Densification, microstructure and properties of α/β-SiAlON ceramic reinforced by SiC whiskers.

SiC whiskers (SiC w)-reinforced α/β-SiAlON ceramic tool materials were synthesized via spark plasma sintering (SPS). A comprehensive study was conducted on densification mechanism, phase composition, microstructure, mechanical properties, and wear resistance of the SiC w /α/β-SiAlON composites. The results indicated that SiC w constrained the densification process and impeded the growth of SiAlON grains, and the introduction of SiC w significantly enhanced mechanical properties of the α/β-SiAlON ceramic. The composite containing 28 wt% SiC w synthesized at 1700 °C showed well mechanical properties, with a density of 3.35 g/cm³, Vickers hardness of 19.38 ± 0.33 GPa, and fracture toughness of 7.35 ± 0.27 MPa m1/2.The principal toughening mechanisms of SiC w /α/β-SiAlON included crack deflection, branching, bridging, as well as transgranular fracture and whisker pullout. The addition of SiC w improved the wear resistance of α/β-SiAlON ceramic. Compared to those without whiskers, the wear volume and wear rate were decreased by 38.8 %. [ABSTRACT FROM AUTHOR]