Effect of Microstructure on Measurements of Fracture Energy of Al2O3

Alumina specimens were fabricated under a wide range of conditions using cold-pressing and sintering techniques. Fracture energies were measured by an analytical technique (notched beam) and by the Tattersall-Tappin method. Problems in using the latter method are discussed. The effects of porosity, pore distribution, and grain size on fracture energy are evaluated. Connected porosity has a deleterious effect on fracture energy. A grain-size effect dominates in dense material; the fracture energy decreases with increasing grain size.