Corrosion and nanomechanical properties of vanadium carbide thin film coatings of tool steel

The corrosion and nanomechanical characteristics of tool steel coated with vanadium carbide thin films deposited by DC reactive magnetron sputtering were investigated. Cyclic polarization and electrochemical impedance spectroscopy measurements in a 3.5% sodium chloride solution indicated that corrosion decreases as the C content and the substrate temperature during deposition increase. The maximum hardness is reached for VC coatings with C/V ratios around unity, decreasing for either higher or lower C/V ratios. Complementary physicochemical analyses, made here or elsewhere, are used to clarify the reasons for such behavior. The present results are discussed in terms of the optimization of the deposition parameters aiming at concomitantly good corrosion resistance and high hardness.