Al2O3-3YTZP-Graphene multilayers produced by tape casting and spark plasma sintering

This work aims to establish a colloidal route to obtain laminates of alumina–zirconia combining layers with and without graphene. Green tapes of alumina, alumina with 5 vol.% of 3Y-TZP and alumina with 5 vol.% of 3Y-TZP and graphene-oxide (2 vol.%) were obtained by aqueous tape casting. It is possible to design materials for different structural applications with a controlled microstructure with a high number of different layers. The tapes were punched into 20-mm discs, joined to form laminates alternating up to 18-layers, and sintered in one-step by spark plasma sintering (SPS) at 1400 °C. It has demonstrated that there is a significant graphite diffusion provoked by the required graphite holders into the SPS-furnace. Dense laminates with layer thicknesses ∼100 μm and good cohesion between layers were obtained. Nanoindentation results showed that hardness and elastic modulus values were higher than 27 GPa and 300 GPa, respectively, and similar for all layers.