Detection method for measuring carbon content in silicon carbide by using infrared carbon-sulfur instrument

Abstract

A detection method for measuring the carbon content in silicon carbide by using an infrared carbon-sulfur instrument specifically comprises the following steps: (1) pretreatment of an actual sample: putting a silicon carbide sample into a muffle furnace to be calcined, and removing free carbon in the silicon carbide sample to obtain calcined silicon carbide; (2) crucible pretreatment: putting the crucible in a muffle furnace for pretreatment, namely putting the crucible in the muffle furnace for heating, and putting the crucible in a dryer for storage after heating to obtain the pretreated crucible; (3) establishing a standard curve: due to the fact that the silicon carbide standard substance is few and non-uniformly distributed, taking lithium carbonate as a standard substance, adopting a method of manually inputting a sample weighing amount, calculating different standard carbon contents through an instrument, and establishing the standard curve; and (4) analyzing an actual sample: weighing the calcined silicon carbide, putting the silicon carbide into the pretreated crucible, adding a fluxing agent, and analyzing in an infrared carbon-sulfur analyzer. The detection method can quickly and accurately analyze the carbon content in silicon carbide.

Description

Technical Field

[0001] This invention relates to the field of analytical testing technology, and in particular to a method for determining the carbon content in silicon carbide using an infrared carbon-sulfur analyzer. Background Technology

[0002] Silicon carbide (SiC) is a non-metallic carbide composed of silicon and carbon bonded by covalent bonds. Its hardness is second only to diamond and boron carbide. It is a colorless crystal, turning bluish-black when oxidized or containing impurities. Silicon carbide variants with a diamond structure are commonly known as corundum. Due to its stable chemical properties, high thermal conductivity, low coefficient of thermal expansion, and good wear resistance, silicon carbide has many uses besides being an abrasive. For example, coating the inner wall of turbine impellers or cylinder blocks with silicon carbide powder using a special process can improve their wear resistance and extend their service life by 1-2 times. High-grade refractory materials made from it are thermally shock resistant, small in size, lightweight, high in strength, and energy-efficient. Low-grade silicon carbide (containing approximately 85% SiC) is an excellent deoxidizer, used to accelerate steelmaking and facilitate control of chemical composition, thus improving steel quality. Furthermore, silicon carbide is widely used in the manufacture of silicon carbide heating elements.

[0003] Currently, conventional methods for determining the carbon content in silicon carbide suffer from large fluctuations in values, long detection cycles, and poor precision. There is a need to research a new method for determining the carbon content in silicon carbide in order to optimize detection parameters and provide faster and more accurate analytical results. Summary of the Invention

[0004] The technical problem this invention aims to solve is to provide a method for determining the carbon content in silicon carbide using an infrared carbon-sulfur analyzer. This method addresses the issues of large fluctuations in carbon content values, long analysis cycles, and poor precision in silicon carbide analysis. It leverages the advantages of instrumental analysis to accurately and rapidly determine the carbon content in silicon carbide. Since existing silicon carbide standards are scarce and unevenly distributed, it is difficult to establish a standard curve using silicon carbide standard materials. This detection method uses lithium carbonate as a standard material, manually inputting the sample weight to obtain different standard carbon contents and establish a standard curve. Furthermore, this detection method lowers the sample melting point by adding flux, pre-treats the crucible to reduce the influence of the carbon content in the crucible on sample detection, optimizes the sample weight to improve the accuracy of analytical results, and selects a better analysis time and comparison level, thus achieving rapid and accurate detection of carbon content in silicon carbide.

