Thermal shock resistance of ZrC matrix ceramics

A ZrC-20 vol% SiC based ceramic matrix composite containing 10 vol% graphite flake was fabricated by hot press sintering. The thermal shock resistance of the materials was investigated through the water-quench method and subsequent three-point bend testing of flexural strength diminution. The ZrC-20 vol% SiC composite containing 10 vol% graphite flake exhibited higher critical temperature difference and higher residual ratio of strength compared with that of ZrC-20 vol% SiC composite. It is the main reason that addition of the graphite flake provides a weak interface into the material which acts to deflect propagating cracks, and the bridging of the cracks occurred. Meanwhile, a laminar structure of the graphite flake would relax the interface stress by sliding of interlayers and provide favorable sites for the dissipation of energy associated with crack growth during fracture.