Fabrication and properties of reactively hot pressed ZrB2–SiC ceramics

摘要: Abstract ZrB2–SiC ceramics with relative densities >99% were fabricated by ‘in situ’ reactive hot pressing from ZrH2, B4C and Si. The reaction was studied using two processes, (1) powder reactions at temperatures 1150 to 1400 °C (2) between 1600 1900 °C. products the of a 2ZrH2:1B4C:1Si molar mixture ZrB2, SiC, ZrO2 ZrC. Modification composition 2ZrH2:1.07B4C:1.16Si resulted in elimination undesired ZrC phases. final approximately ZrB2–27 vol% SiC no phases detected X-ray diffraction, only low concentrations scanning electron microscopy. Elimination accomplished removing surface oxides through chemical elevated temperatures. Reactively pressed samples consisting ZrB2 27 vol% had Young's modulus 508 GPa, flexure strength 720 MPa, fracture toughness 3.5 MPa m1/2 Vickers’ hardness 22.8 GPa.