Effect of morphology and structure of MWCNTs on metal matrix nanocomposites

Abstract

The effect of using different carbon nanotubes (CNTs) on the production of nanocomposites was evaluated in this work. The investigated CNTs were multi-walled carbon nanotubes (MWCNTs) with different morphologies and structures. The main objective was to relate the results reported by numerical simulation with the results obtained experimentally in order to validate these methodologies. A detailed characterization of CNTs was carried out to establish the different main characteristics, such as inner and outer diameters, defects, structure and the number of walls. Metal matrix nanocomposites were produced using the powder metallurgy route. The experimental results show that the morphology and structure of MWCNTs have a significant effect on the dispersion process for nanocomposite production. Straight CNTs with a larger diameter and with few defects allow for the production of nanocomposites with uniform dispersion and strong interface bonding, leading to a higher hardness value. In addition, the CNT introduction into a metal matrix induces a change in the deformation behavior that plays an important role in the strengthening mechanisms. Although some aspects are not considered in the molecular dynamic (MD) simulation, such as the CNT random orientation and CNT agglomeration, some comparative relationships can be performed in order to validate some methodologies. While the structure and morphology of the CNTs have a significant influence on the dispersion process, the influence of the diameter and the functionalization treatment on the properties of the nanocomposites is also identified. The experimental results show that the decrease in the diameter of the CNTs and the use of functionalized CNTs also contribute to the obtention of lower mechanical properties of the nanocomposites, as is pointed out in the results of MD carried out in nanocomposites.