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CN-117888234-B - Method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning

CN117888234BCN 117888234 BCN117888234 BCN 117888234BCN-117888234-B

Abstract

The invention discloses a method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning. The method comprises the steps of 1) preparing a second silica-based sol, adding a spinning auxiliary agent to prepare a spinnable silica-based sol, 2) preparing the spinnable silica-based sol into fiber precursors by adopting a dry spinning process, 3) splitting the fiber precursors into silicon-carbon-oxygen fibers, and 4) sintering the silicon-carbon-oxygen fibers into silicon carbide ceramic fibers. The method is different from the mainstream polycarbosilane precursor method for preparing the silicon carbide ceramic fiber, does not need a non-melting treatment process, has the advantages of adjustable composition, low raw material cost, simple process and the like, and has important significance for low-cost preparation of the silicon carbide ceramic fiber.

Inventors

  • CHEN JIANJUN
  • WANG MEIJING
  • LIU JIALE
  • Yi Shuzheng

Assignees

  • 浙江理工大学

Dates

Publication Date
20260508
Application Date
20240117

Claims (8)

  1. 1. A method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning is characterized by comprising the following steps: 1) After preparing the second silica-based sol, adding a spinning auxiliary agent to prepare spinnable silica-based sol; the second silicon-based sol is prepared by taking deionized water, ethyl orthosilicate, a sintering aid, a supplementary carbon source, a supplementary silicon source and silicon carbide nanoparticle suspension as main raw materials; The method comprises the following steps of: 1.1 Adding 10-30 parts of ethyl orthosilicate serving as a silicon source into 15-30 parts of deionized water, adding 1-5 parts of sintering aid, and stirring to obtain a first silica-based sol; 1.2 Adding a supplementary carbon source, a supplementary silicon source and 5-20 parts of silicon carbide nanoparticle suspension into the first silica-based sol, and stirring to obtain a second silica-based sol; in the silicon carbide nanoparticle suspension, the mass fraction of the silicon carbide nanoparticles is 2-10%, and the particle size is 200-500 nm; 1.3 Adding 0.5-5.5 parts of spinning auxiliary agent into the second silica-based sol, and stirring to obtain spinnable silica-based sol, wherein the viscosity of the spinnable silica-based sol is 100-200 Pa.S; 2) Preparing spinnable silica-based sol into fiber precursor by adopting a dry spinning process; 3) Splitting the fiber precursor into silicon-carbon-oxygen fibers; 4) Sintering the silicon-carbon-oxygen fibers into silicon carbide ceramic fibers.
  2. 2. A method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 1, wherein the method comprises the following steps: In the step 1.1), the sintering aid is aluminum nitrate nonahydrate particles.
  3. 3. The method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 1, wherein in the step 1.2), the following components are calculated according to parts by weight: the carbon source is one or more of 2-10 parts of sucrose, 2-10 parts of glucose, 2-15 parts of polyacrylonitrile, 5-20 parts of phenolic resin and 2-10 parts of carbon powder suspension, wherein the mass fraction of carbon powder in the carbon powder suspension is 2-10%; The supplementary silicon source is 5-15 parts of methyltrimethoxysilane and/or 2-10 parts of silicon powder suspension, wherein the mass fraction of silicon powder in the silicon powder suspension is 2-10%.
  4. 4. The method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 1, wherein in the step 1.3), the spinning auxiliary agent is polyethylene oxide.
  5. 5. The method for preparing the silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 1, wherein in the step 3), cracking is carried out specifically by heating to 600-1200 ℃ at a heating rate of 2-5 ℃ per minute under protective gas, and cooling after heat preservation for 1-2 h.
  6. 6. The method for preparing the silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 1, wherein in the step 4), sintering is specifically performed by heating to 1300-1900 ℃ at a heating rate of 2-5 ℃ per minute under a protective gas, and cooling after heat preservation for 1-2 hours.
  7. 7. The method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 1, wherein in the step 2), a dry spinning device is adopted to prepare the spinnable silicon-based sol into fiber precursors; the dry spinning device comprises a precursor extrusion module, an infrared baking lamp (6), an infrared heating box (7) and a filament collecting drum (9), wherein the precursor extrusion module is connected with an external gas compressor, the precursor extrusion module extrudes the spinnable silica-based sol into fiber precursor (8) through the gas compressor, the infrared heating box (7) is arranged at the downstream of the precursor extrusion module, the two ends of a box body of the infrared heating box (7) are open, the infrared baking lamp (6) is arranged inside the box body, and the filament collecting drum (9) for winding the fiber precursor (8) is arranged at the downstream of the infrared heating box (7); The spinning raw silk extrusion module comprises a feeding pipe support (1), an air flow guide pipe (2), a feeding pipe adapter (3), a spinning feeding pipe (4) and a metal micro-syringe needle (5), wherein the feeding pipe support (1) is placed on an operation table, the spinning feeding pipe (4) is arranged above the feeding pipe support (1) in a supporting mode, a silicon-based sol capable of spinning is arranged in a cavity of the spinning feeding pipe (4), one end of the spinning feeding pipe (4) is connected with the feeding pipe adapter (3) in a sealing mode, the air flow guide pipe (2) is arranged in the feeding pipe adapter (3) in a penetrating mode, one end of the air flow guide pipe (2) stretches into the spinning feeding pipe (4), the other end of the air flow guide pipe (2) is connected with an air outlet of the air compressor, and the other end of the spinning feeding pipe (4) is connected with the metal micro-syringe needle (5) in a sealing mode to serve as a silk outlet of a fiber raw silk (8).
  8. 8. The method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning according to claim 7, wherein in the step 2), the process of preparing the spinnable silica-based sol into fiber precursor (8) by adopting the dry spinning device is specifically as follows: after the spinnable silica-based sol is poured into a spinning supply pipe (4), the spinning supply pipe (4) is sealed, compressed air is introduced into the spinning supply pipe (4) through a gas compressor, the spinnable silica-based sol is extruded from a metal micro-syringe needle (5) by using the gas pressure provided by the gas compressor to obtain fiber precursors (8), the fiber precursors (8) are then penetrated into an infrared heating box (7), the fiber precursors are dried in the infrared heating box (7) through an infrared baking lamp (6), the tail ends of the fiber precursors (8) are wound on a filament winding drum (9) after penetrating out of the infrared heating box (7), the gas pressure is 0.005-0.1 MPa, and the winding speed on the filament winding drum (9) is 25-200 r/min.

