Anisotropic mechanical and functional properties of graphene-based alumina matrix nanocomposites

Graphene platelets (GPLs) containing Al2O3 nanocomposites, which exhibit anisotropic microstructure,have been prepared by spark plasma sintering (SPS), and effects of this anisotropy on mechanical, elec-trical and thermal properties of the nanocomposites have been investigated. 3 vol.% GPLs addition intomonolithic Al2O3caused fracture toughness (Kıc) to increase by 26.7% in the in-plane direction and todecrease by 17.2% in the through thickness direction. Kıcstarted to decrease in the in-plane direction andto increase in the through-thickness direction with further increase in the GPLs amount. The electricalconductivity of the nanocomposites exhibited a slight anisotropy with a lower resistivity in the in-planedirection. Oriented GPLs also led to a less resistive heat conduction path in the in-plane direction. ∼44%increase in the in-plane thermal conductivity was achieved at 600◦C with 15 vol.% GPLs addition into themonolithic Al2O3and this resulted in ∼52% increase in the kin-plane/kthrough-thicknessratio