Abstract: Diamond coated tools are fabricated using WC-Co cemented carbide inserts as substrates by the electronically aided hot filament chemical vapor deposition(EACVD).The new substrate pretreatment methods are investigated to enhance the adhesion of diamond films. An efficient measure is presented to inhabit the catalytic effect of cobalt. The new CVD processes are proposed to improve the surface roughness of diamond thin films. The research results show that the pretreatment using Ar-H2 etching decarburization by microwave plasma is an effective method to enhance adhesive strength. An adequate amount of additive can effectively prevent the overflow of Co from inner to surface of the substrate and avoid the catalytic effect of Co during CVD. The smooth diamond film with low surface roughness can be deposited by increasing the carbon source concentration and reducing the reactive pressure at the later stage of CVD process. Owing to the fabrication and application of diamond thin films with the low surface rough-ness and high adhesion strength, it is of great significance for improvement of the cutting performance of diamond-coated tools and development of high efficiency and precision cutting technology.

Key words: Adhesive strength, Cutting performance, Diamond thin films, Surface roughness