Method for measuring content of silicon carbide

Abstract

The invention relates to the technical field of silicon carbide, in particular to a method for measuring the content of silicon carbide. The determination method comprises the following steps: preparing a sample solution from a sample containing silicon carbide; preparing a silicon dioxide standard solution, a reference solution and a blank solution, and preparing colorimetric gradation; detecting the weight percentage content of silicon dioxide in the sample solution by adopting a multi-element analyzer; calculating the content of silicon carbide according to a formula omega (SiC) = # imgabs0 # / 1.4984; wherein # imgabs 1 # is the measured weight percentage content of silicon dioxide, and omega (SiC) is the weight percentage content of silicon carbide. The determination method disclosed by the invention is low in detection difficulty, high in detection accuracy and particularly suitable for a silicon carbide-containing sample of which the weight percentage content of silicon carbide is less than or equal to 90%.

Description

Technical Field

[0001] The invention relates to the technical field of silicon carbide, and in particular to a method for determining silicon carbide content. Background Art

[0002] Silicon carbide is made from silica and petroleum coke as the main raw materials through a high temperature reaction of 2000-2500℃ in a resistance furnace. The reaction formula is as follows: SiO2+3C=SiC+2CO.

[0003] The SiC content in commercial silicon carbide is usually greater than 95%, and other impurities are mainly SiO2 and C that have not been completely reacted, as well as other trace amounts of Si, Fe2O3, Al2O3, etc.

[0004] The mold abrasive industry and refractory industry are generally more concerned about the SiC content.

[0005] At present, silicon carbide composition analysis generally adopts two categories: chemical method (GB / T 3045) and equipment method (GB / T 16555 Part 11-12): The 12.4 hydrofluoric acid volatile weight method chemical method in GB / T3045 and GB / T16555 is mainly divided into two steps. The first step is to use hydrofluoric acid-nitric acid-sulfuric acid treatment to make the silicon and silicon dioxide on the surface generate volatile silicon tetrafluoride to escape; the second step is to use dilute hydrochloric acid to dissolve the surface impurities, and the amount of residue measured is the silicon carbide content. This method is suitable for the detection of raw materials with a silicon carbide content of more than 90%. For samples with more complex components such as refractory products or recycled silicon carbide materials, there may be a large number of substances that are not easily soluble in acid, such as Al2O3 and insoluble salts. If the acid leaching time is insufficient, the above substances cannot be dissolved and are all regarded as residual silicon carbide content, which will lead to a high silicon carbide content. After a large number of experimental measurements, Al2O3 and insoluble salts are present in the residual substances after dilute hydrochloric acid leaching. Therefore, this method is not suitable for the detection of samples with a silicon carbide content of less than 90%.

[0006] The direct and indirect methods of 12.1-12.2 in GB / T 16555 determine silicon carbide mainly by determining the content of free carbon and total carbon in the product, calculating the bound carbon content by the difference between total carbon and free carbon, and then calculating the content of silicon carbide by multiplying the bound carbon content by a coefficient of 3.3384. On the one hand, this method requires the purchase of an additional carbon-sulfur meter, which can only measure the two chemical components of carbon and sulfur in the sample, which undoubtedly increases the cost of the enterprise when the sample detection amount is not large. On the other hand, since the calculation of silicon carbide content by carbon content needs to be multiplied by a coefficient of 3.3384, the detection error of the sample is undoubtedly enlarged. For example, if the carbon detection error is 0.3%, the silicon carbide detection error is 1%. In addition, when using a carbon-sulfur meter, it is necessary to select a suitable standard sample according to the carbon content in the sample, but since high-content carbon standard samples are difficult to obtain, it undoubtedly increases the difficulty of detection. Summary of the invention

[0007] The present invention provides a method for testing silicon carbide content, which is used to solve the problems of great detection difficulty and low detection accuracy in the existing method for testing silicon carbide content in samples with a silicon carbide content below 90%.