Description

Method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning Technical Field The invention relates to the technical field of dry spinning, in particular to a method for preparing silicon carbide ceramic fibers by combining sol-gel and dry spinning. Background The silicon carbide fiber is used as a novel ceramic fiber, has a series of excellent performances such as high temperature resistance, oxidation resistance, high tensile strength, good creep resistance, good compatibility with a ceramic matrix and the like, and has wide application prospect in the high technical fields such as aerospace, weapons, ships, nuclear industry and the like. The preparation method of the silicon carbide fiber mainly comprises a chemical vapor deposition method, an ultrafine powder sintering method, an active carbon fiber conversion method, a precursor conversion method and a sol-gel method. The silicon carbide ceramic fiber prepared by adopting a chemical vapor deposition method has high purity, but has thick fiber diameter, can not be woven and is difficult to realize large-scale production, the alpha-SiC fiber with high purity can be prepared by adopting a micro powder sintering method, but has structural defects in the decomposition and removal process of an organic high polymer, so that the mechanical property of the alpha-SiC fiber is seriously influenced, the industrial application is not favored, the silicon carbide ceramic fiber prepared by adopting an activated carbon fiber conversion method has low cost, the prepared fiber still has micropores, is easy to generate cracks and seriously influences the mechanical property, and the precursor conversion method is used for preparing the silicon carbide ceramic fiber by adopting the processes of polycarbosilane synthesis, melt spinning, non-melting treatment, cracking firing and the like, so that the fiber has good performance and high purity, but has long reaction period, relatively complex process and high cost. The sol-gel process is to take inorganic salt or metal alkoxide as material, dissolve the precursor in solvent to form homogeneous solution for similar molecular level mixing, hydrolyze and alcoholysis the precursor in solvent and to obtain nanometer linear particle to constitute sol. And when the sol reaches a certain viscosity (within the range of 1-1000 Pa.S), spinning and forming at room temperature to obtain gel fibers, and drying and sintering to obtain the ceramic fibers. At present, the production of the silicon carbide ceramic fiber still has the defects of low production efficiency, high cost, complex preparation and the like. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning. The technical scheme adopted by the invention is as follows: Method for preparing silicon carbide ceramic fiber by combining sol-gel and dry spinning The method specifically comprises the following steps: 1) After preparing the second silica-based sol, adding a spinning auxiliary agent to prepare spinnable silica-based sol; The second silicon-based sol is prepared from deionized water, ethyl orthosilicate, a sintering aid, a supplementary carbon source, a supplementary silicon source and silicon carbide nanoparticle suspension serving as main raw materials. The method comprises the following steps of: 1.1 Adding 10-30 parts of ethyl orthosilicate serving as a silicon source into 15-30 parts of deionized water, adding 1-5 parts of sintering aid, and stirring to obtain a first silica-based sol; In the step 1.1), the sintering aid is aluminum nitrate nonahydrate particles. 1.2 Adding a supplementary carbon source, a supplementary silicon source and 5-20 parts of silicon carbide nanoparticle suspension into the first silicon-based sol, and stirring to obtain a second silicon-based sol, wherein the mass fraction of silicon carbide nanoparticles in the silicon carbide nanoparticle suspension is 2-10%, and the particle size is 200-500 nm; In the step 1.2), for each 5-20 parts of silicon carbide nano particle suspension, the carbon source is supplemented with one or more of 2-10 parts of sucrose, 2-10 parts of glucose, 2-15 parts of polyacrylonitrile, 5-20 parts of phenolic resin and 2-10 parts of carbon powder suspension, and the silicon source is supplemented with 5-15 parts of methyltrimethoxysilane and/or 2-10 parts of silicon powder suspension. Specifically, the mass fraction of carbon powder in the carbon powder suspension is 2-10%, and the mass fraction of silicon powder in the silicon powder suspension is 2-10%. 1.3 Adding 0.5-5.5 parts of spinning auxiliary agent into the second silica-based sol obtained in the step 1.2), and stirring to obtain spinnable silica-based sol, wherein the viscosity of the spinnable silica-based sol is 100-200 Pa.S; in the step 1.3), the spinning auxiliary agent is polyethylene oxide. 2) And prepari