Fundamental Design of Steelmaking Refractories

5 Thermal and Mechanical Behavior

5.1 Introduction

Ceramic matrix has high hardness, compressive strength, elastic modulus, high-temperature resistance, and high stiffness. However, the lack of crack propagation resistance under stress makes it a weak and catastrophic failure. Thus exhaustive microstructure modification can provide all of these together. Refractory is a classic bulk ceramic composite that enormously experiences mechanical, thermal, and thermomechanical stresses, which eventually determine the performance of complete lining or component performance. Thus, a critical understanding of fracture behavior may help to design an adequate matrix.

These mechanical properties are among the crucial criteria (crack initiation and propagation being the most critical) for evaluating the efficiency of ceramics in terms of their applications. After briefly discussing some early brittleness theories suggested, Griffith’s theory of brittle fracture in brittle solids may address this incidence. It illustrates how to apply the physics of fracture behavior under external stress. The fracture toughness is defined from the definition of stress concentration at the crack edge [1]. The variability in strength properties is presented after exploring fracture theories. Addressing the microstructure inconsistency, spontaneous microcracking results from accumulating residual stresses and the prediction of crack growth usually emanating from a preexisting defect produced during processing ...