Effect of oxidation time on the structure and properties of Ti–25Nb–3Zr–2Sn–3Mo titanium alloy microarc oxide film layer

Abstract

In order to improve various properties of medical titanium alloys, Ti–3Zr–2Sn–3Mo–25Nb titanium alloy specimens were subjected to microarc oxidation (BMAO) in 0.1 mol/l sodium tetraborate electrolyte to cover the substrate with a micro-nano double-graded structured coating. The effect of oxidation time on the microstructure, physical phase, hardness, corrosion resistance, and wettability of the micro-nano film layer was investigated. The results show that the microporous size of the film increases with the increase in oxidation time, and the hardness of the BMAO film increases with the increase in oxidation time; the corrosion resistance of the BMAO film is better than that of the substrate, and the self-corrosion potential is the largest at 14 min of oxidation time, reaching −0.1349 V, which is 65% higher than that of the substrate, and the self-corrosion current is the lowest, at 1.1376 × 10−9 A cm−2, which is one order of magnitude lower than that of the substrate; the micro-nano film layer exhibits superhydrophilicity, which increases and then decreases with time, and the contact angle is the smallest at 6 min of oxidation time, 4.4°, which is one order of magnitude lower than that of the substrate, 73.75°.