Effect of Cu content on the structure, and performance of substoichiometric Cr-N coatings

Abstract

Cu-Cr-N coatings with Cu contents between 3-65 at.%, Cu/Cr ratios in the 0.04-4.5 range and 21-27 at.% N, synthesized by twin electron-beam Physical Vapor Deposition (EBPVD) at 450oC, were investigated and compared against substoichiometric Cr-N reference samples. The main objective of the present work was to study the influence of Cu on the structure, and the subsequent effects on the mechanical properties, room (22oC) and high temperature (500oC and 840oC) tribological performance of Cu-Cr- N coatings. Using X-ray photoelectron spectroscopy (XPS), glancing angle X-ray diffraction (GAXRD) and scanning electron microscopy (SEM), in combination with nanoindentation mechanical property measurements and laboratory controlled ball-on-disc sliding experiments, it is shown that Cu-Cr-N coatings with low Cu content (3 at.%) possess sufficient wear resistance for high temperature demanding tribological applications.