Making diamond composite coated cutting tools

A method of making a diamond composite coated tool, comprising the steps of:

• (a) providing a tool substrate selected from materials that retain at least 90% of their strength related properties after exposure to processing temperatures up to 1050.degree. C. for up to 20 hours;
• (b) initiating chemical vapor deposition of substantially separated single crystal diamond nucleation particles onto a surface of said substrate, said deposition being (i) by use of a low pressure surrounding gas containing about 1% by volume methane and the remainder essentially hydrogen, (ii) at a substrate temperature of 800.degree.-950.degree. C., and (iii) for a period of 2-4 hours;
• (c) substantially suppressing further. nucleation of additional particles before formation of a contiguous film of said particles by increasing the substrate temperature to a temperature of 1000.degree. C. or greater for a period of 1-4 hours that permits the existing particles to grow to a crystal size consistent with said separation;
• (d) tooling said coated tool substrate-under vacuum to evolve hydrogen from the tool substrate;
• (e) depositing a mechanically tough, diamond and tool wetting material onto and across said separated particles and exposed substrate surface, said deposited material comprising an alloy selected from the group consisting of the alloy families of Ti-Ni-Cu and Ni-Mn-Sn-Ti;
• and
• (f) either during step (e) or thereafter, heating said deposited material to form a chemical and mechanical bond with diamond and tool substrate.