Microstructure and mechanical properties of ZrB2-SiC composites fabricated by the centrifugal gel casting

Abstract

The high-performance and reliable ZrB2-SiC composites were fabricated by centrifugal gel casting and pressureless sintering. A well-dispersed ZrB2-SiC suspensions with up to 48 vol.% solid loading was achieved by adding 0.6 wt.% PAA dispersant and adjusting pH value to 11. The crack-free green ZrB2-SiC ceramic bodies with homogenous microstructure were prepared successfully by centrifugal gel casting with a relatively low monomer content of 3.5wt.% and centrifugal speed of 9000 r/min. After pressureless sintering at 2000 °C for 1 h, ZrB2-SiC composites with a relative density of 94.8%, a flexural strength of 394 ± 14 MPa and fracture toughness of 4.03 ± 0.10 MPa·m1/2 were achieved. This approach provided a promising colloidal processing to fabricate ceramic composites with reliable properties.