APPLICATION OF HEAT-TREATMENT AND DISPERSIVE STRENGTHENING CONCEPT ININTERLAYER DEPOSITION TO ENHANCE DIAMOND FILM ADHERENCE

Two different deposition processes were carried out to enhance adheren ce of diamond films on WC + 3 similar to 5%Co substrate with Ti-Si as the interlayer. One process can be called two-step diamond deposition process. Another process can be called interlayer heat treatment proce ss. Diamond films were deposited by a microwave plasma chemical vapor deposition system. Ti and Si interlayer are deposited by DC sputter an d an E-gun, respectively. Film morphologies, interface structure and f ilm qualify were examined by SEM, XRD, Auger electron spectroscopy and Raman spectroscopy. The residual stresses and adhesion strengths of t he films were determined by Raman spectroscopy and indentation adhesio n testing, respectively. Comparing the regular one-step diamond deposi tion process with the present two different new processes, the average dP/dX values, which are a measure of the adherence of the film, are 3 54 kgf/mm, 494 kgf/mm and 787 kgf/mm, respectively. In other words, th e interlayer heat treatment process gives the best film adherence on a verage. For the two-step diamond deposition process, the interlayer th ickness and the percent diamond surface coverage of the first diamond deposition step are the main parameters, and there exists an optimum T i thickness and percent diamond coverage for the best film adherence. The main contribution to better film adherence is not a large differen ce in residual stress, but is due to the following reasons. The interl ayer heat treatment can transform amorphous Si to polycrystalline Si, and may form strong TiC and SiC bonding. The polycrystalline Si and th e diamond particles from the first diamond deposition step can be an e ffective seeds to enhance diamond nucleation. Published by Elsevier Sc ience S.A.