Evaluation of Mg-Nd-Zn-Zr magnesium alloy as bipolar plate in simulated polymer electrolyte membrane fuel cell environments

The corrosion behavior and interfacial contact resistance (ICR) of Mg-Nd-Zn-Zr magnesium alloy in simulated PEMFC environments are investigated systematically. The corrosion rate decreases logarithmically with the immersion time due to accumulation of corrosion products. At first, Mg-Nd-Zn-Zr magnesium alloy exhibits lower corrosion rate in anodic environment because the reactions involving formation of hydrogen gas and dissolution of magnesium are inhibited. After long time immersion, it presents higher corrosion rate because of pitting corrosion and cracked corrosion products layer. In the cathodic environment, a compact corrosion products layer composed of amorphous MgCO3 and Mg(OH)2 is formed as a result of precipitation of carbonate-containing corrosion products. The ICR of Mg-Nd-Zn-Zr magnesium alloy immersed in cathodic environment is higher than that in anodic one due to the accumulation of amorphous Mg(OH)2 and MgCO3 corrosion products layer.