Preparation process of high-purity silicon carbide micro powder

Abstract

The invention relates to the field of preparation of silicon carbide micro powder, in particular to a preparation process of high-purity silicon carbide micro powder, which comprises the following steps: mixing silicon powder and carbon powder in proportion; the mixed raw materials generate silicon carbide in the heating chamber; cooling the silicon carbide; preliminarily grinding to obtain silicon carbide particles; purifying the silicon carbide particles; drying equipment is used for removing moisture in the silicon carbide particles, and the silicon carbide particles are finely ground into silicon carbide micro powder; judging the production quality according to the purity of the silicon carbide micro powder; and determining a corresponding mode for improving the purity of the silicon carbide according to the production quality. According to the method, the controllability of the purity of the prepared silicon carbide micro powder is improved through free carbon removal and acid pickling, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of preparation of silicon carbide micropowder, and in particular to a preparation process of high-purity silicon carbide micropowder. Background Art

[0002] As an important wide bandgap semiconductor material, silicon carbide has excellent physical and chemical properties, such as high hardness, high thermal conductivity, and high chemical stability. It is widely used in many fields such as semiconductors, electronics, new energy, and aerospace. However, to achieve these high-performance applications, high-purity silicon carbide powder is often required as a basic raw material. In the past few decades, although the preparation technology of silicon carbide powder has made certain progress, it still faces many challenges. Traditional preparation methods, such as the Acheson method and the vapor deposition method, have certain limitations in purity control. Silicon carbide produced by the Acheson method usually contains more impurities, such as carbon, silicon, iron, and aluminum, which greatly limits its application in high-end fields. Although the vapor deposition method can produce high-purity silicon carbide, it is difficult to achieve large-scale production due to its complex process and high cost. With the rapid development of science and technology, the purity requirements for silicon carbide powder are getting higher and higher. For example, in the field of semiconductor manufacturing, in order to ensure the performance and reliability of chips, silicon carbide powder with a purity of more than 99.999% is required. In the power devices of new energy vehicles, high-purity silicon carbide powder can significantly improve the efficiency and stability of the devices. Therefore, developing an efficient, low-cost, large-scale production process for high-purity silicon carbide powder has become a research hotspot and urgent need in the current field of materials science. This will not only help promote the widespread application of silicon carbide materials in various fields, but also enhance my country's independent innovation capabilities and international competitiveness in the field of high-end materials.

[0003] Chinese patent publication number CN106882806A discloses a method for preparing silicon carbide micropowder, including: mixing silicon powder and carbon powder in a ratio of 1:2 to obtain a mixture; placing the mixture in a heating chamber, heating it to 1200°C to 1300°C with microwaves, and maintaining it for 5 minutes to achieve complete reaction of the mixture to obtain silicon carbide powder; placing the silicon carbide powder in air, heating it to 580°C to 650°C to remove free carbon, and obtaining a high-purity β-silicon carbide micropowder with a diameter of less than 0.4 microns and 99%; both silicon powder and carbon powder use high-purity 99% silicon powder and carbon powder, and the particle diameters of silicon powder and carbon powder are between 20 microns and 100 microns; the microwave frequency uses 2.45GHz. It can be seen that the invention has the problem of being unable to remove metal impurities in silicon carbide micropowder, thereby reducing the purity of silicon carbide micropowder. Summary of the invention

[0004] To this end, the present invention provides a process for preparing high-purity silicon carbide micropowder, so as to overcome the problem in the prior art that metal impurities in the silicon carbide micropowder cannot be removed, thereby reducing the purity of the silicon carbide micropowder.

