Formation and self-assembly of graphene nanoribbons and nanosheets in metals

Composites consisting of carbon nanostructures, such as graphene and carbon nanotubes, and metals are desirable for power transmission lines, interconnects and heat transfer applications due to the combination of excellent charge carrier mobility, thermal conductivity and mechanical strength of the carbon nanostructures and the high density of electrons in the metal. Metal/nanocarbon composites made by chemical vapor deposition, friction stir, ball milling, and plasma spraying have yielded materials with enhanced hardness and tensile strength but their electrical and thermal conductivities usually deteriorate. We use an electrocharge assisted process (EAP) which consists of the application of a high DC current to a mixture of liquid metal and carbon particles to form crystalline graphitic nanoribbons in the liquid metal. The solid composites have shown 5.7% higher electrical conductivity and enhanced local stiffness, measured by nanoindentation, compared to the pure Al alloys. The electrical conductivity shows a linear dependence with graphitic carbon content as well as with total charge infused during the EAP.