Investigation of electrophoretic deposition as a method for coating complex shaped steel parts in solid oxide cell stacks

Electrophoretic deposition (EPD) is a promising method for coating complex shaped interconnects and contact components for solid oxide fuel cells and electrolyzers. In this work, we employ a combination of finite element modelling and experiments to assess the effect of substrate curvature on the fabrication of a Mn_1.5Co_1.5O₄ coating by EPD. The coating is deposited on steel substrates machined to create a well-defined curvature and on a Crofer 22 H steel grid. We find that post-deposition sintering of the coated steel substrate may lead to crack formation in concave surfaces, while a defect-free coating is achieved at convex surfaces. The formation of cracks is found to depend on a complex interplay between the coating thickness, the sintering procedure, and the substrate curvature radius. Oxidation testing in air at 750 °C showed that the Mn_1.5Co_1.5O₄ coating reduced the oxidation rate of the Crofer 22 H steel grid. Sintering the coating by a two-step reduction and re-oxidation procedure resulted in a more protective coating showing a greater tendency for crack healing compared to sintering the coating in air only.