Improvements on the mechanical properties and thermal shock behaviours of MgO–spinel composite refractories by ZrO 2 incorporation

Abstract

Microstructural features and improvements on the mechanical properties and thermal shock behaviours of MgO–spinel composite refractories with ZrO 2 addition were examined. ZrO 2 incorporation into MgO–spinel led to improvements around ∼1.5-fold ratios on mechanical properties, R st values and thermal shock results. The basic parameters improving mechanical properties and thermal shock resistance of MgO–spinel–ZrO 2 composite refractories were determined as follows: (i) propagation of microcracks for a short distance by interlinking each other, (ii) stopping or deviation of microcracks when reaching pores or ZrO 2 particles, (iii) concurrent occurrence of mostly intergranular and some transgranular cracks on fracture surfaces, and with the addition of ZrO 2 (iv) the increase in bulk density, and (v) a significant decrease in MgO grain size. The improvements observed in thermo-mechanical properties confirmed that MgO–spinel–ZrO 2 refractories showed a low strength loss and high thermal shock damage resistance at high temperatures, leading to longer service lives for using industrial applications.