Silicon carbide nanopowder and method of making
By combining rapid Joule heating and a muffle furnace, nano-silicon carbide powder was prepared using biomass waste, solving the problems of high energy consumption and long cycle time of traditional processes. This method achieves efficient and low-cost preparation of nano-silicon carbide and improves downstream application effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANXI UNIV
- Filing Date
- 2024-04-28
- Publication Date
- 2026-06-12
AI Technical Summary
Traditional silicon carbide powder preparation processes involve high reaction temperatures and long reaction times, resulting in high energy consumption, long production cycles, and particle sizes that are mostly in the micrometer range, making it difficult to meet the needs of downstream applications.
A method combining rapid Joule heating and a muffle furnace was adopted to use biomass waste such as distiller's grains or vinegar residues as raw materials, which were mixed with nano-silica to prepare silicon carbide/carbon composite powder at low temperature and in a short time. The powder was then heated in air and purified with hydrofluoric acid to obtain high-purity nano-silicon carbide powder.
The reaction temperature and time were significantly reduced, energy consumption was decreased, production efficiency was improved, high-purity nanoscale silicon carbide powder was obtained, the performance of downstream products was enhanced, and the high-value utilization of distiller's grains and vinegar residues was realized.
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Figure CN118343762B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor materials technology, specifically relating to a silicon carbide nanopowder and its preparation method. Background Technology
[0002] Silicon carbide, due to its advantages such as high hardness, high thermal conductivity, low coefficient of thermal expansion, high temperature resistance, and chemical corrosion resistance, has wide applications in high-power semiconductor components, abrasives, electric heating elements, high-temperature crucibles, and kiln linings. Common silicon carbide products are divided into two varieties: black silicon carbide and green silicon carbide, both composed of the hexagonal α phase. Compared to black silicon carbide, green silicon carbide has higher purity and greater hardness, giving it a greater advantage in high-end markets such as cemented carbide and high thermal conductivity, wear-resistant components.
[0003] Traditional silicon carbide production processes involve mixing silica sand of a specific particle size with carbon sources such as coke, heating the mixture in an electric furnace to temperatures exceeding 2000°C, and reacting for tens or even hundreds of hours. After decarburization and acid washing, high-purity silicon carbide particles are obtained. For example, patent application number 202311369718.3 discloses a silicon carbide powder and its preparation method. This method involves a three-layer classification process of the carbon / silicon powder mixture, controlling the heating mechanism, and reacting at a final temperature of 2050°C to 2250°C for several hours. After oxygen decarburization, micron-sized silicon carbide powder is obtained. From the above process routes, it can be seen that the current industrial silicon carbide powder preparation routes require high reaction temperatures and excessively long reaction times, resulting in high energy consumption and long production cycles. Regarding particle size control, the silicon carbide obtained so far is mostly micron-sized particles. Compared to micron-sized silicon carbide powder, nano-sized powder performs better in downstream applications. When used as a particulate dispersion reinforcing phase and a raw material for silicon carbide ceramics, it can improve the reinforcing effect of composite materials, lower the sintering temperature of ceramics, and improve the density and other properties of products. Summary of the Invention
[0004] To address the problems of high energy consumption and long production cycles caused by excessively high reaction temperatures and long reaction times in traditional silicon carbide powder preparation processes, this invention provides a method for preparing silicon carbide nanopowder, enabling the preparation of high-quality silicon carbide powder materials at low reaction temperatures and ultra-short reaction times. Furthermore, the method produces nanoscale silicon carbide ultrafine powder, which significantly improves the performance of downstream products compared to traditional micron-scale silicon carbide powder.
[0005] To achieve the above objectives, the present invention employs the following technical solutions:
[0006] A method for preparing silicon carbide nanopowder includes the following steps:
[0007] Step 1: Pre-carbonize the dried distiller's grains or vinegar residues under vacuum or inert gas protection to obtain pre-carbonized biomass.
[0008] Step 2: The pre-carbonized biomass is crushed to obtain pre-carbonized biomass powder. The pre-carbonized biomass powder is uniformly mixed with nano-silica and reacted in a rapid Joule thermal reactor to obtain silicon carbide / carbon composite powder.
[0009] Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace and continuously blow air in for heating and reaction to obtain nano-silicon carbide powder material.
[0010] Step 4: The nano-silicon carbide powder material is stirred and purified in hydrofluoric acid aqueous solution, washed with water until neutral, and then dried to obtain high-purity silicon carbide nano-powder.
