Influence of boron on diamond growth on WC-Co hardmetals

Diamond coatings were produced by the hot-filament method, adding B(C2H5)(3) to the gas phase. We compared the results on WC-Co hardmetal and Si substrates. SIMS-measurements revealed high B contents in diamond layers on WC-Co substrates accompanied by high amounts of Co. TEM showed CoB and Co2B inclusions in the diamond layer. Furthermore, B-diffusion in the WC-Co bulk was shown. On Si substrates, crystal quality and growth rate decreased at high B concentrations. Higher B contents were found in the diamond layer than were used in the gas phase.