Mechanical properties of hot-pressed ZrB2–MoSi2–SiC composites

The elastic moduli, hardness, fracture toughness, and flexural strength of a hot-pressed ZrB2–MoSi2–SiC composite were examined. The effects of MoSi2 and SiC contents were assessed. The dense compacts of ZrB2–MoSi2–SiC were produced by hot-pressing at 1800 °C for 30 min under a pressure of 30 MPa in vacuum. Ten series compositions of ZrB2–MoSi2–SiC, with the range from 10 to 40 vol.% for MoSi2 and 5 to 20 vol.% for SiC, were studied. The shear modulus of ZrB2–MoSi2–SiC was in the range of 190–216 GPa, and Young's modulus measured was in the range of 438–490 GPa. The ranges of hardness and fracture toughness values were measured to be 13.2–16.8 GPa, and 2.6–3.7 MPa m1/2, respectively. The average flexural strength of ZrB2–MoSi2–SiC ranged from 369 to 863 MPa, depending on MoSi2 and SiC contents. The highest strength was obtained for 5 vol.% SiC-containing ZrB2–MoSi2–SiC, having the value of 863 MPa.