A Novel Technique for Production of Metal Matrix Composites Reinforced With Carbon Nanotubes

Abstract

The metal matrix composites (MMCs) have been widely used where high specific properties and temperature resistance are required, particularly in aerospace applications. In this work, an ASTM-1100 aluminum alloy in the form of sheets was reinforced with multiwalled carbon nanotubes (MWCNTs) by a novel technique which we have called sandwich technique. Carbon nanotubes (CNTs) are dispersed in a polyvinyl alcohol (PVA) solution; this solution is poured into a container and dried to obtain a reinforced polymer, which is then stretched to obtain a sheet with CNTs aligned in the stretching direction. These composite sheets were stacked with aluminum sheets, and then these stacks were hot compacted in a die using an argon atmosphere to prevent the damage of the CNTs. During this process, most of the polymer evaporates and aluminum diffusion allows obtaining a consolidated matrix with a banded structure of CNTs. The mechanical properties of the composite were measured by tensile and nano-indentation tests, showing increases of up to 100% in the elastic modulus and significant increases in yield and ultimate strength with respect to unreinforced material. Field emission scanning electron microscopy (FESEM) analyses showed a good dispersion of the CNTs within the bands with no evidence of CNTs' damage. No harmful phases were found in the composite after micro X-ray diffraction (XRD) tests. The results showed that the proposed technique is promissory to solve some of the problems in the nano-MMCs manufacturing such as dispersion and alignment of the reinforcing phase.

Mechanical properties and interfacial phenomena in aluminum reinforced with carbon nanotubes manufactured by the sandwich technique

“…In the case of the composite with 2 wt.% of MWCNTs (Figure 6(b)), the alignment was not so good. As explained elsewhere, 29 this poor alignment is probably a result of the low deformability of the reinforced PVA layer during the stretching process, which in turn is due to the high content of MWCNTs.…”

“…In the evaluated zones, the presence of any aluminum carbide phase was not detected, which confirms the findings of micro X-ray diffraction previously reported. 29 However, several studies have shown the formation of aluminum carbides in this kind of composite materials. In addition, the mechanisms of phase growth when the composites are manufactured at temperatures above their melting point have also been studied.…”

“…26,27 However, techniques like powder metallurgy in some cases do not lead to a major increase of the mechanical properties due to the agglomeration of CNTs in the metal matrix, which allows the formation of aluminum carbides that inhibit the effective load transfer because of their brittleness 28 ; in addition, these phases are induced by high temperatures involved in the process. 5,18,21 A new manufacturing technique described elsewhere 29 promises to overcome some of the problems found during the metallic matrix composite materials (MMCs) processing; in that work, indirect verification of good dispersion and alignment has been reported. However, high temperatures were still needed, so that some harmful phases could be produced.…”

Characterization of Metal Matrix Composites Reinforced with Carbon Nanotubes by High Resolution Transmission Electron Microscopy

“…The need to find high-strength lightweight materials in transportation industries has driven the development of new materials and manufacturing methods to reduce CO2 emissions into the atmosphere.Recently, a new manufacturing process for the production of metal matrix composites reinforced with carbon nanotubes, known as sandwich technique, has been proposed [5][6][7]. This technique produces materials comprised of a metallic matrix and banded structured-layers of multiwalled carbon nanotubes (MWCNTs).…”

“…Recently, a new manufacturing process for the production of metal matrix composites reinforced with carbon nanotubes, known as sandwich technique, has been proposed [5][6][7]. This technique produces materials comprised of a metallic matrix and banded structured-layers of multiwalled carbon nanotubes (MWCNTs).…”