2022 年 63 巻 6 号 p. 903-910
In recent years, stainless steel has been used as a separator in polymer electrolyte fuel cells (PEFCs). An electrophoretic deposition (EPD) method has been developed as a surface treatment, in which titanium nitride (TiN) is coated on stainless steel to impart conductivity. Using the EPD method, the surface of SUS316L steel was coated with three types of TiN–styrene-butadiene rubber (SBR) with different TiN particle diameters and impurity contents to improve the contact resistance. A smaller impurity content in the TiN resulted in a lower contact resistance. Furthermore, when the TiN particle size was between 50 nm and 1.5 µm, a larger particle size provided a lower contact resistance. In the polarization curve measurements, no deterioration of the corrosion resistance was observed for TiN–SBR. At the potential of an actual PEFC environment, low current densities were maintained in both the anodic and cathodic environments. Furthermore, scanning electron microscopy and electron probe microanalysis before and after the polarization test confirmed that there was no TiN detachment in the PEFC environment. The above results suggest that TiN-coated SUS316L steel is a promising separator for PEFCs.
