Evolution of Young's Modulus, Strength, and Microstructure during Liquid‐Phase Sintering

This comparative study addresses the influence of microstructural evolution on mechanical properties of porous alumina prepared by partial densification with and without addition of a glassy phase. The composition used for liquid‐phase sintering is heated above and, in order to freeze the starting defect distribution, below the glass transition point. The ensuing densification rate is compared with measurements of the temperature and time‐dependent wetting angle. The strength of the alumina is correlated with microstructural characteristics, Young's modulus, fracture toughness, and crack tip toughness as a function of porosity. Linkage of the crack tip toughness to elastic modulus, in combination with fractography and a description of a linearly shrinking critical defect, yields a predictive capacity to determine strength of porous ceramics.