Ni/NiFe2 dual-layer coating for SOFC steel interconnects application

Ni/NiFe₂ dual-layer coating is fabricated on SUS 430 stainless steel by magnetron sputtering for solid oxide fuel cells (SOFCs) interconnect application. Ni/NiFe₂ coated steels are exposed to air at 800 °C for duration of up to 10 weeks in comparison with NiFe₂ coated steels. Ni/NiFe₂ coating is thermally converted to an oxide structure with an inner NiO layer and an outer NiFe₂O₄ spinel layer. NiO/NiFe₂O₄ oxide layer is more effective in blocking Cr migration and reducing oxidation rate during long-term exposure than a single NiFe₂O₄ layer converted from NiFe₂ coating. Enhancements on oxidation resistance and Cr-blocking capability are attributed to NiO layer serving as a diffusion barrier between Cr₂O₃ and NiFe₂O₄.