CARBON, NITROGEN AND OXYGEN IMPLANTATION INTO TIN COATINGS

TiN coatings are widely used in industry especially for wear reduction of forming and cutting tools. Ion implantation is a very promising po ssibility for a further improvement of the wear behaviour of the coati ngs. Increased surface hardness and reduced wear and friction can be r ealised. In this investigation metallographic and chemical analyses of implanted layers are presented to explain the different changes of th e mechanical coating properties. PVD TiN coatings were implanted with Ni, C+ and O+ at doses between 0.5 and 6X10(17) cm(-2). Color changes in the TiN coating due to the ion implantation were observed and spher ical sections were found to be a suitable metallographic method for in vestigation of radiation effects. With this technique it is possible t o visualize ion- and dose-dependent changes within the implanted zones of about 0.5 mu m thickness. Morphology of the implanted TiN shows a depth dependent coloring which coincides with the theoretical predicti on of the implantation depth profile. Chemical analyses of the implant ed layers were carried out using GDOS and XPS analyses. Good correlati on between chemical composition and results from the metallographic in vestigations were found. Precipitation of non-carbidic carbon were det ected after high-dose carbon implantation. A saturation limit for nitr ogen was found for high-dose nitrogen implantation. Nanoindentation me asurements reveal changes in surface hardness depending on ion species and ion dose. Significant increases of the hardness values were found after carbon implantation in relatively low ion doses. The correlatio n between the changes in hardness and the results of metallographic an d chemical analyses are discussed. (C) 1998 Elsevier Science S.A. All rights reserved.