[0008] The present invention provides a method for determining silicon carbide content, comprising the following steps: Step S1: preparing a sample containing silicon carbide into a sample solution; Step S2: preparing a silica standard solution, a reference solution and a blank solution, and preparing a colorimetric scale; Step S3: using a multi-element analyzer to detect the weight percentage of silicon dioxide in the sample solution of step S1; Step S4: According to the formula To calculate the silicon carbide content; where, is the weight percentage of silicon dioxide measured in step S3, is the weight percentage of silicon carbide.

[0009] Specifically, the formula for calculating the SiC content based on the SiO2 content is as follows:

[0010] =60.0843, =40.10.

[0011] The present invention discloses a method for determining silicon carbide content using a multi-element analyzer. The multi-element analyzer is first used to determine the weight percentage of silicon dioxide in the sample solution, and then converted into the weight percentage of silicon carbide by a formula. The SiC content is calculated by the SiO2 content. Similarly, the SiO2 content detection error is 0.3%. The detection error of SiC is 0.2%, which reduces the detection error of SiC. The determination method of the present invention has low detection difficulty and high detection accuracy. It is particularly suitable for samples containing silicon carbide with a weight percentage of silicon carbide less than or equal to 90%. It can detect samples that usually need to detect the content of aluminum oxide, silicon dioxide, silicon carbide, iron oxide and calcium oxide in the refractory industry. It can also detect samples with complex components such as recycled silicon carbide materials and used silicon carbide products. The equipment utilization rate is very high, which avoids the limitation of using a carbon-sulfur instrument that can only detect carbon and sulfur.

[0012] Furthermore, the weight percentage of silicon carbide in the silicon carbide-containing sample is less than or equal to 90%.

[0013] Furthermore, the step S3 specifically includes the following steps: Step S31: Pipette the color developer used in conjunction with the multi-element analyzer into the sample solution, wait for 10 to 15 minutes for the sample solution to develop color, compare the color with the colorimetric scale, select the colorimetric scale closest to the color in the sample solution, and select the reference solution of the corresponding number; select the standard sample according to the solubility of the reference solution of the corresponding number and prepare the standard sample solution; Step S32: After determining the reference solution and the standard sample solution, the blank solution, the standard sample solution, the sample solution, and the reference solution are respectively mixed evenly with the color developer, and after standing for 15-20 minutes, the weight percentage of silica is measured respectively using the violet light channel of the multi-element analyzer; wherein, a test curve is established based on the blank solution and the reference solution, the curve is corrected with the standard sample solution, and the weight percentage of silica is obtained according to calculation.

[0014] SiO2 calculation principle: Use blank solution as reference starting point, reference solution as maximum value, and standard solution as correction value to establish curve: ; C 标 is the concentration of standard samples in the equipment; A 样 is the reading of the sample solution in the device; A 空 Take a reading for the blank solution in the device; A 标 Take readings for standard samples in the device; Calculate the SiO2 concentration C in the sample solution 样After that, the mass of SiO2 needs to be calculated according to the formula m=c·v: =C 样 ·V 容 is the mass of SiO2 in the sample; V 容 is the volume of the volumetric flask.

[0015] After calculating the mass of SiO2 in the sample, calculate the weight percentage of SiO2 according to the formula:

[0016] is the mass of SiO2 in the sample; m 总 is the total mass of the sample weighed.

[0017] Further, the preparation method of the silica standard solution is as follows: calcine silica with a purity of ≥99.99% at 900-1100°C for 1-3h, and cool; weigh 0.1000-0.300 parts by weight of the cooled silica in a platinum crucible, add 2-4 parts by weight of mixed flux, cover with 0.5-1.5 parts by weight of mixed flux, cover the crucible cover and leave a gap, place at 900-1100°C for melting for 10-30min, and cool; place the crucible and crucible cover in dilute hydrochloric acid, heat and leaching at 150-250°C until the solution is clear, wash out the crucible and crucible cover, and cool; then adjust the cooled solution to a 200-volume volumetric flask, shake well, and transfer to a plastic bottle for storage. Selecting a suitable preparation method to prepare a silica standard solution is conducive to improving measurement accuracy and analysis efficiency.

