Mechanical behavior characterization of high zirconia fused-cast refractories at high temperature : influence of the cooling stage on microstructural changes
Résumé
Up to now few studies concerning the crystallographic features of zirconia materials(HZ) used asrefractory material have been performed. The elaboration processthrough rawmaterialfusion followed by a controlled cooling step lead to amaterial containing 94wt.%of dendriticmonoclinic zirconia. During cooling, ZrO2 passesthrough three differentstructural phase transitions(SPTs), inducing formation of a complex microstructure made of different crystallographic domains called variants. Thisstudy focus on formation of these different monoclinic variantsin a non-doped zirconia based material and the possibility to reconstruct initial cubic parent crystals formed at high temperature using optical microscopy and Electron Back Scattering Diffraction (EBSD). EBSD experiments allow to identify 24 monoclinic variantsissued from tetragonal parent crystal and to highlightthe contours ofthe parent cubic crystal.Then,themicrostructure appearing during thefirststeps ofthe solidification ofthematerial can be evidenced.