Nucleation and growth of diamond films on Ni-cemented tungsten carbide: II, effects of deposition conditions

The effects of substrate temperature and gas phase composition on the nucleation density, growth rate, and phase purity of diamond grown on WC-6 wt% Ni substrates temperature between 600 and 1050 °C are investigated using scanning electron microscopy and automatic image analysis. As a result, the diamond nucleation density does not significantly change in the 600-900 °C temperature range, while at substrate temperature higher than 900 °C, a steep decrease of the density of nuclei is observed and attributed to the thermal annealing of nucleation sites. The activation energy of the growth process is found to be 21±2 kcal/mol. Raman analysis show that phase purity of the films is affected mainly by the substrate temperature: the lower the temperature, the better the film quality.