Factors influencing properties of CrN thin films grown by cylindrical cathodic arc physical vapor deposition on HSS substrates

Abstract

► Process parameter impact on properties of CrN films by cathodic arc PVD studied. ► High hardness and low surface roughness substrates conducive for adherent films. ► Optimized Cr ion etching yields superior film properties than Ti ion etching. ► Nitrogen partial pressure influences phase constitution and stress in CrN x films. ► Alternating high/low toughness CrN x multi-layers yield best film properties. The present study deals with growth of well-adherent and tough CrN thin films by cylindrical cathodic arc physical vapor deposition. The influence of substrate preparation parameters and deposition variables on film properties has been systematically investigated. The adhesion strength, hardness and crack propagation resistance (CPR) of the films were evaluated for different processing conditions. High substrate hardness and low substrate surface roughness were found to be conducive for obtaining well-adherent films. Cr ion etching was found to yield superior film properties, with the duration of etching also being a key determining factor. The nitrogen partial pressure employed during film deposition was noted to significantly influence the phase combination of the CrN x films as well as the stress levels in the deposited films. In case of multilayer CrN x films, alternating high toughness–low toughness layers were found to yield encouraging properties, with CPR values markedly higher than those obtained in mono-layer CrN x films, with no compromise in either hardness or adhesion strength.