EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Nacre-like ceramic composites are of importance in a wide range of applications, because of their mechanical properties, combining high mechanical strength and high fracture toughness. This unusual combination of properties comes from its structure formed by strongly aligned platelets glued in a matrix. To obtain such a ‘brick-and-mortar’ structure in ceramic composites, different processing methods can be used. For example, Bouville et al. used a method based on ice templating [F. Bouville et al., Nat. Mater., 13, 508, 2014]. The final composites are composed of well-aligned alumina platelets glued in a silica-based glass matrix. Starting from compositions similar to those proposed by Bouville et al., we use here the self-assembly of the different components to shape the composites, deriving benefit of oppositely charged surfaces. Our suspensions are mainly composed of alumina platelets, which correspond to the bricks of nacre structure, and silica nanoparticles, which after sintering form a vitreous phase between the platelets mimicking the mortar. The mechanism of heteroaggregation between the alumina platelets and the silica nanoparticles is studied in details both by experiments and numerical simulations. Then, suspensions are formulated and used to shape nacre-like ceramic composites. Observations of green and sintered samples are performed. A particular attention is paid to the alignment of alumina platelets in the composite.