Submicron mullite hollow spheres synthesized via UV polymerization of Pickering emulsions

Abstract

We here propose a simple, facile, and effective method to prepare submicron mullite hollow spheres templated from Pickering emulsions. Dual-phase sol consisted of boehmite and silica nanoparticles decorated by pentanoate ion could assemble at water/oil interface irreversibly to form photosensitive Pickering emulsions. The droplets of emulsions could be separated by dilution and formed by photopolymerization to gain hybrid microspheres, which could completely transform to mullite hollow microspheres via binder removal and sintering. It is found that the prepared hollow microspheres possess intact morphology, favorable sphericity, large cavity volume, and bulk density of 0.356 g/cm 3 . Importantly, the average diameter of mullite hollow spheres obtained via this method could be as low as 0.33-2.31 μm. This steady method is efficient and suitable for various types of inorganic particles, providing an innovative perspective for preparing fine hollow spheres applicable for filtration, drug loading as well as energy storage areas.

Microstructure and Mechanical Properties of a Three‐Dimensional Oxide/Oxide Composite after Long‐Term Thermal Exposure

“…[ 11 ] Kostopoulos et al reported that the tensile strength and failure strain exhibited an abrupt decrease during the early stages of exposure at 1100 °C for 50 h and remained constant thereafter. [ 12 ] In a study by Yang et al, the porosity and compressive strength of an oxide/oxide composite decreased after thermal aging at 1200 °C for 100–500 h. [ 13 ] Long‐term thermally aged oxide/oxide composites have been previously investigated; however, these studies encountered two problems: 1) commercial composites possess two‐dimensional (2D) reinforcements with no fiber in the thickness direction, leading to inadequate delamination resistance under shear loading; [ 14 ] and 2) such studies primarily investigated the relationship between the microstructural evolution and mechanical properties of the composites, and only a few focused on the contribution of the mechanical properties of the constituents to those of the composites after long‐term thermal aging.…”