Porous textured ceramics with controlled grain size and orientation

Abstract

Texture in dense or porous ceramics can enhance their functional and structural properties. Current methods for texturation employ anisotropic particles as starting powders and processes that drive their orientation into specific directions.Using ultra-low magnetic fields combined with slip casting, it is possible to purposely orient magnetically responsive particles in any direction. When those particles are suspended with nanoparticles, templated grain growth occurs during sintering to yield a textured ceramic. Yet, the final grains are usually micrometric, leading weak mechanical properties. Here, we explore how to tune the grain orientation size using magnetic slip casting and templated grain growth. Our strategy consists in changing the size of the anisotropic powders and ensuring that magnetic alignment and densification occurs. The obtained ceramics featured a large range of grain anisotropy, with submicrometric thickness and anisotropic properties. Textured ceramics with tunable grains dimensions and porosity are promising for filtering, biomedical or composite applications.

Magnetically driven in-plane modulation of the 3D orientation of vertical ferromagnetic flakes

“…The time for magnetic orientation depends on the flakes magnetic properties, the magnetic field strength, and the viscosity of the matrix, and typically varies from a few seconds to a few minutes. 31,50 The curing method can thus be chosen accordingly to allow sufficient time for the magnetic orientation. After curing, the flakes retain their orientation.…”

Impact-resistant materials inspired by the mantis shrimp's dactyl club

“…Applied to Al2O3 suspensions, the density of the helicoidal ceramic microstructures could be varied from 50 to 95% after sintering. 79,80 The layer thickness, pitch, and angle, can be modulated as desired by tuning the time-step variation and direction of the magnetic field. Modulating the surface of the mold can further lead to herringbone-like patterns.…”

Toward Sustainable 3D Printing

“…(D) Scanning electron micrographs of cross sections of vertically aligned porous alumina ceramics prepared with initial microplatelets diameter of 3.6 and 6.6 μm. (B)–(D) Reproduced with permission from ref . Copyright 2020 Elsevier.…”

“…Horizontally aligned brick-and-mortar structures, called nacre-like, have been shown to increase the toughness of ceramics up to 10 times. Now, it is required to explore how microstructure impacts properties in ceramics and how the interfacial properties at the grains interface can be tuned, in dense and porous ceramics (Figure B–D) . In addition, the microstructure also influences functional properties, such as morphing, conductivity, transparency, etc.…”

“…Now, it is required to explore how microstructure impacts properties in ceramics and how the interfacial properties at the grains interface can be tuned, in dense 7 and porous ceramics (Figure 2B−D). 8 In addition, the microstructure also influences functional properties, such as morphing, conductivity, transparency, etc. As initial blueprints, taking inspiration from the microstructures found in natural hard materials can help to create enhanced ceramics and composites for applications in healthcare, aerospace, and electronics.…”