Dynamic compressive behavior of ZrB₂-based ceramic composites at room temperature and 1073 K

The dynamic compressive behaviors of ZrB₂-based ceramic composites were investigated through the convenient and high-temperature Splitting Hopkinson Pressure Bars. The effects of strain rate on dynamic compressive strength, stress-strain relationship and fracture mechanisms were discussed in detail. Moreover, the influence of pre-oxidation on dynamic strength was also studied at 1073 K. The results indicate that the relationship between dynamic compressive stress and strain for ZrB₂-SiC-graphite composite is strong nonlinear at room temperature and 1073 K. Dynamic compressive strength increases linearly with the increase of strain rate. The pre-oxidation effect results in the enhancement of dynamic compressive strength at 1073 K in comparison with the room temperature strength. Based on the microstructures, the dominant intergranular fracture and pull-out of graphite flake are observed at low strain rates, whereas the transgranular fracture and cutting of graphite flake are found at high strain rates. Fracture mechanisms play a crucial role on the changes of dynamic compressive strength and critical strain with strain rate.