Deposition, characterization and performance evaluation of ceramic coatings on metallic substrates for supercritical water-cooled reactors

A series of ceramic coatings have been prepared on P91 substrates by spray pyrolysis processes and on Zr–2.5Nb substrates by a plasma electrolytic oxidation process. Preliminary results show that coatings obtained with different solution compositions and procedures can reduce the oxidation weight gain of P91 samples by factors of 2–10 for exposure times up to 500h in deaerated supercritical water at 500°C and 25MPa. Results also show that the weight gain of a P91 sample with an alumina (Al2O3) coating is about nine times less than that of uncoated P91 after exposures for 400h in deaerated supercritical water at 650°C and 25MPa. These results indicate that the Al2O3 coating shows promising results for preventing oxidation of P91 under supercritical water conditions. The samples with ceramic coatings on Zr–2.5Nb substrates show marginally improved corrosion resistance compared to the bare substrates.