LaCrO3-based coatings on ferritic stainless steel for solid oxide fuel cell interconnect applications

A thin layer of doped lanthanum chromite on ferritic steel may act as a protective coating to mitigate the Cr volatility problems and facilitate the use of metallic interconnect in solid oxide fuel cells operated at intermediate temperatures. In this paper, the LaCrO3 thin film was successfully synthesized on a ferritic stainless steel substrate by two approaches, i.e. reactive formation and sol–gel processing. The coating structures and surface morphologies were analyzed using X-ray diffraction and scanning electron microscopy. After isothermal oxidation at 850 °C for 100 h in air, the electrical resistance of the sol–gel coated samples remained very low, as compared to that of the uncoated sample after similar thermal exposure. The sol–gel coating also provided effective protection for the interconnect steel during oxidation of twelve 100-h cycles at 800 °C in air, whereas significant spallation and weight loss were observed for the uncoated steel. The two coating processes (i.e. reactive formation and sol–gel processing) were compared and their advantages and drawbacks were outlined.