combines a wear resistance substantially as high as aluminum oxide cutting materials and a transverse rupture strength of at least 150,000 p.s.i. The coated product is prepared by passing water vapor, hydrogen gas and an aluminum halide over the substate at a temperature of from 900°-1250° C., the ratio of water vapor to hydrogen gas being between about 0.025 and 2.0.

I claim: 
     
       1. A high strength, high-wear resistance coated cemented carbide product comprising: a .Iadd.titanium carbide-containing .Iaddend.cemented carbide substrate, and a .Iadd.generally .Iaddend.fully dense .Iadd.chemically vapor deposited .Iaddend.alpha aluminum oxide coating of from 1-20 microns thickness firmly and adherently bonded to said cemented carbide substrate through an intermediate layer .[.of an iron group metal aluminate.]. .Iadd.comprising   another non-metallic compound formed in situ by chemical vapor reaction, which acts to bond said coating to said substrate, .Iaddend.   said coated cemented carbide product having a wear resistance substantially equivalent to aluminum oxide base cutting materials and having a transverse rupture strength of at least 150,000 p.s.i. .[.   
     
     
       2.  The coated cemented carbide product of claim 1 in which the cemented carbide substrate comprises tungsten carbide and a cobalt matrix..]. .[.3. The coated cemented carbide product of claim 2 in which the intermediate 
     
     
        layer is cobalt aluminate..]. 4. The coated cemented carbide product of claim 1 in the form of a disposable cutting insert for the machining of metal and other materials. .[.5. The coated cemented carbide insert of claim 4 having a centrally disposed hole therein, the insert adapted to be 
     
     
        mounted in a pin-type toolholder..]. 6. The coated cemented carbide product of claim .[.1.]. .Iadd.4 .Iaddend.in which the coating is less 
     
     
        than .[.15.]. .Iadd.10 .Iaddend.microns in thickness. 7. The coated cemented carbide product of claim 1 in which .[.the cemented carbide substrate comprises titanium carbide and a matrix selected from the group consisting of iron, nickel and cobalt.]. .Iadd.said non-metallic compound is a titanium-containing oxide of the rutile type.Iaddend.. .[.8. The coated cemented carbide product of claim 7 containing tantalum carbide..]. 
     
     
        . The coated cemented carbide product of claim .[.1.]. .Iadd.6 .Iaddend.in which .[.the.]. .Iadd.said .Iaddend.cemented carbide substrate comprises tungsten carbide, titanium carbide and tantalum carbide .[.and.]. .Iadd.in .Iaddend.a cobalt matrix .Iadd.and said non-metallic compound comprises a 
     
     
        rutile type oxide phase.Iaddend.. .Iadd.10.  A high-strength, high-wear resistance coated cutting insert for machining metals and other materials, comprising: a substrate which includes a titanium-containing cemented carbide phase;   a generally fully dense, firmly adherent, chemically vapor deposited, aluminum oxide coating of from 1 to less than 10 microns thickness; and   another non-metallic compound formed between said substrate and said coating by oxidation, which non-metallic compound acts to enhance the adherence of said coating. .Iaddend. .Iadd.11. The coated cutting insert of claim 10 in which said non-metallic compound is a titanium-containing oxide phase of the rutile type. .Iaddend. .Iadd.12. A high-strength, high wear resistance coated cutting insert for machining metals and other materials comprising:   a substrate comprising a titanium-containing cemented carbide;   a generally fully dense, firmly adherent, chemically vapor deposited, alpha aluminum oxide coating of from 1-20 microns thickness and   an intermediate layer comprising another non-metallic compound containing titanium, which acts to enhance the adherence of said coating. .Iaddend. .Iadd.13. The coated cutting insert of claim 12, wherein said coating is   
     
