A method for preparing a SiC ceramic powder

Abstract

The application provides a preparation method of SiC ceramic powder and belongs to the field of inorganic nonmetallic materials and nanocomposites. The steps of the specific preparation method are as follows: adding silicon carbide powder into an ethanol aqueous solution and ultrasonically stirring for 1-2 hours; preparing SiO2 sol in the above mixed solution, and obtaining nano-coated silicon carbide particles after drying; adding polyethylene glycol 10000 into anhydrous ethanol, adding treated silicon carbide particles after ultrasonically stirring for 0.5-1 hour, magnetically stirring for 1-2 hours, uniformly mixing after adding PVA, sealing and standing, granulating and drying, heat treating these SiC particles at 1200-1500 DEG C under vacuum for 2-3 hours, cooling to room temperature, and pressureless heat treating at 500-600 DEG C for 2-3 hours to obtain particle size reconstructed SiC ceramic powder. By adding SiO2 sol and polyethylene glycol 10000, the sintering temperature is greatly reduced, the particle size reconstructed ceramic powder has high purity and excellent use performance, and the problem of utilization of waste silicon carbide powder in ceramics is solved.

Description

Technical Field

[0001] This invention belongs to the field of inorganic non-metallic materials and nanocomposite materials, and in particular relates to a method for preparing SiC ceramic powder. Background Technology

[0002] Silicon carbide ceramics, as a new type of structural ceramic material, have many properties that are unmatched by structural materials such as metals, such as high high-temperature strength, low coefficient of thermal expansion, excellent wear resistance, strong corrosion resistance, high hardness, and low high-temperature creep. They are used in fields such as high-temperature corrosion, national defense and military industry, semiconductors, and grinding.

[0003] The particle size of silicon carbide has a crucial impact on its applications. Silicon carbide is widely used in ceramics, where it exhibits excellent properties but is difficult to densify through sintering. Using small-particle-size silicon carbide powder in ceramic preparation hinders molding and negatively impacts the performance of the sintered product. During silicon carbide production, many ultrafine silicon carbide powders are often generated. These excessively fine powders cannot be effectively utilized, leading to increased production costs and environmental pollution. Particle size reshaping can enable ultrafine silicon carbide powders to meet the basic particle size requirements of ceramic materials, thereby more effectively utilizing resources and reducing production costs. Summary of the Invention

[0004] To address the problems in the production and application of silicon carbide, this invention provides a method for preparing SiC ceramic powder by using SiO2 sol, polyethylene glycol, and PVA as additives.

[0005] Specifically, the present invention provides a method for preparing SiC ceramic powder, which is implemented according to the following steps: S1: Weigh a certain amount of silicon carbide micro powder, add the silicon carbide micro powder from S2 to the aqueous solution of ethanol under ultrasonic stirring, and continue stirring for 1~2 hours until fully dispersed. The volume ratio of anhydrous ethanol to water in the aqueous solution of anhydrous ethanol is 1~3:1, and the volume ratio of anhydrous ethanol to silicon carbide micro powder is 0.2~1ml:1g. S2: Preparation of nano-coated silicon carbide particles; S21: Tetraethyl orthosilicate is added to the SiC mixture of S1 under ultrasonic stirring. The mass ratio of SiO2 in tetraethyl orthosilicate to silicon carbide in S1 is 3%~10%. Stirring is continued, and glacial acetic acid is added to adjust the pH value to 1~3. After reacting for 2~6 hours, the mixture is dried at 80~120℃ for 4~8 hours to obtain nano-coated silicon carbide particles. S3: Add polyethylene glycol 10000 to 10-15 ml of anhydrous ethanol under ultrasonic stirring. The molar ratio of C content in polyethylene glycol 10000 to Si content in tetraethyl orthosilicate in S21 is 1.2-2. Continue stirring for 0.5-1 h until fully dispersed. S4: Add the nano-coated silicon carbide particles in S21 to the mixed solution of S3 polyethylene glycol 10000 under magnetic stirring, and continue magnetic stirring for 1~2 hours until fully dispersed. Dry at 100~150℃ for 3~5 hours to obtain silicon carbide mixed powder. S5: PVA is added to the silicon carbide mixed powder of S4. The mass percentage of PVA to the mass of silicon carbide mixed powder of S4 is 3% to 5%. The mixture is mechanically stirred for 1 to 2 hours. After mixing evenly, it is sealed and allowed to stand for 5 to 10 hours to obtain SiC micro powder mixture. S6: Pour the powder mixed evenly in S5 into a granulator for granulation to obtain SiC particles with uniform size and a particle size range of 10~200μm. Dry them at 90~100℃ for 1~2h to obtain SiC particles with appropriate moisture content. S7: The silicon carbide particles processed in S6 are placed in a high-temperature vacuum atmosphere furnace for sintering. They are then heat-treated at 1300~1500℃ for 2~3 hours. After cooling to room temperature, they are placed in a muffle furnace for heat treatment at 500~600℃ for 2~3 hours to obtain particle size remodeled SiC ceramic powder.

