The manufacturing costs of solid oxide fuel cells (SOFCs) could feasibly be reduced by using ferritic stainless steel (SUS) interconnectors. However, the stainless steel interconnector suffers from poor oxidation resistance at the IT-SOFC operating temperature. In order to solve this problem, we coated LaCrO3 or strontium-doped LaCrO3 on SUS444 as an oxidation protective layer by a sol-gel technique. Precursor solutions with different metal ion concentrations (0.1, 0.3, and 0.5 mol/l) were prepared from metal nitrates, ethylene glycol, and nitric acid. Dense coating layers with a thickness of 0.8 to 2 μm could be obtained upon heat-treatment of gel films at 700 oC in an air atmosphere. It was found that the thickness and microstructure of the coating layers depended on the concentration of the precursor solution. The oxidation behavior of the LaCrO3 or strontium-doped LaCrO3-coated SUS444 was compared with that of bare SUS444. Area specific resistances (ASR) of the SUS444 substrates were measured as a function of temperature. The ASR monotonically decreased with an increase in the concentration of the precursor solution.

Keywords: Solid oxide fuel cell, LaCrO3, Interconnector, SUS444, Oxidation protective coating.