Effect of temperature on surface characteristics of nitrogen ion implanted biocompatible titanium.

It has been established that nitrogen implantation can modify metals surface properties such as corrosion, wear, friction, etc. Recent studies have shown that nitrogen implantation into titanium and its alloys leads to the formation of titanium nitride, which has interesting biological, chemical, and mechanical properties. In the present investigation, commercially pure biocompatible titanium implanted by nitrogen. Implantation of ions performed at 80 keV and a dose of 2.1 × 1018 ions/cm2 at four different temperatures of 300, 473, 673 and 873 k. Phase and chemical compositions of modified surfaces after implantation obtained using grazing incidence X-ray diffraction technique (GIXRD) and Fourier transform infrared spectrum (FTIR), respectively. The roughness variations before and after ion implantation were observed by atomic force microscopy (AFM). Electrochemical behavior of the samples was investigated in Ringer solution by using electrochemical impedance spectroscopy and polarization tests. Scanning electron microscopy micrographs was used to evaluate the surface morphology of the samples. Variation of the Young's modulus and hardness of samples were examined using nano-indentation technique before and after ion implantation. Compared to nano-hardness of unimplanted sample, the maximum nano-hardness value of implanted samples is as high as 14.2 GPa, which is at least eight times larger than hardness of the unimplanted sample. The elastic modulus of unimplanted sample was obtained 106 GPa and the maximum elastic modulus value of implanted samples is as high as 178 GPa. Corrosion test results showed that implantation could increase the corrosion resistance of samples, but by increasing the implantation temperature, the corrosion resistance will decrease.