Evaluation of diamond film on cemented carbide substrate

Diamond films with a thickness of 8 μm were deposited using plasma jet chemical vapour deposition on to cemented carbide substrates that had been chemically etched and bombarded by Ar–H₂ plasma before synthesis. The interfaces and cross-sections of the diamond films and cemented carbide substrates were analysed by SEM, TEM, and Fourier transform Raman spectroscopy. Under the deposition conditions used, the typical structure of the diamond film and cemented carbide substrate was diamond film/thin graphite layer/fine WC particle layer/residual chemical etch layer/cemented carbide substrate. Cobalt, which diffused from the substrate to the interface, caused the formation of a graphite layer which was several hundreds of nanometres thick. However in some regions diamond particles grew directly on to the cemented carbide.