High corrosion resistance and surface conductivity of (Ti1-Cr )N coating for titanium bipolar plate

(Ti1-xCrx)N coatings with high corrosion resistance and surface conductivity are developed for Ti bipolar plate. More Cr leads to lower surface conductivity but much higher corrosion resistance. The optimized (Ti0.48Cr0.52)N coating shows a low interfacial contact resistance of 5.1 mΩ cm2 at 140 N/cm2 and small current density of 0.45 μA/cm2 after 10 h corrosion test at 0.2 V vs. Hg/Hg2SO4 (0.5 M H2SO4 + 2 ppm HF, 80 °C with air), which is approximately 50 times lower than that (24 μA/cm2) for TiN. The improved corrosion resistance is majorly owing to the presence of CrOriched bond on the surface.