Faculty of Computing, Health and Science
School of Engineering (SOE)
Nanocomposite Cr–Si–N films were prepared on to Ti–6Al–4V substrates by a novel duplex surface treatment technique. Coatings consisting of a Cr3Si surface layer were deposited using a double cathode glow plasma and subsequent surface plasma nitriding. The surface topography, chemical composition, and microstructure of these treated alloys were analyzed by a variety of surface characterization techniques. The resulting Cr–Si–N films consisted of nanocrystallite CrN grains embedded in amorphous SiNx phase. Nanoindentation tests showed that with increasing nitrogen partial pressure the hardness of the Cr–Si–N films increased and the elastic modulus decreased. Wear experiments showed that the Cr–Si–N films produced at a nitrogen partial pressure of 4.5Pa and 800 °C possessed the lowest wear rate and friction coefficient. Moreover, electrochemical measurements in 5 wt% HCl solution indicated that the Cr–Si–N films acted as an effective barrier against acid attack on the alloys.