Sol–gel method and reactive SPS for novel alumina–graphene ceramic composites

Reinforced ceramic matrix composites of alumina and graphene oxide have been widely researched, but there are still unresolved issues such as the optimum distribution of the graphene or the presence of efficient bonds between filler and matrix. This work introduces a novel fabrication procedure based on the sol–gel method, using boehmite as an alumina precursor, and graphene oxide nanoplatelets as the reinforcing phase. Full densification of the samples was done through reactive spark plasma sintering under milder conditions than usual. Structural characterization was done by XRD, SEM and micro-Raman among other techniques, and the presence of Al-O-C bonds was studied by XPS. Mechanical characterization was performed by Vickers microindentation and nanoindentation. No significant change was observed concerning the Young's modulus, hardness or fracture toughness, though improvements in the homogeneity of the distribution of the graphene and the chemical bonds between the matrix and the reinforcing phase were confirmed.