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In this paper, a chemical treatment method was developed to process the aluminum bipolar plates of proton electrolyte membrane fuel cells. During the surface treatment process, the chemical in the aluminum reacts with the electrolyte forming a metallic compound film with weak-atomic bonding. The adhesion property of this film is stronger than that of electroplating. This process is fast and much cheaper then physical vapor deposition processes. Anti-corrosion capability of the processed bipolar plates was analyzed using chemical and electrochemical methods. The corrosion curves computed by the linear polarization method showed the chemically modified film to have stable chemical and electrochemical characteristics. The surface and bulk electric conductivities, however, decreased slightly. Single cells of the bipolar plates, both with and without the chemically treated aluminum, were assembled for performance tests. The results showed that the single cell with chemically treated bipolar plates had a higher surface contact resistance and a decreased cell performance, but the cell life was longer. Future research efforts need to focus on improving the surface film conductivity and cell performance.

Aluminum was considered a good candidate material for bipolar plates of the polymer electrolyte membrane (PEM) fuel cells due to its low cost, light weight, high strength and good manufacturability. But there were problems of both chemical and electrochemical corrosions in the PEM fuel cell operating environment. The major goals of this research are to find proper physical vapor deposition (PVD) coating materials which would enhance surface properties by making significant improvements on corrosion resistance and electrical conductivity at a reasonable cost. Several coating materials had been studied to analyze their corrosion resistance improvement. The corrosion rates of all materials were tested in a simulated fuel cell environment. The linear polarization curve of electrochemical method measured by potentiostat instrument was employed to determine the corrosion current. Results of the corrosion tests indicated that all of the coating materials had good corrosion resistance and were stable in the simulated fuel cell environment. The conductivities of the coated layers were better and the resistances changed very little after the corrosion test. At last, single fuel cells were made by each PVD coating material. Fuel cell tests were conducted to determine their performance w.r.t. that was made of graphite. The results of fuel cell tests indicated that metallic bipolar plates with PVD coating could be used in PEM fuel cells.