Microstructure and mechanical properties of ZrB_2-SiC composites

摘要

A ZrB_2-based composite containing 20 vol.% nanosized SiC particles (ZSN) was fabricated at 1900 ℃ for 30 min under a uniaxed load of 30 MPa by hot-pressing. The microstructure and mechanical properties of the composite were investigated. It was shown that the grain growth of ZrB_2 matrix was effectively suppressed by submicrosized SiC particles located along the grain boundaries. In addition, the mechanical properties of ZSN composite were strongly improved by incorporating the nanosized SiC particles into a ZrB_2 matrix, especially for flexural strength (925 ± 28 MPa) and fracture toughness (6.4±0.3 MPa·m~(1/2)), which was much higher than that of monolithic ZrB_2 and ZrB_2-based composite with microsized SiC particles, respectively. The formation of intragranular nanostructures plays an important role in the strengthening and toughening of ZrB_2 ceramic.