Structure and Tribological Characteristics of a TiN–Cu Coating with In and Sn Additions

Solid lubricating TiN–Cu films with In and Sn additions 1.7–2.3 μm in thickness, which are formed on rotary substrates in the course of reactive magnetron sputtering of separate cathodes, are studied by scanning electron and confocal microscopy, X-ray diffraction analysis, and tribological tests performed at room and high temperatures in reciprocating wear mode. The coatings are found to be characterized by a nanocolumnar structure, the presence of the Cu and TiN phases, and a pronounced texture. The direction of rotation of samples relative to magnetrons is found to affect the tribological properties of coatings. The lowest friction coefficient (f = 0.15) is observed for the coating formed during counterclockwise rotation at a speed of 2 rpm. Step-by-step heating of the coatings to 100 and 200°C leads to an increase and, then, a decrease in the friction coefficient to f = 0.15 after 2000 tribological test cycles, which is due to the formation of oxides and oxynitrides.