Study on the structure and tribological properties of CrN coating by IBED

CrN coatings were synthesized with different levers of bombarding energy by nitrogen ions with very low N ion/Cr atom arrival ratios. The structures a nd compositions of these coatings were investigated by XRD, XPS and AES. Th e tribological properties of the coatings on AISI 52100 steel were evaluate d by ball-on-disc tests. Results indicate that the fraction of the CrN phas e increases with increasing bombarding energy from 4 to 8 to 12 keV, and re aches a predominant state. For the 4 keV coating, the Cr/N ratio was > 1, w hich indicates that Cr is involved in the coating layer. The 8 and 12 keV c oatings were free of Cr phase. However, the optimum N ion/Cr atom ratio for the coating is far from the stoichiometry of 1:1 Cr/N. The tribological pr operties of CrN coatings with different processing parameters show that the wear mechanisms of coating/substrate systems are micro-ploughing and spall ing. The films processed at a row energy level and with a row N ion/C atom ratio in this study show better tribological properties and higher fracture toughness. (C) 2000 Elsevier Science B.V. All rights reserved.