The relationship between the pore size distribution and the thermo-mechanical properties of high alumina refractory castables

A series of high alumina refractory castables were prepared via casting with tabular alumina aggregates (0.088 - 5 mm), fine powders, and calcium aluminate cement as starting materials. The effect of the median diameter of alumina (D-50 = 7.26 mu m, 5.33 mu m, 2.37 mu m) on the thermo-mechanical properties of the refractory castables was investigated. The results indicate that the decrease in the alumina particle size from 7.26 mu m to 2.37 mu m has little influence on both the apparent porosity and bulk density of castables. However, the median pore size of castables fired after 1 600 degrees C decreased drastically from 4.7 mu m to 2.4 lm correspondingly, which led to significant growth in the strength and thermal shock resistance of castables. The cold modulus of rupture and crushing strength were increased by 201 % and 120 %, respectively. At the same time, the hot modulus of rupture and elastic modulus were also increased by 143 % and 127 %, respectively. The residual elastic modulus was enhanced twice after three thermal cycles.