The internal stress variation in 2D-SiC/SiC composites under high-temperature and oxidation conditions and its effects on mechanical behavior

Internal stress of SiC/SiC composites changed by the manufacturing or service conditions can greatly influence their mechanical properties. This study investigates the evolution of microscopic internal stress and residual mechanical properties for 2D woven PIP-derived SiC/SiC composites after heating and oxidation treatment at 1300°C for 2 h. Raman spectroscopy is employed to quantitatively evaluate the magnitude and distribution of in-situ internal stresses, and to analyze their variation under different environmental factors. Furthermore, cyclic loading-unloading and monotonic tensile tests are conducted to examine the residual mechanical properties after high-temperature oxidation exposure, elucidating the governing influence of internal stress on material elastic performance. With increasing oxidation, the internal stress in the SiC/SiC composites exhibits a trend of initial decrease followed by an increase, resulting in a non-uniform stress distribution in the oxidized material, and contributing to the failure modes transition.