Nickel-based alloy welding material carbon-sulfur analyzer fluxing agent with protection effect on combustion tube and use method of nickel-based alloy welding material carbon-sulfur analyzer fluxing agent

Abstract

The invention discloses a nickel-based welding strip carbon and sulfur analyzer fluxing agent with a protection effect on a combustion tube and a use method of the nickel-based welding strip carbon and sulfur analyzer fluxing agent, and belongs to the field of analysis of carbon and sulfur in nickel-based welding strips. The invention aims to solve the problems of precision, corrosion to equipment and the like when the existing traditional fluxing agent is used for measuring a nickel-based welding strip. The fluxing agent disclosed by the invention is prepared from the following components by weight: 0.48 to 0.72 g of tungsten particles, 0.48 to 0.72 g of tin particles, 0.0024 to 0.0096 g of copper oxide and 0.0144 to 0.024 g of lithium carbonate, wherein the weight ratio of Li2CO3 to copper oxide CuO is 4 to 8. During use, 50% of the total weight of tungsten particles is taken and laid on the bottom layer of a crucible, a sample to be detected is laid on the pre-laid tungsten particle layer, the sample layer is covered with tin particles, lithium carbonate and copper oxide are mixed in proportion and then evenly scattered on the surface of the tin particle layer, and then the top layer is covered with the remaining 50% of tungsten particles. Oxidation, sulfur fixation and neutralization reactions in the combustion process can be precisely regulated and controlled, and the detection precision and the equipment service life are both considered.

Description

Technical Field

[0001] This invention belongs to the field of metal chemical analysis, specifically, it relates to a nickel-based alloy welding material flux for carbon-sulfur analyzers that has a protective effect on combustion tubes and its application method. Background Technology

[0002] Nickel-based alloy welding materials are widely used in aerospace, nuclear power facilities and pressure vessels due to their good high-temperature strength, structural stability and oxidation and corrosion resistance. The key factor to ensure the service performance of nickel-based alloy welding materials is the stability of the composition of the weld joint. Among them, the content of C and S elements has a great influence on the crack sensitivity and corrosion resistance of the weld joint.

[0003] Carbon-sulfur analyzers are core equipment for detecting the composition of metallic materials. They release carbon and sulfur from samples through high-temperature combustion, followed by quantitative analysis using infrared detection. However, traditional fluxes face a series of technical challenges when analyzing high-melting-point materials such as nickel-based alloy welding materials.

[0004] In nickel-based alloy welding materials, sulfur generates sulfur oxides SO3 and SO2 during high-temperature combustion. These acidic gases react with the combustion tube (made of quartz or ceramic), shortening its lifespan. Sulfur in nickel-based materials is highly volatile at high temperatures, and traditional fluxes lack an effective sulfur-fixing mechanism, resulting in low sulfur recovery rates and affecting the detection limit. Furthermore, the high melting point of nickel-based alloys makes it difficult for traditional fluxes to quickly form a molten eutectic, leading to incomplete combustion and reduced carbon release efficiency. Therefore, there is an urgent need to develop a novel flux to improve detection accuracy and equipment reliability. Summary of the Invention

[0005] This invention aims to solve the problems of accuracy and corrosiveness of existing traditional fluxes in determining nickel-based alloy welding materials, and provides a flux for a nickel-based alloy welding material carbon-sulfur analyzer that protects the combustion tube and its application method.

[0006] To address the aforementioned technical problems, the present invention adopts the following technical solution: One of the objectives of this invention is to provide a nickel-based alloy welding material flux for a carbon-sulfur analyzer that provides protection for the combustion tube. The flux consists of individually packaged 0.48g to 0.72g of tungsten granules, 0.48g to 0.72g of tin granules, 0.0024g to 0.0096g of copper oxide, and 0.0144g to 0.024g of lithium carbonate, wherein the weight ratio of lithium carbonate to copper oxide is (4 to 8):1.

