Tough metal-ceramic composites with multifunctional nacre-like architecture

Erik Poloni,Thomas Weber,Andrea R Biedermann,Ann M Hirt,André R Studart,Florian Bouville,Christopher H Dreimol,Tobias P Niebel

doi:10.1038/s41598-021-81068-z

Erik Poloni, Thomas Weber + Show 6 more

Open Access

https://doi.org/10.1038/s41598-021-81068-z

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Abstract

The brick-and-mortar architecture of biological nacre has inspired the development of synthetic composites with enhanced fracture toughness and multiple functionalities. While the use of metals as the “mortar” phase is an attractive option to maximize fracture toughness of bulk composites, non-mechanical functionalities potentially enabled by the presence of a metal in the structure remain relatively limited and unexplored. Using iron as the mortar phase, we develop and investigate nacre-like composites with high fracture toughness and stiffness combined with unique magnetic, electrical and thermal functionalities. Such metal-ceramic composites are prepared through the sol–gel deposition of iron-based coatings on alumina platelets and the magnetically-driven assembly of the pre-coated platelets into nacre-like architectures, followed by pressure-assisted densification at 1450 °C. With the help of state-of-the-art characterization techniques, we show that this processing route leads to lightweight inorganic structures that display outstanding fracture resistance, show noticeable magnetization and are amenable to fast induction heating. Materials with this set of properties might find use in transport, aerospace and robotic applications that require weight minimization combined with magnetic, electrical or thermal functionalities.

Highlights

The brick-and-mortar architecture of biological nacre has inspired the development of synthetic composites with enhanced fracture toughness and multiple functionalities
The formation of metal-coated platelets and their assembly into nacre-like metal-ceramic composites is achieved through a processing route that includes: (i) coating of platelets with a metallic or an oxide layer, (ii) possible reduction of the oxide layer to generate metal-coated platelets, (iii) assembly of the metal-coated platelets into nacre-like architectures, and (iv) pressure-assisted sintering of the nacre-like structure into tough multifunctional composites (Fig. 1)
The bare alumina platelets present flat surfaces (Fig. 2a), while the hematite forms a uniform percolating network comprised of nanoparticles on the surface of the platelets (Fig. 2b,c)

Summary

Introduction

The brick-and-mortar architecture of biological nacre has inspired the development of synthetic composites with enhanced fracture toughness and multiple functionalities. Using iron as the mortar phase, we develop and investigate nacre-like composites with high fracture toughness and stiffness combined with unique magnetic, electrical and thermal functionalities. With the help of state-of-the-art characterization techniques, we show that this processing route leads to lightweight inorganic structures that display outstanding fracture resistance, show noticeable magnetization and are amenable to fast induction heating Materials with this set of properties might find use in transport, aerospace and robotic applications that require weight minimization combined with magnetic, electrical or thermal functionalities. By utilizing building blocks with matched optical properties, nacre-like composites combining for instance crack growth resistance with optical transparency have been r eported[22] In another example, nacre-inspired materials featuring a graphene percolating network as continuous phase have been developed to imbue brick-and-mortar structures with self-sensing c apabilities[23]. The use of metals as continuous phase opens the opportunity to incorporate magnetic, electrical and thermal functionalities that have not yet been fully explored in nacre-like composites with mechanically-robust bulk geometries

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