Effect of Magnetic Field on Corrosion Behaviors of Gold-Coated Titanium as Cathode Plates for Proton Exchange Membrane Fuel Cells

Abstract

Effects of the self-induced magnetic fields generated by the operating current of proton exchange membrane fuel cells (PEMFCs) on metal bipolar plates (BPPs) have hardly been noticed while cannot be ignored. Therefore, corrosion behaviors and surface conductivity of gold-coated titanium (Ti/Au) and bare titanium in simulated PEMFC cathode environment under magnetic fields were evaluated by electrochemical tests and interfacial contact resistance measurements. The results indicated a considerable decrease in corrosion current and interfacial contact resistance of as-received Ti/Au, reaching 1/16 and 1/10 of those of bare titanium, respectively. The applied magnetic field also led to a sharp decline in corrosion current of bare titanium but slight increase for Ti/Au. Electrochemical impedance spectroscopy and scanning electron microscopy results suggested that magnetic field significantly facilitated the corrosion durability of titanium and ameliorating the induced pitting due to coating defects on Ti/Au. Compared to results obtained without MF, interfacial contact resistance of titanium after 24 h potentiostatic polarization under MF further increased by 24%, while a decrease by 8% was recorded for Ti/Au. In sum, effects of self-induced magnetic fields on the corrosion of metal BPPs is significant and these results revised for taking magnetic fields effects in account could be more accurate and realistic.