[0018] It should be noted that, when the volume parts described in the present invention are measured in milliliters, the corresponding weight parts are measured in grams, or when the volume parts are measured in liters, the corresponding weight parts are measured in kilograms.

[0019] Furthermore, the preparation method of the standard sample solution is as follows: weigh 0.0100-0.1 parts by weight of the standard sample, add 3-5 parts by weight of the mixed flux, cover the crucible with a gap, place it in a high-temperature furnace, heat it to 900-110°C and melt it for 20-40 minutes, take it out, rotate the crucible so that the melt is evenly attached to the inner wall of the crucible, and cool it; wipe the outer wall of the crucible with filter paper, put it in a beaker containing 30-40 parts by volume of dilute hydrochloric acid and 10-30 parts by volume of water, heat it at 150-250°C to leach the melt until the solution is clear, wash the crucible and the crucible cover with water, cool it, transfer it to a volumetric flask, dilute it to the scale with water, and shake it well.

[0020] Selecting an appropriate preparation method to prepare standard sample solutions is helpful to improve measurement accuracy and analysis efficiency.

[0021] Furthermore, the blank solution is prepared as follows: 60-80 parts by volume of dilute hydrochloric acid and 5-10 parts by weight of mixed flux are transferred into a 500 parts by volume volumetric flask, dissolved with water until bubbles disappear, fixed to volume, and shaken well.

[0022] Furthermore, the preparation method of the reference solution is as follows: transfer 60-80 parts by volume of dilute hydrochloric acid and 5-10 parts by weight of mixed flux into a 500-part volume volumetric flask, dissolve with water until the bubbles disappear, and then transfer 10 parts by volume, 30 parts by volume, 50 parts by volume, 80 parts by volume, 100 parts by volume, and 130 parts by volume of the silicon dioxide standard solution into a 500-part volume volumetric flask, respectively, make up to the scale, shake well, and mark them as reference solution No. 1, reference solution No. 2, reference solution No. 3, reference solution No. 4, reference solution No. 5, and reference solution No. 6.

[0023] Furthermore, the preparation method of the colorimetric scale is as follows: 2-3 volumes of the reference solution No. 1 to reference solution No. 6 are respectively transferred into test tubes, the test tubes are numbered No. 1 to No. 6, and then 2-3 volumes of the color developer are respectively transferred into test tubes No. 1 to No. 6, and the reference solution develops color after 15 to 20 minutes.

[0024] Furthermore, the step S1 specifically includes the following steps: Step S11: weigh 0.01-0.1 parts by weight of a sample in a platinum crucible, calcine at 800-1200° C. to constant weight, dry, and cool; Step S12: drip water into the cooled platinum crucible to moisten it, add 5-15 parts by volume of hydrofluoric acid, 1-3 parts by volume of nitric acid, and 1-2.5 parts by volume of sulfuric acid, evaporate at 150-250° C. until white smoke disappears, and then evaporate to dryness over high heat for 3-5 minutes; Step S13: remove the crucible, cool it, add 2-6 parts by weight of mixed flux, cover the crucible with a lid and leave a gap, then place it in a high-temperature furnace, heat it to 900-1100° C. and melt it for 20-40 minutes, take it out, rotate the crucible so that the melt is evenly attached to the inner wall of the crucible, and cool it; Step S14: Wipe the outer wall of the crucible with filter paper, put it into a beaker containing 30-40 parts by volume of dilute hydrochloric acid and 10-30 parts by volume of water, heat at 150-250° C. to extract the melt until the solution is clear, wash out the crucible and the lid with water, cool, transfer to a 500 parts by volume volumetric flask, dilute to the mark with water, and shake well.

