Foamed ceramic microspheres with core-shell structure and its preparation method and application

Abstract

The invention discloses a method for preparing core-shell structure foam ceramic microspheres: including silica sol configuration, silica sol gelation, preparation of silicate xerogel microspheres, water washing-surface aging treatment, washing and drying and high temperature Foaming process. The core-shell structure foam ceramic microspheres have a particle diameter of 0.3-5mm and an inner and outer layered structure. The outer layer of the microspheres is a ceramic sealed shell of 45-55μm. The surface of the ceramic sealed shell is composed of micron-sized particles and is polygonal. Aggregates, and the interval between adjacent polygonal aggregates is 0.8-1.2μm, and there are holes with a size of 80-120nm distributed at the intervals. There are a number of capillary channels distributed inside the holes, and the micron-sized particles are used as the core. Nanoparticles are deposited on the surface of the nanoparticles, and the specific surface area of ​​the microspheres deposited with nanoparticles is 3-4 orders of magnitude larger than smooth microspheres of the same diameter; the interior of the microspheres is a three-dimensional through-network microporous structure. There are sealed balls with a diameter of 0.2μm-0.5μm distributed inside the micropores.

Description

technical field [0001] The invention belongs to the technical field of ceramic materials, and in particular relates to a foamed ceramic microsphere with a core-shell structure and a preparation method and application thereof. Background technique [0002] In the wave of global economic development and the rapid development of world industry, the environment and resources are the major problems encountered by human society. The requirements for saving resources and protecting the environment are getting higher and higher. Therefore, materials that adapt to this situation are It is very important and has positive significance to the development of society. Closed-cell foam ceramics is a new material that meets the development requirements of this situation. It can play a significant role in improving efficiency, saving resources, and protecting the ecological environment. [0003] Foam ceramics is a kind of foam-like porous ceramics in shape. It is the third generation of por...

AI Technical Summary

Problems solved by technology

However, the introduced bubbles are inherently thermodynamically unstable systems, which tend to undergo rapid polymerization and disproportionation of the bubbles due to the very high interfacial energy at the gas-liquid interface.

Therefore, this process is difficult to obtain a relatively stable liquid ceramic foam slurry

[0007] (2) Protein foaming method to prepare foam ceramics, protein foaming method also has certain limitations, especially when the solid phase content of foam ceramic powder is high or low

When the solid phase content is high, the viscosity of the ceramic slurry is high, the rheology is poor, and the uniformity of the microstructure of the sample after molding is poor. At the same time, due to the lack of moisture, the foaming process is restricted, resulting in insufficient foaming. The porosity is low; when the solid phase content is low, the foaming is more intense, the sample has a higher porosity, the volume shrinkage is larger when drying, and the sample is easy to crack

[0008] At present, all the basic designs are based on adding other auxiliary foaming substances to the ceramic slurry. The products produced by these methods are large in size and have no microsphere structure, resulting in very limited practical applications.

Due to limited preparation methods, the existing closed-cell foamed ceramics have low porosity, small specific surface area, and large volume, which affect their heat insulation effect

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