[0007] The second objective of this invention is to provide a method for using a nickel-based alloy welding material flux for a carbon-sulfur analyzer that provides protection for the combustion tube. This method includes the following steps: Step 1, prepare the reagents for the test: standard substance, tungsten granules, tin granules, copper oxide, lithium carbonate; Step 2: Set the infrared carbon-sulfur analyzer to an analysis power of 1.5 kW to 3.0 kW, a comparison level of 2%, an oxygen pressure of 0.2 to 0.5 MPa, an oxygen flow rate of 3.0 L / min, a pre-purge time of 40 s, a pre-integration time of 10 s, and an analysis time of 45 to 60 s. Step 3: Soak the sample to be tested in anhydrous ethanol for 3-5 minutes, and then dry it with a hair dryer; Step 4: Input the carbon and sulfur standard values ​​corresponding to the standard substance. Place a ceramic crucible on the analytical balance. Take 50% of the total weight of tungsten particles and spread them on the bottom layer. Spread the standard substance evenly on the pre-spread tungsten particle layer. Cover the standard sample layer with all the tin particles in the formula. Mix lithium carbonate (Li2CO3) / copper oxide (CuO) in a ratio of (4-8) and sprinkle it evenly on the surface of the tin particle layer. Cover the top layer with the remaining 50% of the tungsten particles. Measure at least once to obtain the carbon and sulfur standard values ​​of the standard substance. The test results are expressed as a percentage. Step 5: Select the tested standard substance, select "Calibrate", and the infrared carbon-sulfur analyzer will automatically calibrate and save the coefficients; Step 6: Repeat the test on the standard substance at least once. If the result does not meet the carbon and sulfur standard value range of the standard substance, return to step 4 until the test result meets the carbon and sulfur standard value range of the standard substance. Step 7: Place a ceramic crucible on the analytical balance, spread 50% of the total tungsten particle weight on the bottom layer of the sample, weigh 0.3-0.8g of the sample to be tested and spread it evenly on the pre-spread tungsten particle layer; cover the sample layer with all the tin particles in the formula; mix lithium carbonate (Li2CO3) / copper oxide (CuO) in a ratio of (4-8) and sprinkle it evenly on the surface of the tin particle layer; cover the top layer with the remaining 50% of the tungsten particles, and determine the carbon and sulfur content of the sample according to the working conditions selected by the infrared carbon and sulfur analyzer; Step 8: Input the carbon and sulfur standard values ​​corresponding to the standard substance. Place a ceramic crucible on the analytical balance. Take 50% of the total weight of tungsten particles and spread them on the bottom layer. Spread the standard substance evenly on the pre-spread tungsten particle layer. Cover the standard sample layer with all the tin particles in the formula. Mix lithium carbonate (Li2CO3) / copper oxide (CuO) in a ratio of (4-8) and sprinkle it evenly on the surface of the tin particle layer. Cover the top layer with the remaining 50% of the tungsten particles. Measure at least once to obtain the carbon and sulfur standard values ​​of the standard substance and determine whether the test results meet the carbon and sulfur standard value range. Step 9: Read the detection data of carbon and sulfur content of the sample.

[0008] To further specify, an infrared carbon-sulfur analyzer was used to determine the carbon and sulfur content of nickel-based alloy welding materials.

[0009] Further specified, the tungsten particles contain W ≥ 99.5% (mass), C ≤ 0.0005% (mass), S ≤ 0.0005% (mass), and the particle size of the tungsten particles is 0.4 mm to 1.0 mm.

[0010] Further specified, the tin granules contain Sn ≥ 99.5% (mass), C ≤ 0.0005% (mass), S ≤ 0.0005% (mass), and the particle size of the tin granules is 0.2mm to 0.6mm.

[0011] Further specified, the content of copper oxide is ≥99.5% (mass), C≤0.0005% (mass), S≤0.0005% (mass), and the particle size of copper oxide is 200-400 mesh.

[0012] Further specified, the lithium carbonate content is ≥99.5% (mass), C≤0.0005% (mass), S≤0.0005% (mass), and the lithium carbonate particle size is 300-500 mesh.

[0013] To further specify, the standard values ​​of the reference materials used, in percentage terms, are: C 0.0100%~0.0200% and S 0.0010%~0.0100%.

[0014] Further specified, the anhydrous ethanol used is analytical grade, and the ethanol concentration is 99.0% to 99.9% by mass percentage.

