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. (C) 2009 Elsevier Ltd. All rights reserved.