Development of Ceramic Coatings for Metallic Components in Supercritical Water-Cooled Reactors

Abstract

A series of ceramic coatings have been prepared by spray pyrolysis processes on P91 substrates. Primary results show that coatings obtaining with different coating compositions and procedures can reduce the weight gain of P91 samples by factors of two to ten for exposure times up to 500 hours in deaerated supercritical water at 500oC and 25 MPa. Results also show that the weigh gain of a P91 sample with Al2O3 coating is about nine times less that that of uncoated P91 after exposures for 400 hours in thermally deaerated supercritical water at 650 oC and 25 MPa. These results indicate that the Al2O3 coating shows promise for preventing oxidation of P91 alloy under supercritical water conditions.Ceramic coatings on Zircaloy substrates have also been prepared using a plasma electrolytic oxidation process. After 400 hours of testing in SCW at 500 degrees C, the samples with ceramic coatings show improved corrosion resistance compared to the bare Zircaloy substrates.