Stress distribution in diamond films grown on cemented WC–Co dental burs using modified hot-filament CVD

A modified hot-filament chemical vapour deposition system has been used to deposit diamond films onto dental burs. The as-grown films were found to be polycrystalline and displayed good coverage. Micro-Raman spectra were taken at different positions of the coating to characterise stress distribution in the deposited film. The Raman diamond peak positions were used to calculate the stress along and across the diamond coating. It was found that the stress across the coating remained constant. However, the stresses along the coating displayed some interesting results. The stress at the base, in the middle and at the tip of the bur was calculated to be −1.7, −2.3 and −3.4 GPa in compression, respectively. The temperature of the bur during deposition was found to be different at different positions on the bur. At the base of the cutting area; at the middle of the bur; and at the tip of the bur the temperature was found to be 842, 908 and 952 °C, respectively. The stress in the films increased as the temperature of the bur increased. Scanning electron microscopy analysis was used to characterise the as-grown films for morphology and crystallinity.