Influence of electrodeposition parameters on the characteristics of Mn–Co coatings on Crofer 22 APU ferritic stainless steel

Abstract

Manganese–cobalt coatings are promising candidates for solid oxide fuel cell (SOFC) interconnection applications because of their high conductivity and good oxidation resistance. In the present study, manganese and cobalt are electrodeposited on Crofer 22 APU ferritic stainless steel. The effects of current density, pH, sodium gluconate \((\hbox {NaC}_{6}\hbox {H}_{11}\hbox {O}_{7})\) concentration, cobalt sulphate concentration \((\hbox {CoSO}_{4}{\cdot }7\hbox {H}_{2}\hbox {O})\) and deposition duration on the microstructure and cathodic efficiency are characterized by means of scanning electron microscopy, weight gain measurements and energy-dispersive X-ray spectrometry, respectively. Results show that increases in current density and deposition duration lead to decrease in current efficiency and deposition rate. Increasing the pH to 2.5 causes an initial rise of current efficiency and deposition rate, followed by subsequent decline. In addition, the increases in sodium gluconate and cobalt sulphate concentrations in the electrolyte solution result in an increase in current efficiency and deposition rate. Moreover, the results demonstrate that the variations in the current density, pH, sodium gluconate (\(\hbox {NaC}_{6}\hbox {H}_{11}\hbox {O}_{7}\)) concentration, cobalt sulphate concentration (\(\hbox {CoSO}_{4}{\cdot }7\hbox {H}_{2}\hbox {O}\)) and duration have a significant effect on grain size, uniformity and the adherence of the coating.