Doped ta-C Cover Layer for Fuel Cell Bipolar Plate Corrosion

The patent applies a multi-layer composite coating system consisting of a metallic first layer (e.g., titanium, nickel, or their alloys), a non-metallic second layer (e.g., diamond-like carbon, ceramic, or polymer), and an intermediate layer. This composite structure combines the corrosion resistance of metals with the chemical inertness and mechanical stability of non-metals, creating a coating system that maintains integrity under aggressive fuel cell operating conditions and prevents localized corrosion.

The patent employs different materials with optimized properties for specific functions in different layers: the metallic first layer provides electrical conductivity and corrosion resistance, the intermediate layer ensures adhesion and stress management, and the non-metallic second layer provides chemical inertness and long-term stability. This local optimization of material properties throughout the coating thickness achieves both high electrical conductivity and long-term stability.

The patent divides the corrosion protection function into three specialized layers, each with a specific role: the metallic first layer for corrosion and conductivity protection, the intermediate layer for adhesion and stress relief, and the non-metallic second layer for chemical resistance. This segmentation allows each layer to be optimized independently while simplifying the overall manufacturing process through standardized deposition techniques.