Dual-gradient pore-structure sialon and silicon carbide combined membrane tube and preparation method thereof

Abstract

The invention relates to the field of porous ceramic materials, and specifically relates to a dual-gradient pore-structure sialon and silicon carbide combined membrane tube and a preparation method thereof. The membrane tube material is composed of sialon and silicon carbide. The membrane tube has a dual-gradient filtering structure composed of a support body layer and a surface membrane layer. The support body layer is composed of a combination of sialon produced through a reaction and coarse silicon carbide grains, and has an average pore size of 10-50mum. The surface membrane layer is composed of a combination of sialon produced through a reaction and fine-particle silicon carbide grains, and has an average pore size of 0.1-5mum. An overall porosity of the membrane tube is within a range of 40-50%. The preparation method of the membrane tube sequentially comprises the steps of material preparation, support forming, membrane layer preparation and firing. Isostatic pressing is adopted in the forming step, wherein a forming pressure is controlled at 100-150MPa. The firing temperature is controlled at 1650-1850 DEG C, and a temperature maintaining time is 3-5h. The method is easy to realize. With the method, product performance can be ensured. The membrane tube provided by the invention has the advantages of high application temperature, high acid corrosion resistance and high alkali corrosion resistance. The membrane tube can be used in filtration purification of various fluids with high temperature or low temperature, such as high-temperature high-press gas filtration dedusting, water purification and the like.

Description

technical field [0001] The invention belongs to the field of porous ceramic materials, in particular to a dual-gradient pore structure Sialon-bonded silicon carbide membrane tube and a preparation method thereof. Background technique [0002] High-temperature ceramic filter materials generally work under various harsh environmental conditions. As a high-temperature ceramic filter material for gas purification, it is usually required to have: (1) High mechanical strength, high temperature resistance (300-900°C) and excellent medium corrosion resistance Performance; (2) High filtration accuracy, filtration gas velocity and low pressure drop; (3) Easy to blow back, stable operation, high filtration efficiency; (4) Good thermal stability, able to withstand frequent high-pressure pulse cooling Thermal shock caused by blowback of gas. At the same time, according to the requirements of its application, the high-temperature ceramic filter must be able to withstand the influence of ...

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Problems solved by technology

[0004] However, because silicon carbide ceramics are extremely difficult to sinter, and the conventional pressureless sintering temperature is 2100°C or even higher, the most widely used silicon carbide filter materials in high-temperature gas filtration are mostly low-temperature oxides such as clay combined with SiC ceramics. The disadvantage is high-temperature mechanical properties Poor, resulting in poor thermal shock resistance, making it difficult for ceramic filter materials to withstand large thermal load fluctuations; especially in environments that are corrosive to low-temperature oxygen oxidation, the service life of materials is greatly reduced, and Sialon ceramics are used as an excellent high-temperature Ceramics have the remarkable characteristics of strong medium corrosion resistance, high service temperature and good fracture toughness. If it is used as the bonding phase of silicon carbide, the overall performance of the material will be greatly improved.

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