Flash sintering of yttria-stabilized zirconia/graphene nano-platelets composite

Abstract

A ceramic composite was produced by mixing cubic zirconia with graphene nano-platelets. The samples were consolidated by flash sintering in argon atmosphere to avoid the oxidation of graphene at high temperature. The applied electrical field ranged between 50 V cm and 500 V cm, while the current density limit was set between 35 mA mm and 175 mA mm. The presence of the conductor filler reduced the onset flash temperature, and a good densification of the composite was obtained. Remarkably, the same level of densification was not possible on pure cubic zirconia samples (possessing the same geometry) as they got physically damaged at the flash ignition (likely due to internal temperature gradients). After sintering, part of the conductive filler was still partially present within the ceramic matrix although some zirconium carbide was also formed.