The investigation of crack mechanism for Tyranno-SA SiC/SiC composites with ESI method

Abstract In order to clarify the fracture mechanism of frictional stress and bonding strength in SiC/SiC composites, the mechanical test and HRTEM equipped with electron energy loss spectrometer were used. Due to the high sensitivity of carbon k-edge in the EELS spectrum, EELS is more convenient than other analytical tools. The advanced electronic spectroscopic image (ESI) technique is applied to observe the wide area around the interface of SiC fiber/pyrolytic carbon/SiC matrix. The sp2 fraction mapping reveals the non-uniform and high sp2 concentration existence at the interface of fiber/pyrolytic carbon. This result proves the cracking start at this region and extends to whole specimen.