An innovative approach to study the influence of microstructure on thermal shock resistance of porous ceramics

Abstract

Porosity is a critical microstructural factor in ceramic materials, influencing their mechanical and thermal properties. However, the detailed mechanisms through which porosity, grain size, and grain boundary fracture energy affect the thermal shock resistance of porous ceramics are still not fully understood. This study introduces a dual-scale model that integrates these microstructural parameters to predict fracture toughness and thermal shock resistance. Using the single-edge V-notch fracture toughness testing principle, we calculate the thermal stress intensity factor and establish its relationship with temperature differentials. The critical temperature differential, which marks the onset of thermal shock damage, is determined when the thermal stress intensity factor reaches the fracture toughness threshold. The model reveals a significant interplay between porosity, grain size, and grain boundary fracture energy, with fine-grained ceramics (grain size < 10 µm) showing a sharp decrease in fracture toughness as porosity increases, while coarser-grained ceramics are less affected by porosity. These findings provide a deeper understanding of the microstructural optimization needed to enhance the thermal shock resistance of high-performance porous ceramics.