Al-enhanced nucleation and adhesion of diamond films on WC–Co substrates

Diamond deposition on WC–Co cutting tool inserts with the aid of several intermediate layers has been conducted with microwave plasma enhanced chemical vapour deposition. The results show that the diamond films directly grown on the as-received WC–Co insets are of poor quality in terms of purity, nucleation density, and adhesion strength. The diamond films grown on the inserts pre-coated with TiN, TiCN intermediate layers demonstrate higher phase purity but slow nucleation rates. Severe wrinkles and spontaneous peeling off the substrates occur in the diamond films after cooling to room temperature. When an aluminum thin film was deposited either directly adjacent to WC–Co substrate, or on top of TiN, TiCN intermediate layers, the nucleation density and adhesion ability of diamond films on the tool inserts are significantly improved.