Nitrogen pressure-regulated microstructure and texture of pulsed laser deposited CrN coatings for enhanced corrosion resistance and conductivity in simulated PEMFC cathode environment

This study investigates the microstructural regulation and performance optimization of CrN coatings deposited on 304 stainless steel bipolar plates via pulsed laser deposition (PLD), aiming to enhance the corrosion resistance and interfacial conductive stability of bipolar plates for proton exchange membrane fuel cells (PEMFCs). The nitrogen pressure during deposition was systematically varied to control the phase composition, crystallographic orientation, and microstructural densification of the CrN coatings. At the optimal nitrogen pressure of 10 Pa, the CrN coating exhibited a cubic structure with a (200) preferred orientation, fibrous grains, and low surface roughness. Featuring a compact microstructure with significantly reduced porosity, the optimized coating achieved a corrosion current density of 0.032 μA cm −2 , and an initial interfacial contact resistance (ICR) of 7.03 mΩ cm 2 (140 N cm −2 ). Both properties remained stable after 24 h of potentiostatic polarization at 0.6 V vs. SCE, with ICR value reaching merely 7.61 mΩ cm 2 post polarization. These findings establish a clear correlation between deposition parameters, microstructural evolution, corrosion resistance and interface contact resistance, providing mechanistic insights and design guidance for developing corrosion-resistant and conductive coatings for PEMFC applications.