[0005] According to one aspect of the present invention, a method for determining the carbon content in silicon carbide using an infrared carbon-sulfur analyzer is provided, specifically comprising the following steps: (1) Pretreatment of actual samples: The silicon carbide sample was placed in a muffle furnace for calcination to remove the free carbon in the silicon carbide sample and obtain calcined silicon carbide. (2) Crucible pretreatment: The crucible is placed in a muffle furnace for pretreatment, that is, the crucible is heated in a muffle furnace and then stored in a desiccator to obtain the pretreated crucible; (3) Establishing a standard curve: Since silicon carbide standard materials are scarce and unevenly distributed, lithium carbonate is selected as the standard material. The sample weight is manually input and the different standard carbon contents are calculated by the instrument to establish a standard curve. (4) Actual sample analysis: Weigh the calcined silicon carbide obtained in step (1) and place it in the crucible after pretreatment in step (2), add flux, and analyze it in an infrared carbon-sulfur analyzer. The flux in step (4) is one of tungsten granules, tin granules, tungsten-tin mixture, or tungsten-tin-industrial pure iron mixture, wherein the mass ratio of tungsten to tin in the tungsten-tin mixture is 5~6:2~3, and the mass ratio of tungsten:tin:industrial pure iron in the tungsten-tin-industrial pure iron mixture is 10~12:2~3:5~6.

[0006] Furthermore, the calcination conditions in step (1) are as follows: The calcination temperature is 650℃~850℃; The calcination time is 1 to 2 hours.

[0007] Furthermore, the heating conditions in step (2) are as follows: The heating temperature is 1000℃~1200℃; The heating time is 1 hour to 2 hours; The time for storing the product in a desiccator after heating in step (2) is ≤24h.

[0008] Furthermore, the mass ratio of calcined silicon carbide to flux in step (4) is 1~2:18~20.

[0009] Furthermore, the operating conditions of the infrared carbon-sulfur analyzer described in step (4) are as follows: The power of the operation is 2.2~2.5KW; The working carrier gas flow rate is 3~4 L / min, and the carrier gas is high-purity oxygen; The carrier gas pressure for the operation is 25~450%psi; The working gas pressure is 30~50%psi, and the working gas is nitrogen. The detection limit for the work is 0.001~0.005ppm.

[0010] Furthermore, the analysis time in step (4) is 20~60s, preferably 30~50s.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The detection method disclosed in this invention can effectively improve the traditional method for detecting carbon content in silicon carbide, which has large fluctuations, poor accuracy and precision. The detection method is simple and fast, and the analysis results are stable and reliable, which reduces the labor intensity of the staff and improves the work efficiency.

[0012] (2) The technical solution disclosed in this invention uses lithium carbonate as a standard substance, and adopts manual input of sample weight to obtain different standard carbon contents and establish a standard curve, which solves the problem that existing silicon carbide standard substances are few and unevenly distributed, making it difficult to establish a standard curve using silicon carbide standard substances. (3) The technical solution disclosed in this invention achieves rapid and accurate detection of carbon content in silicon carbide by adding flux to lower the melting point of the sample, pre-treating the crucible to reduce the influence of carbon content in the crucible on sample detection, optimizing the sample weighing amount to improve the accuracy of analysis results, and screening better analysis time and comparison level. Detailed Implementation

[0013] The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0014] The instruments, equipment, and reagents used in this invention are as follows: Instruments and equipment: CS-600 infrared carbon and sulfur analyzer (LECO Corporation, USA), electronic balance with a precision of 0.0001g (XX), ceramic crucible, muffle furnace; Reagents: Magnesium perchlorate, alkali asbestos, platinum-plated silica gel, rare earth copper oxide, silicon carbide 1# (self-made), silicon carbide 2# (self-made), silicon carbide 3# (self-made). All silicon carbide samples used were submitted samples and were ground to 120 mesh using a sample grinder. High-purity oxygen: purity not less than 99.90%; Standard samples: GSB02-1344-2001C1 (C1 standard sample) with a carbon content of 29.57% and GSB02-1344-2001C2 (C2 standard sample) with a carbon content of 26.59%.

[0015] The operating conditions of the CS-600 infrared carbon-sulfur analyzer used in this invention are shown in Table 1.

[0016] Table 1 Operating conditions of the CS-600 infrared carbon and sulfur analyzer .