[0005] To achieve the above object, the present invention provides a process for preparing high-purity silicon carbide powder, comprising:

[0006] Mixing silicon powder and carbon powder to output a mixed raw material;

[0007] The mixed raw material and argon gas are simultaneously introduced into a heating chamber to react and remove free carbon to generate silicon carbide;

[0008] Cooling the silicon carbide to output low-temperature silicon carbide;

[0009] Roughly grinding the low-temperature silicon carbide to obtain finished silicon carbide particles;

[0010] The finished silicon carbide particles are rinsed with a pickling liquid to remove metal impurities in the finished silicon carbide particles to form a silicon carbide mixed liquid;

[0011] The silicon carbide mixed liquid is filtered to preliminarily remove the pickling liquid, and the finished silicon carbide adhering to the pickling liquid is rinsed with clean water to output high-purity silicon carbide particles;

[0012] Using a drying device to remove moisture from high-purity silicon carbide particles to output anhydrous silicon carbide particles;

[0013] Finely grinding anhydrous silicon carbide particles to form silicon carbide powder;

[0014] Obtain the purity of silicon carbide powder to determine production quality;

[0015] Determine whether to adjust the input ratio of argon gas according to the production quality, or preliminarily determine the flushing height of the pickling solution according to the weight change of silicon carbide before and after purification;

[0016] After the flushing is completed according to the initially determined flushing height, the flushing height is re-determined according to the concentration variance of the silicon carbide mixed solution sampling point;

[0017] The temperature of the low-temperature silicon carbide is 25° C., and the anhydrous silicon carbide particles are silicon carbide particles with a water content of 99.99%.

[0018] Further, the mixed raw materials are subjected to a chemical reaction to generate silicon carbide, comprising:

[0019] Heating the mixed raw material to a preset first temperature;

[0020] placing silicon carbide in an alumina crucible and heating it to a preset second temperature to remove free carbon;

[0021] Wherein, the preset first temperature is greater than the preset second temperature.

[0022] Furthermore, the purification of the finished silicon carbide particles comprises:

[0023] The finished silicon carbide particles are rinsed with pickling liquid to remove metal impurities, and purified silicon carbide particles are output;

[0024] The purified silicon carbide particles are rinsed to remove the pickling liquid, and high-purity silicon carbide particles are output.

[0025] Furthermore, obtaining the purity of silicon carbide powder includes:

[0026] Dissolve the silicon carbide powder sample with hydrofluoric acid;

[0027] Prepare a standard solution containing the impurity elements to be analyzed;

[0028] The emission spectrum intensity of impurity elements in the standard solution is measured by inductively coupled plasma optical emission spectrometry;

[0029] Draw a calibration curve between the concentration of each impurity element and the spectral intensity;

[0030] Calculating the content of the impurity elements in the silicon carbide micropowder solution according to the calibration curve equation and the spectral intensity of the impurity elements in the silicon carbide micropowder solution;

[0031] The purity of silicon carbide micropowder is obtained by measuring the content of impurity elements in the silicon carbide micropowder solution;

[0032] The horizontal axis of the calibration curve is the concentration of the impurity element, and the vertical axis is the emission spectrum intensity of the impurity element.

[0033] Further, the determining of production quality includes:

[0034] Comparing the purity of the silicon carbide micropowder with a preset second purity;

[0035] If the purity of the silicon carbide micropowder is less than or equal to the preset second purity, it is determined that the production quality does not meet the requirements;

[0036] If the purity of the silicon carbide powder is greater than the preset second purity, it is determined that the production quality meets the requirements.

[0037] Further, determining whether to adjust the input ratio of argon gas according to the production quality includes:

[0038] Comparing the purity of the silicon carbide micropowder with a preset first purity and a preset second purity respectively;

[0039] If the purity of the silicon carbide powder is greater than the preset first purity and less than or equal to the preset second purity, the input ratio of argon gas is adjusted.

[0040] Further, the flushing height is preliminarily determined based on the weight change of silicon carbide before and after purification, including:

[0041] Comparing the concentration of the silicon carbide micropowder with a preset first purity;

[0042] If the purity of the silicon carbide micropowder is less than or equal to the preset first purity, it is preliminarily determined that the accuracy of the purification process of the silicon carbide micropowder does not meet the requirements, and the accuracy of the purification process is secondary determined according to the weight change of the silicon carbide before and after purification;

[0043] If the weight change of silicon carbide before and after purification is greater than the preset weight change, it is determined that the accuracy of the purification process does not meet the requirements, and the flushing height of the pickling solution is reduced.

