Friction and wear behaviours of Ti(C,O,N) dark decorative coatings

Reactive magnetron sputtering was used to obtain dark Ti(C,O,N) decorative coatings onto high speed steel. From a crystallographic point of view, depending by the amount of (N+O) mixture, the obtained films could be divided in two major regions: the first one with a predominant fcc crystallographic structure (for low amounts of (N+O)), and the second one containing films with amorphous structures. The best results for friction coefficient and wear rates (the minimum values) were registered for samples prepared in the beginning of the amorphous region. These two tribological parameters are mainly influenced by the carbon content in the films. Taking into account the practical goal of these kinds of films, the pure black films were obtained for higher amount of (N+O) mixture. Also for these amorphous darkest films reached in oxygen and nitrogen, the tribological properties are acceptable and the adherence reaches the maximum value.

Research highlights
► High amount of C and an amorphous structure confer good tribological properties of the Ti(C,O,N) coatings.
► High amount of C and an amorphous structure confer a minimum roughness of the Ti(C,O,N) coatings.
► High amount of (N+O) mixture in the general composition of Ti(C,O,N) coatings aggravates the tribological behaviour.