Correlation between microstructure and electrical properties of Cu1.3Mn1.7O4/La2O3 composite-coated ferritic stainless steel interconnects

The goal of this study was to investigate the effect of screen-printed Cu1.3Mn1.7O4/La2O3 composite coating on chromia scale growth and electrical behavior of AISI430 stainless steel interconnects. The coated samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy equipped with energy dispersive spectroscopy (FESEM-EDS) and 4-probe area specific resistance (ASR) tests. The results showed that LaCrO3 conductive perovskite is formed due to the interdiffusion between Cr2O3 and/or CrO3 and La2O3. The presence of LaCrO3 through the composite coating and Cr2O3 sub-scale accompanied by the effective role of spinel phase, acted as a barrier to mitigate the sub-scale growth preventing chromium diffusion through the coating and the cathode. Besides, LaCrO3 particles within the sub-scale provided suitable conductive paths decreasing ASR from 19.3 mΩ cm2 for spinel coated sample to 15 mΩ cm2 for composite coated sample at the end of 500 h oxidation at 750° C.