Microstructure and strengthening behavior in high content SiC nanowires reinforced SiC composites

In this study, the high-content SiCnw reinforced SiC ceramic matrix composites (SiCnw/SiC CMC) were successfully fabricated by hot pressing beta-SiC and sintering additive (Al2O3-Y2O3) with boron nitride interphase modification SiCnw. The effects of sintering additive content and mass fraction (5-25 wt%) of SiCnw on the density, microstructure, and mechanical properties of the composites were investigated. The results showed that with the increase of sintering additives from 10 wt% to 12 wt%, the relative density of the SiCnw/SiC CMC increased from 97.3% to 98.9%, attributed to the generated Y3Al5O12 (YAG) liquid phase from the Al2O3-Y2O3 that promotes the rearrangement and migration of SiC grains. The comprehensive performance of the obtained composite with 15 wt% SiCnw possessed the optimal flexural strength and fracture toughness of 524 +/- 30.24 MPa and 12.39 +/- 0.49 MPa center dot m(1/2), respectively. Besides, the fracture mode of the composites with 25 wt% SiCnw content revealed a pseudo-plastic fracture behavior. It concludes that the 25 wt% SiCnw/SiC CMC was toughened by the fiber pull-outs, debonding, bridging, and crack deflection that can consume plenty of fracture energy. The strategy of SiC nanowires worked as a main bearing phase for the fabrication of SiC/SiC CMC providing critical information for understanding the mechanical behavior of high toughness and high strength SiC nanoceramic matrix composites.