Improved corrosion resistance of dental Ti50Zr alloy with (TiZr)N coating in fluoridated acidic artificial saliva

The electrochemical corrosion behavior of the dental Ti50Zr alloy with and without nanocrystalline (TiZr)N coating was comparatively investigated in artificial saliva solutions with different pH values and fluoride ion concentrations. The chemical stability of the passive films on the coated and non-coated Ti50Zr alloy was evaluated by calculating passive film thickness. The chemical compositions and valence structures of the passive films were analyzed by X-ray photoelectron spectroscopy (XPS). The results show that the (TiZr)N-coated alloy displays distinctly decreased corrosion rate and increased impedance compared with Ti50Zr alloy in non-fluoridated and fluoridated acidic solutions. Particularly, in the solution of pH = 3.9 and 0.15% NaF-containing, the corrosion protection efficiency of (TiZr)N coating reaches 90%. The excellent corrosion resistance of the coated alloy is attributed to that the nanocrystallines in (TiZr)N coating decreases micropores and crack defects, which strongly impedes the corrosive ions diffusion and electrode process at Ti substrate/coating interface. Meanwhile, (TiZr)N coating shows good passivation behavior in acidic solution and active–passive transition behavior in fluoridated acidic solution. The coated Ti50Zr alloy with high chemical stability has potential application prospect for dental implants.