Production method of silicon carbide micro-reactor based on gel molding

Abstract

The invention discloses a production method of a silicon carbide micro-reactor based on gel molding. The method comprises: (1) preparing a concentrated silicon carbide suspension; (2) preparing a polyvinyl alcohol and water-soluble phenolic resin mixed glue; (3) adding the mixed glue to the concentrated silicon carbide suspension, and performing mixing to obtain a slurry; (4) pouring the slurry into a mold, freezing the slurry to obtain a physical gel, unfreezing the physique gel, naturally drying the unfrozen gel, placing and drying the naturally dried gel in an oven, and carrying out cold isostatic pressing, low temperature sintering and phenolic resin curing; (5) shaping the surface of the obtained blank; (6) dumping the blank; (7) embedding the blank in silicon powder in a sintering furnace, and performing reactive sintering; and (8) finishing the assembled surface after the sintering, and carrying out high temperature bonding on two silicon carbide plates to produce the silicon carbide micro-reactor. In the invention, the polyvinyl alcohol physical gel is cured, so all components are uniformly distributed; and the residual carbon rate reaches 60-70% after the introducing of the introduced phenolic resin, and the sintered phenolic resin reacts with a silicon liquid to generate carbon carbide, so the content of free silicon in the silicon carbide is reduced, and the denseness is good.

Description

technical field [0001] The invention belongs to the field of ceramic molding, and relates to a method for preparing a silicon carbide microreactor based on gel molding. Background technique [0002] A microreactor is a three-dimensional structural element that can be used for chemical reactions and is manufactured from a solid matrix by means of special micromachining techniques. Microreactors generally contain small channel sizes and channel multiplicity in which fluids flow and where desired reactions are required to take place. The channel size of the microreactor is much smaller than that of the conventional tubular reactor, and its interior is usually composed of many microchannels of 10-500 μm, with a large specific surface area, which can realize precise control of the reaction temperature and precise proportioning of the reaction materials. According to the different microstructures, microreactors can be divided into microchannel type, multi-stream parallel flow typ...

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Problems solved by technology

[0005] The patent with publication number CN104529460A discloses a method for gel injection molding of water-based C / SiC slurry and C / SiC body, and the patent with publication number CN1636938 discloses a method for surface modification of silicon carbide, which is easy to Zhongzhou conducted research on recrystallized silicon carbide gel injection molding and its properties (Yi Zhongzhou, Xie Zhipeng, Huang Yong et al. Research on recrystallized silicon carbide gel injection molding and its properties[J]. Silicate Bulletin, 2002, 4, 3-7.), Liu Hailin and others from the China Academy of Building Materials Research studied the preparation method of precision silicon carbide ceramic parts for lithography machines (Liu Hailin, Huo Yanli, Hu Chuanqi et al. Lithography Preparation technology of precision silicon carbide ceramic parts for machine [J]. Modern Technology Ceramics, 2016, 37(3), 168-178.), the above methods all use acrylamide gel system, acrylamide has no benzene ring, and it cannot introduce a large amount of At the same time, acrylamide monomer is easy to polymerize with other organic substances, and it is difficult to introduce inorganic carbon through organic substances. Therefore, the above method chooses to introduce carbon black into the slurry, but it is easy to cause the material to be difficult to disperse evenly. In addition, acrylamide is harmful to the human body, and workers cannot contact it for a long time. However, the present invention introduces inorganic carbon through sintering and carbonization of phenolic resin, and the inorganic carbon is evenly distributed. At the same time, the gel system has the advantage of non-toxicity; The patent with the publication number CN104291827A discloses a process for preparing complex-shaped silicon carbide ceramics by solid-phase sintering of phenolic resin as a carbon source. Water-soluble phenolic resin is used for spray granulation, and then dry powder is pressed to form a blank. This method is based on the traditional dry powder pressing process. Manufacturing complex parts easily leads to inconsistencies in local compaction density of the green body, and stress concentration and cracking occur during sintering. However, the present invention adopts the gel method, which can ensure the uniformity of the green body structure while forming complex parts; Li Jiayou (Li Jiayou. Manufacturing rapid prototypes by bonding alumina powder with phenolic resin [D], master's degree thesis of Taipei University of Science and Technology, 2011, Taipei.) Using thermosetting phenolic resin as the binder of alumina ceramic powder, using rapid prototyping method to lay up the blank The study found that the surface of alumina ceramics can be made smooth by mixing polyvinyl alcohol (PVA), but this method only studied the effect of adding PVA to the mixed glue to improve the plasticity of the green body and then affect the cracking of the alumina body, which is useless. Incorporation of inorganic carbon into PVA for low-temperature gelation and phenolic resin decomposition for reactive sintering

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