Microstructure and Thermal Conductivity of Carbon Nanotube Block-Reinforced Aluminum Matrix Composite

Abstract

To solve the problem of pore formation caused by the aggregation of carbon nanotubes (CNTs) in metal matrix composites, unidirectionally aligned CNT (CNT blocks) were used as the reinforcement material. CNT block preforms with high porosities were fabricated via a spacer method using electroless Cu-plated CNT blocks. During the preform manufacture, the thickness of the Cu layer was varied while maintaining a constant CNT block volume fraction (10%). In addition, CNT block-reinforced Al matrix (CNT block/Al) composites were manufactured using a low-pressure infiltration method at 0.1 MPa. The interface between the CNT blocks and the Al matrix and the reactivity of the Al matrix with the Cu layer were investigated. The composites with the CNT block:Cu ratios ≤6.8:3.2 showed an improved CNT block/Al interface. At the CNT block:Cu ratio of 3.7:6.3, an intermetallic compound, Al₂Cu, was formed by the reaction between Cu and Al. Furthermore, the thermal conductivities of the fabricated CNT block/Al composites were determined.

Schematic diagram of CNT blocks/Al composite with different thickness of eletroless Cu plating layer.