Combined plasma surface modification of austenitic stainless steel for bipolar plates

Austenitic stainless steel sheets EN 1.4301 with a thickness of 0.1 mm are coated with chromium films in the range of 5-200 nm by means of magnetron sputtering deposition. Subsequently, short-time plasma-nitriding by means of the strip hollow-cathode method is applied. The diffusion layers are analysed taking into account the nitrogen diffusion into the base material, diffusion processes at the interface between the chromium coating and the base material, the distribution of the elements, and the phase formation, in particular the formation of chromium nitrides. Further investigations are performed to determine the influence of applied plasma treatment on the electrical conductivity and corrosion resistance of the stainless steel surfaces.