As a way to enhance the standard of diamond coatings, this paper mixed the chemical etching and buffer layers to cope with cemented carbide with cobalt (Co) content material of 8%. Diamond coatings had been ready with scorching filament chemical vapor deposition (HFCVD). The floor morphology, high quality and put on property had been explored through the use of scanning electron microscopy, X-ray diffraction, laser Raman spectrometer, and friction and put on tester. In comparison with the pattern with no pretreatment, samples after pretreatment have higher floor morphology. There are not any apparent impurities as effectively. Diamond crystals are uniform and compact. Friction and put on check indicated that the friction coefficient is decrease than 0.1. Samples after pretreatment are a lot decrease and regular amongst them. The pattern utilizing tungsten(W)-molybdenum(Mo) layer has the most effective floor morphology and the bottom friction coefficient. The consequence reveals that the pretreatment mixed the chemical etching and buffer layers can not solely act because the diffusion barrier, but in addition can enhance the adhesion between substrate and diamond coatings. The impact of composite buffer layer is best than single metallic buffer layers.