Indentation Damage of Porous Alumina Ceramics

Abstract

The Hertzian indentation contact damage behaviour of porous alumina with controlled pore shape was investigated. Porous alumina ceramics containing well-defined pore shapes, size and distribution were prepared by incorporation of fugitive spherical starch. Porous alumina with isolated pore structure was prepared with porosity up to 30%. The indentation stress-strain curves of porous alumina were constructed. Elastic modulus and yield stress can be obtained from the stress-strain relationship. Impulse excitation method for the measurement of elastic modulus was also conducted as well as Hertzian indentation, and was confirmed as a useful tool to evaluate the elasticity of highly porous ceramics. Elastic modulus of the inter-connected pore structure is more sensitive to porosity than that of the isolated pore structure. When the specimen had isolated pore structure, higher yield point was obtained than when it had inter-connected pore structure. This study proposes that the elastic modulus of porous ceramics is strongly related to not only porosity, but also the pore structure.