Tribological performance of chromium/chromium carbide multilayers deposited by r.f. magnetron sputtering

Hard ceramic and ductile metal materials combined in multilayered structures are well-known to produce coatings with improved mechanical and tribological behavior. In this paper, we report the tribological properties of nanometric chromium/chromium carbide (Cr/CrC) multilayer coatings deposited by r.f. magnetron sputtering. Adhesion, sliding and abrasive wear tests were performed on Cr/CrC multilayers as well as on Cr3C2 reference coatings. The dry sliding wear behavior of Cr/CrC multilayers was investigated using the ball-on-disk technique with alumina and steel ball counterparts and the abrasive wear was tested against diamond powder wheel. Multilayer coatings have a higher adhesion on steel substrates than the single layer coatings. The multilayered coatings exhibited a dry sliding wear resistance three times better than the reference. The Cr/CrC multilayers showed dry friction coefficients around 0.65 and the Cr3C2 single layer around 0.3, for extended sliding tests. The debris resulting in ball-on-disk tests were analyzed by energy dispersive spectroscopy (EDS) and Raman. The main mechanisms of sliding wear are discussed.