THERMOMECHANICAL BEHAVIOUR OF ANDALUSITE BASED REFRACTORY CASTABLE

摘要

This work deals with the characterisation of the thermomechanical behaviour of an andalusite based low cement refractory castable (And-LCC). Samples have been fired at different temperatures (110, 250, 500, 700, 900, 1100℃) in order to simulate several thermal histories. During these firing stages, microstructural evolutions have been monitored by ultrasonic Young's modulus measurements. Then, the tensile behaviour of each sample has been determined at room temperature. The material initially shows a linear elastic behaviour which moves to a non-linear one by temperature. This non-linear character is less important after 110℃ than in the case of castables fired at higher temperature. In this case, the non-linear behaviour is magnified due to microcracking mechanisms which have been previously developed during the cooling stage of the thermal treatment. Temperature cycling also reduces the maximum strength, but strongly increases the compliance and the strain to rupture. These evolutions result from microstructural effects related to the single-crystal character of the andalusite aggregates whichinvnlves a very strong anisotropy of thermal expansion.