Interlayer thickness influence on the tribological response of bi-layer coatings

The present work deals with the influence of coating thickness on the tribological response of bi-layer model coatings consisting of CrN with Cr interlayer with varying Cr/CrN thickness ratios on high-speed steel. Ball-on-disc experiments were carried out in ambient air at room temperature and alumina balls as counterbodies. The mechanical stresses in both layers generated during the tests were calculated with the software package Elastica. Wear tracks on the samples were characterised using both scanning electron microscopy and optical profilometry. The results show that the interlayer thickness plays a determinant role in the tribological response of the coatings provided that the CrN layer thickness exceeds a critical value to withstand mechanical wear.