SnO2:F Coated Duplex Stainless Steel for PEM Fuel Cell Bipolar Plates

Duplex 2205 stainless steel was deposited with similar to 0.6 mu m thick SnO(2):F coating; coated steel was characterized for PEMFC bipolar plate application. Compared with bare alloy, interfacial contact resistance (ICR) values of the coated 2205 steel are higher. SnO(2):F coating adds its own resistance to the air-formed film on the steel. In a PEMFC anode environment, a current peak of ca. 25 mu A/cm(2) registered at ca. 30 min for coated 2205 steel. It stabilized at ca. 2.0 similar to-1.0 mu A/cm(2). This peak is related to the complicated process of coating dissolution and oxide-layer formation. Anodic-cathodic current transfer occurred at ca. 200 min polarization. In a PEMFC cathode environment, current was stable immediately after polarization. The stable current was ca. 0.5 similar to 2.0 mu A/cm(2) during the entire polarization period. AES depth profiles with tested samples and ICP analysis with the tested solutions confirmed the excellent corrosion resistance of the SnO(2):F coated 2205 alloy in simulated PEMFC environments.