Selection and surface treatment of alloys in solid oxide fuel cell systems

Cost and performance considerations determine the selection of various component materials in a solid oxide fuel cell power system. While the use of commercial alloys provides an opportunity for cost reduction, the requirements of different components vary widely. The interconnect materials must provide low electrical resistance while isolating the oxidizing and reducing gases. The air preheat and heat-exchanger components face high-temperature oxidizing conditions, while the fuel feed and reformer sections encounter highly reducing atmospheres that may contain varying levels of sulfur and CO, and thus are prone to sulfidation and metal dusting. Thus, each of the components requires both a judicious selection of the alloy composition and appropriate surface treatments. Coating processes were developed for two classes of alloy materials for potential use as interconnects and fuel feed hardware or process piping.