Surface properties and mechanism of corrosion resistance enhancement in a high temperature nitrogen ion implanted medical grade Ti

For the 473 K implanted sample as a selected implantation temperature, the enhanced corrosion resistance mechanism was investigated more accurately. The surface layer of 473 K implanted sample was studied by a Multi-Beam Focused Ion Beam-Scanning Electron Microscope (FIB-SEM) and was compared with an unimplanted and a 300 K implanted sample. The cross section of samples was channeled using FIB method to study the distribution of nitrogen atoms by EDS mapping technique. The depth profiles of the nitrogen atoms in the implanted samples were also obtained from EDS analysis. Surface feature and roughness of samples were studied by atomic force microscopy (AFM). According to the AFM results, the surface of 473 K implanted sample with uniformly distributed nano-scaled islands, showed a higher roughness value compared to the 300 K implanted one and was predicted to have more compatibility with body tissues. Electrochemical behavior of unimplanted, 300 K and 473 K implanted samples was studied using impedance spectroscopy methods in the Ringer's solution as a simulated body fluid. The mechanism of the corrosion resistance improvement at high temperature implanted sample was developed according to the impedance spectroscopy results.