Processing of Carbon Nanotube Reinforced Aluminum Composite
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Processing of carbon nanotube reinforced aluminum composite T. Kuzumaki, K. Miyazawa, H. Ichinose, and K. Ito Department of Materials Science, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan (Received 5 February 1998; accepted 8 June 1998)
Carbon nanotube reinforced aluminum (Al) composites were produced by hot-press and hot-extrusion methods. The interfacial structure between the carbon nanotube and Al was examined using a transmission electron microscope (TEM), and the mechanical properties were measured by a tensile test. TEM observations have shown that the nanotubes in the composites are not damaged during the composite preparation and that no reaction products at the nanotubeyAl interface are visible after annealing for 24 h at 983 K. The strength of the composites is only slightly affected by the annealing time at 873 K, while that of the pure Al produced in a similar powder metallurgy process significantly decreases with time. These studies are considered to yield experimental information valuable for producing high performance composites.
I. INTRODUCTION
It has been revealed that a carbon nanotube possesses not only an extremely high elastic modulus1–3 but also plasticity.4–7 These findings together with their excellent mechanical properties and the predicted chemical stability that originates from their seamless cylindrical graphitic structure suggest that the nanotube might be suitable as a novel fiber material for composite materials. However, very few studies using nanotubes as a composite reinforcement have been carried out experimentally. In conventional carbon fiber/aluminum (Al) composites, Al carbide (Al4 C3 ) grows on the prism plane of the carbon fiber. This reaction is serious because the formation of a sharp notch on the fiber by attack of growing Al4 C3 needles results in a drastic decrease in the composite strength.8 In the nanotubeyAl system, however, it is expected that the composite is free from such a chemical reaction problem and can be fabricated using a plastic working process. In general, the mechanical properties of the composites reinforced with whiskers are often affected by microstructures in the composites, such as reaction phase at the interface and the aspect ratio or alignment of the whiskers in the matrix. We describe here the first attempt to fabricate the nanotube-reinforced Al composite, focusing on the processing and the mechanical properties, with the objective of using nanotubes as an engineering material.
as graphitic particles or amorphous carbons, so that the content of the nanotubes was approximately 60 vol %. The density of the carbon powder was assumed to be 2.0 Mgym3 . Al powders (99.99% purity, 40 mm grain size) mixed with 5 or 10 vol % carbon powder (5 or 10% composite) were stirred in ethanol at 300 rpm for 0.5 h and immediately dried in a vacuum furnace. The mixed powder specimens were packed in an Al case. The cases were preheated for 1.5 h at 873 K in a vacuum of
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