Nitriding of nonferrous metals by plasma nitriding method

Ti6Al4V alloys are very attractive materials because of their biocompatibility and corrosion resistance properties. But application of titanium and its alloys are very low in mechanical engineering applications because of poor surface hardness and wear resistance. These problems can be overcome using such surface engineering technologies as thermochemical treatments to obtain desirable properties.To improve wear resistance and the surface hardening of Ti6Al4V alloy has been aimed in this investigation by plasma nitriding treatment which has been performed in 80% N2-20% H2 gaseous mixture, for treatment times of 1, 2 and 4 h at the temperatures of 600, 650, 700, 750, 800 and 900 oC. The study presents the results of the examinations of microstructures, microhardnesses, thicknesses, SEM analyses, X-Ray diffraction analyses, wear behaviors of surface layers on the Ti6Al4V alloy by plasma nitriding.By optic inspection two layers were determined on the samples that called compound and diffusion layers. Compound layer contain TiN and Ti2N nitrides, XRD results support in this formations. By microhardness investigations, the maximum surface hardness has been obtained in the plasma nitrided sample over a period of 4h at 800 oC. By optical microscope investigations, the case depth was found to increase with increasing process temperature and time. The result of wear tests which was carried out using pin-on-disc machine is wear resistance of Ti6Al4V alloy increases as the time and temperature of plasma nitriding increase.