Electrochemical behavior of TiN film coated Ti-Nb alloys for dental materials

In order to study the electrochemical behaviors of TiN film coated Ti-Nb alloys for dental materials, Ti containing Nb up to 3, 20, and 40 wt.% was melted by a vacuum furnace and coated with TiN by EB-PVD. The electrochemical behaviors were investigated using a potentiostat in 0.9 % NaCl solution and the corrosion surface was observed using SEM and XPS. Ti-3Nb and Ti-20Nb alloys have alpha+beta phase structure. In the case of Ti-40Nb, the microstructure had a coarse beta phase. The microstructural changed from equiaxed to acicular and an increase of beta-phase in Ti-Nb alloys was observed with increased Nb content. The current density at 300 mV (potential of oral environment) of Ti-40Nb alloy was lower than that of the other alloys in 0.9 % NaCl. The pitting corrosion resistance of Ti-40Nb was higher than that of Ti-3Nb and Ti-20Nb alloys in the 0.9 % NaCl solution. The corrosion potential and pitting potential of TiN coated Ti alloy increased with increasing Nb content but the current density at 300 mV and the current density at the passive region decreased. The TiN coated Ti-40Nb alloy offers good corrosion resistance for dental implants compared with non-TiN coats alloys.