The Effect of Graphitization Heat Treatment Temperature on ThermalProperties of PAN-based Carbon Fiber Carbon-Carbon Composites inRelation to Microstructure and Fiber Orientation Distribution

摘要

The effect of graphitization-heat-treatment on thermal properties of three-directional `3D' PAN-based carbon fiber with CVI carbon matrix C/C was compared. The material was heat-treated to 1800, 2100, and 2400 °C. Thermal diffusivity (TD), heat capacity, and coefficient of thermal expansion (CTE) were measured, followed by computing the effective thermal conductivity T(C) as a function of test temperature. The computed thermal results are then compared. It was found that TD and consequently TC enhanced for materials heat treated to 2400 °C, the least value was shown for as-received and 1800 C heat-treated materials. Thermal properties gradually increased with heat treatment temperature. The impervious density increased with increase in porosity followed by reduction in impervious volume. Microstructure anisotropy increased as observed by polarized light microscope, X-ray diffraction, and transmission electron microscope analyses when compared to the as-received materials. Polarized micrographs of the materials showed shrinkage of CVI carbon matrix after heat treatment.