Graphite flake carbon composites with a ‘sinterable’ microbead matrix: I. Mechanical properties Original Research Article

In this paper we report a study of the effect of graphite flakes of different size and volume fraction on the mechanical properties of a fine-grained carbon produced by the ‘sinterable’ route. Mesophase microbeads have been used as a matrix and the volume percent and size of the graphite flakes have been varied. It is shown that the flakes significantly increase the work of fracture of the composite, the effect being dependent on both flake size and volume fraction. However, there is a corresponding decrease in the Young Modulus and flexural strength of the composites. The flakes are not bonded to the structure and effectively act as inherent ‘crack-like’ pores. Flakes aligned perpendicular to the surface form the flaws that control the fracture stress. However, they also contribute significantly to the bridging stresses in the wake of the crack, so enhancing the work of fracture. The results should be useful in understanding the role of graphite-flake inclusions in modifying the properties of carbon materials.