Preparation of DB film in the channel of SS304 bipolar plate to improve its water liquidity

Flow channel is one of the important design and part of the bipolar plate, and the water management of flow channel is an important problem to affect the actual application of PEMFCs, therefore surface treatment is needed to improve the water liquidity. Because of the hydrophobic property and corrosion resistance of 6-N,N-(dibutyl)-1,3,5-triazine-2,4-dithiol (DB), DB film is obtained by syringe injecting in the flow channel for self-assemble. Tested by XPS and FT-IR, it was found that the channel of SS304 was covered by uniform DB film entirely, and there are bonds of SFe and SNi between DB film and SS304 substrate, makes the combination stable. Different layers of DB film are prepared in the flow channel to compare their property difference. According to the water liquidity test by gravity force, the liquidity degrees decrease as SS304/DB3 > SS304/DB2 > SS304/DB1 > SS304 substrate. While according to the stability test by polarization, the stability for SS304/DB2 and SS304/DB1 are greater than that for SS304/DB3. Further result by EPMA (electron probe micro-analyzer) to flow channel surface discovers that the uniformity of SS304/DB3 is very poor, accompanied by peeling phenomenon, and the uniformity of SS304/DB2 and SS304/DB1 in the flow channel are quite well. Considering the liquidity to solve the problem of water plugging, the SS304/DB2 is the best choice.