Reactive spark plasma sintering and mechanical properties of ZrB2-SiC-ZrC composites from ZrC-B4C-Si system

摘要

Dense ZrB2-SiC-ZrC composites with four different compositions were prepared using ZrC, B4C and Si powders as the starting materials by reactive spark plasma sintering (R-SPS). The evolutions in the phases and microstructures were investigated using XRD, Raman spectrum and SEM. It was found that the formation of ZrB2 and SiC involved two steps. Lower initial content of ZrC results in microstructural refinement and mechanical enhancement. The composite ZrB2-47.9SiC-4.7ZrC prepared by 5 min sintering at 1800 degrees C under 30 MPa pressure exhibited the most satisfying combination of properties. The flexural strength, fracture toughness and Vickers hardness were 760 +/- 19 MPa, 6.3 +/- 0.3 MPa.m(1/2) and 22.7 +/- 1.4 GPa, respectively.