Carbon, nitrogen and oxygen implantation into TiN coatings

Abstract

TiN coatings are widely used in industry especially for wear reduction of forming and cutting tools. Ion implantation is a very promising possibility for a further improvement of the wear behaviour of the coatings. Increased surface hardness and reduced wear and friction can be realised. In this investigation metallographic and chemical analyses of implanted layers are presented to explain the different changes of the mechanical coating properties. PVD TiN coatings were implanted with N + , C + and O + at doses between 0.5 and 6×10 17 cm −2 . Color changes in the TiN coating due to the ion implantation were observed and spherical sections were found to be a suitable metallographic method for investigation of radiation effects. With this technique it is possible to visualize ion- and dose-dependent changes within the implanted zones of about 0.5 μm thickness. Morphology of the implanted TiN shows a depth dependent coloring which coincides with the theoretical prediction of the implantation depth profile. Chemical analyses of the implanted layers were carried out using GDOS and XPS analyses. Good correlation between chemical composition and results from the metallographic investigations were found. Precipitation of non-carbidic carbon were detected after high-dose carbon implantation. A saturation limit for nitrogen was found for high-dose nitrogen implantation. Nanoindentation measurements 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 correlation between the changes in hardness and the results of metallographic and chemical analyses are discussed.