Effect of Ag/W addition on the wear performance of CrN coatings prepared by RF unbalanced magnetron sputtering

It has been learned that chromium nitride (CrN) performs better than titanium nitride (TiN) under some specific applications. However, the relatively low hardness of CrN still remains a problem. In this study, we tried to increase the hardness of CrN by means of addition of varying content of the third party element Ag/W. The content of Ag/W additive was varied by applying varying levels of currents to the Ag/W targets. Subsequently, a series of tests were conducted to analyze the coatings, including composition and structure analyses, scratch test, Knoop hardness test and wear test. The results showed that the CrN coatings with Ag addition did not show obvious improvement with regard to the hardness and wear performance, while coatings with W addition showed a significant enhancement. Compared with CrN, the W addition led to enhancement in hardness and wear resistance, due to the formation of tungsten nitride (WN) in the CrN coatings. At a W content of 6.8 at.%, the wear was reduced by ∼73%.