Corrosion behaviour of nanochromium coatings deposited by direct current magnetron sputtering

Chromium films are frequently used as corrosion resistant coatings. Chromium coatings with a columnar structure deposited by magnetron sputtering demonstrate poor corrosion resistance. In this paper, a nanochromium coating with a non-columnar structure was deposited on 316L stainless steel by a direct current magnetron sputtering technique. The grain size of chromium coatings with a pyramidal structure was 95 nm. The corrosion performance of the bare and chromium coated steel in 0.5M H2SO4 was examined using electrochemical impedance spectroscopy, polarisation and open circuit potential measurements. The results showed that the corrosion rate of nanochromium coatings was lower than that of uncoated steel by more than one order of magnitude. Electrochemical impedance spectra of the nanochromium coatings exhibited distinct characteristics in corrosive solution. No obvious degradation was observed for the coatings after 768 h exposure to the corrosive solution.