Characterization of ta-C films prepared by a two-step filtered vacuum arc deposition technique

Adhesive strength is one of the most important properties of a coating, and one which could be improved by preparing an interface layer with increased ion energy, i.e. by applying high substrate-bias voltage. Hence, an investigation has been carried out to study the effect of substrate-bias voltage, and of the interface layer on the mechanical and tribological properties of ta-C films. In this presentation, the films are prepared by a two-step process. A relatively thick, hard layer of ta-C film is deposited on top of a relatively thin soft adhesive (interface) layer, which is deposited on a silicon substrate. The thin soft adhesive (interface) layer was prepared with a different ion energy, by controlling the high voltage negative substrate-bias. The thick hard layer on the top was prepared without any substrate-bias. The influence of substrate-bias during the preparation of the interface layer on the properties (structural, mechanical and tribological) of the ta-C films was investigated. The results show that the adhesive strength can be improved to a great extent, without much damage to the mechanical and tribological properties of the coating.