A method for preparing high-purity silicon carbide products

Abstract

This invention relates to the field of silicon carbide product preparation, and discloses a method for preparing high-purity silicon carbide products, comprising the following steps: S1: Slurry preparation; silicon carbide powder, deionized water, and additives are wet-mixed and stirred to obtain a slurry; S2: Molding; under vacuum conditions, the slurry is injected into a pre-made mold, and then demolded, dried, loaded into a kiln, and fired sequentially; S3: Finished product processing; the fired silicon carbide products are pre-oxidized and then processed and modified; S4: Finished product testing; the silicon carbide products are tested, and if the test is qualified, the desired silicon carbide products can be obtained. This invention avoids complex and expensive equipment such as hot press furnaces, which is conducive to achieving automated and mass production. It does not require a high-temperature and high-pressure environment, has low energy consumption, and helps to reduce production costs. Slurry casting can produce more complex shapes and large-sized blanks, while hot pressing sintering is limited by mold size.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide product preparation, and more specifically, to a method for preparing high-purity silicon carbide products. Background Technology

[0002] Silicon carbide ceramic products are an advanced ceramic material. Due to their stable chemical properties, high thermal conductivity, low coefficient of thermal expansion, low density, good wear resistance, high hardness, high mechanical strength, and resistance to chemical corrosion, they are widely used in fine chemicals, semiconductors, metallurgy, and national defense industries.

[0003] Silicon carbide ceramics are often prepared by hot pressing sintering, a method that is energy-intensive, costly, and difficult to control in terms of size and shape. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing high-purity silicon carbide products.

[0005] A method for preparing a high-purity silicon carbide product includes the following steps:

[0006] S1: Mud preparation;

[0007] Silicon carbide powder, deionized water, and additives are wet-mixed to prepare a slurry.

[0008] S2: Molding;

[0009] Under vacuum conditions, the slurry is injected into the precast mold, and then demolding, drying, kiln loading and firing are carried out in sequence.

[0010] S3: Finished product processing;

[0011] The fired silicon carbide products undergo pre-oxidation treatment and are then processed and modified.

[0012] S4: Finished product testing;

[0013] The silicon carbide products are tested, and if they pass the test, the desired silicon carbide products can be manufactured.

[0014] Preferably, in step S1, the additive includes one or more of the following: release agent, water-reducing agent, dispersant, temporary adhesive, temporary adhesive pressure aid, and pressure-enhancing lubricant.

[0015] Preferably, the release agent is a hydroxyl substance.

[0016] Preferably, the dispersant / decoction agent is a carboxylic acid preparation.

[0017] Preferred: The temporary adhesive is a polyvinyl alcohol product.

[0018] Preferred: The pressure-boosting lubricant is a fatty acid preparation or a polyoxyethylene preparation containing a nonionic emulsifier.

[0019] Preferably, in step S1, a high-shear mixer or a grinding ball mill is used for mixing and stirring to ensure that the silicon carbide powder is fully dispersed.

[0020] Preferably, the silicon carbide powder has a purity of 99.999%, and includes fine silicon carbide powder and coarse silicon carbide powder. The particle size of the fine silicon carbide powder is 0.5-4μm, and the particle size of the coarse silicon carbide powder is 80-150μm.

[0021] Preferably, in step S1, high-purity carbon powder and high-purity silicon powder are added and wet-mixed with silicon carbide fine powder, silicon carbide coarse powder, deionized water and additives to obtain slurry.

[0022] Preferred: the particle size of the toner is <1μm, and the particle size of the silicon powder is 1-15μm.

[0023] Preferably, in step S1, the preparation process of silicon carbide powder is as follows:

[0024] S11: Carbon powder and silicon powder are treated with surfactants;

[0025] S12: The treated carbon powder and silicon powder are mixed in a supercritical carbon dioxide environment with ultrasonic assistance to improve uniformity; a nano-graphene catalyst is added during the mixing process to reduce the activation energy of the reaction and promote the carbonization reaction.

[0026] S13: The mixed powder is shaped in an electrostatic field to form a uniform powder block;

[0027] S14: Microwave heating of the pressed powder and gradient heating to ensure uniform temperature distribution and reduce thermal stress.

[0028] Laser-assisted sintering is used during the heating process to quickly complete local sintering and improve reaction efficiency; and high-frequency acoustic vibration is applied during the heating process to promote particle densification and increase material uniformity and strength.

[0029] S15: After the reaction sintering is completed, vacuum annealing is performed to eliminate internal stress and improve the stability and performance of the material;

[0030] S16: The silicon carbide block after reaction sintering is crushed and ground to obtain silicon carbide powder.

