How to improve the thermal shock resistance of high alumina bricks

Aug 11,2016
The main factors affect the thermal shock resistance of refractory  products is material in the heating or cooling process due to thermal  stress generated by thermal expansion and contraction. In general, the  greater the coefficient of thermal expansion of the material, the worse  the thermal shock resistance, such as silica brick, magnesia brick and  so on; the greater the thermal conductivity of the material, the better  the thermal shock resistance, such as silicon carbide products, etc.
From the thermoelastic theory, the small elastic modulus of the  material is, the large intensity is, the greater the thermal conductivity is,  the better thermal shock resistance is. The energy theory is that when  the products have a higher fracture surface energy, can improve  thermal shock resistance. That is, when the article having fine pores,  such products have a greater stress when the temperature changes, the  more stored energy inherent, it is possible to generate fine cracks by  the article, and these may lead to damage of the article energy  released, can greatly improve the thermal shock resistance of  products, namely intentional introduction of micro-cracks in the  products, so the extent of crack propagation is minimized, it is one of  the ways to improve the thermal shock resistance.
For example, Antistripping alumina bricks used for cement kiln ,  because add a small amount of ZrO2 in the ingredients, the changable  of ZrO2 phase causes the formation of many tiny cracks within the  article, when the temperature changes produce thermal stresses, these  tiny cracks may cause damage to the refractory energy to be released,  thereby improving the thermal shock resistance of high alumina bricks.