China's Refractories

Abstract: In order to investigate the effect of zirconia corundum on the preparation of chrome corundum castables, samples were prepared using tabular corundum, white fused corundum, active alumina micropowder, chromium oxide micropowder and fused ziconia corundum particles as the main raw materials, and pure calcium aluminate cement as the binder. The effects of the fused zirconia corundum particles addition (1-0.5 mm, 0, 4.5%, 9%, and 18%, by mass) on the linear change rate, the apparent porosity, the cold modulus of rupture, and the thermal shock resistance of chrome corundum castables were studied, and the microstructure of the samples was analyzed. The results show that: (1) with the zirconia corundum addition increasing, the permanent linear change on heating of the samples gradually increases, the apparent porosity gradually increases, the cold modulus of rupture gradually decreases, and the thermal shock resistance gradually increases; (2) according to SEM, it can be found that the phase transformation of ZrO₂ after heat treatment leads to a large number of microcracks in the material. On one hand, the cold modulus of rupture of the material is reduced; on the other hand, the thermal shock resistance of the material is improved.

Key words: fused zirconia corundum-chrome corundum, castable, thermal shock resistance, microcrack