Mechanical behavior characterization of high zirconia fused-cast refractories at high temperature: Influence of the cooling stage on microstructural changes

Today, the high quality level required by new applications of glass, imposes the use of high zirconia refractories (HZ). These are designed to operate in extreme condition and also require control of the making process. Elaborated by a fused cast process followed by a controlled cooling step, these materials exhibit specific thermo mechanical properties related to a microstructure containing monoclinic zirconia dendrites embedded into a silica–alumina glassy phase.The present paper deals with the understanding of damage phenomena at a low scale during the cooling process after cast-fusion. Mechanical characterizations at high temperature are carried out to identify the chronology of the microdamage. Microstructure observations using SEM and EBSD complete thermal experiments and allow to identify main characteristics of microdamage mechanisms. This work was conducted in the framework of a French national research program “NOREV”, aiming to build numerical tools to optimize the casting process of such materials.