[0015] This invention, through a layered sequence of "bottom tungsten particles → sample → tin particles → CuO / Li2CO3 → top tungsten particles," can precisely control the oxidation, sulfur fixation, and neutralization reactions during the combustion process, balancing detection accuracy and equipment lifespan.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a pre-constructed porous support structure in the bottom tungsten particles to form stable oxygen diffusion channels in the early stages of combustion. This solves the stratification problem caused by density differences in traditional mixed fluxes, especially for high-density nickel-based alloy samples, avoiding combustion lag caused by insufficient oxygen at the bottom. The tin particle layer follows immediately above the sample, rapidly melting and encapsulating it due to its low melting point. This design not only effectively suppresses the risk of splashing during the high-temperature combustion of nickel-based materials but also disperses the sample into the pores of the bottom tungsten particles through the capillary action of liquid tin, significantly increasing the reaction contact area and improving combustion efficiency by approximately 20%. The measured combustion time is reduced from 45 seconds in the traditional mixing method to 36 seconds. Adding too much tungsten granules will cause the melt to become viscous, resulting in insufficient mixing of the sample and flux, and potentially leaving unreacted carbon and sulfur compounds that affect the release efficiency. Adding too much tin granules will cause them to oxidize at high temperatures to generate SnO2 vapor, which may interfere with infrared spectroscopy detection and increase background noise. Therefore, the preferred range for the amount of tungsten granules added is 0.48–0.72 g, and the preferred range for the amount of tin granules added is 0.48–0.72 g.

[0017] This invention places a CuO and Li2CO3 mixed layer above a tin granule layer, fully utilizing the physical characteristics of the rising combustion gas flow to achieve directional reaction control. During the high-temperature stage, the rising sulfur oxides preferentially contact the upper CuO layer, generating stable CuS / CuSO4 through CuO's sulfur-fixing effect, reducing sulfur escape in the gas phase. Meanwhile, the decomposition product Li2O of Li2CO3 precisely neutralizes the subsequently generated SO3 acidic gas, preventing it from penetrating downwards and corroding the combustion tube. In contrast, in traditional mixing methods, CuO and Li2CO3 are randomly distributed around the sample, easily encapsulated by molten tin and losing their reactivity, leading to significant fluctuations in sulfur recovery. The top layer of tungsten granules further forms a high-temperature oxide layer, which promotes complete oxidation of residual carbon in the later stages of combustion through the catalytic action of WO3. Simultaneously, it physically blocks gas flow disturbances from interfering with the detection signal, reducing the carbon detection RSD from 0.8% to 0.3%. The ratio of lithium carbonate to copper oxide is strictly controlled between 4 and 8 because this range balances oxidation efficiency and melting characteristics. If the ratio is below 4, insufficient melt fluidity will lead to uneven dispersion of copper oxide, preventing it from fully contacting the sample and resulting in carbon and sulfur residues. If the ratio is above 8, the concentration of copper oxide will be excessively diluted, reducing its oxidizing power and making it difficult to completely decompose the stable components in the nickel-based alloy. In addition, nickel-based alloy welding materials often contain high-melting-point and chemically inert metals such as nickel and chromium, which require a strong oxidizing environment and continuous high temperature to effectively release carbon and sulfur. The 4-8 ratio has been experimentally verified to suppress interference from metal vapors such as tin and tungsten under these conditions, ensuring the purity of the infrared detection signal. Therefore, the preferred weight ratio of lithium carbonate (Li2CO3) to copper oxide (CuO) is 4-8.

[0018] The layered structure of this invention offers unique advantages in equipment protection. Sulfur released during the combustion of nickel-based alloy welding materials is intercepted in multiple layers during its ascent: the bottom layer of tungsten particles adsorbs nascent sulfur vapor, the middle layer of CuO fixes the sulfur, and the top layer of tungsten particles captures the escaping sulfur, forming a three-tiered protection mechanism. Adopting this layered sequence reduces the sulfur corrosion rate on the inner wall of the combustion tube. Combined with the in-situ NiO-Cr2O3 protective layer generated from the nickel-based material, the combustion tube lifespan is extended from 2000 cycles to over 4500 cycles. Simultaneously, the neutralization reaction of Li2CO3 is concentrated at the end of the airflow path, reducing contamination of the infrared detection cell by alkaline substances and significantly lowering maintenance and consumable costs.

[0019] To further understand the features and technical content of this invention, please refer to the following detailed description and accompanying drawings. However, the accompanying drawings are for reference and illustration only and are not intended to limit the invention. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the application method of a nickel-based alloy welding material that protects the combustion tube and is used as a flux in a carbon-sulfur analyzer. Figure 2 This is an image of the combustion tube from Example 1, which has been used 4500 times. Figure 3 This is an image of a combustion tube used 2000 times in Comparative Example 6. Detailed Implementation

[0021] The following describes a preferred embodiment, with reference to the appendix. Figure 1 To further illustrate the present invention, the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values; for numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed herein; the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified; the experimental methods in the following embodiments are conventional methods unless otherwise specified.

[0022] Example 1: In this embodiment, an infrared carbon-sulfur analyzer, LECO CS744, was used to determine the carbon and sulfur content of the nickel-based alloy welding material. During the sample determination process, the amount of flux added included 0.5g of tungsten granules, 0.5g of tin granules, 0.0030g of copper oxide, and 0.015g of lithium carbonate.