[0025] The step S1 of the present invention prepares a sample containing silicon carbide into a sample solution, and includes steps S11, S12, S13 and S14. The setting of step S11 can remove volatile substances and free carbon. The setting of step S12 can make free silicon, silicon dioxide, silicate and other silicon-containing substances in the sample escape as silicon tetrafluoride, ensuring that Si in the residue exists only in the form of SiC. The setting of step S13 can convert SiC in the residue into SiO2. The setting of step S14 can make Si in SiO2 exist in the form of ions.

[0026] Furthermore, the mixed flux is composed of anhydrous sodium carbonate and boric acid, and the weight ratio of anhydrous sodium carbonate to boric acid is (1-3):1. By selecting a mixed flux with appropriate raw material types and proportions, it is beneficial to promote the melting of the sample, protect the sample components, and improve the stability and accuracy of the measurement results. Preferably, the weight ratio of anhydrous sodium carbonate to boric acid is (1.5-2.5):1.

[0027] The beneficial effects of the technical solution provided by the present invention are: A method for determining silicon carbide content of the present invention uses a multi-element analyzer. The multi-element analyzer is first used to determine the weight percentage of silicon dioxide in a sample solution, and then converted into the weight percentage of silicon carbide through a formula. The determination method of the present invention has low detection difficulty and high detection accuracy, and is particularly suitable for silicon carbide-containing samples with a weight percentage of silicon carbide less than or equal to 90%. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The preparation methods of the silicon dioxide standard solution, reference solution, blank solution, standard sample solution and colorimetric scale used in the following examples and comparative examples are as follows: (1) Prepare the silica standard solution: Calcine silica with a purity of 99.99% in a muffle furnace for 2 hours at 1000℃, take it out and cool it to room temperature in a desiccator for later use. Weigh 0.2000g of high-purity silica reagent cooled to room temperature into a platinum crucible, add 3g of mixed flux and cover it with about 1g of mixed flux, then cover the crucible with a small gap, place it in a muffle furnace at 1000℃ and melt it for about 20 minutes, take it out and cool it. Place the crucible and lid in dilute hydrochloric acid containing 100ml of waste water, heat it at 200℃ and soak it until the solution is clear, wash the crucible and lid with grade 3 water, and cool it to room temperature. Make up to the volume in a 200ml volumetric flask, shake it well, and transfer the solution into a plastic bottle for storage.

[0030] (2) Prepare reference solution: Take 70ml of dilute hydrochloric acid and 8g of mixed flux and transfer them into a 500ml volumetric flask, dissolve them with water until the bubbles disappear completely, then transfer 10ml, 30ml, 50ml, 80ml, 100ml and 130ml of silica standard solution into a group of 500ml volumetric flasks respectively, make up to the scale and shake well. Mark them as reference solution No. 1, reference solution No. 2, reference solution No. 3, reference solution No. 4, reference solution No. 5 and reference solution No. 6.

[0031] (3) Preparation of colorimetric scale: Pipette 2.5 ml of the above-mentioned reference solution No. 1 to reference solution No. 6 into test tubes, numbered 1 to 6, and then pipette 2.5 ml of Si-1 reagent into test tubes No. 1 to 6 respectively. After 15 to 20 minutes, the reference solution will develop color. Due to the different content of silica standard solution in each test tube, the color of the solution in test tubes No. 1 to 6 changes from light yellow to dark yellow.

[0032] (4) Prepare blank solution: transfer 70 ml of dilute hydrochloric acid and 8 g of mixed flux into a 500 ml volumetric flask, dissolve with water until the bubbles disappear completely, make up to the mark, and shake well.

[0033] (5) Prepare standard sample solution: weigh 0.0400g of standard sample, put 4g of mixed flux into the crucible cover and leave a small gap in the high-temperature furnace. Heat to 1000℃±50℃ and melt for 30min. When the sample is completely dissolved, take it out, rotate the crucible so that the molten material adheres evenly to the inner wall of the crucible, and cool it. Wipe the outer wall of the crucible with filter paper, put it into a 400ml beaker containing 35ml of dilute hydrochloric acid and 20ml of water, heat at 200℃ to leach the molten material until the solution is clear, wash the crucible and cover with water, cool to room temperature, transfer to a 500ml volumetric flask, dilute with water to the customer, and shake well.

