Effect of α-Al2O3 Additive on the Surface Micro-Arc Oxidation Coating of Ti6Al4V Alloy

Abstract

α-Al2O3 nanoparticles can enter a micro-arc oxidation coating and participate in the coating-formation process through chemical reaction or physical–mechanical combination in the electrolyte. The prepared coating has high strength, good toughness and excellent wear and corrosion resistance. In this paper, 0, 1, 3 and 5 g/L of α-Al2O3 nanoparticles were added to a Na2SiO3-Na(PO4)6 electrolyte to study the effect on the microstructure and properties of a Ti6Al4V alloy micro-arc oxidation coating. The thickness, microscopic morphology, phase composition, roughness, microhardness, friction and wear properties and corrosion resistance were characterized using a thickness meter, scanning electron microscope, X-ray diffractometer, laser confocal microscope, microhardness tester and electrochemical workstation. The results show that surface quality, thickness, microhardness, friction and wear properties and corrosion resistance of the Ti6Al4V alloy micro-arc oxidation coating were improved by adding α-Al2O3 nanoparticles to the electrolyte. The nanoparticles enter the coatings by physical embedding and chemical reaction. The coatings’ phase composition mainly includes Rutile-TiO2, Anatase-TiO2, α-Al2O3, Al2TiO5 and amorphous phase SiO2. Due to the filling effect of α-Al2O3, the thickness and hardness of the micro-arc oxidation coating increase, and the surface micropore aperture size decreases. The roughness decreases with the increase of α-Al2O3 additive concentration, while the friction wear performance and corrosion resistance are improved.