[0017] The present invention provides a method for determining the carbon content in silicon carbide using an infrared carbon-sulfur analyzer in the specific embodiments section, which includes the following steps: (1) Sample pretreatment: The silicon carbide sample was placed in a muffle furnace for calcination to remove the free carbon in the silicon carbide sample and obtain calcined silicon carbide. (2) Crucible pretreatment: The crucible is placed in a muffle furnace for pretreatment, that is, the crucible is heated in a muffle furnace and then stored in a desiccator to obtain the pretreated crucible; (3) Since silicon carbide standard materials are scarce and unevenly distributed, lithium carbonate is selected as the standard material. The sample weight is manually input and the different standard carbon contents are calculated by the instrument to establish a standard curve. (4) Weigh the calcined silicon carbide obtained in step (1) and place it in the crucible after pretreatment in step (2), add flux, and analyze it in an infrared carbon-sulfur analyzer.

[0018] Based on the above technical solution, the calcination conditions in step (1) are as follows: The calcination temperature is 650℃~850℃; The calcination time is 1 to 2 hours.

[0019] Based on the above technical solution, the heating conditions in step (2) are as follows: The heating temperature is 1000℃~1200℃; The heating time is 1 hour to 2 hours; The time for storing the product in a desiccator after heating in step (2) is ≤24h.

[0020] Based on the above technical solution, the flux in step (4) is one of tungsten granules, tin granules, tungsten-tin mixture, and tungsten-tin-industrial pure iron mixture, wherein the mass ratio of tungsten to tin in the tungsten-tin mixture is 5~6:2~3, and the mass ratio of tungsten:tin:industrial pure iron in the tungsten-tin-industrial pure iron mixture is 10~12:2~3:5~6.

[0021] Based on the above technical solution, the mass ratio of calcined silicon carbide to flux in step (4) is 1~2:18~20.

[0022] Based on the above technical solution, the operating conditions of the infrared carbon-sulfur analyzer in step (4) are as follows: The working carrier gas flow rate is 3~4 L / min, and the carrier gas is high-purity oxygen; The carrier gas pressure for the operation is 25~45%psi; The working gas pressure is 30~50%psi, and the working gas is nitrogen. The detection limit for the work is 0.001~0.005ppm.

[0023] Based on the above technical solution, the analysis time in step (4) is 20~60s, preferably 30~50s.

[0024] Example 1 A method for determining the carbon content in silicon carbide using an infrared carbon-sulfur analyzer, specifically including the following steps: (1) Sample pretreatment: Weigh 1.0g of silicon carbide No.1 and calcine it in a muffle furnace at 850℃ for 2h to obtain the calcined silicon carbide sample.

[0025] (2) Crucible pretreatment: The blank value required for the detection of carbon content in silicon carbide is low. However, the blank value of untreated ceramic crucibles is high and unstable due to contamination and absorption of moisture and gas from the air. Therefore, the analytical crucibles must be pretreated before use. The ceramic crucibles are placed in a muffle furnace at 1200℃ for 2 hours and then stored in a desiccator for 1 hour to obtain the pretreated ceramic crucibles.

[0026] (3) Selection of flux: The role of flux in carbon and sulfur analysis is to lower the melting point of the sample, increase the combustion temperature, and prevent sample splashing. The flux used is tungsten granules, tin granules, tungsten-tin mixture (mass ratio of tungsten to tin is 3:5), and tungsten-tin-industrial pure iron mixture (mass ratio of tungsten:tin:industrial pure iron is 3:5:12). Weigh 0.1g of standard sample GSB02-1344-2001C2 (C2 standard sample) with a carbon content of 26.59% into the pretreated crucible, add 2g of the above flux, and perform multiple analyses to take the average value. The analysis results are shown in Table 2. As can be seen from Table 2, the measured values ​​are lower and the stability is poor when using tungsten granules, tin granules or tungsten-tin mixture flux, and the dust is larger during the measurement. Therefore, tungsten-tin mixture is used and industrial pure iron is added as flux.