[0031] Preferably, in step S11, the surfactant is a compound that reduces the surface tension of a liquid, and the surfactant contains a hydrophilic (oleophobic) group and an oleophilic (hydrophobic) group.

[0032] Preferably, the surfactant can be one of alkyl sulfates, alkylammonium salts, polyethylene glycol ethers, and sulfobetaine.

[0033] Preferred method: In step S13, the powder treated with surfactant and mixed with catalyst is completely dried, static electricity is applied to the powder, and an electrostatic device is used to make the powder uniformly charged; the charged powder is uniformly filled into a mold, the filled mold is placed in a hydraulic press, pressure is applied, and the powder is pressed into shape; finally, the powder block is obtained by demolding.

[0034] The beneficial effects of this invention are as follows: This invention proposes a method for preparing silicon carbide products, avoiding complex and expensive equipment such as hot press furnaces, which facilitates automated and mass production. It eliminates the need for a high-temperature and high-pressure environment, resulting in lower energy consumption and reduced production costs. Slip casting can produce more complex shapes and larger-sized blanks, while hot pressing is limited by mold size.

[0035] With the help of additives, the dispersion effect of silicon carbide powder can be improved, the coagulation problem can be effectively solved, and the adhesion effect can be improved.

[0036] The silicon carbide powder preparation method used in this invention can achieve the preparation of high-purity silicon carbide powder, resulting in denser and more uniform silicon carbide powder. It can also reduce energy consumption during preparation, thereby reducing the overall manufacturing cost of silicon carbide products by lowering the manufacturing cost of silicon carbide powder.

[0037] The silicon carbide powder preparation method employed in this invention utilizes supercritical fluid-assisted mixing, resulting in more uniform and finer powder mixing, and improving the uniformity and dispersibility of the particle surface. While ensuring uniformity, it does not affect the particle structure and avoids the contamination that may occur with traditional wet mixing methods.

[0038] By employing laser-assisted sintering, high energy density is provided, promoting rapid reaction and sintering, reducing impurity formation, and improving product quality. Overall thermal stress is reduced, and energy consumption is lowered through precise control of the sintering zone.

[0039] By employing acoustic-assisted sintering, the resulting micro-vibrations enhance interparticle contact, promote densification, and improve the mechanical strength and uniformity of the material. This also reduces particle agglomeration and optimizes the bonding between particles.

[0040] By combining supercritical fluids with lasers, the supercritical fluids provide a more uniform initial powder base, while the lasers can more effectively perform local heating, thus improving the sintering effect.

[0041] By combining laser and sound waves, the laser provides rapid energy, while the sound wave vibrations promote closer bonding of particles, enhancing the density and structural integrity of the material.

[0042] By combining supercritical fluids with sound waves, the vibration of the sound waves can eliminate tiny voids that may be generated during the mixing of supercritical fluids, further enhancing uniformity. Attached Figure Description

[0043] Figure 1 This is a screenshot of the SEM observation results table in Embodiment 4 of the present invention;

[0044] Figure 2 This is a screenshot of the XRD analysis table in Embodiment 4 of the present invention;

[0045] Figure 3 This is a screenshot of the density measurement table in Embodiment 4 of the present invention;

[0046] Figure 4 This is a screenshot of the material properties table from Embodiment 4 of the present invention;

[0047] Figure 5 This is a screenshot of the product quality table in Embodiment 4 of the present invention. Detailed Implementation

[0048] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, features described in some examples may be combined in other examples. Example 1

[0049] This embodiment presents a method for preparing high-purity silicon carbide products, comprising the following steps:

[0050] S1: Mud preparation;

[0051] Silicon carbide powder, deionized water, and additives are wet-mixed to prepare a slurry.

[0052] S2: Molding;

[0053] Under vacuum conditions, the slurry is injected into the precast mold, and then demolding, drying, kiln loading and firing are carried out in sequence.

[0054] S3: Finished product processing;

[0055] The fired silicon carbide products undergo pre-oxidation treatment and are then processed and modified.

[0056] S4: Finished product testing;

[0057] The silicon carbide products are tested, and if they pass the test, the desired silicon carbide products can be manufactured.

[0058] In step S1, the additives include one or more of the following: release agent, water-reducing agent, dispersant, temporary adhesive, temporary adhesive pressure aid, and pressure-enhancing lubricant; the additives are selected in this embodiment.

