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CN-118164771-B - Preparation method of carbon-ceramic composite material for heat insulation of reduction furnace

CN118164771BCN 118164771 BCN118164771 BCN 118164771BCN-118164771-B

Abstract

The invention discloses a preparation method of a carbon-ceramic composite material for reducing furnace heat insulation, which comprises the steps of alternately laminating carbon fiber cloth, a carbon fiber net tire and a polymer film and needling the carbon fiber cloth, the carbon fiber net tire and the polymer film layer by layer to obtain a carbon fiber@polymer film preform, sequentially carrying out carbonization treatment, primary purification treatment and densification treatment on the carbon fiber@polymer film preform to obtain a low-density carbon-carbon porous body, carrying out secondary purification treatment and silicon carbide densification treatment on the low-density carbon-carbon porous body to obtain the carbon-ceramic composite material, and carrying out three purification treatments on the carbon-ceramic composite material. The carbon ceramic composite material for heat insulation of the reducing furnace, which is obtained by the preparation method, has high purity, low heat conductivity and high strength, and greatly saves the power consumption for producing polysilicon.

Inventors

  • LI JINWEI
  • XIAO PENG

Assignees

  • 湖南世鑫新材料有限公司

Dates

Publication Date
20260508
Application Date
20240311

Claims (8)

  1. 1. A preparation method of a carbon-ceramic composite material for heat insulation of a reducing furnace is characterized by comprising the steps of alternately laminating carbon fiber cloth, a carbon fiber net tire and a polymer film and needling the carbon fiber cloth, the carbon fiber net tire and the polymer film layer by layer to obtain a carbon fiber@polymer film preform, sequentially carrying out carbonization treatment, primary purification treatment and densification treatment on the carbon fiber@polymer film preform to obtain a low-density carbon-carbon porous body, and carrying out secondary purification treatment and silicon carbide densification treatment on the low-density carbon-carbon porous body to obtain the carbon-ceramic composite material; The volume ratio of the polymer film to the carbon fiber cloth is (0.1-3) 1, and the carbon residue ratio of the polymer film is controlled to be 20-60%.
  2. 2. The method for preparing the carbon-ceramic composite material for heat insulation of the reduction furnace according to claim 1, which is characterized in that: the polymer film is at least one of PE, PET, PP, PS, EVA and PLA.
  3. 3. The method for preparing the carbon ceramic composite material for heat insulation of the reduction furnace according to claim 1 or 2, wherein the method comprises the following steps: the mass ratio of the carbon fiber net tire to the carbon fiber cloth is (0.25-10) 1.
  4. 4. The method for preparing the carbon-ceramic composite material for heat insulation of the reducing furnace, which is disclosed in claim 1, is characterized in that the carbonization treatment is carried out at a temperature of 800-1100 ℃ for 1-10 hours.
  5. 5. The method for preparing the carbon-ceramic composite material for heat insulation of the reducing furnace, which is disclosed in claim 4, is characterized in that the conditions of the primary purification treatment, the secondary purification treatment and the tertiary purification treatment are independently selected from the group consisting of a temperature of 1800 ℃ or more, a purification time of 2-15H, and an atmosphere of one of vacuum, freon, H 2 atmosphere and ammonia atmosphere.
  6. 6. The method for preparing the carbon ceramic composite material for reducing furnace heat insulation according to claim 5, wherein the densification and carbonization treatment is characterized in that carbon fiber@polymer film preform is densified to 0.4-1.5 g/cm 3 by adopting carbon-containing organic gas chemical vapor deposition and/or resin impregnation and carbonization.
  7. 7. The method for preparing the carbon-ceramic composite material for heat insulation of the reducing furnace, as set forth in claim 1, wherein the densification treatment of the silicon carbide is one of silane gas chemical vapor deposition, silane immersion cracking and melt siliconizing.
  8. 8. The method for preparing the carbon-ceramic composite material for heat insulation of the reducing furnace, which is disclosed in claim 7, is characterized in that the condition of the fused siliconizing is that the temperature is 1550-2200 ℃, the time is 0.5-4 h, the pressure is negative pressure or micro positive pressure, and the silicon purity is more than or equal to 6N.