[0006] Preferably, the particle size of the SiC micro powder used in S1 is 0.5~3μm.

[0007] Preferably, the mass ratio of SiO2 in the tetraethyl orthosilicate used in S21 to silicon carbide in S1 is 3% to 10%.

[0008] Preferably, the molar ratio of the carbon content in polyethylene glycol 10000 used in S3 to the silicon content in tetraethyl orthosilicate in S21 is 1.2 to 2. The organic carbon source polyethylene glycol 10000 can be replaced with polyethylene glycol 2000, polyethylene glycol 6000, polyethylene glycol 20000, glucose, etc.

[0009] Preferably, the sintering temperature of SiC particles in S7 is 1300℃~1500℃, and the sintering atmosphere can be vacuum argon protection or vacuum nitrogen protection; the temperature of the secondary heat treatment is 500~600℃.

[0010] The silicon carbide ceramic powder prepared by the above method has high purity, low porosity, and excellent performance.

[0011] The silicon carbide ceramic powder with resized particles prepared by the above method has a wide range of applications, especially in high-temperature corrosion resistance, national defense and military industries, and special ceramics.

[0012] The technical solution of the present invention has the following beneficial effects: This invention first provides a method for preparing SiC ceramic powder, using polyethylene glycol 10000, SiO2 sol, and PVA as additives to solve the problem of unusable silicon carbide micropowder due to its excessively fine particle size. The addition of nano-SiO2 sol and polyethylene glycol 10000 lowers the sintering temperature, and the resized ceramic powder exhibits high purity, low porosity, and excellent performance, effectively solving the problem of reusing waste silicon carbide powder in ceramics. The SiC ceramic powder preparation method provided by this invention can also be well applied to other types of ceramic micropowders, demonstrating excellent practicality. Detailed Implementation

[0013] The present invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the embodiments are for better understanding of the technical solution of the present invention and for implementation, and should not be regarded as a limitation of the present invention.

[0014] All technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the methods used in the following embodiments are conventional methods, and the raw materials used are commercially available analytical grade raw materials. This is not intended to limit the invention; those skilled in the art can repeat the invention using similar methods, equipment, and materials based on their mastery of the prior art and the description of this invention.

[0015] The technical solution of the present invention will be illustrated with specific examples below.