[0044] Furthermore, the distribution uniformity of silicon carbide particles in the pickling liquid is determined based on the concentration variance of several sampling points of the silicon carbide mixed liquid. If the concentration variance of the sampling points is greater than the preset concentration variance, it is determined that the silicon carbide particles are unevenly distributed in the pickling liquid, and the flushing height is adjusted a second time.

[0045] Furthermore, the weight change of silicon carbide before and after purification is the difference between the weight of the finished silicon carbide and the weight of anhydrous silicon carbide.

[0046] Furthermore, the silicon carbide mixed liquid is a mixed liquid of silicon carbide particles and pickling liquid during purification.

[0047] Furthermore, the input ratio of the argon gas is the ratio of the volume of the argon gas input into the heating chamber to the volume of the mixed raw material under standard atmospheric pressure.

[0048] Compared with the prior art, the beneficial effect of the present invention lies in that, by setting a purification method for removing free carbon and pickling, the crystal structure and particle size of silicon carbide can be controlled through a heating reaction, cooling and fine grinding process, thereby improving the hardness and thermal conductivity of silicon carbide micropowder; by setting and controlling the input ratio of argon gas, the stability of the production quality of silicon carbide micropowder is improved, and fine grinding helps to obtain micropowder with uniform particle size.

[0049] Furthermore, the present invention overcomes the problem of uneven particle size of finished silicon carbide particles by setting up a ball mill and screening the ball mill, thereby improving the accuracy of the particle size of the finished silicon carbide particles and obtaining a more concentrated particle size distribution; by setting up the processing of equal mass fractions of low-temperature silicon carbide, the problem of insufficient ball mill grinding caused by uneven distribution of low-temperature silicon carbide, or high wear caused by uneven force on the ball mill is overcome, which helps to subject each part to the same grinding and grading conditions, thereby improving the use efficiency and life of the equipment.

[0050] Furthermore, the present invention overcomes the problem of unqualified purity of the finished product due to the entry of some valve components into the reaction powder during pipeline transportation of the powder raw material by setting the first purity and the second purity. When the purity does not meet the requirements, the amount of argon is increased to solve the problem of increased internal air pressure due to the accumulation of raw material powder at the bottom of the pipeline, decreased stability of the pipeline transportation process, resulting in increased vibration of the valve or increased friction between the raw material powder and the pipeline, and increased probability of material falling off, which helps to improve product purity and quality stability.

[0051] Furthermore, the present invention monitors the weight change of silicon carbide micropowder before and after purification by setting a preset weight change, thereby overcoming the problem that the purity of silicon carbide micropowder does not meet the requirements due to the excessively high content of metal impurities. By adjusting the flushing height of the pickling solution according to the weight change, the problem of the pickling solution water seal being torn due to the height being too high, or new impurities being introduced during the pickling or water washing process is overcome, which helps to improve the efficiency and accuracy of the purification process.

[0052] Furthermore, the present invention sets the concentration variance of several sampling points of the silicon carbide mixed liquid, determines the distribution uniformity of the silicon carbide particles in the pickling liquid, and makes a secondary adjustment to the flushing height, thereby avoiding the problem of repeated treatment due to insufficient treatment of some silicon carbide particles, helping to optimize the cleaning process, improve the utilization efficiency of the pickling liquid, and thus improve the overall purification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The figure is a diagram showing the overall steps of the preparation process of high-purity silicon carbide micropowder according to an embodiment of the present invention;

[0054] Figure 2 A diagram showing the steps of generating silicon carbide by reaction in a process for preparing high-purity silicon carbide micropowder according to an embodiment of the present invention;

[0055] Figure 3 This is a diagram showing the steps of grinding to obtain silicon carbide particles in a preparation process of high-purity silicon carbide micropowder according to an embodiment of the present invention;

