In-situ reaction between SiC whiskers and sintering additives to strengthen and toughen SiC ceramic

The application scope of advanced ceramics is significantly limited due to their inherent brittleness, making the enhancement of fracture toughness a critical area of research. Although the incorporation of SiC whiskers (SiCw) has been shown to effectively improve fracture toughness, a high content of whiskers complicates the densification process. Herein, we discovered that the addition of SiCw can react in-situ with sintering additives, enabling SiC ceramics to achieve densification while incorporating a substantial quantity of whiskers. We systematically investigated the effects of stacking faults in SiC whiskers on the densification and microstructure of ceramics. SiCw with stacking faults reacted with sintering additives, leading to improved densification and refined grains. In contrast, whiskers without stacking faults maintained a rod-like structure within the ceramic matrix, resulting in whisker debonding and pull-out. When 40 vol.% SiCw was added, the optimized flexural strength and fracture toughness can reach 885 MPa and 8.94 MPa·m^0.5, respectively.