Tribological properties of CrCN/CrN multilayer coatings

Abstract

The wear of the coating is one of the most important parameters determining its applications. The quality of the coating is highly influenced by the adhesion. An improvement of these properties can open new areas of applications. In this paper, the adhesion and wear results for CrCN/CrN multilayer coatings are presented. The coatings were deposited on HS6-5-2 steel substrate using cathodic arc evaporation. Two series of CrCN/CrN coatings were tested: (1) with fixed bilayer thickness and various thickness ratios of CrCN and CrN layers in the bilayer and (2) with fixed thickness ratios of CrCN and CrN layers in the bilayer and various numbers of bilayers (Λ).The adherence of the coatings to the steel substrate was evaluated using a scratch test and the Daimler–Benz test. In the scratch test, the critical force as the beginning of spalling or delamination of the coating was determined. The tribological properties were defined using the ball-on-disc method with an Al2O3 ball as the counterpart.All the coatings show Lc2 values higher than 80N. The critical load and wear rate depend on the thickness ratio of the CrCN and CrN layers in the bilayer. The increase in the CrCN layer thickness leads to the critical load decrease.