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.