In this study, ceramic coatings were prepared on the surface of TC4 titanium alloy by micro-arc oxidation (MAO). The morphology, element distribution and phase composition of MAO coatings were analyzed by SEM, EDS, XRD and other analytical methods. The effect of hexagonal boron nitride(h-BN) doping on wear resistance and corrosion resistance of micro-arc oxidation layer was studied. The results show that the coating is mainly composed of rutile TiO2, anatase TiO2 and a small amount of h-BN. Furthermore, the composite coating containing h-BN was less porous than particle-free coating. The test results show that h-BN doping slightly affects the hardness of the MAO coating, and it is helpful in improving the thickness, corrosion resistance and wear resistance of the coatings. When the amount of h-BN is 3 g/L, the corrosion current density of the coating is the smallest; When the addition of h-BN is 1.5 g/L, the friction coefficient of the coating is the smallest. The wear mechanism was adhesive wear, accompanied by slight abrasive wear.

To improve the surface micropores and high-temperature oxidation resistance of micro-arc oxidation (MAO) coating on TC4 titanium alloy, cerium dioxide (CeO2) particles were introduced into the electrolyte to prepare MAO composite coatings with different CeO2 content. X-ray diffractometer, scanning electron microscope and multifunctional material surface performance tester were used to analyze the phase composition, surface morphology and bonding force of the samples. TC4 substrate, undoped MAO sample and optimally doped MAO sample were oxidized at 650°C, 750°C and 850°C respectively. The results show that the best doped MAO samples show excellent high-temperature oxidation resistance at three temperatures. Compared with the undoped MAO sample, the maximum oxidation weight gain per unit area of the optimally doped MAO sample decreased by 10.8%, 19.6% and 22.1%, respectively. This is mainly because the thickness, hardness and adhesion of MAO coating are all increased by doping CeO2 particles, and a dense protective layer can also be formed on the surface of TC4 substrate. The invasion of oxygen medium is effectively prevented. In this research work, the optimal addition amount of CeO2 is 6 g/L.