Microstructure and mechanical properties of SiC composite ceramics modified by (TixZr1–x)B2 solid solution

Abstract

Dense SiC-(TixZr1–x)B2 composite ceramics were prepared via solid-state spark plasma sintering (SPS) by controlling the proportion of ZrB2 (in the range of 5–25 vol%). Through data fitting, a linear functional relationship was established between x and 2θ for the (TixZr1–x)B2 solid solution, which rendered it amenable to characterization analysis. The results show that the 2-D morphology of (TixZr1–x)B2 tended to transform from angular to round as the ZrB2 proportion was increased, which was beneficial in crack deflection and increasing the fracture toughness. Moreover, the growth of SiC grains around the solid solution was inhibited, which improved its mechanical properties. The composite ceramic containing 15 vol% of ZrB2 had the best mechanical properties, with its Vickers hardness, bending strength and fracture toughness reaching 26.12 GPa, 499 MPa, and 6.45 MPa•m1/2, respectively.