Development of a superlattice (Ti,Hf,Cr)N coating for cold metal forming applications

Tribosystems in mechanical engineering put high demands towards tools, surface technology and lubrication. Cold forming processes in particular represent a significant challenge for wear reduction. Mineral-based oils with high contents of ecologically harmful additives are state of the art due to high abrasive and adhesive wear. In order to reduce the ecological impact and to increase tool life, biodegradable lubricants and hard coatings have been developed, which are deposited by modern vacuum technologies. In the collaborative research center ‘Environmentally friendly tribological systems’ (SFB 442), which has been established by the German Science Foundation (DFG), a new arc-PVD Ti–Hf–Cr–N coating has been developed. This nanolayer system with single layers of different hardness is supposed to fulfill the requirements of high hardness and abrasive wear resistance while possessing low Youngʹs modulus values at the same time. In this paper, the results of coating characterization based on various standardized tests and on microscopic analysis are shown. The influence of the structure and the coating process on the performance is evaluated using nanoindentation and pin-on-disc tests.