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.

Research on the Tribological Properties of a New Generation of Multi-Layer Nanostructured PVD Coatings for Increasing the Technological Lifetime of Moulds

“…As a result, the friction curves of the coating sample without laser dimples vibrated more strongly, as shown in Figure 16. This mechanism is in good agreement with Y. Chen and M. Yuan's investigation [34].…”