Development of CNT based carbon-carbon composites for thermal management system (TMS)

Abstract

Carbon-Fibre-Carbon matrix composites having high thermal conductivity per unit density is a competitive material for thermal management for aerospace applications. Due to anisotropic nature of Carbon-Carbon(C-C) composites, the thermal conductivity in the thickness direction which is dominated by the matrix carbon is comparatively low. In the present study, work is carried to increase the thermal conductivity in the thickness direction of 2D-CC composites. Multi-Walled Carbon Nanotubes (MWNT) were functionalised and dispersed in Phenolic Resin. C-C composites were densified with MWNT dispersed Phenolic Resin through impregnation, curing & carbonisation cycle. CNT-CC composites were densified through Chemical Vapor Infiltration process and further graphitised. The effects of MWNT in amorphous carbon for thermal conductivity were investigated. The result shows that Multi Walled Carbon Nanotubes (MWNT) can induce the ordered arrangement of micro-crystallites in amorphous carbon leading to increase in thermal conductivity of the bulk composites. There exists an optimum MWNT concentration in resin to enhance the thermal conductivity of C-C composites in the perpendicular direction. However, excess MWNT in resin is disadvantageous to enhance the thermal conductivity due to problems like agglomeration, resulting in reduced thermal conductivity. This can be attributed to the interfacial contact resistance due to improper heat transmission channels arising due to agglomeration. Investigation has been carried out to study the effect of agglomeration for the thermal conductivity of the bulk composites.