Performance of CrN/MoS2(Ti) coatings for high wear low friction applications

A CrN/MoS2(Ti) coating was developed in order to improve the tribological characteristics of single CrN coatings as a possible alternative for high wear low friction applications. The MoS2(Ti) coating was produced by PVD closed-field unbalanced magnetron sputtering on CrN coated stainless steel substrates. The tribological performance of both, the single CrN coating and the CrN/MoS2(Ti) coating was evaluated and compared. Characterization of the coatings included: scratch testing, wear testing, nanoindentation, X-ray diffraction, optical and scanning electron microscopy. The CrN coating exhibited excellent adhesion, hardness and stiffness. However, adding the MoS2(Ti) layer led to a significant improvement in the tribological properties, while maintaining the good adhesion characteristics of the underlying CrN layer. A maximum wear volume and coefficient of friction reduction of 95% was observed. Surface roughness of the coatings did not play a major role on the tribological properties. The results of this work provide with enough evidence to consider the CrN/MoS2(Ti) coating as a promising alternative for high wear low friction applications.