Durability and characterization studies of chromium carbide coated aluminum fuel cell stack

Corrosion and interfacial contact resistance measurements were performed on chromium carbide coated aluminum 6061 and as-received aluminum 6061 samples. The coating was thermally sprayed onto the aluminum sample using the High Velocity Oxygen Fuel (HVOF) thermal spray technique. The chromium carbide coating consists of Cr₃C₂ top layer and Cr[sbnd]C[sbnd]Ni intermediate layer. The coating thickness was approximately 150 μm. A three-cell stack with chromium carbide coated aluminum bipolar plates was also fabricated for the durability and characterization studies. The coating thicknesses on the lands of the ribs and the walls of the valleys were approximately 300 μm and 150 μm, respectively. The stack was operated at the temperatures of 37 °C for 250 h and 80 °C for additional 500 h. The scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX) analysis shows that the thickness, chemistry, and surface morphology of the coating material remained consistent after 750 h of operation. The inductively coupled plasma – optical emission spectroscopy (ICP-OES) analysis was performed on the samples of membrane electrode assembly (MEA) and byproduct water that was produced during the fuel cell electrochemical reaction.