Effects of SiC whiskers on the mechanical properties and microstructure of SiC ceramics by reactive sintering

As-received and pre-coated SiC whiskers (SiCw)/SiC ceramics were prepared by phenolic resin molding and reaction sintering at 1650 °C. The influence of SiCw on the mechanical behaviors and morphology of the toughened reaction-bonded silicon carbide (RBSC) ceramics was evaluated. The fracture toughness of the composites reinforced with pre-coated SiCw reached a peak value of 5.6 MPa m1/2 at 15 wt% whiskers, which is higher than that of the RBSC with as-received SiCw (fracture toughness of 3.4 MPa m1/2). The surface of the whiskers was pre-coated with phenolic resin, which could form a SiC coating in situ after carbonization and reactive infiltration sintering. The coating not only protected the SiC whiskers from degradation but also provided moderate interfacial bonding, which is beneficial for whisker pull-out, whisker bridging and crack deflection.