Influence of Applied Voltage on Surface Morphology and Wettability of Biological Coatings on Ti6-Al-4V by Micro-Arc Oxidation Treatment

Abstract

Micro-arc oxidation (MAO) treatment with various voltages was carried out on Ti alloys in 10% H₂SO₄ aqueous solution to enhance surface wettability for biological application. The effects of applied voltage on the surface morphology, phase constituents, functional group, roughness and wettability of the MAO coatings were investigated comprehensively. Increasing applied voltages significantly change phase constituents, surface morphology and wettability of the MAO coatings. Higher applied voltages are favorable to form higher fraction of rutile phase, larger micro-pores and higher surface roughness. The apparent contact angle decreases slightly after treated at 80 V but it decreases sharply after treated at 160 V or 200 V. The significant change in wettability of MAO coatings is attributed to hydroxyl group content and morphology of the MAO coatings. Differences in hydroxyl group content and surface morphology result in different contact interface types between water and MAO coatings, which is attributed to air captured or no air captured interface models.

Keywords:
Microarc oxidation; oxide film morphology; roughness; wettability; biomedical applications