Damage behavior and toughening mechanism of SiCf/SiC-Ti3SiC2 composites: A combination of digital image correlation and acoustic emission

Abstract

Matrix modification is an effective method to improve the mechanical properties of ceramic matrix composites, while the elucidation of corresponding damage mechanism is essential for the design and engineering application of composites. In this work, Ti₃SiC₂ particles were introduced into SiC matrix to fabricate Ti₃SiC₂ modified SiC_f/SiC (SiC_f/SiC-Ti₃SiC₂) composites by a hybrid technique of slurry suspension impregnation combined with polymer infiltration and pyrolysis. Compared with SiC_f/SiC composites, the flexural strength and modulus of SiC_f/SiC-Ti₃SiC₂ composites were increased by 17.8 % and 61.0 %, respectively. The three-point flexural damage behavior and failure mechanism of composites were systematically investigated and compared by the combination of digital image correlation and acoustic emission techniques. Based on the collaborative analysis of in-situ damage process, matrix micro-zone toughness and fracture morphology, the modification effect and toughening mechanism of Ti₃SiC₂ were revealed. The improved mechanical properties of SiC_f/SiC-Ti₃SiC₂ composite could be ascribed to the more sufficient matrix cracking before composite failure and the increased matrix fracture energy by microcrack deflection. After matrix modification, the failure mechanism was dominated by the gradual propagation and growth of microcracks until the critical crack size, instead of the fast and unstable propagation of main crack.