Effect of hollow corundum microspheres additive on physical and mechanical properties and thermal shock resistance behavior of refractory castable

Abstract

Most high temperature processes in industrial furnaces are combined with cycles of heating and cooling. In these applications, refractory materials are exposed to temperature gradient during operation, which causes thermal stresses and damage to the material. Therefore, the durability of the structures significantly depends on the thermal shock resistance of refractory materials used in thermal units. This work analyses the effect of hollow corundum microspheres (HCM) on both physicalmechanical properties (density, modulus of elasticity, and compressive strength) and thermal shock resistance behavior of refractory cement based castable with bauxite aggregate. It was found that the replacement of bauxite of 0–0.1 mm fraction by HCM (2.5%, 5%, and 10% by weight of dry mix) had no significant effect on the density and compressive strength of castable, while the modulus of elasticity decreased by 15%. Ultrasonic pulse velocity values and the visual analysis of the samples after thermal cycling showed that a small amount of HCM in composition of refractory castable could reduce the formation and propagation of cracks and thus increase its thermal shock resistance.