Investigation of Cr(N)/DLC multilayer coatings elaborated by PVD for high wear resistance and low friction applications

Cr/CrN/(Cr,N)-DLC/DLC and Cr/Cr-DLC/DLC multilayer coatings have been synthesized using DC sputtering magnetron technique to protect steel substrates from wear. The microstructure was investigated by scanning electron microscopy and the chemical structure of the DLC layers was investigated by Raman spectroscopy. The mechanical and tribological properties were evaluated by nanoindenter, scratch tester and Rockwell 'C' indentation test, ball-on-disk tribometer and surface profiler. A new methodology for the selection of coating performance was proposed by using a performance index based on a mix of adhesion, mechanical and tribological properties.