Improved Wear and Corrosion Resistance of Microarc Oxidation Coatings on Ti–6Al–4V Alloy with Ultrasonic Assistance for Potential Biomedical Applications

Abstract

Although microarc oxidation is frequently used in producing wear‐ and corrosion‐resistant coatings on Ti and Ti alloys for biomedical applications, the formation of nonuniform microstructure of the coatings is still unavoidable. To overcome this drawback, this work adopts ultrasonic assistance in the microarc oxidation of Ti–6Al–4V and systematically investigates the influences of ultrasonic treatment with different durations on the coating microstructures and resultant properties. The positive effects of ultrasonic, such as cavitation effect, sound flow effect, and mechanical effect, accelerate the cooling rate of electrolyte and promote the homogeneity of the solute on the sample surface. Therefore, the ultrasonic‐assisted coatings exhibit uniform microstructures with fewer cracks and therefore improve performances. For instance, compared with the counterpart without ultrasonic assistance, the ultrasonic‐assisted coating with 15 min duration demonstrates 25.1% lower mass loss in the tribology test and half corrosion density in Hank's solution. Such results indicate that ultrasonic assistance in microarc oxidation of Ti–6Al–4V can homogenize the microstructures of coatings and enhance their corrosion resistance and wear resistance in human body.