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CN-121974701-A - In-situ reaction sintering silicon carbide ceramic and preparation method thereof

CN121974701ACN 121974701 ACN121974701 ACN 121974701ACN-121974701-A

Abstract

The invention relates to the technical field of silicon carbide ceramic preparation, in particular to an in-situ reaction sintering silicon carbide ceramic and a preparation method thereof, wherein the preparation method comprises the following steps of S1, preparing silicon carbide slurry, and weighing organic precursor raw materials according to mass content percentage to form the silicon carbide slurry; S2, vacuum grouting, namely injecting silicon carbide slurry in a vacuum grouting tank into a shaping die from the bottom of the shaping die to form a silicon carbide green body, S3, performing in-situ reaction sintering, namely placing the silicon carbide green body into a sintering furnace, and heating, preserving heat and cooling the silicon carbide green body by adopting a sectional temperature control process under an argon atmosphere to obtain the silicon carbide ceramic. The silicon carbide ceramic prepared by the method has higher density and excellent mechanical property.

Inventors

  • LIU HAO
  • YU SHENGJIE
  • HUANG HONGFU
  • LIAO JIAHAO

Assignees

  • 湖南德智新材料股份有限公司

Dates

Publication Date
20260505
Application Date
20260330

Claims (10)

  1. 1. The preparation method of the in-situ reaction sintering silicon carbide ceramic is characterized by comprising the following steps of: S1, preparing silicon carbide slurry, namely weighing the following raw materials, by mass, 80-85% of silicon carbide powder, 10-15% of organic precursor and 5-7% of other additives, adding a dispersion liquid accounting for 25-30% of the total mass of the raw materials, and stirring for 36-48 hours to form the silicon carbide slurry; S2, vacuum grouting, namely injecting the silicon carbide slurry into a vacuum grouting tank, injecting the silicon carbide slurry in the vacuum grouting tank from the bottom of a shaping die, and drying for 1-2 hours at 80-120 ℃ to form a silicon carbide green body; S3, in-situ reaction sintering, namely placing the silicon carbide green body into a sintering furnace, uniformly scattering silicon particles accounting for 20-40 wt% of the total mass of the silicon carbide green body around the silicon carbide green body, heating, preserving heat and cooling the silicon carbide green body by adopting a sectional temperature control process under an argon atmosphere to obtain silicon carbide ceramic, wherein the pressure of the argon atmosphere in the sintering furnace is in the range of 0.05-0.1 MPa when the temperature in the sintering furnace is lower than 1550 ℃ in the sectional temperature control process, and the pressure of the argon atmosphere in the sintering furnace is increased to 5-10 MPa when the temperature in the sintering furnace reaches or exceeds 1550 ℃.
  2. 2. The method for preparing in-situ reaction-sintered silicon carbide ceramic according to claim 1, wherein the organic precursor in the silicon carbide slurry is coated on the surface of the silicon carbide powder; And/or the granularity size of the silicon carbide powder is 3-5 mu m.
  3. 3. The method for preparing in-situ reaction sintered silicon carbide ceramic according to claim 1, wherein the organic precursor comprises at least one of phenolic resin, polycarbosilane, epoxy resin, isopropanol, glucose, sucrose, and starch; And/or the dispersion liquid comprises at least one of deionized water, ethanol and acetone.
  4. 4. The method for preparing in-situ reaction sintered silicon carbide ceramic according to claim 1, wherein the other auxiliary agents include a dispersant, a binder and a defoaming agent, wherein, The dispersing agent comprises at least one of sodium dodecyl benzene sulfonate, tetramethyl ammonium hydroxide, polyacrylic acid, ammonium polyacrylate, ammonium citrate and sodium silicate; And/or the adhesive comprises at least one of polyvinyl alcohol and polyethylene glycol; And/or the defoamer comprises at least one of polydimethylsiloxane, GP type glycerol polyether and GPE type polyoxyethylene ether.
  5. 5. The method for preparing an in-situ reaction sintered silicon carbide ceramic according to claim 4, wherein the dispersant is 1.0wt% to 4.0wt%, the binder is 1.0wt% to 4.0wt%, and the defoamer is 0.1wt% to 1.5wt% based on the total mass of the raw materials.
