High hardness nanocomposite coatings on cemented carbide

A method for depositing an adherent polycrystalline diamond-containing coating on a tool substrate comprising metal carbide particles in a metallic cobalt binder, the metal carbide particles and cobalt both being exposed at the substrate surface;

• the method comprising:
• selecting a combination of hydrogen and at least one gasesous refractory metal halide compound as a gaseous mixture for deposition of a refractory metal carbide on the substrate;
• a first step of predetermining refractory metal halide compound and hydrogen gaseous mixtures for the selected substrate, and temperature and pressure parameters for contacting the tool substrate with the gaseous mixture to deposit on the substrate surface a coating layer comprising an at least one refractory metal carbide;
• thereafter
• depositing such coating layer on the substrate using the predetermined gaseous mixture and parameters;
• followed by
• a second step of predetermining an at least one gaseous hydrocarbon compound and hydrogen gaseous mixture for the selected substrate and temperature and pressure parameters for contacting the tool substrate with the gaseous mixtures to deposit on the substrate surface a coating layer comprising polycrystalline diamond;
• and thereafter
• depositing such coating layer on the substrate using the predetermined gaseous mixture and parameters.