Dynamic Fracture Toughness of Porous Ceramics

The paper presents experimental results of static (K-Ic) and dynamic (K-Id) fracture toughness testing. The tests were performed for two kinds of porous ceramics with various porosity fraction. The influence of porosity content, as well as loading rate on fracture toughness of alumina (Al2O3) and magnesia (MgO) as analyzed. It was found that an increase of initial porosity reduces values of both static and dynamic fracture characteristics. However, values of K-Id were much higher than K-Ic for both kinds of tested materials. In case of Al2O3, they were approximately three times higher, whereas in case of MgO-five to seven times higher depending on the porosity content.