[0016] Example 1 A method for preparing SiC ceramic powder, the specific steps of which are as follows: S1: Weigh 30g of silicon carbide micro powder, add the silicon carbide micro powder from S2 to 30ml of ethanol aqueous solution under ultrasonic stirring, and continue stirring for 2h until fully dispersed. The volume ratio of anhydrous ethanol to water in the anhydrous ethanol aqueous solution is 1.5:1, and the volume ratio of anhydrous ethanol to silicon carbide micro powder is 1ml:1g. S2: Preparation of nano-coated silicon carbide particles; S21: Tetraethyl orthosilicate is added to the SiC mixture of S1 under ultrasonic stirring. The mass ratio of SiO2 in tetraethyl orthosilicate to silicon carbide in S1 is 5%. Stirring is continued, glacial acetic acid is added to adjust the pH value to 2, and after reacting for 6 hours, it is dried at 80°C for 8 hours to obtain nano-coated silicon carbide particles. S3: Add polyethylene glycol 10000 to 15 ml of anhydrous ethanol under ultrasonic stirring. The molar ratio of C content in polyethylene glycol 10000 to Si content in tetraethyl orthosilicate in S21 is 1.5. Stir continuously for 1 hour until fully dispersed. S4: Add the nano-coated silicon carbide particles in S21 to the mixed solution of polyethylene glycol 10000 in S3 under magnetic stirring, continue magnetic stirring for 2 hours until fully dispersed, and dry at 100℃ for 5 hours to obtain silicon carbide mixed powder. S5: PVA is added to the silicon carbide mixed powder of S4. The mass percentage of PVA to the mass of silicon carbide mixed powder of S4 is 5%. The mixture is mechanically stirred for 1 hour. After being mixed evenly, it is sealed and allowed to stand for 10 hours to obtain SiC micro powder mixture. S6: Pour the powder mixed evenly in S5 into a granulator for granulation to obtain SiC particles with uniform size and a particle size of 15μm. Dry at 90℃ for 1h to obtain SiC particles with appropriate moisture content. S7: The silicon carbide particles processed in S6 are placed in a high-temperature vacuum atmosphere furnace for sintering, and then heat-treated at 1450℃ for 3 hours. After cooling to room temperature, they are placed in a muffle furnace and heat-treated at 500℃ for 2 hours to obtain SiC ceramic powder with resized particles.

[0017] Example 2 A method for preparing SiC ceramic powder, the specific steps of which are as follows: S1: Weigh 30g of silicon carbide micro powder, add the silicon carbide micro powder from S2 to 20ml of ethanol aqueous solution under ultrasonic stirring, and continue stirring for 2h until fully dispersed. The volume ratio of anhydrous ethanol to water in the anhydrous ethanol aqueous solution is 2:1, and the volume ratio of anhydrous ethanol to silicon carbide micro powder is 1ml:1g. S2: Preparation of nano-coated silicon carbide particles; S21: Tetraethyl orthosilicate is added to the SiC mixture of S1 under ultrasonic stirring. The mass ratio of SiO2 in tetraethyl orthosilicate to silicon carbide in S1 is 7%. Stirring is continued, glacial acetic acid is added to adjust the pH value to 3, and after reacting for 6 hours, it is dried at 80°C for 8 hours to obtain nano-coated silicon carbide particles. S3: Add polyethylene glycol 10000 to 15 ml of anhydrous ethanol under ultrasonic stirring. The molar ratio of C content in polyethylene glycol 10000 to Si content in tetraethyl orthosilicate in S21 is 1.5. Stir continuously for 1 hour until fully dispersed. S4: Add the nano-coated silicon carbide particles in S21 to the mixed solution of polyethylene glycol 10000 in S3 under magnetic stirring, continue magnetic stirring for 1 hour until fully dispersed, and dry at 100℃ for 5 hours to obtain silicon carbide mixed powder. S5: PVA is added to the silicon carbide mixed powder of S4. The mass percentage of PVA to the mass of silicon carbide mixed powder of S4 is 5%. The mixture is mechanically stirred for 1 hour. After being mixed evenly, it is sealed and allowed to stand for 10 hours to obtain SiC micro powder mixture. S6: Pour the powder mixed evenly in S5 into a granulator for granulation to obtain SiC particles with uniform size and a particle size of 20μm. Dry at 90℃ for 1h to obtain SiC particles with appropriate moisture content. S7: The silicon carbide particles processed in S6 are placed in a high-temperature vacuum atmosphere furnace for sintering, and then heat-treated at 1450℃ for 3 hours. After cooling to room temperature, they are placed in a muffle furnace and heat-treated at 500℃ for 2 hours to obtain SiC ceramic powder with resized particles.

