Enhancing wide-temperature tribological properties and oxidation resistance of Ti-MAO coatings with h-BN

Titanium alloys are widely used in lightweight mechanical components, but their limited mechanical and tribological properties often lead to failure under service conditions. In this study, a titanium-based micro-arc oxidation (Ti-MAO) composite coating was developed by incorporating hexagonal boron nitride (h-BN) while optimizing electrolyte composition and process parameters. Proper control of h-BN content effectively improved the high-temperature oxidation resistance and tribological properties of the Ti-MAO coating. The research results showed that h-BN could regulate the energy distribution during MAO discharge, promote coating densification, and reduce structural defects. At a concentration of 4 g/L, h-BN maintained good dispersibility. Compared with an additive-free Ti-MAO coating, the h-BN/Ti-MAO composite coating showed an 86% reduction in the oxidation rate constant at 600 °C. Due to the stable layered structure of h-BN over a wide temperature range, the composite coating maintained a friction coefficient (COF) below 0.31 from room temperature (RT) to 500 °C, reduced to below 0.21 within 300 °C. However, excessive h-BN led to particle aggregation and a decline in overall coating performance. In summary, this approach enhances the durability of titanium alloy components through improved oxidation resistance and tribological properties.