Effects of Multilayered Interfaces on Mechanical Damage of SiCf/SiC Composites

SiCf/SiC ceramic matrix composites have excellent prospects in aeroengine applications. Importantly, the interface design becomes a research focus. Multilayered interfaces can effectively improve the oxidation resistance of ceramic matrix composites, while their effect on the mechanical properties and damage mechanism are still unclear. Here, SiCf/SiC minicomposites with BN and (BN/SiC)(3) interfaces were fabricated via the chemical vapor infiltration (CVI) method. Then, effect of multilayered interfaces on the failure mechanism of SiCf/SiC composites was evaluated. According to the two kinds of mechanical experiments and acoustic emission (AE) detection, the damage mechanism of minicomposites was analyzed. Results indicate that the minicomposites prepared by CVI have an obvious interface structure and a dense matrix. The maximum load of BN and (BN/SiC)(3) minicomposites was 139 and 160 N, respectively. Besides, the two types of minicomposites possess typical load-displacement curves, and the damage processes of composites with different interfacial coatings exhibit various load-acoustic characteristics correspondingly. The AE characteristics of two mechanical loading tests can effectively assess the damage evolution of the minicomposites at each stage. In conclusion, multilayered interfaces can deflect cracks better, delay cracks extending to fibers, and thus improving mechanical properties of SiCf/SiC composites.