Researchers from the Korea Advanced Institute of Science and Technology (KAIST) have developed a new metamaterial that is proven to be hundreds of times stronger than pure metals. To maximize the potential increase in strength provided by the use of graphene, the KAIST team created a multi-layered structure, alternating layers of graphene and metal—this composite nanomaterial consists of graphene inserted into copper and nickel. The resulting metal-graphene multilayer composite material is the first of its kind, and the team’s research was published in the science journal, Nature Communications in July of 2013.
Nuclear Reactor © Tysh
To build this structure the team utilized a process called Chemical Vapor Deposition (CVD) allowing them to grow a single layer of graphene on a metal deposited substrate. The team then deposited another layer of metal on top of the graphene, and the two step process was repeated to add additional layers to create the new composite.
To measure the strength of the new material, the team conducted a series of micro-compression tests administered through a Transmission Electronic Microscope and Molecular Dynamics Simulation. The results showed the composite material’s ability to block dislocations and cracks caused by external damage traveling inwards to be much greater than that of conventional metal-metal multilayered materials. The increase in strength varied depending on the interlunar distance, with 70nm exhibiting 500 times more strength than pure copper, and 100nm measuring to be 180 times stronger than pure nickel. A clear relationship between the interplanar distance and the strength of the material was identified. It was also concluded that the smaller interplanar distance made dislocation more difficult, thus resulting in a stronger material.
Seung Min Han, the KAIST professor who led the research team to success commented “the result is astounding as 0.00004% in weight of graphene increased the strength of the materials by hundreds of times” and that “improvements based on this success, especially enabling mass production with roll-to-roll process or metal sintering process, in the production of automobile and spacecraft lightweight, ultra-high strength parts may become possible.” He went on to explain how the new material could also be applied to coating material for the construction of nuclear reactors and products that require a high level of reliability.