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CN-121974714-A - Preparation method of in-situ heated silicon dioxide ceramic matrix composite

CN121974714ACN 121974714 ACN121974714 ACN 121974714ACN-121974714-A

Abstract

The invention relates to a preparation method of an in-situ heated silicon dioxide ceramic matrix composite. The method comprises the steps of (1) preparing a quartz fiber preform, (2) preparing silica sol, (3) vacuum/pressure impregnation, (4) heating for solidification, (5) demolding and drying, (6) ceramic sintering, and (7) repeated cycle impregnation. The sandwich structure for in-situ heating is additionally arranged in the side wall of the in-situ heating tool, can be connected with an external liquid heater/refrigerator and is communicated with a circulating heating medium, so that the whole heating/refrigerating function of the whole in-situ heating tool is realized, and the in-situ heating tool is used for in-situ heating gel solidification and rapid cooling. According to the invention, the equipment such as a constant-temperature air oven and the like conventionally used for producing the silica ceramic matrix composite is replaced by the newly designed in-situ heating tool, so that the process flow of the silica ceramic matrix composite is effectively optimized, the production and preparation efficiency is improved, and the equipment and site requirements and the production cost are reduced.

Inventors

  • MA XINZHOU
  • QIN GAOLEI
  • WANG HUADONG
  • WU DAO

Assignees

  • 航天特种材料及工艺技术研究所

Dates

Publication Date
20260505
Application Date
20251230

Claims (10)

  1. 1. The preparation method of the in-situ heated silica ceramic matrix composite is characterized by comprising the following steps of: Pretreating a fiber preform formed by three-dimensional braiding, and removing the impregnating compound on the fiber surface in the preform; Concentrating the silica sol to obtain concentrated silica sol; Placing the fiber preform into an in-situ heating tool, sucking the concentrated silica sol into the liner of the in-situ heating tool in a vacuum suction injection mode, applying a certain pressure in the liner of the in-situ heating tool, and maintaining the pressure for a period of time to ensure that the silica sol fully enters the gaps of the fiber three-dimensional fabric; After the pressure maintaining is finished, maintaining the pressure of the inner container of the in-situ heating tool unchanged, introducing a heating medium into an interlayer of the in-situ heating tool, and heating the whole in-situ heating tool by the circulating heating medium to enable the silica sol added into the in-situ heating tool to undergo a gelation reaction; After the silica sol is completely solidified, the in-situ heating tool is quickly cooled to room temperature by continuously and circularly cooling a heating medium, and then a quartz fiber preform with silica sol gel blocks is taken out and dried to obtain a ceramic blank; Sintering the ceramic blank in a high-temperature furnace to obtain a fiber reinforced silica ceramic matrix composite blank; and (3) carrying out repeated cyclic impregnation on the fiber reinforced silica ceramic matrix composite blank until the weight of the composite is no longer increased, and obtaining the fiber reinforced silica ceramic matrix composite after the final sintering and natural cooling to room temperature.
  2. 2. The method according to claim 1, wherein the structure of the fiber preform is one of a needled structure, a cloth-stitched structure, an orthorhombic three-way structure, and a 2.5D structure, the type of the fiber used for the fiber preform is one of a quartz fiber, a glass fiber, an alumina fiber, and a nitride fiber, and the pretreatment is a solvent-immersed cleaning or a high-temperature heat treatment.
  3. 3. The method according to claim 1, wherein the concentration treatment comprises reduced pressure distillation and ultrafiltration using an ultrafiltration membrane, and the silica sol has a density of 1.14 to 1.45 after the concentration treatment 。
  4. 4. The method of claim 1, wherein the vacuum suction injection comprises the steps of placing the fiber preform into a liner of an in-situ heating tool, sealing and closing the mold, vacuumizing the liner, connecting a material pool containing silica sol, and sucking the silica sol into the sealed liner under the action of vacuum and air pressure until the silica sol fills the whole liner, wherein the vacuum degree in the vacuum suction injection process is-0.05 MPa to-0.1 MPa.
  5. 5. The method of claim 1, wherein the liner of the in-situ heating tool can bear 3-5MPa of internal hydraulic pressure and is sealed, and the pressure is applied for a certain period of time, wherein the pressure is 2-5 MPa, and the pressure holding time is 5-24h.
  6. 6. The method of claim 1, wherein the heating is performed by heating to 60-90 ℃ for 12-36 hours, and the heating medium is water or silicone oil.
  7. 7. The method of claim 1, wherein the cooling time is 10-20 h, the final temperature after cooling is 5-10 ℃, the drying equipment adopted in the drying treatment is a high-temperature air oven, the highest drying temperature is 200-250 ℃, the heating time from room temperature to the highest temperature is not less than 16h, the highest temperature holding time is not less than 2h, and the gel block in the ceramic body is thoroughly dried.
  8. 8. The method according to claim 1, wherein the sintering temperature is 500-800 ℃ and the sintering time is 1-3 hours.
  9. 9. The method according to claim 1, wherein the number of times of the repeated impregnation is 2 to 5 times.
  10. 10. An in situ heated silica ceramic matrix composite prepared by the method of any one of claims 1 to 9.