[0034] The dilute hydrochloric acid used in the embodiments and comparative examples is a dilute hydrochloric acid prepared by mixing concentrated hydrochloric acid and water in a ratio of 1:1; the mixed flux used in the embodiments and comparative examples is a mixture of anhydrous sodium carbonate and boric acid in a weight ratio of 2:1; the Si-1 reagent used in the embodiments and comparative examples is a color developer used in conjunction with a multi-element analyzer, and as the SiO2 content in the solution increases, the color changes from light yellow to dark yellow.

[0035] The multi-element analyzer used in the embodiments and comparative examples is a DFH multi-element analyzer.

[0036] Example 1 This embodiment provides a method for determining silicon carbide content, comprising the following steps: Step S1: Select GSB08-3221-2014ZBN430 silicon carbide standard material sample and prepare a sample solution, which specifically includes the following steps: Step S11: First, accurately weigh 0.0400 g of the sample in a platinum crucible and calcine it at a high temperature of 1000° C. to constant weight to remove volatile substances and free carbon. Then, take it out and put it in a desiccator to cool to room temperature.

[0037] Step S12: Add a few drops of water to the cooled platinum crucible to moisten it, add 10 ml of hydrofluoric acid, 2 ml of nitric acid, and 3-5 drops of sulfuric acid (each drop is 0.3-0.5 ml), evaporate at 150-250°C until white smoke disappears, and then evaporate to dryness for 3-5 minutes on high heat. This step is mainly to allow free silicon, silicon dioxide, silicates and other silicon-containing substances in the sample to escape as silicon tetrafluoride, ensuring that Si in the residue exists only in the form of SiC.

[0038] Step S13: Remove the crucible, cool it, put in 4g of mixed flux, cover the crucible and leave a small gap in the high temperature furnace. Heat to 1000℃±50℃ and melt for 30min. When the sample is completely dissolved, take it out, rotate the crucible so that the melt is evenly attached to the inner wall of the crucible, and cool it. This step is to convert the SiC in the residue into SiO2.

[0039] Step S14: Wipe the outer wall of the crucible with filter paper, put it into a 400ml beaker containing 35ml of dilute hydrochloric acid and 20ml of water, heat at 150-250℃ to extract the melt until the solution is clear, wash out the crucible and cover with water, cool to room temperature, transfer to a 500ml volumetric flask, dilute to scale with water, and shake well. This step is to make Si in SiO2 exist in ionic form.

[0040] Step S2: Prepare a silica standard solution, a reference solution and a blank solution, and prepare a colorimetric scale.

[0041] Step S3: Using a DFH multi-element analyzer to detect the silicon dioxide content in the sample solution of step S1, specifically as follows: Step S31: Pipette 2.5 ml of sample solution into a test tube, and pipette 2.5 ml of Si-1 reagent into the sample solution. After 10-15 minutes, the sample solution develops color. The color is compared with the color scale. The color is closest to the color of reference solution No. 6, so reference solution No. 6 is selected. According to the solubility of the reference solution, the standard sample of GBW03114 siliceous sandstone (SiO2 content 89.59%) is selected to prepare the standard sample solution.

[0042] Step S32: After determining the reference solution and the standard sample solution, clean the multi-element analyzer pipette three times with Si-1 reagent solution, and then use the multi-element analyzer to accurately and parallelly transfer 2.5ml of Si-1 reagent into the colorimetric tube. Then transfer the blank solution, standard sample solution, sample solution to be tested, and reference solution respectively and wash them three times. After cleaning, transfer 2.5ml of the corresponding solution and inject it into the colorimetric tube where 2.5ml of Si-1 reagent has been transferred. Vibrate and shake the solution to mix it evenly, and let it stand for 15-20min. After standing, use the second channel (purple light channel) of the multi-element analyzer to measure its value respectively. Establish a test curve based on the blank solution and reference solution No. 6. Correct the curve with the standard sample solution. The SiO2 content is obtained according to the calculation.