[0056] Figure 4This is a flow chart of a process for preparing high-purity silicon carbide micropowder according to an embodiment of the present invention;

[0057] Figure 5 This is a structural diagram of a pickling device for a process for preparing high-purity silicon carbide micropowder according to an embodiment of the present invention;

[0058] The accompanying drawings are marked as follows: 1-pickling liquid delivery pipeline, 2-adjusting rod, 3-liquid storage tank, 4-liquid injection port, 5-adjusting valve, 6-pickling tank, 7-positioning clamp, 8-sprinkler. DETAILED DESCRIPTION

[0059] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0060] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0061] It will be understood by those skilled in the art that, unless otherwise stated, the singular forms "a", "an" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in this specification refers to the presence of features, integers, steps, operations, elements / components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements / components. It should be understood that when we refer to a module as being "connected" or "coupled" to another module, it may be directly connected or coupled to the other module, or there may be an intermediate unit. In addition, "connected" or "coupled" used herein may include wireless connection or wireless coupling.

[0062] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 as well as Figure 5 As shown, they are respectively an overall step diagram of the preparation process of high-purity silicon carbide micropowder according to an embodiment of the present invention, a step diagram of the reaction to generate silicon carbide, a step diagram of grinding to obtain silicon carbide particles, a flow chart, and a structural diagram of the pickling device. A preparation process of high-purity silicon carbide micropowder according to the present invention comprises:

[0063] Step S1, mixing silicon powder and carbon powder to output a mixed raw material;

[0064] Step S2, simultaneously inputting the mixed raw material and argon gas into a heating chamber for chemical reaction and removing free carbon to generate silicon carbide;

[0065] Step S3, cooling the silicon carbide to output low-temperature silicon carbide;

[0066] Step S4, coarsely grinding the low-temperature silicon carbide to obtain finished silicon carbide particles;

[0067] Step S5, washing the finished silicon carbide particles with a pickling solution to remove metal impurities in the finished silicon carbide particles to form a silicon carbide mixed solution;

[0068] Step S6, filtering the silicon carbide mixed liquid to preliminarily remove the pickling liquid, and washing the finished silicon carbide with the pickling liquid adhered to it with clean water to output high-purity silicon carbide particles;

[0069] Step S7, using a drying device to remove moisture from the high-purity silicon carbide particles to output anhydrous silicon carbide particles;

[0070] Step S8, finely grinding the anhydrous silicon carbide particles to form silicon carbide powder;

[0071] Step S9, obtaining the purity of silicon carbide powder to determine the production quality;

[0072] Determine whether to adjust the input ratio of argon gas according to the production quality, or preliminarily determine the flushing height of the pickling solution according to the weight change of silicon carbide before and after purification;

[0073] After the flushing is completed according to the initially determined flushing height, the flushing height is re-determined according to the concentration variance of the silicon carbide mixed solution sampling point;

[0074] The temperature of the low-temperature silicon carbide is 25° C., and the anhydrous silicon carbide particles are silicon carbide particles with a water content of 99.99%.

[0075] Specifically, the purity and mixing ratio of the carbon powder and silicon powder are respectively 100% purity silicon powder and 100% purity carbon powder, and the mixing mass ratio of silicon powder to carbon powder is 1:3.

[0076] Specifically, the device used for cooling is a fluidized bed cooler, the drying equipment is an oven, the grinding device used for fine grinding of anhydrous silicon carbide particles is a jet mill, and the filtering device is a plate and frame filter press.

