Speaker: Prof. Florian Bouville

Abstract

Composites with intricate microstructures are ubiquitous in the natural world where they fulfil the specific functional demands imposed by the environment. For instance, nacre presents a fracture toughness 40 times higher than its main constituent, a crystalline form of calcium carbonate. This relative increase in toughness value is obtained as a crack propagating within this natural brick-and-mortar structure have to interact with the multiple reinforcing mechanisms present from the nanometre to the millimetre scale. The boost in performance obtained has pushed scientists for a few decades to use nacre as a blueprint to increase the toughness of synthetic ceramics and composites. More recently, our ability to reproduce accurately the structure of nacre from the nanometre to the millimetre scale has improved with the introduction of Magnetically-Assisted Slip Casting (M.A.S.C.), a technique that combines an aqueous-based slip casting process with magnetically-directed anisotropic particle assembly. Using this approach and pressure-assisted sintering, we are now able to carefully study several structure-property relationships in these composites, from the amount and strength of the added nanobridges, the toughness of the polymeric, metallic, or ceramic mortar used, to finally the large-scale orientation of the bricks. Using these results, we can fine tune the structural properties of nacre-inspired alumina-based composites to reach strengths up to 670 MPa, KIC up to 7 MPa.m1/2 with subsequent stable crack propagation and this even at temperature up to 1200°C. From all these data using different mortars, it is now possible to rationally study the influence of the mechanical properties of the interface with respect to the toughening mechanisms developed in the samples.

Biography

Florian Bouville is a lecturer (assistant professor) in the Centre for Advanced Structural Ceramics in the Department of Materials of the Imperial College London. He obtained his Master’s degree in Material Sciences at the Institut National des Sciences Appliquées de Lyon (INSA de Lyon, France) in 2010. He then moved to the South of France for his PhD between three partners: the company Saint-Gobain, the Laboratory of Synthesis and Functionalization of Ceramics and the MATEIS laboratory (INSA de Lyon). His research was based on the freezing of colloidal suspensions and self-assembly to process bio-inspired materials. From 2014 to 2018, he was a postdoctoral researcher and then scientist in the Complex Materials group at the Department of Materials at the ETH Zürich. His research is focused on new manufacturing processes for inorganic materials, with an emphasis on toughening mechanisms and functional properties of architectured ceramics