Diamond deposition on WC–Co substrate with amorphous SiC interlayer

An amorphous SiC (a-SiC) thin film is deposited on the WC–Co insert from dimethyldiethoxysilane/hydrogen gas mixture using hot filament chemical vapour deposition (HFCVD) technique. Energy dispersive X-ray spectroscopy, scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy and transmission electron microscope are used to characterise the as fabricated a-SiC thin film. Subsequently, the a-SiC film is used as an intermediate film, and an adherent top layer of CVD diamond with well faceted crystallites is synthesised on the a-SiC interlayer. Rockwell indentation tests indicate that the CVD diamond film with a-SiC interlayer results in less delamination in comparison with that directly deposited on WC–Co substrate. The multilayer (a-SiC+diamond) film coated insert exhibits better cutting performance and longer lifetime than the CVD diamond coated insert with no interlayer in dry turning of Al–Si alloy. By introducing the a-SiC interlayer, the adhesion and wear endurance of diamond film on WC–Co substrate can be dramatically improved.