[0027] (4) Selection of sample quantity: The sample quantity affects the accuracy of the analytical results. The main reason is that if the sample quantity is too low, the sample will have low representativeness, while if the sample quantity is too high, the analytical results will be too low due to the poor melting of the sample. Weigh 0.10g±0.002g, 0.20g±0.002g, 0.30g±0.002g, 0.40g±0.002g, and 0.50g±0.002g of standard sample GSB02-1344-2001C2 (C2 standard sample) with a carbon content of 26.59%. The specific sample quantity and carbon content determination value are shown in Table 3. As can be seen from Table 3, by comparing the average value and the standard deviation, the sample quantity is selected as 0.3g.

[0028] (5) Precision test: Since silicon carbide standard materials are scarce and unevenly distributed, it is difficult to establish a standard curve using silicon carbide standard materials. This method uses lithium carbonate standard materials and adopts the method of manually inputting the sample weight. Different standard carbon contents are calculated by using a CS-600 infrared carbon-sulfur analyzer to establish a standard curve and achieve the purpose of calibrating silicon carbide samples. Using analytical grade lithium carbonate standard materials, the required mass of lithium carbonate standard materials with carbon contents of 5%, 10%, 15%, 20%, and 25% is calculated when the input weight is 0.3g. Each weight is measured in parallel 5 times. The experimental results are shown in Table 4 (precision test results). As can be seen from Table 4, a standard curve can be drawn using lithium carbonate standard materials. The standard materials have good uniformity and good linearity. Lithium carbonate can be used as a standard sample to measure high carbon content in silicon carbide.

[0029] (6) Analysis time and comparison level: The analysis time of the sample is determined by both the analysis time and the comparison level in the analytical method, which is generally 30 to 50 seconds. In actual testing, the integral curve on the computer screen should be observed. If tailing occurs, the comparison level should be appropriately increased to avoid affecting the analysis results due to excessive blank. The CS-600 infrared carbon-sulfur analyzer was used to analyze 0.3g of standard sample GSB02-1344-2001C2 (C2 standard sample) with a carbon content of 26.59%. The analysis time was set to 20s, 30s, 40s, 50s, and 60s to test the comparison level. The specific test results are shown in Table 5. From the data in Table 5 and the analysis results of the integral curve, it can be seen that the analysis time is 50s and the comparison level is 2.

[0030] (7) Standard sample test: Weigh 0.1g of C1 standard sample and 0.1g of C2 standard sample into the pretreated ceramic crucible, add 2g of tungsten-tin industrial pure iron mixed flux, set the analysis time to 50s, and analyze it using a CS-600 infrared carbon-sulfur analyzer. The specific analysis results are shown in Table 6. As can be seen from Table 6, the method used in this invention has good accuracy.

[0031] (8) Actual sample analysis: Weigh 0.1g of silicon carbide 1# after calcination in step (1) into the ceramic crucible after pretreatment in step (2), add tungsten-tin-industrial pure iron mixture flux (i.e., 1.2g tungsten granules, 0.3g tin granules, and 0.5g industrial pure iron), set the analysis time to 50s, and analyze it in a CS-600 infrared carbon-sulfur analyzer. The specific test results are shown in Table 7. The results show that the sample analysis results are good and the precision is good.

[0032] Table 2 shows the test results for different fluxes. .

[0033] Table 3 shows the test results of the effect of sample weight on analytical accuracy. .

[0034] Table 4 shows the precision test results. .

[0035] Table 5 shows the test results for analysis time and comparison level. .

[0036] Table 6 shows the test results for the standard samples. .

[0037] Example 2 The difference from Example 1 is that the actual sample tested is different, that is, the test sample is silicon carbide 2#. The rest of the process is the same as in Example 1. The specific test results are shown in Table 7. The results show that the sample analysis results are good and the precision is good.

[0038] Example 3 The difference from Example 1 is that the actual sample tested is different, that is, the test sample is silicon carbide 3#. The rest of the process is the same as in Example 1. The specific test results are shown in Table 7. The results show that the sample analysis results are good and the precision is good.

