Development of Magnetron Protective Coatings of Chromium Nitrides and Carbides on Titanium Bipolar Plates of a Fuel Cell with Proton-Exchange Membrane

Abstract

This article presents results of a study of titanium bipolar plates of fuel cells with proton-exchange membrane with functional coatings based on chromium nitride, carbide and carbonitride, obtained by magnetron sputtering of a chromium target in argon plasma with different nitrogen and propane contents. The microstructure and morphology of pure CrN and CrС films on titanium and composite coatings of chromium carbonitride Cr_хN_yС_z were studied. The protective chromium carbide films obtained by adding propane to argon plasma were shown to exhibit increased contact surface resistance at the gas diffusion electrode/bipolar plate interface (CrС: ICR = 119.4 mΩ cm²). However, for chromium carbonitride coatings this quantity is only 1.9 mΩ cm², which is lower than for pure CrС films and significantly lower than for uncoated titanium (Ti: ICR = 38.9 mΩ cm²). This is an important indicator for using such bipolar plates in fuel cell power plants with high specific characteristics. Corrosion measurements performed using conventional techniques showed that the corrosion current for chromium carbonitride was less than 1 μA/cm², which is better than for uncoated titanium and pure CrN and CrC films.