Improving the Tribological Properties of Steel by Static Ion Beam Mixing

By static ion beam mixing treatment using the physical vaporized deposition of the titanium followed by nitrogen ion implantation, the titanium nitride coating was formed onto the disk surface of hardening steel and tribological properties were evaluated in pin-on-disk tests under a lubricated condition. In comparison with the uncoated case, the coating increased microhardness by 1.3 times and decreased the coefficient of friction from 0.6 to 0.1 and the volumetric wear rate of pin material to 1/10. Break away of the coating was not observed. By the glancing angle X ray diffraction and the Rutherford back scattering analysis, titanium oxide and TiN were observed in the coating. It was confirmed that atomic mixing occurred at the interface between coating and substrate. This results indicate that this structure consisting of TiN including Ti oxides and atomic mixing at the interface results in superior tribological properties and stiffness of the coating.