简介: |
Abstract
Stainless steels (types 304 and 310S) were employed as bipolar plates for polymer electrolyte membrane fuel cells. For the cell operation, the decayed cell voltage was approximately 22mV for the type 310S stainless steel after 1000 h operation, while that for type 304 stainless steel was about 46mV. Corrosion products appeared on the cathode side bipolar plate for the type 304 stainless steel, while trace of corrosion was barely detected for type 310S stainless steel. In order to follow the pH on the bipolar plates during fuel cell operation, polarization tests were carried out for the type 310S stainless steel in synthetic solutions (0.05M SO42− (pH 1.2–5.5) + 2 ppm F−) as a function of pH (1.2–5.5) at 353 K. In the synthetic solutions with lower pHs (≤ 3.3), the films were thinner and were mainly composed by enriched with chromium oxide. Whereas in case of the solution pH was higher (≥4.3), the films mainly consisted of relatively thick iron oxide. XPS analyses for the bipolar plate of type 310S stainless steel on cathode side after cell operation demonstrated pH gradient on the plate, i.e., the thicker iron-rich surfaces presented relatively higher pH from the gas inlet to center area, and the thinner chromium-rich surface appeared with lower pH around the gas outlet.
|
