Microstructure and strengthening behavior in high content SiC nanowires reinforced SiC composites
Jiahao Yang, Zahoor Ahmad, Mingming Zhu, Jianjun Chen
Abstract
Abstract In this study, the high‐content SiC nw reinforced SiC ceramic matrix composites (SiC nw /SiC CMC) were successfully fabricated by hot pressing β‐SiC and sintering additive (Al 2 O 3 ‐Y 2 O 3 ) with boron nitride interphase modification SiC nw . The effects of sintering additive content and mass fraction (5–25 wt%) of SiC nw 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 SiC nw /SiC CMC increased from 97.3% to 98.9%, attributed to the generated Y 3 Al 5 O 12 (YAG) liquid phase from the Al 2 O 3 ‐Y 2 O 3 that promotes the rearrangement and migration of SiC grains. The comprehensive performance of the obtained composite with 15 wt% SiC nw possessed the optimal flexural strength and fracture toughness of 524 ± 30.24 MPa and 12.39 ± 0.49 MPa·m 1/2 , respectively. Besides, the fracture mode of the composites with 25 wt% SiC nw content revealed a pseudo‐plastic fracture behavior. It concludes that the 25 wt% SiC nw /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.