Pressure-Less Processing of Ceramics with Deliberate Elongated Grain Orientation and Size

Abstract

Ceramics with heterogeneous microstructures have the potential to exhibit local variations in properties and unusual combinations of those, just like highly mineralized biomaterials do. However, to date, the microstructures achieved in technical and structural ceramics cannot rival the diversity and complexity of those found in biomaterials due to the lack of adapted processing methods. Recent research, however, demonstrated that local hardness and elastic modulus can be realized in alumina ceramics by controlling the orientation of the grains in periodically varying structures. This deliberate tuning of the grain orientation resulted from the magnetically-driven alignment of anisotropic template particles in the initial liquid suspension. During the sintering at high temperature, the template particles grew as anisotropic grains with the orientation set by the magnetic field. To expand the design freedom of such ceramics in terms of microstructure and properties, this paper aims at tuning the grain size, grain orientation, and final porosity of sintered alumina. The methodology to build multilayered ceramics using varying template particles sizes is described and examples of the microstructures obtained are provided. This work contributes to pushing forward the field of bioinspired ceramics that would hopefully give rise to structural ceramics with unusual combinations of local properties.