[0059] In this embodiment, the additive can be selected from one of the following: release agent, water-reducing agent, dispersant, temporary adhesive, temporary adhesive pressure aid, and pressure-enhancing lubricant.

[0060] In this embodiment, the preferred additive is a combination of release agent, water-reducing agent, dispersant and decoction agent, temporary adhesive and pressure-enhancing agent, and pressure-enhancing lubricant.

[0061] The release agent is a hydroxyl-based substance.

[0062] The dispersant / decoction agent is a carboxylic acid preparation.

[0063] The temporary adhesive is a polyvinyl alcohol product.

[0064] The pressure-boosting lubricant is a fatty acid preparation or a polyoxyethylene preparation containing a nonionic emulsifier.

[0065] In step S1, in this embodiment, a high-shear mixer or a grinding ball mill is used for mixing and stirring to ensure that the silicon carbide powder is fully dispersed. Example 2

[0066] This embodiment proposes a method for preparing high-purity silicon carbide products. The difference from Embodiment 1 is that silicon carbide fine powder, silicon carbide coarse powder, high-purity carbon powder, high-purity silicon powder, deionized water, and additives are wet-mixed and stirred to obtain a slurry.

[0067] Purity: 99.9% fine silicon carbide powder, 99.9% coarse silicon carbide powder, 99.9% carbon powder, and 99.9% silicon powder.

[0068] Purity: 99.99% fine silicon carbide powder, 99.99% coarse silicon carbide powder, 99.99% carbon powder, and 99.999% silicon powder.

[0069] Particle size: silicon carbide fine powder 0.5-4μm, silicon carbide coarse powder 80-150μm, carbon powder <1μm, silicon powder 1-15μm.

[0070] Additives: dispersants, strength agents, suspending agents, defoamers, release agents, binders

[0071] Molding method: High-pressure injection molding.

[0072] Process flow:

[0073] High-purity raw materials → particle coating treatment → mixing → adding various additives and water → slurry → high-pressure grouting → demolding → trimming → processing → sintering → finished product treatment → densification sintering, finished product processing → chemical cleaning → drying → cleanroom packaging → shipping.

[0074] Product properties: density ≥3.0g / cm³, strength ≥200Mpa, purity ≥99.99%. Example 3

[0075] This embodiment presents a method for preparing silicon carbide powder. The preparation process of silicon carbide powder is as follows:

[0076] S11: The carbon powder and silicon powder are treated with surfactants;

[0077] S12: The treated carbon powder and silicon powder are mixed in a supercritical carbon dioxide environment with ultrasonic assistance to improve uniformity; a nano-graphene catalyst is added during the mixing process to reduce the activation energy of the reaction and promote the carbonization reaction.

[0078] S13: The mixed powder is shaped in an electrostatic field to form a uniform powder block;

[0079] S14: Microwave heating of the pressed powder and gradient heating to ensure uniform temperature distribution and reduce thermal stress.

[0080] Laser-assisted sintering is used during the heating process to quickly complete local sintering and improve reaction efficiency; and high-frequency acoustic vibration is applied during the heating process to promote particle densification and increase material uniformity and strength.

[0081] S15: After the reaction sintering is completed, vacuum annealing is performed to eliminate internal stress and improve the stability and performance of the material;

[0082] S16: The silicon carbide block after reaction sintering is crushed and ground to obtain silicon carbide powder.

[0083] In step S11, the surfactant is a compound that reduces the surface tension of a liquid. The surfactant contains one hydrophilic (oleophobic) group and one oleophilic (hydrophobic) group. The surfactant can be one of alkyl sulfates, alkyl ammonium salts, polyethylene glycol ethers, or sulfobetaine.

[0084] In step S13, the powder treated with surfactant and mixed with catalyst is completely dried, static electricity is applied to the powder, and an electrostatic device is used to make the powder uniformly charged; the charged powder is uniformly filled into a mold, the filled mold is placed in a hydraulic press, pressure is applied, and the powder is pressed into shape; finally, the powder block is obtained by demolding. Example 4

[0085] In this embodiment, experimental methods are used to compare the uniformity, density, structural integrity, and other properties of silicon carbide powder prepared by conventional methods and the preparation method disclosed in Example 3.

[0086] Experimental steps:

[0087] 1. Sample preparation

[0088] Silicon carbide powder (sample A) was prepared using a traditional process.

[0089] Optimized silicon carbide powder was prepared using a new process, combining supercritical fluid, laser, and acoustic wave technologies (sample B).

[0090] 2. Microstructure observation (SEM)

[0091] Samples A and B were placed in a scanning electron microscope.

