Effects of lanthanum-based perovskite coatings on the formation of oxide scale for ferritic SOFC interconnect

Three lanthanum-based perovskite ceramic compounds, La0.8Ca0.2CrO3, La0.8Sr0.2CrO3, and La0.8Sr0.2MnO3, were coated on ferritic stainless steel by the spin coating technique, and the effects on the formation of oxide scale have been investigated. The coated samples were aged at 800 °C in ambient air atmosphere for up to 1600 h. After each ageing period, the measurement of electrical area-specific resistance (ASR) was conducted. The evolution of crystalline phases and microstructures of aged samples were examined using the X-ray diffractometer and the scanning electron microscope. It was found that the perovskite pastes could facilitate the growth of (Mn, Cr)3O4 spinel phases with coarser crystalline structures and higher levels of Mn content. After 1600-h ageing, coated samples exhibited an average ASR result of ∼3 mΩ cm−2, approximately one-third that of the uncoated sample. The ASR difference was attributed to the Mn content and crystallite size of the spinel phase.