Research on thermal shock resistance of porous refractory material by strain-life fatigue approach

摘要

The study aims to investigate the effects of pore structure on the thermal shock resistance of porous refractory materials. Porous material is constituted by a solid frame and the pores filling with air. A direct thermo-mechanical coupling simulation and strain-life approach were employed to predict the number of thermal shock cycles of the materials; thus, influences of the porosity and distribution of pores on the thermal shock resistance were studied. The specimen was subjected to a mechanism of thermal shock damage in which alternating thermal stress under cyclic 'hot' and 'cold' shock. The simulation results show that the magnitude of thermal stress is large during the thermal shock process. And the residual thermal stresses generate at the solid/air interface since stress gradients occur inside the bulk. Furthermore, higher or lower porosity had no positive effect on the thermal shock resistance of the porous material; the highest thermal shock resistance was attained at a porosity of 20%. The uniform distribution of pores is favorable to improve the thermal shock resistance of materials of high porosity. The validation test results show that the number of thermal shock cycles of the two samples in the experiments were closer to the situations of chaotic pore distributions in the simulations.