[0077] Specifically, the pickling equipment used in the pickling process includes:

[0078] Liquid storage tank 3, used for storing pickling liquid;

[0079] A liquid injection port 4, which is connected to the liquid storage tank 3 and is used to inject pickling liquid into the liquid storage tank;

[0080] A pickling liquid delivery pipeline 1, which is connected to the liquid storage tank 3 and is used to deliver the pickling liquid;

[0081] A regulating valve 5, which is connected to the pickling liquid delivery pipeline 1 and is used to adjust the water output of the pickling liquid;

[0082] A nozzle 8, which is connected to the pickling liquid delivery pipeline 1 and is used to change the flow direction of the pickling liquid;

[0083] An adjusting rod 2, which is arranged on one side of the liquid storage tank 3 and is used to adjust the flushing height;

[0084] A positioning clamp 7, which is connected to the adjusting rod 2 and is used to fix the height of the pickling liquid delivery pipeline 1;

[0085] The pickling tank 6 is arranged below the spray head 8 to provide a container for the pickling process.

[0086] In practice, the present invention can control the crystal structure and particle size of silicon carbide by setting a purification method for removing free carbon and pickling, and through the heating reaction, cooling and fine grinding processes, thereby improving the hardness and thermal conductivity of silicon carbide micropowder; by setting and controlling the input ratio of argon gas, the stability of the production quality of silicon carbide micropowder is improved, and fine grinding helps to obtain micropowder with uniform particle size.

[0087] Specifically, the mixed raw materials are subjected to a chemical reaction to generate silicon carbide, including:

[0088] heating the mixed raw material to 1500° C.;

[0089] Silicon carbide was placed in an alumina crucible and the temperature was maintained at 600° C. using a box-type resistance furnace to remove free carbon.

[0090] Specifically, the rough grinding of low-temperature silicon carbide includes:

[0091] Divide the low-temperature silicon carbide into several 2kg portions and put them into the ball mill one by one;

[0092] The low-temperature silicon carbide is ground using a ball mill and the ball mill screen is adjusted to a particle size of 5 μm to screen the low-temperature silicon carbide to output finished silicon carbide particles.

[0093] In practice, the present invention overcomes the problem of uneven particle size of finished silicon carbide particles by setting up a ball mill and screening the ball mill, thereby improving the accuracy of the particle size of the finished silicon carbide particles and obtaining a more concentrated particle size distribution; by setting up equal mass fractions of silicon carbide for processing, the problem of insufficient ball mill grinding caused by uneven distribution of finished silicon carbide particles or high wear caused by uneven force on the ball mill is overcome, which helps to subject each part to the same grinding and grading conditions, thereby improving the use efficiency and life of the equipment.

[0094] Specifically, the purification of the finished silicon carbide particles comprises:

[0095] The silicon carbide particles are rinsed with a pickling solution having a content of hydrofluoric acid: nitric acid = 1:5 to remove metal impurities, and the purified silicon carbide particles are output;

[0096] The purified silicon carbide particles are rinsed to remove the pickling liquid, and high-purity silicon carbide particles are output.

[0097] Specifically, obtaining the purity of silicon carbide micropowder includes:

[0098] Dissolve the silicon carbide powder sample with hydrofluoric acid;

[0099] Prepare a standard solution containing the impurity elements to be analyzed;

[0100] The emission spectrum intensity of impurity elements in the standard solution is measured by inductively coupled plasma optical emission spectrometry;

[0101] Draw a calibration curve between the concentration of the impurity element and the spectral intensity, where the abscissa is the concentration of the impurity element and the ordinate is the emission spectral intensity of the impurity element;

[0102] According to the calibration curve equation and the spectral intensity of the impurity elements in the silicon carbide micropowder solution, the content of the impurity elements in the silicon carbide micropowder solution is calculated. The calculation formula for the content of n impurity elements is:

[0103]

[0104] Wherein, y is the spectrum intensity, X is the content of impurity elements, m is the slope, b is the intercept; n is a natural number not equal to 0;

[0105] The purity of silicon carbide micropowder is obtained by the content of impurity elements in the silicon carbide micropowder solution. The calculation formula of the purity P of silicon carbide micropowder is: P=1-X.

[0106] Specifically, the measurement of emission spectrum intensity using the inductively coupled plasma emission spectrometry is carried out in an inductively coupled plasma emission spectrometer, using inductively coupled plasma as an excitation source, introducing a sample into the plasma, the elements in the sample are excited and emit characteristic spectra, and the types and contents of the elements present in the sample are determined by detecting the wavelengths and intensities of these characteristic spectra.

