THIN-FILMS COMPARABLE WITH WC-CO CEMENTED CARBIDES AS UNDERLAYERS FORHARD AND SUPERHARD COATINGS - THE STATE-OF-THE-ART

A new method for deposition of barrier underlayers, which completely p revent Co penetration to the substrate surface and are highly compatib le with WC-Co cemented carbides, has been developed. It allows deposit ion of thin hard continuous, highly adherent and defect-free TiCN-base d films by the use of high energy titanium ions. The method ensures de position without any damage of the cemented-carbide substrate or its d ecarburization, leading to formation of the eta phase near the surface layer. As a result, CVD TiC, TiCN, TiN etc. coatings can be deposited onto cemented carbides preliminarily plated with barrier underlayers almost without a decrease in transverse rupture strength. Special addi tional interlayers are applied for enhancement of the adhesion between the underlayers and plasma CVD diamond coatings, resulting in excelle nt resistance of the near-surface layer of the cemented-carbide substr ate with these coatings to high static loading when subjected to inden tation.