A Novel Method for Evaluating the Toughness of Porous Ceramics- Uniaxial Compression Testing

Traditionally, the fracture toughness (K_IC) of porous ceramics is evaluated by single edge notched beam method (SENB). For porous ceramics, the fracture toughness tested by SENB increases with decreasing porosity, and it demonstrates that lower porosity improves the crack propagation resistance. However, previous experimental experience suggests that the thermal shock damage resistance (R ⁗) of porous ceramics will increase with increasing porosity, indicating that the high-porosity ceramics have the better capability to improve the crack propagation resistance in thermal shock situation. The SENB method is obviously concluded to be in contradiction with the thermal shock damage theory. The uniaxial compression testing of porous ceramic shows that the σ-ε curve can be divided into two parts, linear part and nonlinear part. Due to the metastable propagation of multi-micro-crack, the σ-ε curve displays nonlinear behavior. The fracture energy measured by uniaxial compression testing can be also used to characterize the quantity of mirco-crack-toughen effect, and it can improve the test method of fracture toughness for porous ceramics.