Study of damage of high zirconia fused-cast refractories by measurement of Young's modulus

Young's modulus evolutions versus temperature have been studied for two high zirconia fused-cast refractories undergoing thermal solicitations up to 1700 °C. As well as the step of cooling from very high temperature of the manufacturing process, the first heating up can lead to the formation of internal stresses that are released by microcracking. Young's modulus has been assessed by using the impulse excitation technique at room and high temperature. Damage and healing phenomena for different temperatures are compared and discussed taking into account the physico-chemical evolutions. The effect of the allotropic transformation of zirconia, through its associated change of volume, is in particular emphasized. Furthermore, the behaviour of the glassy phase, responsible for healing at high temperature and damage at lower temperature by thermal expansion mismatch, is discussed.