High-hydrophobicity silicon carbide foam ceramic as well as preparation method and application thereof

Abstract

The invention discloses high-hydrophobicity silicon carbide foam ceramic as well as a preparation method and application thereof. The high-hydrophobicity silicon carbide foam ceramic is prepared fromsubstrate silicon carbide foam ceramic, and polydopamine and a long-chain alkyl amine molecule or fluorine-containing molecule covering layer at the surface, wherein the polydopamine is a bottom layerof a covering layer; the long-chain alkyl amine molecules or fluorine-containing molecules are the surface layer of the covering layer. The prepared silicon carbide foam ceramic is of a three-dimensional network communicated structure; the porosity is high; the size is controllable; the cost is low; the industrial production requirements are met; hyperbranched liquid-state polycarbosilane is usedas a bonding agent for preparing the silicon carbide foam ceramic; the low-temperature sintering is realized; the ceramic yield is high. The three-dimensional porous silicon carbide foam ceramic is used; due to large surface area and high surface roughness, relatively good adsorption kinetics are realized in the adsorption process; the adsorption equilibrium can be fast reached; macroporous structures and micropores can be used as oil storage spaces, so that wide application prospects are realized in the aspect of oil adsorption agents.

Description

technical field [0001] The invention belongs to the field of preparation of special functional materials, and in particular relates to a highly hydrophobic silicon carbide foam ceramic and its preparation method and application. Background technique [0002] Silicon carbide foam ceramics have the advantages of high temperature resistance, corrosion resistance, large surface area, low density, high porosity, etc., and are widely used in high temperature gas purification, diesel engine exhaust filtration, molten metal filtration, heat preservation and sound insulation and other fields. [0003] There are various preparation methods for silicon carbide foam ceramics, and different preparation methods can prepare foam ceramics with different porosity, pore structure, and pore size. The key to the preparation of foamed ceramics is to form a three-dimensional network structure with a certain pore strength. According to different purposes and performances, people have developed a ...

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Problems solved by technology

According to different purposes and performances, people have developed a variety of molding and preparation processes. At present, there is not enough research on the low-temperature sintering molding technology of silicon carbide foam ceramics. The temperature required for firing foam ceramics is still high, and there are few foam templates to choose from. In addition, the traditional binder polycarbosilane shrinks in volume after thermal decomposition and produces cracks, which affects the density of ceramics and the ceramic yield is low. The existing methods for preparing silicon carbide foam ceramics mainly include:

[0004] (1) Reaction sintering method: powder sintering method and solid state reaction sintering method require high sintering temperature (above 2000°C), and sintering aids need to be added, which affects the high temperature performance of the material and limits the application of foam ceramic materials

[0005] (2) Adding pore-forming agent method: the disadvantage of this method is that it is difficult to produce high-porosity products, the distribution of pores is uniform, and the dispersibility of the pore-forming agent is relatively high. After sintering, the pore-forming agent will remain in the silicon carbide In foamed ceramics, it will affect its wave transmission performance

[0006] (3) Silicone-containing resin pyrolysis method: the silicone precursor is made into a polymer gel, and the organic solvent in the gel is removed to obtain a foamy silicon-containing resin, which is fully pre-oxidized and pyrolyzed to obtain silicon carbide Foam ceramics, the disadvantage of this method is that due to the lack of hot pressing process, the initial density is not high, the prepared foam ceramics are not dense, and the strength is low, and the pore volume and size are difficult to control

[0008] In recent years, due to the frequent occurrence of oil pollution accidents, cleaning up crude oil spills has become a global challenge. Traditional solutions such as gravity separation, skimming, flotation, etc. can effectively achieve oil-water separation, but their low efficiency and high cost limit its wide application

The preparation of hydrophobic and lipophilic materials and filter membranes has the advantages of low cost and convenient use, and can be popularized and applied in actual production, but there are still the following problems: ① During the separation process, oil and water are simultaneously adsorbed, showing low separation selectivity and separation efficiency; ②Long-term use will cause oil or grease to cause pore blockage and material surface contamination, resulting in a significant reduction in material adsorption capacity and fluid flow

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