Effects of Substrate Temperature on the Corrosion Behaviour of Nanochromium Coatings Deposited by Direct Current Magnetron Sputtering

Nanochromium coatings were deposited on 316L stainless steel bipolar plates of a proton-exchange membrane fuel cell (PEMFC) by a direct current magnetron sputtering technique. The effect of substrate temperature on the corrosion resistance of nanochromium coatings was investigated. The corrosion performance of the bare and chromium-coated steel in a simulated environment of PEMFC (0.5M H2SO4 + 2 ppm F-) was studied using electrochemical impedance spectroscopy, polarisation, and open circuit potential measurements. The results showed that the corrosion rates of two nanochromium coatings deposited at 300 degrees C and 500 degrees C were lower than those of uncoated steel by more than one order of magnitude. Electrochemical impedance spectra of both nanochromium coatings exhibited distinct characteristics in corrosive solution. The nanochromium coating deposited at 500 degrees C showed superior stability in the corrosive solution.