Enhanced Wear Resistance of TC4 Surface by h-BN/TiO₂-WO₃ In Situ Composite Film Layer

There is an urgent need to improve the self-lubricating, wear-resistant, and high-thermal conductivity properties of metal surfaces in titanium alloys, such as TC4, in extreme aerospace environments. In this study, a new h-BN/TiO₂-WO₃ in situ composite film layer with high hardness and a self-lubricating, multifunctional coating was proposed using a microarc oxidation (MAO) technique to improve the wear resistance of TC4. During the MAO breakdown process, WO₃ uniformly enters the film layer, accompanied by a strong electric field in the breakdown channel, which adsorbs the h-BN particles. This causes the h-BN particles to cluster inside the breakdown channel and in the surrounding area. The h-BN/TiO₂-WO₃ composite structure significantly improved the hardness performance. The optimized composite coating has the lowest average coefficient of friction of 0.12 and the lowest specific wear rate of 4.29 (10^-5 mm³·N^-1·m^-1), and the hardness reaches 1269 HV_1N. The strong chemical and physical bonding at the interface further enhances the high hardness, wear resistance, and self-lubrication properties of TC4. The composite film layer prepared in this article has become an ideal solution to improve the service performance and life of TC4 titanium alloy components under extremely harsh conditions.