[0107] Specifically, the determination of production quality includes:

[0108] Comparing the purity of the silicon carbide micropowder with a preset second purity;

[0109] If the purity of the silicon carbide micropowder is less than or equal to the preset second purity, it is determined that the production quality does not meet the requirements;

[0110] If the purity of the silicon carbide powder is greater than the preset second purity, it is determined that the production quality meets the requirements.

[0111] Specifically, determining whether to adjust the input ratio of argon gas according to the production quality includes:

[0112] Comparing the purity of the silicon carbide micropowder with a preset first purity and a preset second purity respectively;

[0113] If the purity of the silicon carbide powder is greater than the preset first purity and less than or equal to the preset second purity, the input ratio of argon gas is adjusted.

[0114] Optionally, the preset value range of the first purity may be [90%, 95%]; the preset value range of the second purity may be [95%, 100%];

[0115] Preferably, the first purity is preset to be 93% and the second purity is preset to be 97%.

[0116] In a specific embodiment, the purity of the silicon carbide powder is 96%, which is greater than the preset first purity and less than the preset second purity, and it is determined that the production quality does not meet the requirements;

[0117] When the purity of silicon carbide powder exceeds the preset first purity by 0.5%, the input ratio of argon increases by 1% compared with the current input ratio of argon. The current input ratio of argon is 70%, and the increased input ratio of argon is 70+[(96-93) / 0.5]=76%.

[0118] In practice, the present invention overcomes the problem of unqualified purity of the finished product due to the entry of some valve components into the reaction powder during pipeline transportation of the powder raw material by setting the first purity and the second purity. When the purity does not meet the requirements, the amount of argon is increased to solve the problem of increased internal air pressure due to the accumulation of raw material powder at the bottom of the pipeline, decreased stability of the pipeline transportation process, resulting in increased vibration of the valve or increased friction between the raw material powder and the pipeline, and increased probability of material falling off, which helps to improve product purity and quality stability.

[0119] Specifically, the flushing height is initially determined based on the weight change of silicon carbide before and after purification, including:

[0120] Comparing the concentration of the silicon carbide micropowder with a preset first purity;

[0121] If the purity of the silicon carbide micropowder is less than or equal to the preset first purity, it is preliminarily determined that the accuracy of the purification process of the silicon carbide micropowder does not meet the requirements, and the accuracy of the purification process is secondary determined according to the weight change of the silicon carbide before and after purification;

[0122] If the weight change of silicon carbide before and after purification is greater than the preset weight change, it is determined that the accuracy of the purification process does not meet the requirements, and the flushing height of the pickling solution is reduced.

[0123] Optionally, the preset weight change value range may be [10g, 15g];

[0124] Preferably, the preferred embodiment of the preset weight change amount is 12g;

[0125] In one or more specific embodiments, the weight change of silicon carbide before and after purification is 16g, which is greater than the preset weight change. The secondary judgment shows that the accuracy of the purification process does not meet the requirements. For every 2g increase in the weight change of silicon carbide that is greater than the preset weight change, the flushing height of the pickling solution is reduced by 1cm compared with the current flushing height of the pickling solution. The current flushing height of the pickling solution is 20cm, and the flushing height of the pickling solution after reduction is 20-(16-12) / 2=18cm.

[0126] The flushing height is the distance between the nozzle 8 and the bottom of the pickling tank 6, which is adjusted by the adjusting rod 2 of the pickling device; the adjusting rod 2 is an electric telescopic rod, and the pickling liquid delivery pipeline 1 is a telescopic hose.

[0127] In implementation, the present invention monitors the weight change of silicon carbide micropowder before and after purification by setting a preset weight change, thereby overcoming the problem that the purity of silicon carbide micropowder does not meet the requirements due to the excessively high content of metal impurities. By adjusting the flushing height of the pickling solution according to the weight change, the problem of the pickling solution water seal being torn due to the height being too high, or new impurities being introduced during the pickling or water washing process is overcome, which helps to improve the efficiency and accuracy of the purification process.

