Low-temperature densification, microstructures and mechanical properties of ZrB₂–SiC composites with Cr₃C₂ additives

Abstract

In this study, the densification, microstructures and elastic and mechanical properties of hot-pressed ZrB₂–20 vol % SiC composites with 3–10 wt % Cr₃C₂ additives were examined. The effects of the Cr₃C₂ content on the densification, microstructures and elastic and mechanical properties are discussed. The elastic moduli of the composites were calculated using measured longitudinal and transverse soundwave velocities, and the hardness and fracture toughness of the composites were determined using indentation measurements. The results show that the elastic moduli and fracture toughness are constant and independent of the Cr₃C₂ content, with a shear modulus of ∼200 GPa, Young’s modulus of ∼450 GPa and toughness of ∼4.7 MPa m^1/2. The hardness was measured as 18.2–20.9 GPa and was dependent on the Cr₃C₂ content. The flexural strengths of the composites were affected by the Cr₃C₂ content, with resulting strength values of 426–523 MPa.