Preparation of HFCVD spherical diamond films and the effect of crystal orientations on adhesion and tribological properties

The different coefficients of thermal expansion of WC-Co cemented carbide and diamond have limited the development of spherical diamond-coated tools. In this study, diamond sphere films with different crystal orientation and texturing were successfully prepared by hot filament chemical vapor deposition (HFCVD). The adhesion and friction characteristics of the films were investigated by indentation and friction tests. The results show that the adhesion of the (111) orientation micron diamond (111MDF) spherical film, (110) orientation micron diamond (110MDF) spherical film, and (110) orientation texturized micron diamond (110TDF) spherical film increase sequentially at the same position. Under dry friction conditions, the average coefficient of friction of 110TDF spherical film was reduced by 28%, the wear resistance was increased by 80%, the surface roughness of the workpiece was reduced by 23%, and the material removal rate was reduced by 23.6% compared with that of 111MDF spherical film.