Evaluation of Thermal and Mechanical Properties of Refractories - Fundamentals and Applications - 8.1 Fractures by Thermal Stress - Fundamentals

摘要

In order to secure the reliability of the strength of refractories during operation, it is necessary to obtain sufficient knowledge of the thermal stresses during operation and the thermal stress fracture (thermal spalling) caused by these thermal stresses. Furthermore it is essential to reflect such acknowledge into the materials design and furnace-installation design. The thermal stress is defined as the stress generated by temperature gradients in the internal region of the material and/or by mechanical constraints due to thermal expansion (or contraction) when the materials experience thermal loading. These stresses are separated into steady thermal stress in a steady temperature field and non-steady thermal stress in a non-steady temperature field. They are also separated into the elasticity problem and the elasto-plasticity problem (visco-elasticity and creep are excluded) (see Fig. 1).