Study for the Evaluation of Fracture Properties on Silicon Carbide Under High Temperature by Means of an Acoustic Emission Technique

Modified Small Punch(MSP) Test using Acoustic Emission(AE) technique was examined on silicon carbide(SiC), preparing by sintering or chemical vapor deposition(CVD), from room temperature to very high temperatures. MSP testing method based on miniaturized test technique was developed to evaluate the each fracture property from once a test, and is effective especially for the material evaluation at the initial developed stage on new materials such as Functionally Gradient Materials(FGMs). From these results, the change of mechanical properties with the difference of crystal structure and fabrication method on ceramics was examined. Furthermore, micro fracture process for ceramics at high tenperature environment was evaluated by AE data and the cause for the strength degradation of ceramics at very high temperatures was also discussed. The proposed simultaneous use of MSP test and AE method could provide a great deal of the useful information on the microscopic fracture mechanism in silicon carbide ceramics at very high terrperatures.