Spark plasma sintering of alumina composites with graphene platelets and silicon carbide nanoparticles

This paper reports a study on sintering and characterization of alumina (Al₂O₃) ceramic composites with graphene platelets (GPLs) and silicon carbide (SiC) nanoparticles. 1, 3, and 5 vol% SiC and 0.38 vol% GPL are mixed with Al₂O₃powders and sintered in a spark plasma sintering system. The microstructures and mechanical properties of the composites are investigated. It is found that the composites reinforced with the dual fillers exhibit more uniform and finer microstructures than pure Al₂O₃ and average grain sizes of the composites decrease with the increasing percentage of SiC. Compared with pure Al₂O₃, the composites show approximately a 36% increase in hardness, a 40% increase in flexural strength and a 50% increase in fracture toughness. Toughening mechanisms induced by GPLs, such as crack bridging, pullout and crack deflection in the composites, are observed and discussed.