Research on the innovative pretreatment to improve the adhesion and performance of diamond coatings

In order to improve the quality of diamond coatings, this paper combined the chemical etching and buffer layers to deal with cemented carbide with cobalt (Co) content of 8%. Diamond coatings were prepared with hot filament chemical vapor deposition (HFCVD). The surface morphology, quality and wear property were explored by using scanning electron microscopy, X-ray diffraction, laser Raman spectrometer, and friction and wear tester. Compared to the sample with no pretreatment, samples after pretreatment have better surface morphology. There are no obvious impurities as well. Diamond crystals are uniform and compact. Friction and wear test indicated that the friction coefficient is lower than 0.1. Samples after pretreatment are much lower and steady among them. The sample using tungsten(W)-molybdenum(Mo) layer has the best surface morphology and the lowest friction coefficient. The result shows that the pretreatment combined the chemical etching and buffer layers cannot only act as the diffusion barrier, but also can improve the adhesion between substrate and diamond coatings. The effect of composite buffer layer is better than single metal buffer layers.