High performance Cr/CrN coatings fabricated by regulated magnetron sputtering for proton exchange membrane fuel cell bipolar plates application

Proton exchange membrane fuel cells (PEMFCs) are one of the key technologies for clean energy conversion, and the development of bipolar plate coatings with excellent corrosion resistance and high electrical conductivity is crucial. In this study, Cr/CrN bilayer composite coatings are deposited on titanium substrates via magnetron sputtering to improve their corrosion resistance and conductivity. Key process parameters of working pressure (0.4, 0.6, 0.8 Pa) and sputtering power (100, 150, 200 W) are optimized. Results indicate that the regulation of process parameters significantly affects the crystallinity and microstructure of the films. The Cr/CrN coating deposited at a working pressure of 0.4 Pa and a sputtering power of 150 W exhibits a denser surface structure and superior corrosion resistance, with a corrosion current density of 0.32 μA cm−2 (60 °C, pH = 0) and a low interfacial contact resistance (ICR) of 6.5 mΩ cm2. Additionally, the coating demonstrates excellent hydrophobicity (water contact angle of 118.1°) and good adhesion properties. Thus, the pulsed magnetron-sputtered Cr/CrN coating is a promising candidate for developing low-cost, high-corrosion-resistance Ti bipolar plates for PEMFCs.