Research on a novel deposition process for a-C multilayer films with enhanced interfacial bonding strength on SS316L bipolar plates

To address the critical limitations of conventional amorphous carbon (a-C) films on stainless steel bipolar plates, including poor adhesion, high interfacial contact resistance (ICR), and insufficient corrosion resistance under fuel cell operating conditions, this study proposes a novel multilayer coating strategy based on a gradient interfacial structure. A three-layer architecture is constructed via magnetron sputtering by sequentially depositing a metallic transition layer, a carbide intermediate layer, and an a-C surface layer. This design leverages the synergistic functions of each layer: Cr or Ti metallic layers enhance interfacial bonding through metallic interactions, CrC or TiC layers serve as chemical diffusion buffers, and the tailored sp 2 /sp 3 carbon network improves both electrical conductivity and chemical stability. Electrochemical corrosion tests under simulated PEMFC conditions demonstrate that the C/CrC/CrN/SS316L bipolar plate exhibits excellent corrosion resistance and low interfacial contact resistance. The corrosion current density is reduced to 1.41 × 10 -6 A/cm 2 , and the ICR reaches as low as 8.67 mΩ·cm 2 , meeting the DOE 2025 standard. This strategy provides a promising route for improving the stability of carbon-based films in fuel cell environments and offers theoretical and technical insights into interfacial engineering for multilayer coating design.