  6. 6. The method for preparing an in-situ reaction sintered silicon carbide ceramic according to claim 1, wherein in the step of S2 vacuum grouting, the silicon carbide slurry is injected into the shaping mold from the bottom of the shaping mold at a grouting pressure ranging from 0.3MPa to 0.5MPa.
  7. 7. The method for preparing in-situ reaction sintered silicon carbide ceramic according to claim 1, wherein the sectional temperature control process specifically comprises a sectional temperature raising process, and the sectional temperature raising process comprises the following steps: (1) A first temperature rising stage, namely rising the temperature in the sintering furnace from room temperature to 200 ℃, wherein the temperature rising time is 30-60 min, and the pressure range of argon atmosphere is 0.05-0.1 MPa; (2) A first heat preservation stage, wherein the temperature in the sintering furnace is preserved for 60-120 min at 200 ℃, and the pressure range of argon atmosphere is 0.05-0.1 MPa; (3) A second temperature rising stage, namely rising the temperature in the sintering furnace from 200 ℃ to 400 ℃ for 30-60 min, wherein the pressure range of the argon atmosphere is 0.05-0.1 MPa; (4) A second heat preservation stage, namely preserving the temperature in the sintering furnace at 400 ℃ for 60-120 min, wherein the pressure range of argon atmosphere is 0.05-0.1 MPa; (5) A third temperature rising stage, namely rising the temperature in the sintering furnace from 400 ℃ to 800 ℃, wherein the temperature rising time is 60-180 min, and the pressure range of the argon atmosphere is 0.05-0.1 MPa; (6) A third heat preservation stage, namely preserving the temperature in the sintering furnace at 800 ℃ for 60-120 min, wherein the pressure range of argon atmosphere is 0.05-0.1 MPa; (7) A fourth heating stage, namely heating the temperature in the sintering furnace from 800 ℃ to 1550 ℃ for 120-240 min, wherein the pressure range of the argon atmosphere is 0.05-0.1 MPa, and when the temperature in the sintering furnace is 1550 ℃, the pressure range of the argon atmosphere is 5-10 MPa; (8) A fourth heat preservation stage, wherein the temperature in the sintering furnace is preserved for 60-150 min at 1550 ℃ and the pressure range of argon atmosphere is 5-10 MPa; (9) A fifth heating stage, namely heating the temperature in the sintering furnace from 1550 ℃ to 1950 ℃ for 60-180 min, wherein the pressure range of the argon atmosphere is 5-10 MPa; (10) And a fifth heat preservation stage, wherein the temperature in the sintering furnace is preserved at 1950 ℃ for 60-120 min, and the pressure of the argon atmosphere is 5-10 MPa.
  8. 8. The method for preparing silicon carbide ceramic by in-situ reaction sintering according to claim 7, wherein in the sintering furnace at 1550-1950 ℃ or the fifth heating stage, the pressure of the argon atmosphere is controlled in a range of 5-10 MPa in a periodically changing manner, and the periodically changing manner is pulse pressure, wherein the periodically changing manner is required to meet the condition that a peak pressure is applied every 30-60 min, the peak pressure is 8-10 MPa, the duration is 5-15 min, and the rest time maintains the basic pressure of 5-8 MPa.
  9. 9. The method for preparing in-situ reaction sintered silicon carbide ceramic according to claim 7, wherein the sectional temperature control process specifically further comprises a sectional cooling process, and the sectional cooling process comprises the following steps: (11) Cooling along with the furnace, namely reducing the temperature in the sintering furnace from 1950 ℃ to 800 ℃ for 480-600 min; (12) A rapid cooling stage, namely cooling the temperature in the sintering furnace from 800 ℃ to room temperature for 60-80 min; Wherein argon forced convection cooling is adopted in the rapid cooling stage, and the cooling rate is 10-15 ℃ per minute.
  10. 10. An in-situ reaction sintered silicon carbide ceramic prepared by the method for preparing the in-situ reaction sintered silicon carbide ceramic according to any one of claims 1 to 9, wherein the volume density of the silicon carbide ceramic is more than or equal to 3.15g/cm < 3 >, the flexural strength is more than or equal to 240MPa, and the porosity is less than or equal to 1.5%.

