Elastic modulus, strength and fracture toughness of alumina ceramics containing pores

The effect of pores on elastic modulus, strength and fracture toughness of alumina ceramics was studied. Elastic modulus decreased with increasing porosity, and slightly increased with increasing pore size. On the other hand, strength decreased with increasing both porosity and pore size, being proportional to a reciprocal square root of the pore size. Fracture toughness decreased with increasing porosity and increased with increasing pore size. Fracture surface energy slightly increased with increasing pore size. The crack size at fracture origin were bigger 10 times or more than the maximum pore size, and increased with increasing pore size.