[0043] Step S4: According to the formula To calculate the silicon carbide content. is the SiO2 content measured using a multi-element analyzer.

[0044] Example 2 This embodiment provides a method for determining silicon carbide content, comprising the following steps: Step S1: Select sample A and prepare a sample solution. The method for preparing the sample solution is the same as that in Example 1.

[0045] Step S2: Prepare a silica standard solution, a reference solution and a blank solution, and prepare a colorimetric scale.

[0046] Step S3: Using a DFH multi-element analyzer to detect the silicon dioxide content in the sample solution of step S1, specifically as follows: Step S31: Pipette 2.5 ml of sample solution into a test tube, and pipette 2.5 ml of Si-1 reagent into the sample solution. After 10-15 minutes, the sample solution develops color. The color is compared with the color scale. The color is closest to the color of reference solution No. 4, so reference solution No. 4 is selected. According to the solubility of the reference solution, the standard sample of GBW03132 borosilicate glass (SiO2 content 53.98%) is selected to prepare the standard sample solution.

[0047] Step S32: After determining the reference solution and the standard sample solution, clean the multi-element analyzer pipette three times with Si-1 reagent solution, and then use the multi-element analyzer to accurately and parallelly transfer 2.5ml of Si-1 reagent into the colorimetric tube. Then transfer the blank solution, standard sample solution, sample solution to be tested, and reference solution respectively and wash them three times. After cleaning, transfer 2.5ml of the corresponding solution and inject it into the colorimetric tube where 2.5ml of Si-1 reagent has been transferred. Vibrate and shake the solution to mix it evenly, and let it stand for 15-20min. After standing, use the second channel (purple light channel) of the multi-element analyzer to measure its value respectively. Establish a test curve based on the blank solution and reference solution No. 4. Correct the curve with the standard sample solution (GBW03132).

[0048] Step S4: According to the formula To calculate the silicon carbide content. is the SiO2 content measured using a multi-element analyzer.

[0049] Example 3 This embodiment provides a method for determining silicon carbide content, comprising the following steps: Step S1: Select sample B and prepare a sample solution. The method for preparing the sample solution is the same as that in Example 1.

[0050] Step S2: Prepare a silica standard solution, a reference solution and a blank solution, and prepare a colorimetric scale.

[0051] Step S3: Using a DFH multi-element analyzer to detect the silicon dioxide content in the sample solution of step S1, specifically as follows: Step S31: Pipette 2.5 ml of sample solution into a test tube, and pipette 2.5 ml of Si-1 reagent into the sample solution. After 10-15 minutes, the sample solution develops color. The color is compared with the color scale. The color is closest to the color of reference solution No. 2, so reference solution No. 2 is selected. According to the solubility of the reference solution, the standard sample of GBW03133 alumina (SiO2 content 8.17%) is selected to prepare the standard sample solution.

[0052] Step S32: After determining the reference solution and the standard sample solution, clean the multi-element analyzer pipette three times with Si-1 reagent solution, and then use the multi-element analyzer to accurately and parallelly transfer 2.5ml of Si-1 reagent into the colorimetric tube. Then transfer the blank solution, standard sample solution, sample solution to be tested, and reference solution respectively and wash them three times. After cleaning, transfer 2.5ml of the corresponding solution and inject it into the colorimetric tube where 2.5ml of Si-1 reagent has been transferred. Vibrate and shake the solution to mix the solution evenly and let it stand for 15-20min. After standing, use the second channel (purple light channel) of the multi-element analyzer to measure its value respectively. Establish a test curve based on the blank solution and reference solution No. 2. Correct the curve with the standard sample solution (GBW03133). The SiO2 content is obtained according to the calculation.

[0053] Step S4: According to the formula To calculate the silicon carbide content. is the SiO2 content measured using a multi-element analyzer.

