Tribological studies of Zr-implanted PVD TiN coatings deposited on stainless steel substrates

Abstract TiN films deposited by a commercial physical vapour deposition (PVD) process were implanted with Zr ions at an energy of 40 keV and with doses ranging from 6×10 16 to 2×10 17  ions/cm 2 . The films were characterised by glancing incident angle X-ray diffraction (GIXRD), optical microscopy and scanning electron microscopy (SEM). Friction and wear tests were carried out using a pin-on-disc tribometer with a 6 mm diameter ruby pin. The Zr ion implantation reduced the surface hardness, friction coefficient and wear. The friction coefficient was reduced for all doses compared with the untreated sample, but shows an optimum at a dose of 1×10 17  ions/cm 2 . X-ray photoelectron spectroscopy (XPS) results show the formation in the implanted zone (IZ) of ZrN/TiZrN. X-ray diffraction (XRD) shows evidence of crystal damage, which increases with dose. Nanohardness results show that implantation causes softening of the IZ layer. The tribological behaviour is explained in view of these results.