[0128] Specifically, the distribution uniformity of silicon carbide particles in the pickling liquid is determined based on the concentration variance of several sampling points of the silicon carbide mixed liquid. If the concentration variance of the sampling points is greater than the preset concentration variance, it is determined that the silicon carbide particles are unevenly distributed in the pickling liquid, and the flushing height is adjusted secondary.

[0129] Specifically, several sampling points are randomly selected in the silicon carbide mixed liquid to extract equal volumes of the mixed liquid, and the concentrations of the n sampling points are respectively recorded as C1, C2, C3, ..., C n , where n is a natural number greater than 0;

[0130] Optionally, the preset concentration variance may be in the range of [1.5 g / L, 3 g / L];

[0131] Preferably, the preferred embodiment of the preset concentration variance is 2 g / L;

[0132] In a specific embodiment, the concentration variance of the sampling point is 2.5 g / L, which is greater than the preset concentration variance, and the silicon carbide particles are determined to be unevenly distributed in the pickling solution. For every 0.1 g / L that the concentration variance of the sampling point exceeds the preset concentration variance, the flushing height of the pickling solution is increased by 1 cm compared with the current flushing height of the pickling solution; the current flushing height of the pickling solution is 10 cm, and the flushing height of the pickling solution after the increase is 10+(2.5-2) / 0.1=15 cm.

[0133] In practice, the present invention sets the concentration variance of several sampling points of the silicon carbide mixed liquid, determines the distribution uniformity of the silicon carbide particles in the pickling liquid, and makes a secondary adjustment to the flushing height, thereby avoiding the problem of repeated treatment due to insufficient treatment of some silicon carbide particles, helping to optimize the cleaning process, improve the utilization efficiency of the pickling liquid, and thus improve the overall purification effect.

[0134] Specifically, the concentration variance of several sampling points of the silicon carbide mixed liquid is an indication of the degree of discreteness of the silicon carbide concentration at the several sampling points. Those skilled in the art can understand that the concentration variance of several sampling points of the silicon carbide mixed liquid is a conventional technical means well known to those skilled in the art, and therefore the calculation process of the concentration variance of several sampling points of the silicon carbide mixed liquid will not be repeated here.

[0135] Specifically, the silicon carbide mixed liquid is a mixed liquid of silicon carbide particles and pickling liquid.

[0136] Specifically, the input ratio of the argon gas is the ratio of the volume of the argon gas input into the heating chamber to the volume of the mixed raw material under standard atmospheric pressure.

[0137] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A process for preparing high-purity silicon carbide micropowder, It is characterized in that include: Mixing silicon powder and carbon powder to output a mixed raw material; The mixed raw material and argon gas are simultaneously introduced into a heating chamber to react and remove free carbon to generate silicon carbide; Cooling the silicon carbide to output low-temperature silicon carbide; Roughly grinding the low-temperature silicon carbide to obtain finished silicon carbide particles; The finished silicon carbide particles are rinsed with a pickling liquid to remove metal impurities in the finished silicon carbide particles to form a silicon carbide mixed liquid; The silicon carbide mixed liquid is filtered to preliminarily remove the pickling liquid, and the finished silicon carbide adhering to the pickling liquid is rinsed with clean water to output high-purity silicon carbide particles; Using a drying device to remove moisture from high-purity silicon carbide particles to output anhydrous silicon carbide particles; Finely grinding anhydrous silicon carbide particles to form silicon carbide powder; Obtain the purity of silicon carbide powder to determine production quality; Determine whether to adjust the input ratio of argon gas according to the production quality, or preliminarily determine the flushing height of the pickling solution according to the weight change of silicon carbide before and after purification; After the flushing is completed according to the initially determined flushing height, the flushing height is re-determined according to the concentration variance of the silicon carbide mixed solution sampling point; The temperature of the low-temperature silicon carbide is 25° C., and the anhydrous silicon carbide particles are silicon carbide particles with a water content of 99.99%.

