Improving functional properties of protective coatings obtained by electrophoretic deposition on steel interconnects for solid oxide cells by tuning particle size distribution

This paper analyses the effect of particle size distribution in the suspension on the quality of the resulting coating in the electrophoretic deposition of a protective coating on a steel interconnect for solid oxide cells (SOCs). Mn1.5Co1.5O4 commercial powder was subjected to grinding for 2, 4 and 18 h, and admixing it with the finest fraction was used to form thin layers on Crofer 22APU steel. The functional properties of the coatings, such as density and area-specific resistance (ASR) were evaluated over the respective temperature ranges. The resistivity of the coatings was measured in 60 and 1000 h tests. It was shown that the increase of the fine powder fractions yields a higher density layer, which contributes to slowing down the growth rate of the oxide scale and therefore can decrease ASR by 65%. The lowest resistivity was performed by the samples fabricated with the admixed powder. Post-test analysis by FIB/SEM/EDS did not reveal diffusion of chromium through the fabricated layers (after the 1000 h test), which is a key indicator of the reliability of the formed protective barrier