W WC DIFFUSION BARRIER LAYERS FOR CVD DIAMOND COATINGS DEPOSITED ON WC-CO - MICROSTRUCTURE AND PROPERTIES/

WC films are investigated for use as intermediate layers for adhesion improvement between the cemented carbide (WC-Co) substrate and a CVD d iamond wear resistant layer. WC layers are prepared by reactive magnet ron sputtering. Deposition conditions during the sputtering are adjust ed to change the WC layer stoichiometry and the microstructure. Layers are investigated by X-ray diffraction and scanning electron microscop y (SEM) in as deposited and in annealed states. Adhesion of diamond is investigated by Rockwell-C indentation. Adhesion data shows a strong dependency on the deposition conditions for the WC layers. This data i s explained in terms of Co diffusion from the substrate through the in termediate layer and of mechanical properties of the intermediate laye r itself. (C) 1998 Published by Elsevier Science S.A.