2. The process for preparing high-purity silicon carbide micropowder according to claim 1, It is characterized in that The mixed raw materials are subjected to a chemical reaction to generate silicon carbide, comprising: Heating the mixed raw material to a preset first temperature; placing silicon carbide in an alumina crucible and heating it to a preset second temperature to remove free carbon; Wherein, the preset first temperature is greater than the preset second temperature.

3. The process for preparing high-purity silicon carbide micropowder according to claim 2, It is characterized in that The step of obtaining the purity of silicon carbide micropowder comprises: Dissolve the silicon carbide powder sample with hydrofluoric acid; Prepare a standard solution containing the impurity elements to be analyzed; The emission spectrum intensity of impurity elements in the standard solution is measured by inductively coupled plasma optical emission spectrometry; Draw a calibration curve between the concentration of each impurity element and the spectral intensity; Calculating the content of the impurity elements in the silicon carbide micropowder solution according to the calibration curve equation and the spectral intensity of the impurity elements in the silicon carbide micropowder solution; The purity of silicon carbide micropowder is obtained by measuring the content of impurity elements in the silicon carbide micropowder solution; The horizontal axis of the calibration curve is the concentration of the impurity element, and the vertical axis is the emission spectrum intensity of the impurity element.

4. The process for preparing high-purity silicon carbide micropowder according to claim 3, It is characterized in that Determining the production quality includes: Comparing the purity of the silicon carbide micropowder with a preset second purity; If the purity of the silicon carbide powder is less than or equal to the preset second purity, it is determined that the production quality does not meet the requirements; If the purity of the silicon carbide powder is greater than the preset second purity, it is determined that the production quality meets the requirements.

5. The process for preparing high-purity silicon carbide micropowder according to claim 4, It is characterized in that Determining whether to adjust the input ratio of argon gas according to the production quality includes: Comparing the purity of the silicon carbide micropowder with a preset first purity and a preset second purity respectively; If the purity of the silicon carbide powder is greater than the preset first purity and less than or equal to the preset second purity, the input ratio of argon gas is adjusted.

6. The process for preparing high-purity silicon carbide micropowder according to claim 5, It is characterized in that The flushing height is initially determined based on the weight change of silicon carbide before and after purification, including: Comparing the concentration of the silicon carbide micropowder with a preset first purity; If the purity of the silicon carbide micropowder is less than or equal to the preset first purity, it is preliminarily determined that the accuracy of the purification process of the silicon carbide micropowder does not meet the requirements, and the accuracy of the purification process is secondary determined according to the weight change of the silicon carbide before and after purification; If the weight change of silicon carbide before and after purification is greater than the preset weight change, it is determined that the accuracy of the purification process does not meet the requirements, and the flushing height of the pickling solution is reduced.

7. The process for preparing high-purity silicon carbide micropowder according to claim 6, It is characterized in that The distribution uniformity of silicon carbide particles in the pickling liquid is determined based on the concentration variance of several sampling points of the silicon carbide mixed liquid. If the concentration variance of the sampling points is greater than the preset concentration variance, it is determined that the silicon carbide particles are unevenly distributed in the pickling liquid, and the flushing height is adjusted a second time.

8. The process for preparing high-purity silicon carbide micropowder according to claim 7, It is characterized in that The weight change of the silicon carbide before and after the purification is the difference between the weight of the finished silicon carbide and the weight of anhydrous silicon carbide.

9. The process for preparing high-purity silicon carbide micropowder according to claim 8, It is characterized in that The silicon carbide mixed liquid is a mixed liquid of silicon carbide particles and pickling liquid during purification.

10. The process for preparing high-purity silicon carbide micropowder according to claim 9, It is characterized in that The input ratio of the argon gas is the ratio of the volume of the argon gas input into the heating chamber to the volume of the mixed raw material under standard atmospheric pressure.

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