High-temperature nacre-like ceramics

Reference Presenter Authors
03-052 Pedro Ivo Batistel Galiote Brossi Pelissari Pelissari, P.B.(Universidade Federal de São Carlos); Bouville, F.(ETH Zurich); Pandolfelli, V.C.(Universidade Federal de São Carlos); Carnelli, D.(ETH Zurich); Giuliani, F.(Imperial College); Luz, A.(UFSCar); Saiz, E.(Imperial College London); Studart, A.R.(ETH Zurich); Refractories are structural materials widely used in high temperature processes for manufacturing commodities, energy generation and aerospace applications. They are usually made of ceramic materials which are strong and stiff but fragile due to the lack of plastic deformation and other intrinsic toughening mechanisms. This inherent brittleness limits their use in applications where catastrophic failure is not tolerated. Recently, the authors of the present work have reported the design and fabrication of refractories with a bio inspired nacre-like microstructure comprising aligned alumina platelets, separated by an aluminium borate interphase, obtained through transient liquid phase sintering. Using the Magnetically Assisted Slip Casting (MASC) processing route, the synthesized material presented hierarchical organization, from nano to micro scale. The choice of the aluminium borate as interphase led to impressive enhancements of the materials mechanical properties at room and at temperature up to 1200°C. The bioinspired composites exhibit high strength, 672 MPa, toughness, 7.4 MPa.m 1/2 , and stable crack propagation at high temperatures, up to 1200 °C, due to the aluminium borate interlayer. From ex-situ observations of the crack path, we suspect that the materials presented identical toughening mechanisms through the whole tested temperature range. This new development makes the nacre-like ceramic refractories sintered with a transient liquid phase a suitable candidate for high temperature applications, competing favourably with ceramic matrix composites and following a simpler and cheaper processing route.
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