High Temperature Tribological Properties of Laser Cladding Titanium Matrix Self-Lubricating Wear Resistant Composite Coating on TA2 Alloy

Titanium matrix high-temperature self-lubricating anti-wear composite coating was fabricated by laser cladding with Ti-TiC-WS₂ powders to improve its tribological properties. The phase compositions, microstructure and microhardness were investigated systematically. Tribological properties of the composite coating and TA2 alloy were investigated at room temperature (20 ℃), 250 ℃ and 500 ℃, respectively, and the wear mechanisms are discussed. Results indicate that the microhardness of the coating is HV_0.51 005.4, which is 5 times higher than that of the substrate (HV_0.5190). Due to the combined effects of hard TiC/(Ti, W)C_1-x carbides and self-lubricating Ti₂SC/TiS sulfides, the composite coating had lower friction coefficient and wear rate than that of the substrate at all test temperatures. The friction coefficient of the coating decreased firstly and then increased with the increase of temperature. The lowest friction coefficient was 0.257 at 250 ℃. Wear rate of the coating decreased with the increase of temperature, and the lowest wear rate was 0.487×10^-5 mm³/(Nm).