CNT-reinforced metal and steel nanocomposites: A comprehensive assessment of progress and future directions

Carbon nanotubes (CNT) are rolled graphene sheets and are an exceptional invention in the field of nanotechnology. They have outstanding material characteristics such as high surface-to-volume ratio, high tensile strength, high thermal conductivity, and low density. Carbon nanotubes are many times stronger and yet lighter than steel and other metals, and thus a good candidate for reinforcing them. However the integration of CNTs into a metal or steel matrix is challenging and dispersion uniformity depends on processing parameters. The composite material properties are a function of the uniformity of CNT dispersion, interfacial bonding, CNT weight percent, length and alignment with the matrix. This paper reviews various methods of processing CNT-metal and CNT-steel nanocomposites, and their reported mechanical and material properties. Ways to overcome technical challenges are proposed and potential applications of CNT-steel composites as next generation structural material for the operationally demanding offshore oil petroleum industry are specifically discussed.