Description

Preparation method of carbon-ceramic composite material for heat insulation of reduction furnace Technical Field The invention relates to a preparation method of a carbon-ceramic composite material, in particular to a preparation method of a carbon-ceramic composite material for heat insulation of a reduction furnace, and belongs to the field of preparation of photovoltaics and semiconductors. Background Polysilicon is the main raw material for producing semiconductors and solar photovoltaic products, and the main methods currently used for producing polysilicon comprise a modified Siemens method, a fluidized bed method, a silane method and the like, wherein the modified Siemens method adopts a reduction furnace for production, uses high-purity trichlorosilane, hydrogen and the like as raw materials, and deposits silicon on an initial silicon core to form a polysilicon rod at a high temperature of about 1030 ℃. Because the preparation process has high temperature, high purity of materials used in the furnace and high ash content requirement, and large-flow gas scouring exists in the furnace, the traditional heat-insulating materials such as heat-insulating cotton, carbon felt and the like can not meet the use requirement of the polysilicon reduction furnace. Because no proper heat preservation and insulation material exists, the heating and heat preservation power of the current polysilicon reduction furnace is high, the power consumption per kilogram of polysilicon is as high as 50 kw.h, which is far higher than the power consumption of the granular silicon prepared by the fluidized bed method. Based on the above, it is necessary to design and develop a carbon ceramic composite material which has high purity, low heat conductivity and gas scouring resistance and can meet the requirement of heat insulation of a polysilicon reduction furnace, so as to improve the heat efficiency of the reduction furnace and reduce the electricity cost for producing polysilicon. Disclosure of Invention Aiming at the problems in the prior art, the invention aims to provide a preparation method of a carbon-ceramic composite material for heat insulation of a reduction furnace, wherein a certain polymer film is introduced in the preparation process of a carbon fiber preform, so that the strength of the preform is ensured, the use amount of carbon fibers is reduced, and the heat conductivity of the carbon-ceramic composite material is further reduced. The invention provides a preparation method of a carbon ceramic composite material for reducing furnace heat insulation, which comprises the steps of alternately laminating carbon fiber cloth, a carbon fiber net tire and a polymer film and needling the carbon fiber cloth, the carbon fiber net tire and the polymer film layer by layer to obtain a carbon fiber@polymer film prefabricated body, sequentially carbonizing the carbon fiber@polymer film prefabricated body, purifying the carbon fiber@polymer film prefabricated body for one time and densifying the carbon fiber@polymer film prefabricated body to obtain a low-density carbon porous body, purifying the low-density carbon porous body for the second time and densifying the silicon carbide to obtain the carbon ceramic composite material, and purifying the carbon ceramic composite material for three times to obtain the carbon ceramic composite material. The key of the technical scheme of the invention is that a certain polymer film is introduced in the preparation process of the carbon fiber preform, so that aggregation or knotting of carbon fibers is avoided, and simultaneously, the needled fibers can be well fixed, so that a uniformly distributed carbon fiber network can bear load more equally, and meanwhile, the polymer film is used as a reaction control layer, so that the chemical reaction is slowed down, the effective combination between the carbon fibers and a matrix is ensured, and the overall strength and rigidity of the composite material are ensured. The polymer film reduces the consumption of carbon fiber, and in the high temperature carbonization process, the polymer film is subjected to thermal decomposition process, and the polymer chain is broken into small molecules, so that the ordered carbon structure is difficult to form, thereby reducing the carbon content of the whole material, forming a low-density carbon fiber@polymer film preform, and simultaneously forming a certain gap in the material in the carbonization process, reducing the thermal conductivity of the composite material, and the carbon fiber@polymer film preform is further subjected to densification carbon treatment to form a low-density carbon-carbon porous body, so that the compressive strength of the carbon ceramic composite material is improved. In addition, the invention ensures the high purity of the carbon ceramic composite material by introducing purification treatment and a fused siliconizing process. As a preferred embodiment, the polymer film is a