EFFECT OF SANDBLASTING ON ADHESION STRENGTH OF DIAMOND COATINGS

Premature failure of a diamond-coated tool often results from a poor a dhesion of the coating and shortens the lifetime of the tool. This stu dy presents the results of increasing the adhesion strength of diamond coatings on cutting tool inserts by pretreating the inserts with sand blasting technique to obtain a desirable surface morphology of the ins erts. A geometric model representing the ideal surface morphology is e stablished to enhance the nucleation density and adhesion strength of diamond coatings. Diamond coating experiment is conducted on the subst rates of four different sample groups. Indentation and wear tests are performed on diamond-coated inserts to evaluate the effect of sandblas ting on the adhesion strength of the coatings. A theoretical analysis is provided on the formation and growth of atom clusters in terms of t he contact angle and the thermodynamic barrier of a substrate to predi ct diamond nucleation. The theoretical prediction has a good agreement with the experimental results obtained in this study and by Dennig an d Stevenson [P.A. Dennig, D.A. Stevenson, Proceedings of the Internati onal Conference on New Diamond Science and Technology, 403 (1991); P.A . Dennig, D.A. Stevenson, Proceedings of the First International Confe rence on the Applications of Diamond Films and Related Materials, 383 (1991).]. (C) 1997 Elsevier Science S.A.