Abstract:
In order to improve the corrosion resistance of stainless steel bipolar plate of proton exchange membrane fuel cell (PEMFC), Ni60 alloy coating was prepared on the surface of 316L stainless steel by atmospheric plasma spraying technology, and the coating was subjected to vacuum heat treatment at different temperatures. Scanning electron microscope, X-ray diffractometer and electrochemical test were used to study the effect of vacuum heat treatment temperature on corrosion resistance of the coating. The results show that with the increase of vacuum heat treatment temperature, the number of microcracks and pores in the coating was greatly decreased, so that the density of the coating was improved and the influence of internal structural defects on the corrosion resistance of the coating was reduced. The CrB in the coating was obviously polymerized, which had a positive effect on the corrosion resistance of the coating. When the vacuum heat treatment temperature reached 1 100 ℃, Cr
7C
3 precipitated with darker color appeared on the CrB phase, which further improved the corrosion resistance of the coating, the self-corrosion potential of the coating sample reached the highest value, and the corrosion tendency of the coating was low. The coating sample had a large capacitance ring in the high frequency region of the Nyquist diagram, and the resistance of the coating capacitance and the micropores in the coating reached the maximum and minimum values, respectively, that was, the corrosion resistance of the coating was the best.