As solid-oxide fuel cells near commercialization a key barrier to widespread adoption is the high cost of the technology. The U.S. Department of Energy cost goal of $700/kW for SOFC power generation systems requires the selection, wherever possible, of common grade stainless steel into the stack design, including the "balance of plant" components (gas manifolding and delivery, thermal management equipment, fuel processors, and compression systems) as well as the high temperature stack itself (metallic interconnects). Chromia forming steel and nickel-based alloys have been traditionally used for fabricating these components. However, without protective coatings, the air-facing surfaces of steel components oxidize and volatize chromium species that poison the stack. Similarly, air/exhaust heat exchangers must be designed to prevent chromium volatilization; on the fuel side, oxidation (due to high steam content gas streams), carburization and coking are all catastrophic failure mechanisms for metals facing high carbon fuel streams.
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