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

Abstract

The invention discloses a preparation method of a foamed ceramic microsphere of a core-shell structure. The method comprises the steps of silica sol preparation, silica sol gelation, preparation of a silicic acid xerogel microsphere, washing-surface aging treatment, secondary washing and drying and high-temperature foaming. The foamed ceramic microsphere of the core-shell structure has the grain diameter of 0.3-5 mm and is of an inner-outer layered structure, a ceramic hermetic shell with the diameter of 45-55 micrometers is arranged on the outer layer of the microsphere, polygonal aggregates are composed of micron-grade particles on the surface of the ceramic hermetic shell, the interval of every two adjacent polygonal aggregates is 0.8-1.2 micrometers, holes with the diameter of 80-120 nm are distributed in the intervals, a plurality of capillary channels are distributed in the holes, the micron-grade particles are used as a base core, nano particles are deposited on the surfaces of the micron-grade particles, and the specific area of the microsphere of the particles with nano particles deposited is larger than that of a smooth microsphere with the same diameter by 3-4 orders of magnitude; the interior of the microsphere is of a three-dimensional cut-through net micropore structure, and hermetic balls with the diameter of 0.2-0.5 micrometers are distributed in 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...

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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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