[0054] Comparative Example 1 Select GSB08-3221-2014ZBN430 silicon carbide standard material sample, first pre-sinter the GSB08-3221-2014ZBN430 silicon carbide standard material sample at 850℃, burn off the free carbon in the sample, and record the free carbon LOI content of the sample. Select YSBC28686-2021 silicon carbide 357# (carbon content 23.91%) standard sample to calibrate the carbon sulfur instrument equipment curve, and then use the carbon sulfur instrument to test the total carbon T·C content in the residue after burning. According to the formula ω(SiC)=ω(T·C)×3.3384×[1-ω(LOI) 850℃ / 100] to calculate the SiC content in the sample.

[0055] Comparative Example 2 Select sample A, pre-burn sample A at 850℃, burn off the free carbon in sample A, and record the free carbon LOI content of the sample. Select YSBC26802-2013 (carbon content 12.71%) protection slag standard sample to calibrate the carbon-sulfur instrument equipment curve, and then use the carbon-sulfur instrument to test the total carbon T·C content in the residue after burning. According to the formula ω(SiC)=ω(T·C)×3.3384×[1-ω(LOI) 850℃ / 100] to calculate the SiC content in the sample.

[0056] Comparative Example 3 Select sample B, pre-burn sample B at 850℃, burn off the free carbon in the sample, and record the free carbon LOI content of the sample. Select YSBC26803-2013 (carbon content 5.98%) protective slag standard sample to calibrate the carbon-sulfur instrument equipment curve, and use the carbon-sulfur instrument to test the total carbon T·C content in the residue after burning. According to the formula ω(SiC)=ω(T·C)×3.3384×[1-ω(LOI) 850℃ / 100] to calculate the SiC content in the sample.

[0057] The test results of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Tables 1 to 3 below.

[0058] Table 1

[0059] Table 2

[0060] Table 3

[0061] It can be seen from the results of Tables 1 to 3 that, compared with the conventional method for determining the SiC content in a silicon carbide sample in GB / T16555, the method for determining the silicon carbide content of the present invention has high detection accuracy.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for determining silicon carbide content, characterized in that: The steps include: Step S1: preparing a sample containing silicon carbide into a sample solution; Step S2: preparing a silica standard solution, a reference solution and a blank solution, and preparing a colorimetric scale; Step S3: using a multi-element analyzer to detect the weight percentage of silicon dioxide in the sample solution of step S1; Step S4: According to the formula To calculate the silicon carbide content; where, is the weight percentage of silicon dioxide measured in step S3, is the weight percentage of silicon carbide.

2. The measuring method according to claim 1, characterized in that The weight percentage of silicon carbide in the silicon carbide-containing sample is less than or equal to 90%.

3. The measuring method according to claim 1, characterized in that The step S3 specifically includes the following steps: Step S31: Pipette the color developer used in conjunction with the multi-element analyzer into the sample solution, wait for 10 to 15 minutes for the sample solution to develop color, compare the color with the color scale, select the color scale closest to the color in the sample solution, and select the reference solution with the corresponding number; According to the solubility of the corresponding reference solution, select the standard sample and prepare the standard sample solution; Step S32: After determining the reference solution and the standard sample solution, the blank solution, the standard sample solution, the sample solution, and the reference solution are respectively mixed evenly with the color developer, and after standing for 15-20 minutes, the weight percentage of silica is measured respectively using the violet light channel of the multi-element analyzer; wherein, a test curve is established based on the blank solution and the reference solution, the curve is corrected with the standard sample solution, and the weight percentage of silica is obtained according to calculation.

4. The measuring method according to claim 1, characterized in that The preparation method of the silicon dioxide standard solution is as follows: calcining silicon dioxide with a purity of ≥99.99% at 900-1100°C for 1-3h, and cooling; weighing 0.1000-0.300 parts by weight of the cooled silicon dioxide into a platinum crucible, adding 2-4 parts by weight of a mixed flux, covering with 0.5-1.5 parts by weight of the mixed flux, and then covering the crucible with a lid with a gap, placing it at 900-1100°C for melting for 10-30min, and cooling; placing the crucible and the crucible lid in dilute hydrochloric acid, heating and leaching at 150-250°C until the solution is clear, washing out the crucible and the crucible lid, and cooling; then making the cooled solution dilute to a 200-volume volumetric flask, shaking it well, and transferring it into a plastic bottle for storage.

