Effect of CoSO4 on the corrosion performance of Ti6-Al4-V plasma electrolytic oxidation coatings

Abstract

To investigate the impact of CoSO4 on Ti6-Al4-V titanium alloy plasma electrolytic oxidation coatings and their erosion resistance, plasma electrolytic oxidation was performed in electrolytes with varying CoSO4 concentrations. Scanning electron microscopy, XRD, XPS, electrochemical workstations, and corrosion testers were used to study the effects of CoSO4 on the morphology, phase composition, corrosion resistance, and erosion properties of the coatings. Results indicated that increasing CoSO4 concentration led to higher oxidation voltages, fewer micropores and microcracks, and a more uniform and dense surface. The coatings mainly consisted of Ti, Anatase, Rutile, and CoO phases. The best overall performance was achieved with 0.8 g L−1 CoSO4, where the self-corrosion current density decreased from 1.04 × 10−7 A cm−2 (substrate) to 2.21 × 10−8 A cm−2, indicating enhanced corrosion resistance.