Influence of the thermal history on the mechanical properties of two alumina based castables

Monolithic refractories are of importance due to their increasing applications in the metallurgical industries. In a wide range of industrial applications, refractory castables are subjected to demanding requirements, and their properties strongly depend on their thermal history.This work is devoted to the study of the evolution of the mechanical properties of two refractory castables related to different thermal treatments corresponding to their conditions of use. The studied materials are two alumina refractory castables: an ultra low cement content bauxite based one (Bau-ULCC) and a low cement content andalusite based one (And-LCC).Samples of both refractories have been fired at different temperatures (110, 250, 500, 700, 900 and 1100 °C) in order to simulate several conditions of use. During these firing stages, microstructural evolutions have been monitored by Young's modulus ultrasonic measurements. Then, the tensile loading behaviour of each sample has been determined both at room temperature and for a specific temperature (800 °C), chosen according to thermal history ultrasonic measurements.