An example of nanocomposites is the aerospace industry where composite usage has risen from one/two percent in the 1970s to 50 percent in 2010. Other industries that are incorporating composites include the automobile, marine, construction, biomedical and sporting equipment.
What are composite materials?
Composite materials are typically composed of multiple materials that complement each other. For instance, strong and stiff carbon fibres that are protected by a plastic which encapsulates the fibres and allows load or force to be effectively distributed amongst them.
So what is preventing complete adoption of composite materials? And where can the development take us? We believe nanotechnology can play a pivotal role in answering these questions.
Our experience in nanomaterial fabrication, manipulation and analysis has enabled us to make significant progress in addressing a current issue in the aerospace industry: How to remove the dependence of metallic structures which are employed to give lightning strike protection as composites have poor electrical conductivity.
Achieving this would reduce weight further and avoid manufacturing difficulties in incorporating metals with composites.
Our method was to use carbon nanotubes – hexagonal array of carbon atoms (graphene), rolled into tubes. These carbon nanotubes are very small, with a thickness measuring around 1/5000th of a human hair (roughly speaking, 5000 carbon nanotubes stacked in a line would equal a human hair). Nonetheless, they have exceptional mechanical, electrical and thermal properties.
These carbon nanotubes are grown directly on the carbon fibres at a very high density, in fact 10 billion per cm2, substantially increasing the surface area of the carbon fibre and increasing the ability of the carbon fibres to ‘hold on to’ the plastic, improving key mechanical properties. Crucially, however, the carbon nanotubes bridge from carbon fibre-to-carbon fibre (see image below) imparting electrical and thermal conductivities.
Furthermore, the technology will lead to exciting possibilities such as energy harvesting within storage structures and sensory technology with self-healing capabilities. Therefore, we expect structures to combine additional functionality.
For instance, a plane, where the vibrations and motions made by the wing are utilised in generating and storing electrical power and any damage occurred can be detected and repaired – in flight!