Unraveling the role of shell thickness and pore size on the mechanical properties of ceramic‐based macroporous structures

Abstract

Macroporous structures are of interest for several technological applications such as catalysis, sensors, filters, membranes, batteries, energy conversion devices, structural colors, and reflective thermal barrier coatings. Ceramic‐based inverse opal macroporous structures are especially interesting for high‐temperature applications. However, the interrelation between the structural parameters, mechanical properties, and thermal stability of such structures is not yet clarified. In this work, we analyzed the mechanical properties as well as the thermal stability of aluminum oxide inverse opal three‐dimensional macroporous structures with different macropore sizes and shell thicknesses produced by atomic layer deposition. Our results show that the structures’ thermal stability increased with increasing shell thickness and macropore size, however, their higher stability was not linked to their mechanical properties. To be able to explain this unexpected behavior, finite element modeling simulations were performed, showing that bending stresses became more pronounced with increasing shell thickness, potentially creating additional critical sites for crack initiation and consequent structural failure.

Multi-scale structural characterization of ceramic-based photonic glasses for structural colors

“…However, one must also account for the fact that the smaller packing directly relates to a smaller green density, which has been known and associated to higher shrinkage upon sintering under the same conditions when compared with samples of higher green density [ 37 ]. Moreover, thinner shells are hypothesized to be weaker than thicker shells, as in the case of atomic layer deposition (ALD)-based photonic crystals, and thus, less stable against cracking and distortions [ 38 ]. As a result, the macropores shrinkage is not only bigger, but more variations in the average diameter are observed for the 0.4-PhG compared to the 1.0-PhG.…”