Diamond nucleation and growth on WC-Co inserts with Cr2O3-Cr interlayer

Cr2O3-Cr interlayer was prepared by magnetron sputtering to restrict graphite formation on WC-Co before diamond nucleation. Continuous diamond coatings containing little graphite phase were successfully deposited on single Cr2O3 interlayered WC-Co substrates. For Cr2O3/Cr duplex interlayer, a low nucleation density was observed at a low CH4 concentration, but a continuous diamond coating was readily obtained with an increased CH4 concentration during nucleation stage. X-ray diffraction and X-ray absorption analysis reveal that the Cr top layer was carburized to Cr3C2 and Cr7C3 after diamond deposition while Cr2O3 layer kept unchanged. In addition, the indentation test shows that the diamond coating has poor adhesion to the substrate with a single Cr2O3 interlayer, while the adhesion was significantly enhanced with the Cr2O3/Cr duplex interlayer combined with a high CH4 concentration for nucleation.