Effect of chlorine distribution profiles on tribological properties for chlorine-implanted titanium nitride films

The tribological properties of chlorine-implanted TiN films prepared on high-speed tool steel were investigated. Chlorine ion implantation up to 1 × 10¹⁷ ions/cm² was performed at energy ranging from 33 to 100 keV. Friction and wear tests were carried out using a pin-on-disk tribometer with steel balls as the counter material. The modified surface layers were characterized by X-ray diffractometry (XRD) and transmission electron microscopy (TEM) for crystal structure identification, and by glow-discharge optical emission spectrometry (GD-OES) for chemical composition analysis. Auger electron spectroscopy (AES) was also utilized for composition analysis of the wear debris. The chlorine ion implantation reduced the friction coefficient of the TiN films from 1.1 to less than 0.2 against the stainless steel balls. The wear volume of the stainless steel balls was also reduced. We suggest that adhesion of the counter material has been prevented in the wear track by the chlorine ion implantation. The tribological behavior of TiN film is related to the distribution of the implanted chlorine atoms. In the case of the low implantation energy, the low dose of chlorine was enough to improve the tribological properties of the TiN film in the initial stages of testing. This is because the implanted chlorine atoms have been distributed close to the surface of the TiN film in a manner dependent on the implantation energy.