The effect of the substrate bias voltage on the mechanical and corrosion properties of chromium carbide thin films by filtered cathodic vacuum arc deposition

High quality Cr3C2 thin films on the AISI D2 steel and on the silicon wafer using a Cr target (99.95%) and an Ar/C2H2 gas mixture were studied. A 90°-bend magnetic filtered cathodic vacuum arc (FCVA) system has been employed to eliminate the macroparticles during the thin film deposition. Various negative bias voltages ranging from −50 to −550 V were applied to the substrate during the deposition. The mechanical properties of the Cr3C2 films were evaluated by the nanoindentation, nanoscratch and scratch tests. The corrosion resistances of the Cr3C2 thin films were studied in aerated 3.5 wt.% NaCl aqueous solutions by electrochemical polarizations. It is concluded that the nanohardness and corrosion resistance of the Cr3C2 coated steel were significantly enhanced by increasing the substrate negative bias voltage, which also accounted for the crystalline nature of the dense and compact microstructure, i.e. a void and macroparticle free intact Cr3C2 thin film.