Improvement of friction and wear performance of titanium nitride films by chlorine ion implantation

TiN films were prepared on high speed tool steel substrates by means of hollow cathode discharge ion plating, and were implanted with chlorine ions at doses from 1 × 10²⁰ to 1 × 10²¹ m^-2 to improve tribological properties. Friction and wear tests were carried out on a pin-on-disk tribometer with type 304 stainless steel ball as the counter material. The structure of the surface layers modified by ion implantation was characterized by X-ray diffraction analysis (XRD). X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical bonding states and the depth distribution of elements in surface layers of TiN films. Surface observation and chemical composition analysis of the wear track were also carried out by scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDX), respectively. The chlorine ion implantation significantly reduced the friction coefficient of the TiN films against the stainless steel balls. The wear mode has drastically changed from adhesive wear to abrasive wear by this Cl-implantation to the TiN film. With increasing Cl dose, not only the friction coefficient but also the wear volume of the stainless steel balls were reduced. This implies that the implanted chlorine prevents the adhesion of the counter material, resulting in the significant reduction of the friction coefficient.