[0011] Furthermore, in step 1, the pre-carbonization treatment temperature is 550℃~800℃, and the pre-carbonization treatment is followed by holding at that temperature for 0.5~3 hours. Preferably, the pre-carbonization treatment temperature is 600℃~750℃, and the holding time is preferably 1~2 hours.
[0012] Furthermore, in step 2, the reaction in the rapid Joule heating reactor is specifically carried out by heating to 1600℃~2500℃ at a rate of 500℃ / min~4000℃ / min, and holding at that temperature for 0.5 seconds~120 seconds. The preferred heating rate in the rapid Joule heating reactor is 1000℃ / min~3000℃ / min, the preferred reaction temperature is 1800℃~2300℃, and the preferred holding time is 5~100 seconds.
[0013] Furthermore, in step 3, the heating rate of the reaction is 3°C / min to 12°C / min, the reaction temperature is 500°C to 800°C, and the holding time is 1 to 10 hours. Preferably, the heating rate of the reaction in step 3 is 5°C / min to 10°C / min, the reaction temperature is 600°C to 750°C, and the holding time is 2 to 8 hours.
[0014] Furthermore, in step 4, the temperature for stirring and purification is 20-60℃, and the stirring time is 2-8 hours.
[0015] Furthermore, the inert gas in step 1 is nitrogen, argon, or a mixture of nitrogen and argon in any proportion.
[0016] Furthermore, in step 2, the average particle size of the pre-carbonized biomass powder is 48 μm to 300 μm; the particle size of the nano-silica is 10 nm to 200 nm. Preferably, the average particle size of the pre-carbonized biomass powder is 100 μm to 250 μm, and the particle size of the nano-silica is preferably 20 nm to 150 nm.
[0017] Furthermore, in step 4, the concentration of the hydrofluoric acid aqueous solution is 3 mol / L to 20 mol / L. Preferably, the concentration of the hydrofluoric acid aqueous solution is 5 mol / L to 15 mol / L.
[0018] Furthermore, in step 3, the nano-silicon carbide is in the α phase with a purity >98%, and the silicon carbide nanopowder purified by hydrofluoric acid solution in step 4 has a purity >99.5% and an average particle size of 20~190 nanometers.
[0019] Silicon carbide nanopowder was prepared according to the above preparation method.
[0020] Compared with the prior art, the present invention has the following advantages:
[0021] 1. This invention addresses the drawbacks of traditional silicon carbide powder production processes, such as high energy consumption and long production cycles. It develops a novel preparation method using rapid Joule heating technology to solve these problems, significantly reducing the silicon carbide formation reaction temperature and achieving rapid and complete conversion of silica raw materials to silicon carbide in just seconds or tens of seconds. In actual production, this significantly improves quality and efficiency, and effectively reduces energy consumption and costs.
[0022] 2. This invention utilizes biomass solid waste, such as distiller's grains and vinegar lees, which are produced in large quantities in the brewing and vinegar-making industries, as raw materials, resulting in extremely low costs. Furthermore, the silica content in the ash of this type of biomass exceeds 60%, existing as silica nanoparticles in the biomass pre-carbonization material. The remaining impurities are mostly alkali (earth) metal oxides that are easily removed at high temperatures, making the impurity removal process simple. Considering the high reactivity of the carbon components in this type of biomass pre-carbonization material, the conversion to silicon carbide can be achieved at a relatively low temperature and in a very short time after uniform mixing with nano-silica. The resulting nano-silica exhibits better downstream application effects and higher economic value compared to micron-sized silicon carbide.
[0023] 3. This invention also solves the problem of high-value utilization of solid wastes such as distiller's grains and vinegar residues, and has significant social benefits. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the rapid Joule thermal reaction apparatus used in the present invention for preparing silicon carbide nanopowder materials.
[0025] Figure 2 This is the X-ray diffraction pattern of the product in Embodiment 1 of the present invention.
[0026] Figure 3 This is a scanning electron microscope image of the product of Embodiment 1 of the present invention.
[0027] Reference numerals in the attached diagram: 1. DC power supply; 2. Contactor switch; 3. Left conductive stainless steel rod; 4. Right conductive stainless steel rod; 5. Left graphite electrode rod; 6. Right graphite electrode rod; 7. Base; 8. Quartz tube; 9. Vacuum chamber; 10. Reaction materials. Detailed Implementation
[0028] To gain a deeper understanding of this invention, we will provide a comprehensive and detailed description. However, this invention has various implementations and is not limited to the specific examples listed herein. These examples are presented to enhance a full understanding of the disclosure of this invention.