5. The measuring method according to claim 3, characterized in that The preparation method of the standard sample solution is as follows: weigh 0.0100-0.1 parts by weight of the standard sample, put 3-5 parts by weight of the mixed flux, cover the crucible with a gap, place it in a high-temperature furnace, heat it to 900-110° C. and melt it for 20-40 minutes, take it out, rotate the crucible to make the melt evenly adhere to the inner wall of the crucible, and cool it; wipe the outer wall of the crucible with filter paper, put it in a beaker containing 30-40 parts by volume of dilute hydrochloric acid and 10-30 parts by volume of water, heat it at 150-250° C. to leach the melt until the solution is clear, wash the crucible and the crucible cover with water, cool it, transfer it into a volumetric flask, dilute it to the scale with water, and shake it well.

6. The measuring method according to claim 1, characterized in that The blank solution is prepared as follows: 60-80 parts by volume of dilute hydrochloric acid and 5-10 parts by weight of mixed flux are transferred into a 500-part volume volumetric flask, dissolved with water until bubbles disappear, fixed to volume, and shaken well.

7. The measuring method according to claim 1, characterized in that The preparation method of the reference solution is as follows: 60-80 parts by volume of dilute hydrochloric acid and 5-10 parts by weight of mixed flux are transferred into a 500-part by volume volumetric flask, dissolved with water until bubbles disappear, and then 10 parts by volume, 30 parts by volume, 50 parts by volume, 80 parts by volume, 100 parts by volume, and 130 parts by volume of silicon dioxide standard solution are respectively transferred into a 500-part by volume volumetric flask to the scale, shaken well, and marked as reference solution No. 1, reference solution No. 2, reference solution No. 3, reference solution No. 4, reference solution No. 5, and reference solution No.

6.

8. The measuring method according to claim 7, characterized in that The preparation method of the colorimetric scale is as follows: 2-3 volumes of the reference solution No. 1 to reference solution No. 6 are respectively transferred to test tubes, the test tubes are numbered No. 1 to No. 6, and then 2-3 volumes of the color developer are respectively transferred to test tubes No. 1 to No. 6, and the reference solution is colored after 15 to 20 minutes.

9. The measuring method according to claim 1, characterized in that The step S1 specifically includes the following steps: Step S11: weigh 0.01-0.1 parts by weight of a sample in a platinum crucible, calcine at 800-1200° C. to constant weight, dry, and cool; Step S12: drip water into the cooled platinum crucible to moisten it, add 5-15 parts by volume of hydrofluoric acid, 1-3 parts by volume of nitric acid, and 1-2.5 parts by volume of sulfuric acid, evaporate at 150-250° C. until white smoke disappears, and then evaporate to dryness over high heat for 3-5 minutes; Step S13: remove the crucible, cool it, add 2-6 parts by weight of mixed flux, cover the crucible with a lid and leave a gap, then place it in a high-temperature furnace, heat it to 900-1100° C. and melt it for 20-40 minutes, take it out, rotate the crucible so that the melt is evenly attached to the inner wall of the crucible, and cool it; Step S14: Wipe the outer wall of the crucible with filter paper, put it into a beaker containing 30-40 parts by volume of dilute hydrochloric acid and 10-30 parts by volume of water, heat at 150-250° C. to extract the melt until the solution is clear, wash out the crucible and the lid with water, cool it, transfer it into a 500 parts by volume volumetric flask, dilute it to the mark with water, and shake it well.

10. The determination method according to any one of claims 4 to 9, characterized in that: The mixed flux is composed of anhydrous sodium carbonate and boric acid, and the weight ratio of anhydrous sodium carbonate to boric acid is (1-3):1.

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