Study of thermal conductivity and microstructure of copper-5 wt%titanium/carbon nanofibre composites

Carbon nanofibres have high thermal conductivities of approximately 1200 W m-1 K-1, thus have great potential as the high conducting phase in composite materials for use as heat distributors in high heat flux applications. A copper-5wt% titanium/carbon nanofibre composite was fabricated, and its thermal conductivity and microstructure was studied. Microstructural characterisation involved focussed ion beam milling coupled with scanning electron microscopy, to obtain the fibre distribution, and transmission microscopy, to study the fibre/matrix interface. The composite thermal conductivity was determined from laser flash measurements and was found to be much lower than that predicted using the Eshelby mean field approach. A study of the structure showed that this was the result of cracking at the CNF/matrix interface and degradation of the carbon fibre graphitic structure.