Description

In-situ reaction sintering silicon carbide ceramic and preparation method thereof Technical Field The invention relates to the technical field of silicon carbide ceramic preparation, in particular to an in-situ reaction sintering silicon carbide ceramic and a preparation method thereof. Background The reaction sintered silicon carbide ceramic is widely applied to the fields of high-temperature heat exchangers, semiconductor manufacturing equipment, aeroengine parts and the like due to the excellent high-temperature strength, corrosion resistance and heat conduction performance. The core preparation principle is that silicon carbide (SiC) is generated by the reaction of molten silicon and a carbon source at high temperature so as to fill pores among original silicon carbide particles, thereby improving the compactness of the material. The conventional reaction sintering technology generally adopts a method of externally adding carbon sources such as carbon black, graphite powder and the like, and the carbon sources and the silicon carbide powder are mixed and sintered to react molten silicon with the carbon sources to generate SiC. However, the method has the obvious defects that firstly, carbon black or graphite powder is easy to agglomerate in slurry, so that carbon sources are unevenly distributed, partial reaction is insufficient during sintering, the mechanical property of the material is reduced by residual carbon black or graphite powder, secondly, the proportion of carbon and silicon is required to be accurately controlled, the process control difficulty is high, thirdly, impurities such as metal ions, oxides and the like are easily introduced when the purity of the carbon sources is insufficient, and the thermal conductivity and corrosion resistance of the material are affected. To improve the above problems, the prior art attempts to improve by process optimization or carbon source replacement. For example, in part of the process, starch is used as a carbon source, nano SiC is generated through in-situ reaction of starch carbonization and metal silicon, the carbon distribution is random after starch carbonization, a generated carbon layer is loose and porous, a silicon carbide substrate is difficult to be coated preferentially, the reaction efficiency is low, and the problem of uneven carbon source distribution still exists. In summary, the core bottleneck of the prior art is that the carbon source distribution uniformity is poor and impurities are introduced, so that the compactness and mechanical properties of the silicon carbide ceramic material are limited. Disclosure of Invention In order to solve the problems in the prior art, the invention provides an in-situ reaction sintering silicon carbide ceramic and a preparation method thereof. In order to achieve the above object, a first aspect of the present invention provides a method for preparing an in-situ reaction sintered silicon carbide ceramic, comprising the steps of: S1, preparing silicon carbide slurry, namely weighing the following raw materials, by mass, 80-85% of silicon carbide powder, 10-15% of organic precursor and 5-7% of other additives, adding a dispersion liquid accounting for 25-30% of the total mass of the raw materials, and stirring for 36-48 hours to form the silicon carbide slurry; S2, vacuum grouting, namely injecting the silicon carbide slurry into a vacuum grouting tank, injecting the silicon carbide slurry in the vacuum grouting tank into a shaping die from the bottom of the shaping die, and drying for 1-2 h at 80-120 ℃ to form the silicon carbide green body; S3, in-situ reaction sintering, namely placing the silicon carbide green body into a sintering furnace, uniformly scattering silicon particles accounting for 20-40 wt% of the total mass of the silicon carbide green body around the silicon carbide green body, heating, preserving heat and cooling the silicon carbide green body by adopting a sectional temperature control process under an argon atmosphere to obtain silicon carbide ceramic, wherein the pressure of the argon atmosphere in the sintering furnace is in the range of 0.05-0.1 MPa when the temperature in the sintering furnace is lower than 1550 ℃ in the sectional temperature control process, and the pressure of the argon atmosphere in the sintering furnace is increased to 5-10 MPa when the temperature in the sintering furnace reaches or exceeds 1550 ℃. In one example, the organic precursor in the silicon carbide slurry coats the surface of the silicon carbide powder. In one example, the silicon carbide powder has a particle size of 3 μm to 5 μm. In one example, the organic precursor includes at least one of phenolic resin, polycarbosilane, epoxy resin, isopropyl alcohol, glucose, sucrose, starch. In one example, the dispersion includes at least one of deionized water, ethanol, and acetone. In one example, the other adjuvants include dispersants, binders, and defoamers. In one example, the dispersant includes