Anisotropy effect of bioinspired ceramic/ceramic composites: Can the platelet orientation enhance the mechanical properties at micro- and submicrometric length scale?

In advanced ceramics, improving toughness usually relies on the introduction of a soft metallic or polymeric ductile phase, which decreases the mechanical properties. Some natural materials are strong, stiff and tough due to a combination of mechanisms operating at different length scales. However, such structures have been extremely difficult to replicate into synthetic materials. Here we investigate the microstructure and the micro-mechanical properties of a bioinspired ceramic-ceramic composite. The micromechanical properties at room temperature show slight differences as a function of the platelet orientation. The hardness strongly decreases with increasing temperatures (up to 550 degrees C) for all the investigated orientations. The elastic strain to failure, defined as the H/E ratio, was used to estimate the wear resistance of materials, which is higher at room temperature because the dislocation mobility is lower than that at high temperature.