Layered functionally graded alumina ceramic composite with anisotropic properties

Multi-layered ceramic composites with alteration of grain sizes in layers have been produced by adding thin inter-layers of graphenated alumina nanofibers (GAIN) between layers of pure alumina. The composite was mounted layer... [ view full abstract ]

Multi-layered ceramic composites with alteration of grain sizes in layers have been produced by adding thin inter-layers of graphenated alumina nanofibers (GAIN) between layers of pure alumina. The composite was mounted layer by layer directly in the graphite mould, using a filter to precipitate alumina nanopowder and GAIN layers from corresponding suspensions. The 20 mm diameter samples were consolidated by Spark Plasma Sintering (SPS) technology at 1350 °C in a nitrogen atmosphere under 50 MPa pressure. The effect of inter-layers on microstructure and mechanical properties of alumina has been studied. Moreover, directional thermal and electrical conductivity of the samples was measured to quantify the anisotropic conductions. SEM analysis of microstructure reveals distinct grain size reduction in the areas surrounding GAIN layers. Vickers hardness, fracture toughness and nanoindentation tests have been performed.