Temperature dependence on thermal and strength properties of aluminum based high thermal conductive composites containing VGCF-CNT fillers

Abstract

Aluminum (Al) based composites containing vapor-growth carbon fibers (VGCF) and carbon nanotubes (CNT) has been developed by authors for a decade using spark plasma sintering (SPS). It has been clarified that the thermal conductivity of the composite is three times higher than that of a normal Al matrix. The maximum volume fraction of VGCF within the composites to obtain high thermal conductivity was 60%. However, this high volume fraction of VGCF may have a negative effect on the strength of the composite. These composites are intended for use in controlling heat in radiation fins of a heat exchanger or a heat sink. Thus, strength properties and thermal conductivities of the composite at high temperatures should be precisely clarified. In this paper, temperature dependencies of both thermal conductivities and strength properties of the composite are investigated. Pure tensile tests and measurements of thermal conductivity by laser flash methods are conducted at high temperatures. Both the strength properties and the thermal conductivities of the composite decrease with increase in temperature. However, the decreasing behaviors of these properties were different in the Al matrix. The change in the strength of the composite due to temperature is smaller than that of the Al matrix and also smaller than the thermal conductivity of the composites.