[0023] Furthermore, the method includes the following steps: Step 1, prepare the reagents for the test: standard substance, tungsten granules, tin granules, copper oxide, lithium carbonate; Step 2: Set the infrared carbon-sulfur analyzer to an analysis power of 1.5 kW to 3.0 kW, a comparison level of 2%, an oxygen pressure of 0.2 to 0.5 MPa, an oxygen flow rate of 3.0 L / min, a pre-purge time of 40 s, a pre-integration time of 10 s, and an analysis time of 45 to 60 s. Step 3: Soak the sample to be tested (nickel-based alloy welding material) in alcohol for 3-5 minutes, and then dry it with a hair dryer; Step 4: Input the carbon and sulfur standard values ​​corresponding to the standard substance. Place a ceramic crucible (DC type Φ25mm×25mm produced by Liling Chashan Wancai Crucible Porcelain Industry Co., Ltd.) on the analytical balance. Take 50% of the total tungsten particle weight and spread it on the bottom layer. Spread the standard substance evenly on the pre-spread tungsten particle layer. Cover the standard sample layer with all the tin particles in the formula. Mix copper oxide (CuO) and lithium carbonate (Li2CO3) in the specified proportion and sprinkle them evenly on the surface of the tin particle layer. Cover the top layer with the remaining 50% of the tungsten particles. Measure at least once to obtain the carbon and sulfur standard values ​​of the standard substance. The test results are expressed as a percentage. Step 5: Select the tested standard substance (standard value is C 0.0127%, S 0.0100%), select "Calibrate", and the infrared carbon-sulfur analyzer will automatically calibrate and save the coefficients; Step 6: Repeat the test on the standard substance at least once. If the result does not meet the carbon and sulfur standard value range of the standard substance, return to step 4 until the test result meets the carbon and sulfur standard value range of the standard substance. Step 7: Place a ceramic crucible on the analytical balance, spread 50% of the total tungsten particle weight on the bottom layer of the sample, weigh 0.5g of the sample to be tested and spread it evenly on the pre-spread tungsten particle layer; cover the sample layer with all the tin particles in the formula; mix copper oxide (CuO) and lithium carbonate (Li2CO3) in the specified ratio and sprinkle them evenly on the surface of the tin particle layer; cover the top layer with the remaining 50% of the tungsten particles, and determine the carbon and sulfur content of the sample according to the working conditions selected by the infrared carbon and sulfur analyzer; Step 8: Input the carbon and sulfur standard values ​​corresponding to the standard substance. Place a ceramic crucible on the analytical balance. Take 50% of the total tungsten particles and spread them on the bottom layer. Spread the standard substance evenly on the pre-spread tungsten particle layer. Cover the standard sample layer with all the tin particles in the formula. Mix copper oxide (CuO) and lithium carbonate (Li2CO3) in the specified ratio and sprinkle them evenly on the surface of the tin particle layer. Cover the top layer with the remaining 50% of the tungsten particles. Measure at least once to obtain the carbon and sulfur standard values ​​of the standard substance and determine whether the test results meet the carbon and sulfur standard value range. Step 9: Take sample 1 and measure it 6 times consecutively. Read the detection data of carbon and sulfur content of the sample. The measurement results are shown in Table 1.

[0024] Table 1 Statistical Table of Measurement Results

[0025] Comparative Example 1 It is basically the same as Example 1, but with the following changes: In steps 4 and 8, first weigh 0.5g of standard substance, then take 50% of the total tungsten particles and spread them on the standard substance; cover all the tin particles in the formula on the tungsten particle layer; mix copper oxide (CuO) and lithium carbonate (Li2CO3) in proportion and sprinkle them evenly on the surface of the tin particle layer; cover the top layer with the remaining 50% of the tungsten particles. In step 7, first weigh 0.5g of the sample, then take 50% of the total tungsten particle weight and spread it on the sample; all the tin particles in the formula cover the tungsten particle layer; after mixing copper oxide (CuO) and lithium carbonate (Li2CO3) in proportion, sprinkle them evenly on the surface of the tin particle layer; the remaining 50% of the tungsten particles cover the top layer. The measurement results are shown in Table 2.

[0026]

[0027] Table 2 Comparison of measurement results between Example 1 and Comparative Example 1 As can be seen from Table 2, the nickel-based alloy welding material flux for carbon and sulfur analyzers and its application method provided by the present invention, which has a protective effect on the combustion tube, can make the sample 1 burn more completely and release carbon and sulfur more completely by changing the order of adding the flux.

