The effects of MEVVA ion implantation on the tribological properties of PVD-TiN films deposited on steel substrates

摘要

The effects of post-deposition metal vapour vacuum arc (MEVVA) ion implantation into TiN films were studied as part of a continuous effort to improve the wear performance of coatings used for cutting tools. This is a first account on the tribological behaviour of PVD-TiN coatings deposited on steel substrates and treated by MEVVA ion implantation. Two types of species were selected, C and W, one light and one heavy. In all cases, after implantation, tribological improvements were observed: The friction coefficient of the PVD-TiN against ruby was significantly reduced from 0.75 to 0.18 with carbon implantation at a dose of 10(17) cm(-2) and the lifetime to spalling was improved by more than 200%. (Untreated films detached after approx. 5000 cycles, whereas implanted films were still well adhered after 19 000 cycles.) For C-implanted samples, an increase in nano-hardness in the near surface region was also observed. These effects are attributed to the formation of a carbonaceous layer on the surface, accompanied by the formation of TiC in the sub-surface region, as detected by XRD. In contrast, W implantation improved coating wear life, but not friction coefficient or nano-hardness. The results are compared to those obtained for MEVVA implantation into CVD-TiN and to conventional implantation. (C) 2002 Elsevier Science B.V. All rights reserved. [References: 24]