Gradient-porosity pure silicon carbide membrane tube

Abstract

The invention belongs to the technical field of multipore ceramic materials and preparation thereof, and particularly relates to a gradient-porosity pure silicon carbide membrane tube and a preparation method thereof. The gradient-porosity pure silicon carbide membrane tube consists of pure SiC; a gradient filter structure consists of a supporting body layer and a surface membrane layer, wherein the supporting body is formed by stacking and combining roughly granular SiC, and the average aperture is 5-120 mu m; the surface membrane layer is formed by stacking and combining finely granular SiC, and the aperture is 0.1-20 mu m; and the whole porosity of the membrane tube is 25-50%. The preparation method comprises burdening, forming the supporting body, preparing the membrane layer and sintering, wherein forming is performed under equal static pressure; the forming pressure is controlled between 40 and 150MPa; the sintering temperature is controlled between 1,500 and 2,400 DEG C; and heat is preserved for 0.5-5 hours. The method is easy to implement, and the performance of a product can be guaranteed. The gradient-porosity pure silicon carbide membrane tube can be used under an oxidization atmosphere and a reduction atmosphere, is high in acid and alkaline corrosion resistance and can be applied to gas chemical engineering and integrated gasification combined cycle (IGCC) and pressurized fluidized bed combustion (PFBC) power generation and used for filtering and purifying various types of high- and low- temperature fluid, such as high-temperature flue, automobile tail gas, water and the like.

Description

technical field [0001] The invention belongs to the technical field of porous ceramic materials and their preparation, and specifically relates to a gradient pore pure silicon carbide membrane tube and a preparation method thereof. The pure silicon carbide membrane tube has a gradient pore structure and is composed of pure silicon carbide. It has the characteristics of high porosity, low pressure drop, high strength, good thermal shock resistance, and high service temperature. The preparation method is easy to implement and can guarantee product performance. 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 pres...

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Problems solved by technology

[0004] However, at present, the most widely used silicon carbide filter materials in high-temperature gas filtration are clay and other oxides combined with SiC ceramics. The disadvantage is that the thermal conductivity is low, resulting in poor thermal shock resistance, which makes it difficult for ceramic filter materials to withstand large thermal load fluctuations; especially In the high-temperature coal gasification power generation technology (such as IGCC, PFBC), because the coal contains sodium silicate and NaCl, the Na 2 Si 2 o 5 It will seriously corrode the oxide combined with silicon carbide filter material, resulting in the failure of the filter, but the research shows that the pure SiC ceramic material is not subject to the above corrosion, and the pure silicon carbide material can be used under high temperature oxidation and reduction atmosphere, but At present, there is little technology in the development of pure silicon carbide filter materials, and the shortcomings of the obtained products are low strength, uneven pore size distribution, low filtration efficiency, large filtration pressure drop, and difficult backflushing cleaning of the pore structure, which limits the application of silicon carbide filter materials. process

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