On Superstoichiometric Ti-C, Si-C and Ta-C PVD Coatings

Different PVD coatings are used to reduce the wear of tools and other machine parts, and to improve their service life [1]. During the last years, a number of developments have been made in the field of carbon coatings. These coatings show a low friction coefficient, e.g. against steel, and therefore have a high potential in decreasing the friction and wear of coatings in tribological applications. This PVD process can be stabilised by using a metallic target which is vaporised in a carbon and hydrogen atmosphere. The carbon rich side of the metal/carbon system is object of this study. Slightly superstoichiometric coatings in the range of 50–60% carbon content have very good friction properties too and with the potential to better film properties (coating adhesion due to internal stress, microhardness). In this paper the mechanical properties of coatings in the systems Ti-C, Si-C and Ta-C are described and the different microstructures are discussed.