Enhancement of Adhesion of Diamond Coating on Cemented Carbide by Laser Modified Substrate Surface Structure Pretreatment

The bond strength between the thin film diamond coating and the substrate has an extremely important influence on the thin film coating tool. Improving the microstructure of the surface of carbide substrates not only promotes the diamond nucleation but also increases the bond strength between the film and the substrate. In this paper, we investigate the effect of laser's instantaneous high heat on the surface of the substrate to prepare the microstructure topography, which causes the surface structure to melt, cool, and reconstruct, causing the surface topography and superficial microstructure changes of the substrate. The conclusion shows that after laser and the ultrasonic pretreatment, the surface roughness of the tool increases significantly and appears regular wavy texture, the number, and size of defects in the reconstruction area of the substrate shallow structure increases significantly, forming a unique stereoscopic defect structure and wavy step height structure, enhancing the density and number of nuclei at the defects, the hole connectivity structure strengthens the growth conditions of crystal nuclei and improves the mechanical interlocking of the coating and substrate and releases the residual stresses in the substrate surface layer.