The research is aimed at understanding the failure of ceramic materials as a result of applied mechanical loads over a wide range of ambient temperature. Failure in the low to moderate temperature range is typically the result of slow crack growth where mechanical creep alters the driving forces for the crack growth. Failure in the intermediate temperature region results from slow crack growth, but the major effect of the mechanical creep is to alter the microstructure of the material in the vicinity of the crack tip. The high temperature range is characterized by failure which is dominated by mechanical creep, e.g., creep-induced microcrack nucleation, coalescence, and finally rupture. Digital Image Correlation will be used to map the creep deformations in crack tip regions, and to identify possible inhomogeneities in the overall deformation and damage. The research will build upon the advances made during the last three years of support by the National Science Foundation under grant number DMR-8311699. The results will be used to develop models which predict reliability and lifetime for ceramics in high temperature applications.
