Study of the Structure and Mechanisms of Wear of Solid-Lubricant Coatings of the TiN–Pb System

Abstract

Сomposite solid lubricating coatings TiN–Pb with a thickness of ~2 μm were produced by co-sputtering of Ti and Pb cathodes of two separate magnetrons on titanium alloy VT6. The Pb content in the coating averages ~12 at. %. The inner layer is coating characterized by a uniform distribution of Pb, and the upper layer is characterized by the presence of islands with a high content of Pb. The coating structure is globular, predominantly containing nanometer-sized crystallites. The absence of a columnar structure of the coating is associated with a high content of Pb, which is insoluble in the TiN matrix and interrupts the growth of crystallites. X-ray diffraction analysis showed the presence of Pb, PbO, and TiN phases in the coatings. The diffraction lines are broadened, which indicates that the crystallite size is ~10–20 nm in the coating. Tribological tests of the TiN–Pb coating were carried out under conditions of low-amplitude friction – fretting wear in a wide range of loading parameters. In the full slip mode, a friction coefficient of ~0.25 is observed. During the transition from the full slip mode to the reciprocating slip mode, the energy dissipated during friction drops by more than three times, which is also reflected in a sharp decrease in the friction coefficient from 0.25 to 0.05.