Analysis of Interlayer between WC–Co and CVD Diamond Film

Electroplated Cr, Ni and Cu were used as interlayer for chemical vapor deposition (CVD) diamond coating on WC-Co cemented carbide cutting tools. The electroplated interlayers were studied by Scanning Electron Microscope (SEM), Electron Probe Micro Analyzer (EPMA) and X-ray diffraction (XRD). The CVD diamond coatings were studied by SEM and Raman Scattering Spectroscopy (Raman). The experimental results show that there is diffusion bonded interface between electroplated layer and WC-Co substrate after H plasma treatment, the bond between electroplated layers and WC-Co substrate changes from mechanical bond to metallurgical bond and the adhesion becomes stronger. Electroplated Cr interlayer forms new phases of Cr3C2 and Cr7C3 under CVD conditions, while electroplated Ni and Cu interlayers do not form carbides under CVD conditions. Cr carbides have good chemical compatibility to diamond, and they are propitious to diamond nucleation and growth during the deposition period. The diamond crystal microstructure, diamond quality and adhesion on Cr interlayer are better than those on electroplated Ni and Cu interlayers.