[0029] Example 1
[0030] Step 1: Place the dried distiller's grains in a tubular carbonization furnace and heat to 700°C under nitrogen protection. Hold for 1.5 hours to obtain pre-carbonized biomass.
[0031] Step 2: After pulverizing and sieving the pre-carbonized biomass, a powder with an average particle size of 150 μm is obtained. This powder is then uniformly mixed with silica with a particle size of 30 nanometers and placed in a rapid Joule heating reactor. The temperature is increased to 1800°C at a rate of 2000°C / min and held at that temperature for 30 seconds to obtain silicon carbide / carbon composite powder.
[0032] Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace, continuously blow air in, and heat it to 600°C at a rate of 5°C / minute. Hold the temperature for 6 hours to obtain nano-silicon carbide powder material.
[0033] Test results show that the purity of the silicon carbide powder is 98.6% and the average particle size is 45 nanometers.
[0034] Figure 2 The X-ray diffraction pattern of the product in Example 1 shows that the prepared nano-silicon carbide is an α phase with a hexagonal crystal structure and the phase has a high purity.
[0035] Figure 3 This is a scanning electron microscope (SEM) image of the product from Example 1. It can be seen that most particles in the powder are smaller than 50 nanometers. Due to the high surface energy, soft agglomeration occurs between the particles, requiring ultrasonic dispersion treatment before use to ensure uniformity.
[0036] Example 2
[0037] Step 1: Place the dried vinegar residue in a tubular carbonization furnace and heat it to 550°C under argon protection. Hold the temperature for 3 hours to obtain pre-carbonized biomass.
[0038] Step 2: After pulverizing and sieving the pre-carbonized biomass, a powder with an average particle size of 300 μm is obtained. This powder is then uniformly mixed with silica with a particle size of 200 nanometers and placed in a rapid Joule heating reactor, where the temperature is raised to 2200°C at a rate of 500°C / min and held at that temperature for 40 seconds to obtain silicon carbide / carbon composite powder.
[0039] Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace, continuously blow air in, and heat it to 800°C at a rate of 3°C / minute. Hold the temperature for 4 hours to obtain nano-silicon carbide powder material.
[0040] Step 4: To obtain higher purity, the powder was stirred in a 10 mol / L hydrofluoric acid aqueous solution at 20°C for 4 hours, washed with water until neutral, and then dried to obtain purified nano-silicon carbide powder.
[0041] Test results show that the purity of the silicon carbide nanopowder is 99.1% and the average particle size is 190 nanometers.
[0042] Example 3
[0043] Step 1: Place the dried distiller's grains in a tubular carbonization furnace and heat to 800°C under vacuum conditions, then hold for 0.5 hours to obtain pre-carbonized biomass.
[0044] Step 2: After pulverizing and sieving the pre-carbonized biomass, a powder with an average particle size of 48 μm is obtained. This powder is then uniformly mixed with silica with a particle size of 10 nanometers and placed in a rapid Joule heating reactor. The temperature is increased to 2500℃ at a rate of 4000℃ / min and held at that temperature for 0.5 seconds to obtain silicon carbide / carbon composite powder.
[0045] Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace, continuously blow air in, and heat it to 500°C at a rate of 12°C / min. Hold the temperature for 10 hours to obtain nano-silicon carbide powder material.
[0046] Step 4: To obtain higher purity, the powder was stirred in a 15 mol / L hydrofluoric acid aqueous solution at 40°C for 2 hours, washed with water until neutral, and then dried to obtain purified nano-silicon carbide powder.
[0047] Test results show that the purity of the silicon carbide nanopowder is 99.9% and the average particle size is 20 nanometers.
[0048] Example 4
[0049] Step 1: Place the dried vinegar residue in a tubular carbonization furnace and heat it to 650°C under argon protection. Hold the temperature for 2.5 hours to obtain pre-carbonized biomass.
[0050] Step 2: After pulverizing and sieving the pre-carbonized biomass, a powder with an average particle size of 100 μm is obtained. This powder is then uniformly mixed with silica with a particle size of 50 nanometers and placed in a rapid Joule heating reactor. The temperature is increased to 2000℃ at a rate of 1500℃ / min and held at that temperature for 45 seconds to obtain silicon carbide / carbon composite powder.
