Corrosion resistant quaternary Al–Cr–Mo–N coating on type 316L stainless steel bipolar plates for proton exchange membrane fuel cells.

Insufficient corrosion resistance, electrical conductivity and wettability of bipolar plates are some of the important issues affecting the performance of hydrogen fuel cells. To address these issues, an amorphous Al–Cr–Mo–N coating is deposited on type 316L stainless steel using direct current (DC) magnetron sputtering. The electrochemical corrosion behaviour is investigated under simulated fuel cell anode (H 2 -purging) and cathode (air-purging) environment consisting of 0.5 M H 2 SO 4 + 2 ppm NaF at 70 ± 2 °C. The corrosion current density is reduced to 0.02 μA cm−2 comparable to the commercially used Ta/TaN coatings. The polarization resistance increases by two orders of magnitude and the interfacial contact resistance (ICR) reduces significantly due to the application of the coating. Further, the coating shows better water management due to high hydrophobicity than the bare stainless steel. • Amorphous Al–25Cr–5Mo–40N alloy coating is developed on type 316L SS. • Corrosion resistance of the present coating is comparable to Ta/TaN coating. • ICR of the coating is significantly lower than that of the bare substrate. • High hydrophobicity of the coating can lower water flooding within PEMFC stacks. [ABSTRACT FROM AUTHOR]