Synergistically Enhancing Tribological Properties, Oxidation Resistance and Anti-Corrosion of Ti-MAO Coatings via h-BN/SiC Co-doping

To enhance the service performance of titanium alloys for demanding high-end equipment applications, an h-BN/SiC-Ti-MAO composite coating was fabricated on Ti6Al4V via one-step micro-arc oxidation (MAO). Optimizing the SiC additive concentration offers an effective way to improve the overall performance of the composite coating in mechanical, tribological, oxidation resistance and anti-corrosion properties. The research results show that the coating prepared with 4 g/L SiC yielded superior multifunctional properties. It possessed a dense microstructure with the lowest porosity (6.45%), high hardness (712 HV) and excellent adhesion. This coating maintained a low friction coefficient of approximately 0.20 from RT to 5 0 0 ∘ C and exhibited the best oxidation resistance at 6 0 0 ∘ C, with a parabolic rate constant ( K P ) of 3 . 3 3 × 1 0 − 4 . Electrochemical tests in 3.5 wt.% NaCl solution further confirmed its optimal anti-corrosion, showing the lowest corrosion current density ( 3 . 3 2 5 × 1 0 − 9 A/cm 2 ) . In contrast, insufficient SiC concentration results in limited performance improvement of the composite coating, whereas excessive concentration introduces microstructural defects, ultimately degrading the overall performance. This study demonstrates that optimized h-BN/SiC co-doping represents an effective strategy for developing high-performance MAO protective coatings on titanium alloys.