High Temperature Steam Electrolysis Materials Degradation: Preliminary Results of Corrosion Tests on Ceramatec Electrolysis Cell Components

摘要

Corrosion tests were performed on stainless steel and nickel alloy coupons in H2O/H2 mixtures and dry air to simulate conditions experienced in high temperature steam electrolysis systems. The stainless steel coupons were tested bare and with one of three different proprietary coatings applied. Specimens were corroded at 850°C for 500 h with weight gain data recorded at periodic intervals. Post-test characterization of the samples included surface and cross-section scanning electron microscopy, grazing incidence x-ray diffraction, and area-specific resistance measurements. The uncoated nickel alloy outperformed the ferritic stainless steel under all test conditions based on weight gain data. Parabolic rate constants for corrosion of these two uncoated alloys were consistent with values presented in the literature under similar conditions. The steel coatings reduced corrosion rates in H2O/H2 mixtures by as much as 50% compared to the untreated steel, but in most cases showed negligible corrosion improvement in air. The use of a rare-earth-based coating on stainless steel did not result in a significantly different area specific resistance values after corrosion compared to the untreated alloy. Characterization of the samples is still in progress and the findings will be revised when the complete data set is available.