Oxidation protective (La, Sr)CrO3 thin film coating on SUS430 substrate for IT-SOFCs

초록

A cheap ferritic stainless steel (Fe-Cr alloy) has been used to replace the lanthanum chromite-based ceramic as the technology of the operating temperature range of SOFCs being reduced from approximately 1000°C to 600~800°C was significantly progressed. However, the ferritic stainless steel suffers from its poor oxidation resistance. (La, Sr)CrO3 (LSC) has been used to ceramic coating material because it keeps away separator from reaction with solid electrolyte, protects from carbon deposition, as well as oxidation and has enough electric conductivity. In this study, ceramic coating technique was applied to obstruct voltage drop caused by the oxidation and carbon deposition of metallic separator in intermediate temperature SOFC systems. LSC precursor solutions were prepared by adding nitric acid and ethylene glycol into an aqueous lanthanum, strontium and chromium nitrates solution. Dried LSC gel films have been heat-treated at 400 to 800℃ after dip-coating on SUS 430 substrates. XRD and FT-IR analysis was used for chemical structure and crystallization behaviors. Oxidation behavior of SUS430 substrates and microstructural evolution of the thin films were discussed in terms of the precursor solution synthesis conditions.