Effect of Fused MgO-ZrO_2 Clinker Addition on Thermal Shock Resistance of MgO-ZrO_2 Unfired Bricks

MgO-ZrO2 unfired bricks with ZrO2 content up to 8% at the interval of 2% were prepared,using fused magnesia(mgo:97%)and fused MgO-ZrO2 clinker (ZrO2:14.33%) as starting materials and phenolic resin as binder.The effects of ZrO2 content on thermal shock resistance (TSR) and other properties such as cold and hot modulus of rupture have been investigated.Re-sidual cold modulus of rupture ratio after heating at 1 000 ℃ and quenching by air blowing was adopted to characterize TSR.Addition of the Mgo-ZrO2 clinker improves TSR,attributing to the microcrack toughening effect by thermal expansion mismatch between different phases.When ZrO2 content goes above 4%,the impro-ving effect tends to be moderate.The introduction of MgO-ZrO2 clinker can also improve the HMOR at 1 500 ℃,while the increased ZrO2 content reduces CMOR of the bricks prefired at 1 600 ℃.due to the thermal expansion mismatch effect.Compromising the overall properties,the optimal ZrO2 content for such magnesia based unfired brick is suggested to be 4%.