Behavior of cr-coated m5 claddings during and after high temperature steam oxidationfrom 800c up to 1500c

International audienceOne-sided steam oxidation tests have been conducted at various temperatures between 1000 and 1500°C on several facilities on 12-15µm thick Cr-coated M5 claddings. Microstructural observations and micro-chemical analysis have been performed after oxidation and quenching. Some post-quenching ring compression tests have been also carried out to assess the residual strength/ductility of the Cr-coated materials oxidized at High Temperature (HT). It was confirmed that in the 1000-1300°C oxidation temperature range, the oxidation resistance of the coated materials was enhanced, with a significant additional "coping period" at HT before the material became macroscopically brittle during and/or after quenching. The study was then extended to steam oxidation temperatures higher than 1300°C (Design Extension Conditions). Those tests have confirmed that a eutectic reaction occurred between the zirconium-based substrate and the residual metallic Cr coating above 1300°C. For the DEC-type conditions applied, the tested Cr-coated clad segments did not fail upon the final water quenching while some uncoated reference segments did