Effect of mechanical pretreatment on nucleation and growth of HFCVD diamond films on cemented carbide tools with a complex shape

To enhance the mechanical pretreatment efficiency for WC-Co complex-shaped cutting tools, a self-made vibrating grinding equipment and mixed abrasives made up of walnut shell and diamond particles are proposed. The technique can abrade the dozens of tools simultaneously, modify surface properties of tools, and maintain sharpness of the cutting edges. Several experiments are performed to explore effects of the different types and proportions of walnut shell and diamond powders on the properties of nucleation, growth, and adhesion of diamond films deposited via a chemical vapor deposition method. Subsequently, Field Emission Scanning Electron Microscopy (FE-SEM), Atomic Force Microscopy (AFM,), Laser scanning micro-gauge, Micro-Raman Spectroscopy, Stylus Profiler, and Rockwell hardness tester are adopted to characterize the as-pretreated substrates and as-deposited diamond films. According to the results, a low residual cobalt content around 0.2 wt% and a markedly increased surface defects are detected on the pretreated milling tools when the preferred types and proportions of mixed abrasives are applied, which can help to significantly enhance the nucleation density and growth rate of diamond films, and strengthen the adhesion between the films and substrates.