Description

Preparation method of in-situ heated silicon dioxide ceramic matrix composite Technical Field The invention belongs to the technical field of silica ceramic matrix composite materials, and particularly relates to a preparation method of a silica ceramic matrix composite material without large-scale constant-temperature heating equipment, which has the advantages of rapidness, convenience and easiness in mass production. Background The continuous quartz fiber reinforced silica ceramic matrix composite has the advantages of high temperature resistance, oxidation resistance and corrosion resistance of oxide ceramics, overcomes the defects of high brittleness, no impact resistance and low reliability commonly existing in the traditional oxide ceramic materials due to the toughening effect of the reinforcement continuous fibers, and has good normal temperature and high temperature mechanical properties. The silica ceramic matrix composite can be added with different types of reinforcing fibers including alumina fibers, quartz fibers, glass fibers and the like according to actual use requirements, and the mechanical properties, the temperature resistance and the like of the silica ceramic matrix composite and the preparation cost of the silica ceramic matrix composite are greatly different according to different types of reinforcing body fibers. Silica ceramic matrix composites are commonly used at 800-1200 ℃. Compared with the alumina ceramic matrix composite, the silica ceramic matrix composite has the obvious advantages of mature production process and stable material performance due to simple preparation process and wide raw material sources, and is widely applied to furnace lining and other hot junction components at present. The preparation process of the quartz fiber reinforced silica ceramic matrix composite material commonly used at present is a vacuum impregnation method, namely, ceramic precursors such as silica sol are introduced into a three-dimensional fabric, the pores of the three-dimensional quartz fiber fabric are filled with the ceramic precursors such as the silica sol through vacuum or pressurization, then gel curing or drying is carried out, a ceramic matrix is reserved in the fabric, and a final product is obtained after high-temperature ceramic sintering. In the traditional preparation process of the quartz fiber reinforced silica ceramic matrix composite, the commonly adopted process method is to put the whole mould containing a large amount of silica sol and a three-dimensional fabric/ceramic blank into large-scale constant temperature heating equipment for heat treatment gel curing, drying and ceramization. In the process, the mould containing the silica sol and the preform/blank needs to be integrally put into and taken out of the constant temperature oven, so that the weight is difficult to move, and a certain danger exists. In addition, the large constant temperature heating equipment transfers heat through hot air, so that the heat transfer efficiency is low, the heating rate is low, the heating time is long, and the energy consumption is high. Disclosure of Invention Based on the above situation, the invention aims to provide a convenient, quick and easy mass production and small space occupation tooling and method for preparing a silica ceramic matrix composite material, and solve the problem that a large-scale constant-temperature heating device is generally required to cure a die filled with a silica sol precursor, a blank body or a fiber preform in the sol-gel step in the existing preparation method. The technical scheme of the invention is as follows: the preparation method of the in-situ heated silicon dioxide ceramic matrix composite material comprises the following steps: (1) Preparing a quartz fiber preform, namely preprocessing the fiber preform formed by three-dimensional braiding, removing the impregnating compound on the fiber surface in the preform, and taking the impregnating compound as an introduction form of a continuous fiber reinforcement in the ceramic matrix composite material; (2) Preparing silica sol, namely concentrating the silica sol to obtain concentrated silica sol with a certain concentration, wherein the concentrated silica sol is used as a matrix precursor of the fiber reinforced silica ceramic matrix composite material; (3) Vacuum/pressure impregnation, namely placing the prepared fiber preform into an in-situ heating tool, pumping the concentrated silica sol into an in-situ heating tool liner in a vacuum suction injection mode to fill the whole in-situ heating tool liner, and then applying a certain pressure in the in-situ heating tool liner and maintaining the pressure for a period of time to ensure that the silica sol fully enters gaps of the fiber three-dimensional fabric; (4) Heating and curing, namely maintaining the pressure of the liner of the in-situ heating tool unchanged after pressure maintaining, introducing a heating medium into an int