High strength metallurgical graphene as an additional reinforcing phase for carbon fibre composites

Abstract

The main objective of the present study is an elaboration of a method for a transfer of high strength metallurgical graphene (HSMG) and its introduction into the structure of fibre laminates. In this work, two transfer procedures have been established: a transfer onto structural adhesive film (SAF) and a direct transfer onto two types of carbon fibre pre-impregnates (uniaxial and biaxial cloth). An important novelty of the presented experimental work is a use of scanning electron microscopy (SEM) operating in the absorbed electrons (AE) mode. This technique enables the evaluation of graphene continuity on a large area within a relatively short time. The SEM/AE technique made it possible to ascertain that the transferred graphene was characterised by a low level of defects, indicating that it could be used as a reinforcing phase in composites. Both transfer procedures, one onto SAF and the other directly onto the pre-impregnates were used for manufacturing flat laminates as well as tubular profiles. The flat samples, containing 0.68 ppm HSMG by weight, exhibited a 9% increase of low cycle fatigue strength. The tubular profiles (bicycle components) with approximately 0.22 ppm of HSMG exhibited a significant increase of fatigue wear during initial tests. In addition, no fatigue delamination was observed at interfaces between the pre-impregnates separated with HSMG graphene.