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

The simultaneous sputtering of Ti and Pb cathodes of two separate magnetrons on titanium alloy VT6 is used to obtain composite solid lubricating coatings of TiN-Pb with a thickness of similar to 2 mu m. The Pb content in the coating averages similar to 12 at %. The inner layer of the coating is characterized by the 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 nanoscale 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 similar to 10-20 nm in the coating. Tribological tests of the TiN-Pb coating are carried out under conditions of low-amplitude friction (fretting wear) in a wide range of loading parameters. In the full sliding mode, a friction coefficient of similar to 0.25 is observed. During transition from the full sliding mode to the reciprocating sliding 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.