Fabrication of Carbon Fiber Oriented Al–Based Composites by Hot Extrusion and Evaluation of Their Thermal Conductivity

Abstract

New heatsink materials having higher thermal conductivities have recently been required due to the recent rapid improvements in performance of the central processing unit, CPU, with increasing heat generation from computer devices. As an alternative material to conventional heatsink materials such as Al and Cu, composites containing carbon bers have recently been gaining much attentions because of their extremely high thermal conductivity. However, carbon ber exhibits high thermal conductivity only in its longitudinal direction. Therefore, it is essential to control the orientation of the carbon bers in the composite materials. In the present study, hot extrusion of a powder-ber mixture is applied to realization of unidirectional array of carbon bers in Al matrix, and the effects of volume fraction of the carbon bers on the thermal conductivity of the carbon ber oriented Al-based composite have been investigated. It has been demonstrated that the carbon bers are unidirectionally oriented in the extrusion direction, and the thermal conductivity in this direction increases with the increase in volume fraction of the carbon bers. For the composites with more than 30 vol% of carbon bers, the addition of Al-Si alloy powder or the application of the spark plasma sintering, SPS, before the extrusion was found to be effective for improving the sinterability of the powder-ber mixture.

Effect of Anisotropic Thermal Conductivity of Graphite Flakes and Interfacial Thermal Resistance on the Effective Thermal Conductivity of Graphite Flakes/Aluminum Composites

“…These properties may be enhanced when diamonds undergo a surface treatment; however, such treatment is complicated, and diamonds are expensive materials. 7) CF exhibits TC values of 10 and 1100 W m ¹1 K ¹1 , along the radial direction 5) and the axial direction, 7) respectively. CF is a one-dimensional material, and its TC has significant anisotropy.…”