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

Texture in ceramics can enhance their functional and structural properties. In porous bodies, it may be used for applications as implants, batteries, filters, etc; in dense bodies, for turbine, shielding, etc. Current methods for texturation in dense ceramics employ plate-like particles or microplatelets as starting powders and processes that drive their orientation in specific directions, such as freeze-casting, tape-casting, pressing, or external fields. However, anisotropy in porous bodies is generally created by aligning the pores in specific directions, using anisotropic porogens, sacrificial templates, or freeze-drying. There is thus lesser control of the grain orientation and texture in porous ceramics. Here, we use rotating low magnetic fields to create alumina ceramics with anisotropic grains, controllable orientations and texture, grain length of 3 to 7 um, open porosity between 30-40% and interesting cracking behaviour. We also apply similar method for slurries containing mixtures of alumina nanoparticles and alumina platelets to control the grain growth at the sintering and yield relative densities from 60 to 95 %. Using predictive models and experiment, we can study the crack propagating path in the specimens. Building hierarchical microstructures that resemble those found in natural materials, we aim at improving the toughness of initially brittle ceramics through microcracking. Future improvement combine these methods with 3D printing and other toughness mechanisms.