Boron-doped diamond coating and diamond-coated tool

Abstract

A boron-doped diamond coating that is to be disposed on a surface of a body includes a plurality of diamond microcrystal whose crystal grain diameter is substantially not larger than 2 μm, wherein the diamond microcrystal is doped with boron.

Description

[0001] This application is based on Japanese Patent Application No. 2004-349150 filed Dec. 1, 2004, the contents of which are incorporated hereinto by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a boron-doped diamond coating that is to be disposed on a surface of a body of such as a tool, especially, to an improvement in oxidation resistance and lubricity. [0004] 2. Description of Related Art [0005] A diamond-coated tool coated with a diamond coating on the body made of such as cemented carbide is suggested for a cutting tool such as an end mill, a turning tool, a tap, a drill or other tools. JP 2519037B and JP 2002-79406A disclose examples of such tools. These diamond-coated tools have very high hardness, superior wear resistance and adhesion resistance. JP 2004-193522A and JP 10-146703A disclose technology of doping with boron (B) upon the crystal growth of the diamond by such as the microwave plasma CVD (chemical...

AI Technical Summary

Benefits of technology

[0018] In this boron-doped diamond coating, a layer of boron oxide such as B2O3 is formed on the surface when the surface is oxidized, and therefore the progression of oxidation is blocked by the layer of boron oxide. This provides a high oxidation resistant and lubricative coating with a lower coefficient of friction. Especially further superior lubricity is achieved in this invention with a further lower coefficient of friction because the surface of the diamond coating including diamond microcrystals in this invention is more even than that of the conventional diamond coating and furthermore the layer of boron oxide is formed on that surface. This provides superior durability by preventing flaking or early wearing of the diamond coating by oxidation in cutting of the composite material including a material of iron series or in cutting of the heat-resistant alloy such as a titanium alloy with the cutting point at a high temperature. And high lubricity in this invention preventing heat generation by friction contributes to high durability of the diamond coating and advancement in quality of the worked surface of the workpiece.

[0019] The diamond-coated tool that the above boron-doped diamond coating is disposed on the surface of the body according to the third aspect of the invention substantially achieves the effects as described above.

[0021] While hard tool material such as cemented carbide is preferably used for the body to be coated with boron-doped diamond coating for the diamond-coated tool, other tool materials such as high-speed steel may be used. The predetermined pretreatment as the surface roughening treatment or coating of other coating as a substrate on the surface of the tool body may be conducted for high adhesion.

Problems solved by technology

Doping with boron for the diamond coating disposed on the surface of such as a tool body, however, has not been suggested yet.

Inferior oxidation resistance and lubricity frequently cause the insufficiency of the diamond coating in durability by oxidation and early wearing in cutting of composite material including iron series material and heat-resistant alloy such as titanium alloy suffering at high temperature on its cutting point.

And heat by friction frequently causes low durability of the diamond coating and damages in quality on the cut surface of the workpiece.

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