Hydroxyapatite coating on the Ti–35Nb–xZr alloy by electron beam-physical vapor deposition

The aim of this study was to investigate the hydroxyapatite coating on the Ti–35Nb–xZr alloy by electron beam-physical vapor deposition. The Ti–35Nb–xZr ternary alloys contained from 3 wt.% to 10 wt.% Zr content were manufactured by arc melting furnace. Hydroxyapatite (HA) coatings were prepared by electron-beam physical vapor deposition (EB-PVD) method, and crystallization treatment was performed in Ar atmosphere at 300 and 500 °C for 1 h. The coated surface morphology of Ti–35Nb–xZr alloy was examined by FE-SEM, EDX and XRD, respectively. In order to evaluate the corrosion behavior, the tests were performed by potentiodynamic, cyclic polarization and AC impedance test. All the electrochemical data were obtained using a potentiostat. The Ti–35Nb–xZr alloys exhibited equiaxed structure with β phase, the peak of β phase increased with Zr contents. The hardness and elastic modulus of Ti–35Nb–xZr alloys decreased as Zr content increased. The HA coated layer was approximately 150 nm and Ca/P ratio of HA coated surface after heat treatment at 500 °C was around 1.67. The HA thin film consisted of small droplets with spherical shape by crystallization. From the anodic polarization curves, HA coated and heat treated Ti–35Nb–10Zr alloy showed higher corrosion potential than other samples. HA coated film on the Ti–35Nb–10Zr alloy can be shown high polarization resistance by crystallization.