INFLUENCES OF INTERMEDIATE SI-NI THIN-FILM CONDITIONS ON ADHESION OF NI-TIN GRADIENT THICK-FILMS

The influences of the intermediate thin film properties, that is inter nal stress and preferred orientation, on the adhesion of thick film we re studied. The intermediate layers were designed Si and Ni multilayer structures, which were formed by the ion beam and vapor deposition me thod. Si films were prepared by evaporation of Si and simultaneous irr adiation with Ar ions on to WC-Co substrates after surface cleaning by Ar ion beam irradiation. After the preparation of Si films, Ni films were also prepared by evaporation of Ni and Ar ion irradiation simulta neously. The internal stresses and preferred orientations of both film s were controlled by changing the ion beam energy. Ni-TiN gradient thi ck films were formed on to these Si-Ni multilayer films by the cathodi c are ion plating method. It was found that the improvements of the in ternal stress and the preferred orientation conformities at the interf ace between the intermediate films and the thick films were important factors for high adhesion of thick film. The Ni-TiN gradient thick fil m reached a thickness of 600 mu m with an adhesion high enough for pra ctical use. (C) 1998 Elsevier Science S.A. All rights reserved.