Abstract:The C/C composites reinforced by different fiber preforms are fabricated by electric-coupling chemical vapor infiltration. The effects of fabric types and lay-up sequences on the mechanical properties, fracture behaviors and thermophysical properties are investigated. The results showed that the C/C composites with a mat reinforcement had the poorest mechanical properties; both of tensile and flexural strengths and moduli of the weftless C/C and the twill C/C decreased with the lay-up

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... equences changing from 0°/0°, 0°/90° to 0°/45°. Under the tensile loading, the fracture mode of 0°/0° weftless C/C mainly exhibited the pull-out and fracture of 0° fiber bundles; that of 0°/90° weftless C/C mainly show the interfacial debonding and matrix crack of the 90° fiber layers, and the pull-out and fracture of 0° fiber bundles; that of 0°/45° weftless C/C mainly presented the interfacial debonding and matrix crack along ±45° and 90° fiber layers, and the pull-out and fracture of the ±45° and 0°fiber bundles. The mechanical properties of the C/C composites are dependent on the fiber content and arrangement in the loading direction, the pore distribution and the interfacial bonding between the bundles and between the layers. For the thermophysical properties, the 0°/90° weftless C/C and the mat C/C exhibited the lowest and the highest coefficient of thermal expansion, respectively; the 0°/45° weftless C/C and the mat C/C performed the highest and lowest thermal conductivity, respectively; and the 0°/45° weftless C/C had the largest the TSR value. The effects of the different preforms on the thermophysical properties are related to the fiber content and arrangement in the measuring direction and the pyrocarbon laminar arrangement. Key words:carbon fiber preform;C/C composite;electric-coupling chemical vapor infiltration;mechanical property;fracture behavior;thermophysical property * 国家自然科学基金资助项目(U153720046) 。20170714 收到初稿, 20171123 收到修改稿