Stainless Steel Fuel Cell Separator Dual Coating

The patent applies composite materials by forming a dual-layer coating structure on the metallic separator surface. The first layer is a metal nitride film (such as chromium nitride) formed through nitridation treatment, and the second layer is a metal oxide film (such as chromium oxide) formed through oxidation treatment. This composite coating structure combines the low contact resistance property of metal nitrides with the corrosion resistance of metal oxides, thereby resolving the contradiction between electrical conductivity and corrosion resistance while maintaining the productivity advantages of metallic separators

The patent applies parameter changes by controlling the thickness and composition ratios of the coating layers. The metal nitride layer thickness is controlled at 0.1-5 μm and the metal oxide layer thickness at 0.01-2 μm. By adjusting these parameters and the elemental composition ratios (such as Cr content at 10-30 wt%, Mo content at 0.5-7 wt%), the patent optimizes both electrical conductivity and corrosion resistance, transforming the metallic separator from having poor contact resistance to achieving low contact resistance below 10 mΩ·cm²

The patent applies porous materials by forming a metal nitride film with controlled porosity and surface roughness through nitridation treatment. This porous structure provides mechanical interlocking that firmly anchors the subsequent metal oxide coating layer, preventing any powder-like material from separating due to vibration. The porous nitride layer acts as a binding matrix that holds the oxide layer in place while maintaining electrical conductivity pathways

The patent replaces the loose carbon powder composite with a bonded metal nitride-metal oxide composite structure. The metal nitride layer serves as the base layer with low contact resistance, and the metal oxide layer is firmly attached to it through chemical bonding and mechanical interlocking. This composite structure eliminates the separation problem of carbon powder while maintaining electrical conductivity, as the metal-metal bonding in the nitride layer provides stable conductive pathways that cannot detach

The patent applies parameter changes by modifying the nitridation process parameters to reduce treatment time and eliminate vacuum requirements. Instead of conventional high temperature vacuum nitridation, the patent uses atmospheric pressure plasma nitridation or low temperature chemical vapor deposition nitridation, reducing the treatment time from several hours to minutes. The temperature is reduced from above 500°C to below 200°C, and the process is performed at atmospheric pressure rather than vacuum, dramatically reducing manufacturing costs while maintaining the corrosion resistance benefits of the metal nitride coating

The patent replaces the mechanical vacuum system with a chemical or plasma-based atmospheric process. Instead of using vacuum chambers and pumping systems for nitridation, the patent employs atmospheric pressure plasma generation or chemical vapor deposition methods that work in ambient air. This substitution eliminates the need for expensive vacuum equipment and long pumping times, reducing both capital investment and operational costs while achieving the same nitride film formation and corrosion protection