Wettability and reactivity between molten aluminum and randomly aligned carbon nanotubes
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Wettability and reactivity between molten aluminum and randomly aligned carbon nanotubes Hui-Zhen Shen1, Yi Wang1, Shuo-Ming Chen1, and Ping Shen1,* 1
Key Laboratory of Automobile Materials (Ministry of Education), School of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025, People’s Republic of China
Received: 26 July 2020
ABSTRACT
Accepted: 24 November 2020
The wettability and reactivity between molten aluminum (Al) and carbon nanotubes (CNTs) are a key issue in the preparation of CNTs-reinforced Almatrix composites using a solidification route. In this work, we measured the wettability of randomly aligned multi-walled carbon nanotubes (buckypaper) by molten Al at 973–1173 K in a high vacuum using a modified sessile-drop method and examined their interactions using a droplet-sucking technique. The wettability between Al and CNTs is even worse than that of the Al/graphite system. The contact angles are basically larger than 140° and show only a sluggish decrease with time during isothermal dwelling. The chemical stability of CNTs in contact with Al is closely related to their structural integrity. The CNTs with good crystallinity and structural integrity have relatively high chemical stability and exhibit only a weak interfacial reaction with Al at 973 K. However, the stability of structural defective parts is much lower. They are readily eroded by molten Al, leading to the fragmentation of the CNTs. These CNT fragments having an open tubular structure are then rapidly dissolved in molten Al along the axial and radial directions. Simultaneously, a large amount of Al4C3 is formed at the interfaces.
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Handling Editor: Philip Nash.
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https://doi.org/10.1007/s10853-020-05616-0
J Mater Sci
GRAPHICAL ABSTRACT
Introduction Since Kuzumaki et al. [1] first prepared carbon nanotubes reinforced Al-matrix composites via a powder metallurgical route in 1998, a lot of work has been performed on the synthesis, processing, microstructures and properties of CNTs-reinforced metal-matrix composites. Among various questions, the key and difficult point in the preparation of these composites is how to make CNTs uniformly disperse in metal matrix and maintain their structural integrity. It is well known that the dispersion of reinforcements in a metal matrix is closely related to the wettability between them if a liquid processing route is employed. However, the research on the wettability of CNTs by liquid metals is still very scarce. As far as we know, So et al. [2] used a conventional sessiledrop method to measure the wettability of pure Al with two kinds of preforms composed of CNT powders and SiC-coated CNT powders, respectively. After holding at 1073 K for 5 min, the systems showed contact angles of 145.8° and 134.6°. However, considering that the vacuum in their experiments was very poor (1.3 Pa), serious oxidation at the Al surface was inevitable, and t
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