     
        less than 10 microns thick. .Iaddend. .Iadd.14.  The coated cutting insert product of claim 12 or 13, wherein said non-metallic compound comprises a rutile-type oxide phase formed in situ by chemical vapor reaction. .Iaddend. .Iadd.15. A high-strength, high-wear resistance coated cutting insert for the machining of metal and other materials, comprising: a cemented carbide substrate including tungsten carbide, titanium carbide, tantalum carbide and a cobalt matrix;   a generally fully dense alpha aluminum oxide coating of from 1 to less than 10 microns thickness firmly and adherently bonded to said cemented carbide substrate, and   an intermediate layer comprising another non-metallic compound of a titanium-containing oxide phase of the rutile type which acts to enhance the adherence of said coating to said substrate. .Iaddend. .Iadd.16. A cemented carbide tool comprising a titanium-containing cemented carbide substrate coated with a generally fully dense chemically vapor deposited layer of aluinum oxide of from about 1.0 to about 20 microns thickness, and a titanium containing non-metallic phase formed in situ by chemical reaction and located intermediate the coating and substrate which acts to enhance the adherence of said coating. .Iaddend. .Iadd.17. The cemented carbide tool of claim 16 in the form of a disposable cutting insert adapted to be mounted in a pin type tool holder for the machining of metal and other materials. .Iaddend. .Iadd.18. The cemented carbide tool of claim 16 in the form of metal cutting machine insert and in which the   
     
     
        coating is less than 10 microns in thickness. .Iaddend. .Iadd.19.  The cemented carbide tool of claim 16 in which the cemented carbide substrate comprises titanium carbide and a bonding matrix selected from the group consisting of iron, nickel and cobalt. .Iaddend. .Iadd.20. The cemented carbide tool of claim 16 in the form of an insert for machining metal and in which the aluminum oxide coating is between about 7 and about 10 microns thick. .Iaddend. .Iadd.21. The cemented carbide tool of claim 16, 32 or 34, in which the cemented carbide substrate comprises tungsten carbide, titanium carbide and tantalum carbide and a cobalt matrix and said non-metallic phase is a product of oxidation of said substrate. .Iaddend. .Iadd.22. A high-strength, high-wear resistance metal cutting tool comprising: a titanium-containing cemented carbide substrate;   a generally fully dense coating of aluminum oxide of from 1 to less than 10 microns thickness; and   bonding means located intermediate said cemented carbide substrate and aluminum oxide coating for enhancing the adherence of said aluminum oxide coating such as to prevent spalling and separation of said coating when subjected to an adherency test of sliding the tool under a Rockwell hardness test type diamond brale indentor having a load of 2 kilograms. .Iaddend. .Iadd.23. The metal cutting tool of claim 22 in the form of a disposable insert having a centrally disposed hole for mounting in a pin   
     
     
        type holder. .Iaddend. .Iadd.24.  The metal cutting tool of claims 22 or 23, in which said bonding means comprises a phase formed by oxidation of said substrate. .Iaddend. .Iadd.25. The metal cutting tool of claim 22 or 23, in which the cemented carbide substrate comprises titanium carbide and a matrix selected from the group consisting of iron, nickel and cobalt, and said bonding means comprises an oxide phase containing titanium from said substrate. .Iaddend. .Iadd.26. The metal cutting tool of claim 22 or 23, in which the cemented carbide substrate comprises tungsten carbide, titanium carbide and tantalum carbide and a cobalt matrix, and said bonding means comprises a phase formed in situ by oxidation of said substrate. .Iaddend. .Iadd.27. A cemented carbide tool comprising a titanium-containing cemented carbide substrate coated with a generally fully dense, chemically vapor deposited, layer of aluminum oxide from 1.0 to 20 microns thick, and a titanium-containing oxide phase located intermediate the coating and substrate which acts to enhance the adherence between said coating and said substrate to prevent spalling and separation of said coating when subjected to an adherency test of sliding the tool under a Rockwell hardness diamond brale indentor having a load of 2 kilograms. .Iaddend. .Iadd.28. The cemented carbide tool of claim 27 in the form of a disposable cutting insert for the machining of metal and other materials. .Iaddend. .Iadd.29. The cemented carbide tool of claim 28 having a centrally disposed hole therein, the insert being adapted to be mounted in a pin type toolholder. .Iaddend. .Iadd.30. The cemented carbide tool of claim 27, 28 or 29 in which the coating is less than 10 microns in 
     
     
        thickness. .Iaddend. .Iadd.31.  The cemented carbide tool of claim 27, 28 or 29, in which the cemented carbide substrate comprises titanium carbide and a matrix selected from the group consisting of iron, nickel and cobalt, and wherein said oxide phase is a rutile phase formed by oxidation of said substrate, and said coating is less than 10 microns in thickness. .Iaddend. .Iadd.32. The article of manufacture according to claim 1, 6, 10, 11, 12, 13, 15, 22, or 27, wherein the phase which enhances coating adherence comprises an oxide of metal ions from said substrate. .Iaddend.