Graphene/ceramic composites have settled as a promising vehicle for exploiting graphene’s outstanding combination of properties and obtaining high-performance structural materials with enhanced capabilities. Innovative processing techniques, such as freeze-casting, have arisen to produce highly structured ceramic-based composites inspired by hierarchical natural materials (e.g. nacre), known to display combinations of specific strength and toughness beyond manmade materials. Graphene oxide, a water-based, highly oxidised material produced by chemical exfoliation of graphite, represents an upscalable opportunity to develop highly structured ceramic-based composites. Graphene oxide´s role in processing these composites can be defined as an enabler of wet-processing due to its hydrophilic nature, and as enhancer of thermal and electrical conductivity after its thermal reduction in vacuum or inert atmospheres, such as in Spark Plasma Sintering.
This work shows a novel processing strategy for graphene/ceramic composites, using a scaffold and infiltration strategy and applying it to water-based graphene oxide (GO) suspensions and alumina slurries as precursor materials. Two different approaches of this scaffold and infiltration strategy will be shown, demonstrating the advantages of using graphene oxide suspensions to design new composites using new materials. In the first approach, a partially-reduced graphene scaffold will be infiltrated with an alumina slurry, whilst in the second the pre-sintered alumina scaffold will be vacuum infiltrated by a graphene oxide suspension. Both approaches allow highly structured graphene/alumina composites to be fabricated by Spark Plasma Sintering.