Strong, Tough and Stiff Bioinspired Ceramics from Brittle Constituents

TL;DR

This paper presents a bioinspired ceramic design that achieves a rare combination of high strength, toughness, and stiffness without ductile phases, maintaining high-temperature performance for structural applications.

Contribution

A novel bioinspired approach to create bulk ceramics with simultaneous high strength, toughness, and stiffness using only mineral constituents, avoiding ductile phases.

Findings

Achieved 470 MPa strength, 22 MPa·m^{1/2} toughness, and 290 GPa stiffness.

Maintained mechanical properties at 600°C.

Demonstrated a structure inspired by natural multi-scale mechanisms.

Abstract

High strength and high toughness are usually mutually exclusive in engineering materials. Improving the toughness of strong but brittle materials like ceramics thus relies on the introduction of a metallic or polymeric ductile phase to dissipate energy, which conversely decreases the strength, stiffness, and the ability to operate at high temperature. In many natural materials, toughness is achieved through a combination of multiple mechanisms operating at different length scales but such structures have been extremely difficult to replicate. Building upon such biological structures, we demonstrate a simple approach that yields bulk ceramics characterized by a unique combination of high strength (470 MPa), high toughness (22 MPa.m1/2), and high stiffness (290 GPa) without the assistance of a ductile phase. Because only mineral constituents were used, this material retains its mechanical properties at high temperature (600{\deg}C). The bioinspired, material-independent design presented here is a specific but relevant example of a strong, tough, and stiff material, in great need for structural, transportations, and energy-related applications.