The failure mechanism of ZrB_2-SiC-graphite composite heated by high electric current

摘要

The failure mechanism of the ZrB_2-SiC-graphite composite heated by high electric current was investigated. The results indicated that a large numbers of graphite flake was torn along their basal planes, which was attributed to that the thermal stress is perpendicular to graphite flake. The thermal stress resulted from the thermal expansion mismatch during rapid heating was calculated to be above 1.5 GPa using Hsueh's formula. Although the thermal stresses were relaxed through the deformation of graphite, the maximum thermal stresses were higher than the strength of < 500 MPa for the ZrB_2-SiC-graphite composite, which resulted in the destruction of the specimen.