Preliminary investigations on the anodic oxidation of Ti–13Nb–13Zr alloy in a solution containing calcium and phosphorus

Investigations on the surface modification of Ti–13Nb–13Zr alloy by anodic oxidation are reported here. The oxidation process was carried out in a solution containing 4 mol dm⁻³ H₃PO₄ and 100 g dm⁻³ Ca(H₂PO₂)₂. The anodising was realised at voltages of 80 V and 150 V. Moreover, a portion of the samples that had been oxidised at 150 V were held at a temperature of 500 °C. It was found that the morphology of the sample surface did not change during the oxidation of the alloy at 80 V. An application of 150 V led to the incorporation of calcium and phosphorus into the formed oxide layer and to significant modification of the surface morphology. The electrochemical characteristics of the modified alloy was also determined in Ringer's solution. It was shown that the electropolishing and anodising result in a considerable increase in the corrosion resistance of the Ti–13Nb–13Zr alloy.