[0051] Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace, continuously blow air in, and heat to 700°C at a rate of 6°C / min. Hold the temperature for 5 hours to obtain nano-silicon carbide powder material.
[0052] Step 4: To obtain higher purity, the powder was stirred in a 3 mol / L hydrofluoric acid aqueous solution at 60°C for 8 hours, washed with water until neutral, and then dried to obtain purified nano-silicon carbide powder.
[0053] Test results show that the purity of the silicon carbide nanopowder is 99.3% and the average particle size is 65 nanometers.
[0054] Example 5
[0055] Step 1: Place the dried distiller's grains in a tubular carbonization furnace and heat to 750°C under vacuum conditions, then hold for 0.5 to 3 hours to obtain pre-carbonized biomass.
[0056] Step 2: After pulverizing and sieving the pre-carbonized biomass, a powder with an average particle size of 250 μm is obtained. This powder is then uniformly mixed with silica with a particle size of 50 nanometers and placed in a rapid Joule heating reactor. The temperature is increased to 1600°C at a rate of 1200°C / min and held at that temperature for 120 seconds to obtain silicon carbide / carbon composite powder.
[0057] Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace, continuously blow air in, and heat it to 650°C at a rate of 5°C / min. Hold the temperature for 6 hours to obtain nano-silicon carbide powder material.
[0058] Step 4: To obtain higher purity, the powder was stirred in a 20 mol / L hydrofluoric acid aqueous solution at 30°C for 5 hours, washed with water until neutral, and then dried to obtain purified nano-silicon carbide powder.
[0059] Test results show that the purity of the silicon carbide nanopowder is 99.8% and the average particle size is 46 nanometers.
[0060] Contents not described in detail in this specification are prior art known to those skilled in the art. Although illustrative specific embodiments of the invention have been described above to facilitate understanding by those skilled in the art, it should be understood that the invention is not limited to the scope of the specific embodiments. Various modifications are readily apparent to those skilled in the art as long as they fall within the spirit and scope of the invention as defined and determined by the appended claims, and all inventions utilizing the concept of this invention are protected.
Claims
1. A method for preparing silicon carbide nanopowder, characterized in that, Includes the following steps: Step 1: Pre-carbonize the dried distiller's grains or vinegar residues under vacuum or inert gas protection to obtain pre-carbonized biomass. Step 2: The pre-carbonized biomass is crushed to obtain pre-carbonized biomass powder. The pre-carbonized biomass powder is uniformly mixed with nano-silica and reacted in a rapid Joule thermal reactor to obtain silicon carbide / carbon composite powder. Step 3: Place the silicon carbide / carbon composite powder in a muffle furnace and continuously blow air in for heating and reaction to obtain nano-silicon carbide powder material. Step 4: The nano-silicon carbide powder material is stirred and purified in hydrofluoric acid aqueous solution, washed with water until neutral, and then dried to obtain high-purity silicon carbide nano-powder. The nano-silicon carbide in step 3 is the α phase.
2. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: The temperature of the pre-carbonization treatment in step 1 is 550℃~800℃, and the temperature is maintained for 0.5~3 hours after the pre-carbonization treatment.
3. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 2, the reaction in the rapid Joule heating reactor is specifically carried out by heating to 1600℃~2500℃ at a rate of 500℃ / min~4000℃ / min and holding at that temperature for 0.5 seconds~120 seconds.
4. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 3, the heating rate of the reaction is 3℃ / min to 12℃ / min, the reaction temperature is 500℃ to 800℃, and the holding time is 1 to 10 hours.
5. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 4, the temperature for stirring and purification is 20-60℃, and the stirring time is 2-8 hours.
6. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 1, the inert gas is nitrogen, argon, or a mixture of nitrogen and argon in any proportion.
7. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 2, the average particle size of the pre-carbonized biomass powder is 48 μm to 300 μm; the particle size of the nano-silica is 10 nm to 200 nm.
8. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 4, the concentration of the hydrofluoric acid aqueous solution is 3 mol / L to 20 mol / L.
9. The method for preparing silicon carbide nanopowder according to claim 1, characterized in that: In step 3, the purity of the nano-silicon carbide is >98%, and the purity of the silicon carbide nanopowder after purification with hydrofluoric acid solution in step 4 is >99.5%, with an average particle size of 20~190 nanometers.
10. Silicon carbide nanoparticles prepared by the preparation method according to any one of claims 1 to 9.