Effect of high pressure and high temperature on the mechanical behavior of diamond coated WC–Co

Polycrystalline diamond films were grown on WC–Co substrates by microwave assisted chemical vapor deposition using a gas mixture of hydrogen, oxygen and methane. The diamond coated WC–Co substrates were processed at high pressure (7.7 GPa) and high temperature (1000 °C) and their mechanical behavior was investigated by hardness instrumented testing before and after the high-pressure/high-temperature (HPHT) processing. The results indicated the diamond films became less friable after the HPHT processing, probably due to the infiltration of Co from the substrate. This conclusion was corroborated by corrosion tests performed with the samples before and after the HPHT processing.