Fabrication of titanium bipolar plates by rubber forming process and evaluation characteristics of TiN coated titanium bipolar plates

Abstract

In this study, the rubber forming process is used to fabricate a micro-channel titanium plate for a PEM fuel cell. The micro-channel plate is fabricated using a 200 ton hydraulic press, and various parameters (punch speed, press pressure, rubber thickness, rubber hardness) are investigated in order to evaluate the formability. TiN films are deposited by reactive DC magnetron sputtering (DCMS) with an electromagnetic field system (EMFS). For the uncoated titanium and TiN-coated titanium substrates, the hardness, surface roughness, and corrosion resistance are estimated by nano-indentation and electrochemical methods, respectively. The improved corrosion resistance of the TiN films can be attributed to the densification of the film caused by enhancement of nitrification with increasing high reactive nitrogen radicals. The uncoated titanium and TiN-coated titanium bipolar plates are combined with a unit cell for a performance test, and respective current densities of 0.396 and 0.888 A cm-2 at 0.6 V are obtained.