[0092] Observe the morphology and size distribution of the particles and record the surface characteristics.

[0093] 3. Crystallinity analysis (XRD)

[0094] The crystal structures of samples A and B were analyzed using X-ray diffraction.

[0095] Compare the peak intensity and width of the two groups of samples.

[0096] 4. Density measurement

[0097] The density of the sample was measured using a gas displacement apparatus.

[0098] Record data to analyze differences in density.

[0099] 5. Thermal conductivity test

[0100] The thermal conductivity of samples A and B was measured using laser flash analysis.

[0101] 6. Mechanical strength

[0102] Mechanical strength is measured using a compressive strength testing machine.

[0103] 7. Product quality assessment

[0104] Purity analysis: The purity of the two samples was analyzed using X-ray photoelectron spectroscopy (XPS).

[0105] Uniformity detection: Particle size distribution is measured using dynamic light scattering (DLS).

[0106] 8. Experimental Results

[0107] See attached Figures 1-5 .

[0108] 9. Conclusion

[0109] Experimental results show that, compared with traditional methods, the silicon carbide powder (sample B) prepared in Example 3 has significantly improved particle uniformity, surface smoothness, crystal quality and density. The thermal conductivity and mechanical strength of sample B are much higher than those of sample A. Sample B powder has achieved higher standards in purity and particle uniformity.

[0110] The embodiments of the present invention have been described above, but the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the embodiments described above, all of which are within the protection scope of the embodiments described above.

Claims

1. A method for preparing a high-purity silicon carbide product, characterized in that, Includes the following steps: S1: Mud preparation; Silicon carbide powder, deionized water, and additives are wet-mixed to prepare a slurry. The preparation process of silicon carbide powder is as follows: S11: The carbon powder and silicon powder are treated with surfactants; S12: The treated carbon powder and silicon powder are mixed in a supercritical carbon dioxide environment with ultrasonic assistance to improve uniformity; a nano-graphene catalyst is added during the mixing process to reduce the activation energy of the reaction and promote the carbonization reaction. S13: The mixed powder is shaped in an electrostatic field to form a uniform powder block; S14: Microwave heating of the pressed powder and gradient heating to ensure uniform temperature distribution and reduce thermal stress. Laser-assisted sintering is used during the heating process to quickly complete local sintering and improve reaction efficiency; and high-frequency acoustic vibration is applied during the heating process to promote particle densification and increase material uniformity and strength. S15: After the reaction sintering is completed, vacuum annealing is performed to eliminate internal stress and improve the stability and performance of the material; S16: The silicon carbide block after reaction sintering is crushed and ground to obtain silicon carbide powder; S2: Molding; Under vacuum conditions, the slurry is injected into the precast mold, and then demolding, drying, kiln loading and firing are carried out in sequence. S3: Finished product processing; The fired silicon carbide products undergo pre-oxidation treatment and are then processed and modified. S4: Finished product testing; The silicon carbide products are tested, and if they pass the test, the desired silicon carbide products can be manufactured.

2. The method for preparing a high-purity silicon carbide product according to claim 1, characterized in that, In step S1, the additives include one or more of the following: release agent, water-reducing agent, dispersant, temporary adhesive, temporary adhesive pressure aid, and pressure-enhancing lubricant.

3. The method for preparing a high-purity silicon carbide product according to claim 2, characterized in that, The release agent is a hydroxyl-based substance.

4. The method for preparing a high-purity silicon carbide product according to claim 2, characterized in that, The dispersant / decoction agent is a carboxylic acid preparation.

5. The method for preparing a high-purity silicon carbide product according to claim 2, characterized in that, The temporary adhesive is a polyvinyl alcohol product.

6. The method for preparing a high-purity silicon carbide product according to claim 2, characterized in that, The pressure-boosting lubricant is a fatty acid preparation or a polyoxyethylene preparation containing a nonionic emulsifier.

7. The method for preparing a high-purity silicon carbide product according to claim 1, characterized in that, In step S1, a high-shear mixer or a grinding ball mill is used for mixing and stirring to ensure that the silicon carbide powder is fully dispersed.

8. The method for preparing a high-purity silicon carbide product according to claim 1, characterized in that, In step S11, the surfactant is a compound that reduces the surface tension of a liquid, and the surfactant contains a hydrophilic group and a lipophilic group.

9. The method for preparing a high-purity silicon carbide product according to claim 8, characterized in that, Surfactants are one of the following: alkyl sulfates, alkylammonium salts, polyethylene glycol ethers, and sulfobetaine.

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