Electrochemical modification of Ti-13Nb-13Zr alloy surface in phosphate based solutions

The Ti-13Nb-13Zr alloy can successfully be used as a bone implant because it contains elements that are not harmful to the human body. However, to increase its osseointegration and corrosion resistance, this alloy is subjected to surface modifications. In this work, Ti-13Nb-13Zr alloy was modified by plasma electrolytic oxidation (PEO) in a 0.1 M NH4H2PO4 solution with the addition of Ca3(PO4)2 powder (25 g/dm3) under voltages of 150, 300 and 400 V. The morphology, cross-section, chemical composition, surface roughness and corrosion resistance of the coatings formed on the substrate by the PEO process are presented in this work. An increase in the applied voltage caused an increase in the number of pores and an increase in the amounts of calcium and phosphorus incorporated in the oxide layer. Analysis showed that all samples were covered by titanium oxide, which was present in the form of anatase. The results demonstrated that the surface modification of the Ti-13Nb-13Zr alloy through the PEO process improves its corrosion resistance.