M. Huger,
C. Gault
T. Chotard

Abstract: A pulse-echo technique, based on ultrasonic "long-bar" mode (LBM) velocity measurements, working up to ۱۷۰۰°C is described. Magnetostrictive transducers and ultrasonic lines used in a ۴۰-۸۵ kHz frequency range are detailed. The conditions of choice of fundamental parameters (frequency, line geometry, sample size) are discussed in relation with the nature and the microstructure of the materials under test. This technique can be used to study the variations of elastic moduli of materials at high temperature. Examples are reported concerning a wide range of refractory materials used in steel making industry: Al۲O۳/C refractories used for ladles shrouds, Al۲O۳-MgAl۲O۴ castables used for steel ladle lining, and MgO/C refractories used for basic oxygen furnace.