Adhesion Improvement of CVD Diamond Coatings on WC-Co Substrates for Machining Applications

摘要

In order to improve the performance of WC-Co cutting tools, high quality microcrystalline diamond coatings were produced using microwave plasma enhanced chemical vapor deposition (MPECVD) method. The adhesion of the diamond film deposited on the substrate has been considered to play an important role in the performance of the cutting tools in machining applications. A thin layer of Cr was coated on the WC-Co substrate before the diamond deposition; 75 μm diamond powders were sandblasted on the surface at 40 Psi to increase the nucleation density. Diamond film has been successfully deposited on the substrate at temperature around 750°C with 1.5 % CH_4 in Hydrogen plasma. Scanning electron microscopy (SEM) has been used to study the surface morphology and Raman spectroscopy has been performed to characterize the quality of the diamond films and measure the residual stress. The adhesion of the diamond film has been evaluated by Rockwell indentation test. The results indicated that film grown on the Cr interlayer with diamond powder sandblasting has much better adhesion strength.