La_(0.7)Sr_(0.3)MnO_3-coated SS444 alloy by dip-coating process for metallic interconnect supported Solid Oxide Fuel Cells

摘要

Sol-gel and dip-coating technologies have been used to deposit La_(0.7)Sr_(0.3)MnO_3 (LSM) porous thin films on stainless steel SS444-Cr-17% interconnect plates. Single and double LSM layers were fired in air at 800 ℃ for 2 h to achieve a sufficient adhesion on the substrate. The microstructure and composition of oxide scales were investigated using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. The area specific resistance (ASR) for coated and uncoated plates was evaluated during long term oxidation in air at 800 ℃ for 200 h, and between 600 and 900 ℃, by DC two point measurements. The formation of an interfacial oxide scale based on (Cr,Mn)_3O_4 spinel and Cr_2O_3 has been evidenced for uncoated and LSM-coated SS444. The results indicate that the oxidation resistance of the alloy is enhanced by a protective coating consisting of one single LSM layer. ASR values as low as 0.6 mΩ cm~2 were recorded after 200 h at 800 ℃. The effectiveness of the LSM layer as a protective coating depends on the stability of the film and its adherence on the alloy substrate.