Tribological, Anti-corrosion, and Electrical Conductivity Properties of CrC_x Coatings Deposited on Stainless Steel 316L and Used as Metal Bipolar Plates for Fuel Cells

CrC_x coatings (where x = 5 ~ 35 sccm is the acetylene flux) were deposited on stainless steel 316L substrates using radio frequency unbalanced magnetron sputtering. The CrC₃₅ coating showed the highest C-sp² content and H/E ratio of all the coatings, and thus exhibited the lowest friction coefficient and wear rate. However, the CrC₂₅ coating showed the best anti-corrosion performance in 0.5 M H₂SO₄ solution due to its low surface roughness and small cluster size. The electrochemical properties of the CrC₂₅ coating were investigated in a simulated Proton Exchange Membrane Fuel Cell (PEMFC) environment with hydrogen and oxygen purging. The coating showed a low corrosion current density in both the anode and the cathode environments. Finally, the CrC₃₅ coating showed the lowest interfacial contact resistance (ICR) of the various coatings under a compaction force of 140 Ncm⁻² due to its high C-sp² content.