Quantitative measurement for the effect of enhanced nucleation on the adhesive strength of diamond coatings

Nucleation of chemically vapor deposited (CVD) diamond can be enhanced by applying negative bias voltage to the substrates. The bias-enhanced nucleation of diamond was examined in this report for the case of microwave plasma CVD on cobalt-cemented tungsten carbide (WC–Co) substrates. Nucleation density was enhanced up to 1×109 cm−2, although the reproducibility of the experiment was poor. Adhesive toughness of diamond films with different nucleation density was measured by a new technique recently developed by the authors. The results suggest that the adhesion of diamond coatings on WC–Co substrates can be considerably improved by higher nucleation density as the consequence of bias application.