[0018] The SiC ceramic powders prepared in Examples 1 and 2 exhibit stable processing, reliable quality, and excellent performance. For instance, we selected SiC particles with particle sizes of 15μm and 20μm prepared in Examples 1 and 2, respectively, to prepare SiC ceramics. Compared with SiC ceramics prepared from commercially available SiC powder of the same particle size, the sintering temperature was lower. The sintering temperatures of the SiC ceramics prepared in Examples 1 and 2 were reduced by 50℃ and 40℃, respectively, and their strengths increased by 2% and 3%, respectively. Furthermore, the ceramic powder prepared by this invention has good molding fluidity and higher density.

[0019] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and their protection scope is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the protection scope of the present invention, which is defined by the claims.

Claims

1. A method for preparing SiC ceramic powder, characterized in that, The specific implementation steps are as follows: S1: Weigh silicon carbide micro powder, add it to an aqueous solution of anhydrous ethanol under ultrasonic stirring, and continue stirring for 1-2 hours until fully dispersed; the volume ratio of anhydrous ethanol to water in the aqueous solution is 1-3:1, and the volume ratio of anhydrous ethanol to silicon carbide micro powder is 0.2-1 ml:1 g; the particle size of the silicon carbide micro powder is 0.5-3 μm. S2: Preparation of nano-coated silicon carbide particles: Tetraethyl orthosilicate is added to the silicon carbide mixture of S1 under ultrasonic stirring. The tetraethyl orthosilicate contains... The mass ratio of silicon carbide in S1 to the amount of silicon carbide is 3%~10%. The mixture is stirred continuously, and glacial acetic acid is added to adjust the pH value to 1~3. After reacting for 2~6 hours, the mixture is dried at 80~120℃ for 4~8 hours to obtain nano-coated silicon carbide particles. S3: Add polyethylene glycol 10000 to 10-15 ml of anhydrous ethanol under ultrasonic stirring. The molar ratio of C content in polyethylene glycol 10000 to Si content in tetraethyl orthosilicate in S2 is 1.2-2. Continue stirring for 0.5-1 h until fully dispersed. S4: Add the nano-coated silicon carbide particles from S2 to the polyethylene glycol 10000 mixed solution from S3 under magnetic stirring. Continue magnetic stirring for 1-2 hours until fully dispersed, and dry at 100-150℃ for 3-5 hours to obtain silicon carbide mixed powder. S5: PVA is added to the silicon carbide mixed powder of S4. The mass percentage of PVA to the mass percentage of silicon carbide mixed powder of S4 is 3%~5%. The mixture is mechanically stirred for 1~2 hours. After mixing evenly, it is sealed and allowed to stand for 5~10 hours to obtain SiC micro powder mixture. S6: Pour the powder that has been mixed evenly in S5 into a granulator for granulation to obtain SiC particles with uniform size and a particle size range of 10~200μm, and dry them at 90~100℃ for 1~2h. S7: The silicon carbide particles processed in S6 are placed in a high-temperature vacuum atmosphere furnace for sintering. The sintering atmosphere is vacuum argon protection or vacuum nitrogen protection. The particles are heat-treated at 1300~1500℃ for 2~3 hours. After cooling to room temperature, they are placed in a muffle furnace for heat treatment at 500~600℃ for 2~3 hours to obtain SiC ceramic powder with resized particles.

2. The preparation method according to claim 1, characterized in that, Replace the polyethylene glycol 10000 mentioned in S3 with any one of polyethylene glycol 2000, polyethylene glycol 6000, polyethylene glycol 20000, or glucose.

3. A SiC ceramic powder, characterized in that, Prepared by the method according to claim 1 or 2.

4. The SiC ceramic powder according to claim 3, characterized in that, It is used in high-temperature and corrosion-resistant applications.