Abstract
The fabrication of advanced ceramic matrix composites (CMCs) with low-dimensional carbon allotrope phases is currently an open research topic. One of the modern challenges still remains to overcome common experimental issues, regarding the homogeneity of the nanocarbon dispersion, their location within the ceramic matrix, and the type of bonding between the filler and the matrix. This work introduces the fabrication of fully-dense alumina/graphene ceramic matrix composites by the sol-gel route and reactive spark plasma sintering, as an alternative methodology to improve the dispersion of the graphene flakes within the composite, and to promote the formation of strong bonds between graphene flakes and the ceramic matrix such as Al-O-C oxygen bridges. The micro/nanostructures are researched by: nitrogen physisorption, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray Photoelectron Spectroscopy (XPS). SEM observations revealed the absence of graphene agglomerations suggesting the efficacy of this fabrication approach. Raman mapping analyses confirmed the integrity of the graphene along the fabrication process. Mechanical features such as hardness, Young's modulus and indentation fracture toughness were measured for different graphene contents. Our results are compared with those from conventional alumina/graphene CMCs, and suggest that the current approach would offer an appealing route to fabricate reinforced alumina/nanocarbon based ceramics.