[0039] Table 7 shows the test results of the actual samples. .

[0040] Example 4 The difference from Example 1 is that the flux composition ratio is different, that is, the ratio of tungsten granules, tin granules and pure iron is different. The rest of the process is the same as that of Example 1. The specific test results are shown in Table 8. When the mass ratio of tin: industrial pure iron: tungsten is 3:5:12, the sample analysis results are good and the precision is good.

[0041] Table 8 shows the test results for different flux composition ratios. .

[0042] Example 5 The difference from Example 1 is that pig iron standard samples were used to create a standard curve. That is, pig iron with different carbon contents was used as standard samples to draw a standard curve and extended to a high content (25%). The specific test results are shown in Table 9. The sample analysis values ​​were much lower and the precision was also poor.

[0043] Table 9 shows the test results of plotting the standard curve using pig iron standard samples. .

[0044] Through the above technical solution, the detection method uses lithium carbonate as a standard reference to plot a standard curve. The standard reference exhibits good homogeneity and linearity, allowing lithium carbonate to be used as a standard sample for measuring high carbon content in silicon carbide. The detection method, by adjusting the conditional analysis time and observing the integral curve, avoids tailing phenomena and adjusts the comparison level to prevent the sample analysis time and comparison level from affecting the sample detection results.

[0045] The above description is merely a few embodiments of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any modifications or alterations made by those skilled in the art without departing from the scope of the technical solution of the present invention using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for determining the carbon content in silicon carbide using an infrared carbon-sulfur analyzer, characterized in that, Specifically, the steps include the following: (1) Pretreatment of actual samples: The silicon carbide sample was placed in a muffle furnace for calcination to remove the free carbon in the silicon carbide sample and obtain calcined silicon carbide. (2) Crucible pretreatment: The crucible is placed in a muffle furnace for pretreatment, that is, the crucible is heated in a muffle furnace and then stored in a desiccator to obtain the pretreated crucible; (3) Establishing a standard curve: Since silicon carbide standard materials are scarce and unevenly distributed, lithium carbonate is selected as the standard material. The sample weight is manually input and the different standard carbon contents are calculated by the instrument to establish a standard curve. (4) Actual sample analysis: Weigh the calcined silicon carbide obtained in step (1) and place it in the crucible after pretreatment in step (2), add flux, and analyze it in an infrared carbon-sulfur analyzer. The flux in step (4) is one of tungsten granules, tin granules, tungsten-tin mixture, or tungsten-tin-industrial pure iron mixture, wherein the mass ratio of tungsten to tin in the tungsten-tin mixture is 5~6:2~3, and the mass ratio of tungsten:tin:industrial pure iron in the tungsten-tin-industrial pure iron mixture is 10~12:2~3:5~6.

2. The detection method according to claim 1, characterized in that, The calcination conditions in step (1) are as follows: The calcination temperature is 650℃~850℃; The calcination time is 1 to 2 hours.

3. The detection method according to claim 1, characterized in that, The heating conditions described in step (2) are as follows: The heating temperature is 1000℃~1200℃; The heating time is 1 hour to 2 hours; The time for storing the product in a desiccator after heating in step (2) is ≤24h.

4. The detection method according to claim 1, characterized in that, The mass ratio of calcined silicon carbide to flux in step (4) is 1~2:18~20.

5. The detection method according to claim 1, characterized in that, The operating conditions of the infrared carbon-sulfur analyzer described in step (4) are as follows: The power of the operation is 2.2~2.5KW; The working carrier gas flow rate is 3~4 L / min, and the carrier gas is high-purity oxygen; The carrier gas pressure for the operation is 25~45%psi; The working gas pressure is 30~50%psi, and the working gas is nitrogen. The detection limit for the work is 0.001~0.005ppm.

6. The detection method according to claim 1, characterized in that, The analysis time in step (4) is 20~60s, preferably 30~50s.