Study on the preparation of CeO2-doped AlCoCrFeNiTi high entropy alloy bioinert coatings by laser cladding: The effect of CeO2 particle size on the tribological properties of the coatings

The AlCoCrFeNiTi high entropy alloy (HEA) bioinert wear-resistant coatings reinforced by doping CeO2 particles were prepared on the surface of Ti6Al4V via laser cladding technique. In order to find out the effect of CeO2 particle size on the tribological properties of AlCoCrFeNiTi HEA coatings, the coatings doped with 1 wt% nano, submicron, and micron CeO2 particles were prepared respectively. The phase composition and microstructure of the coatings were analyzed, and the fracture toughness values of the coatings were tested. Friction and wear properties of the coatings sliding against Si3N4 ceramic grinding balls were tested under dry friction and wet friction (simulated body fluid, SBF) conditions, respectively. The results showed that the CeO2 particle size had a significant impact on the wear mechanisms of the coating and thereby improved its tribological properties. Doping with submicron CeO2 particles had the most significant improvement on the tribological properties of the coatings, followed by micron CeO2 particles, and doping with nano CeO2 particles had the weakest improvement on the tribological properties of the coatings. The distribution of submicron CeO2 particles in the coating was more dispersed and uniform, which significantly reduced the crack sensitivity of the coatings, inhibited the peeling off of the oxide film on the coating surfaces, and played a lubricating role. Under dry friction and SBF conditions, the friction coefficient of the coatings doped with submicron CeO2 particles decreased by 41.81% and 27.27%, respectively, and the wear resistance increased by 55.14% and 50.69%, respectively. This study has important reference value for the development of new bioinert wear-resistant coatings.