Evaluation of Thermal and Mechanical Properties of Refractories - Fundamentals and Applications - 4.2 Modulus of Elasticity - Applications - Determination of Elastic Modulus of Refractories

摘要

The measurement of elastic modulus of refractories, especially at high-temperature, including comparison of the dynamic and static methods, was summarized, and pertinent results were presented. For refractories, it is important to consider the elastic modulus for improving the thermal spalling resistance. Elastic modulus is becoming a more and more important property, especially because it is required for the popular FEM calculations. However, the standardization has actually been delayed because of the difficulty of making the measurements, or the difference between the dynamic and static methods. And, the fact that refractories exhibit elastoplastic mechanical properties, which are closer to concrete, being a mixture of aggregate and fine particles, unlike ceramics or metals. Refractories show viscous or viscoelastic behavior at high temperature, which is not the case for concrete. As a result, although ceramics are high temperature materials, which have a small difference between the static and dynamic elasticity values, refractories have smaller static elasticity values than the dynamic elasticity values. It has been reported by many researchers that the static elastic modulus decreases by more than one digit in comparison with the dynamic elastic modulus, in the region of viscoelasticity at high temperature. The measurement of the elastic modulus by only dynamic and static methods is not sufficient for the highly complicated, nonlinear refractory materials which change to elastoplastic approx viscoelastic approx viscous bodies. It seems that internal friction or relaxation modulus, etc., need to be included with both methods, for a comprehensive evaluation.