Effect of aluminum carbide on thermal conductivity of the unidirectional CF/Al composites fabricated by low pressure infiltration process

The coal-tar pitch based carbon fiber reinforced aluminum (CF/Al) composite material is one of the potential candidates of heat dissipation components for its high thermal conductivity (TC). Low pressure infiltration (LPI) method is a useful casting process for fabrication of CF/Al composites with its cost-effectiveness by using extremely low pressure. However, the detrimental product of the reaction between aluminum alloy and CF, such as aluminum carbide (Al4C3), is able to affect not only mechanical properties but also TC of CF/Al composites. In the present study, the effect of the growth of Al4C3 during LPI process on TC of unidirectional (UD) CF/Al composites has been characterized. The variation of longitudinal TC was sensitive to growth of Al4C3 during ‘cooling process’ of LPI, whereas the longitudinal TC was not influenced by that during ‘infiltration process’ mostly. The progress of local damages on CF surfaces caused by Al4C3 growth during ‘cooling process’ was a main reason of the decreasing of the longitudinal TC of UD-CF/Al composites.