Highly aligned reduced graphene oxide in alumina composites for strengthening, toughening, and electromagnetic interference shielding

Abstract

Engineering ceramics with high strength, toughness and electromagnetic interference (EMI) shielding effectiveness (SE) are highly desirable as electromagnetic protecting material in harsh environment. Herein, we show that both excellent mechanical and EMI shielding performance can be realized in alumina composites embedded with highly aligned reduced graphene oxide (RGO), which are readily prepared via sintering of core-shell structured RGO@Al2O3 nanoplates with pressure. Compared to monolithic Al2O3, the highly aligned RGO/Al2O3 composites show simultaneously improved strength and toughness up to ∼26.1% and ∼60.2%, respectively. The steeply rising R-curve behavior proves the better crack tolerance in the highly aligned structure with respect to randomly oriented one. Moreover, the RGO/Al2O3 composites also exhibit a high specific EMI SE reaching ∼34 dB/mm in K band, due to the reflection and highly enhanced absorption after percolation in the out-of-plane direction. These findings provide a novel strategy of designing mechanically reliable engineering ceramic for EMI shielding.