A novel cobalt-free Cu 1.2 Mn 1.8 O 4 spinel coating is prepared and evaluated for the metal interconnect of solid oxide fuel cell. Mn-35Cu and Co-35Mn alloy coatings are deposited on 430 SS substrate and then in-situ oxidized in air at 750 • C for 100 h. XRD results confirm that Cu 1.2 Mn 1.8 O 4 spinel with some Mn 2 O 3 is formed, and the average thickness of the coating is 70-80 µm according to cross section image. Spinel oxide coating is compact and has good adherence to the substrate, and very low Cr and Fe contents are detected in the coating. A small area specific resistance of 8.7 mΩ cm 2 is achieved at 800 • C for the composited Cu 1.2 Mn 1.8 O 4 spinel coating, which is much less than that of the composited (Co,Mn) 3 O 4 spinel coating. The research indicates that the Cu 1.2 Mn 1.8 O 4 coating evolved by the high-energy micro-arc alloying process is a promising coating material for the metallic interconnects.
Abstract:To prevent Cr poisoning of the cathode and to retain high conductivity during solid oxide fuel cell (SOFC) operation, Cu or La doped Co-Mn coatings on a metallic interconnect is deposited and followed by oxidation at 750 • C. Microstructure and composition of coatings after preparation and oxidation is analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). High energy micro arc alloying process, a low cost technique, is used to prepare Cu or La doped Co-Mn coatings with the metallurgical bond. When coatings oxidized at 750 • C in air for 20 h and 100 h, Co 3 O 4 is the main oxide on the surface of Co-38Mn-2La and Co-40Mn coatings, and (Co,Mn) 3 O 4 spinel continues to grow with extended oxidation time. The outmost scales of Co-33Mn-17Cu are mainly composed of cubic MnCo 2 O 4 spinel with Mn 2 O 3 after oxidation for 20 h and 100 h. The average thickness of oxide coatings is about 60-70 µm after oxidation for 100 h, except that Co-40Mn oxide coatings are a little thicker. Area-specific resistance of Cu/La doped Co-Mn coatings are lower than that of Co-40Mn coating. (Mn,Co) 3 O 4 /MnCo 2 O 4 spinel layer is efficient at blocking the outward diffusion of chromium and iron.
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