[0028] Comparative Example 2 It is basically the same as Example 1, but with the following changes: In steps 4, 7, and 8, the amount of flux added includes 1.0g of tungsten particles, 0.0050g of copper oxide, and 0.015g of lithium carbonate. The test results are shown in Table 3.

[0029] In step 9, sample 1 was measured 3 times, and the results are shown in Table 3. Comparative Example 3 It is basically the same as Example 1, but with the following changes: In steps 4, 7, and 8, the amount of flux added includes 1.0g of tin granules, 0.0050g of copper oxide, and 0.015g of lithium carbonate. In step 9, sample 1 was measured 3 times, and the results are shown in Table 3.

[0030] Comparative Example 4 It is basically the same as Example 1, but with the following changes: In steps 4, 7, and 8, the amount of flux added includes 0.5g of tungsten granules, 0.5g of tin granules, 0.0050g of copper oxide, and 0.015g of lithium carbonate.

[0031] In step 9, sample 1 was measured 3 times, and the results are shown in Table 3.

[0032] Comparative Example 5 It is basically the same as Example 1, but with the following changes: In steps 4, 7, and 8, the amount of flux added includes 0.5g of tungsten granules, 0.5g of tin granules, 0.0024g of copper oxide, and 0.024g of lithium carbonate.

[0033] In step 9, sample 1 was measured 3 times, and the results are shown in Table 3.

[0034]

[0035] As can be seen from Table 3, the nickel-based alloy welding material carbon-sulfur analyzer flux and its usage method provided by the present invention, which has a protective effect on the combustion tube, can make the sample 1 burn more completely and release carbon and sulfur more completely by specifying the type, amount and ratio of the flux.

[0036] Comparative Example 6 It is basically the same as Example 1, but with the following changes: In steps 4, 7, and 8, the amount of flux added does not include copper oxide or lithium carbonate; The combustion tube used is compared with the combustion tube in Example 1, for example... Figure 2 and 3 As shown, by Figure 2 and 3 It can be seen that the nickel-based alloy welding material flux for carbon-sulfur analyzers and its application method provided by the present invention, which has a protective effect on the combustion tube, significantly reduces the sulfur corrosion rate of the inner wall of the combustion tube after adopting this layering sequence, and can extend the life of the combustion tube from 2000 cycles to more than 4500 cycles.

[0037] The specific embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A nickel-based alloy welding material flux for carbon-sulfur analyzers that provides protection for combustion tubes, characterized in that, The flux consists of individually packaged 0.48g to 0.72g tungsten granules, 0.48g to 0.72g tin granules, 0.0024g to 0.0096g copper oxide, and 0.0144g to 0.024g lithium carbonate, wherein the weight ratio of lithium carbonate to copper oxide is (4 to 8):

1.

2. The flux according to claim 1, characterized in that, The flux consists of 0.5g of individually packaged tungsten granules, 0.5g of tin granules, 0.0030g of copper oxide, and 0.015g of lithium carbonate.

3. The flux according to claim 1, characterized in that, The carbon and sulfur content of nickel-based alloy welding materials was determined using an infrared carbon-sulfur analyzer.

4. The flux according to claim 1, characterized in that, The tungsten particles contain W ≥ 99.5% (mass), C ≤ 0.0005% (mass), and S ≤ 0.0005% (mass); the particle size of the tungsten particles is 0.4 mm to 1.0 mm.

5. The flux according to claim 1, characterized in that, The tin granules contain Sn ≥ 99.5% (mass), C ≤ 0.0005% (mass), and S ≤ 0.0005% (mass). The particle size of the tin granules is 0.2mm to 0.6mm.

6. The flux according to claim 1, characterized in that, The content of copper oxide is ≥99.5% (mass), C≤0.0005% (mass), S≤0.0005% (mass), and the particle size of copper oxide is 200-400 mesh.

7. The flux according to claim 1, characterized in that, The lithium carbonate content is ≥99.5% (mass), C≤0.0005% (mass), S≤0.0005% (mass), and the lithium carbonate particle size is 300-500 mesh.

8. The method of using the flux as described in any one of claims 1-7, characterized in that, Includes the following steps: Step 1: Set the infrared carbon-sulfur analyzer to an analysis power of 1.5 kW to 3.0 kW, a comparison level of 2%, an oxygen pressure of 0.2 MPa to 0.5 MPa, an oxygen flow rate of 3.0 L / min, a pre-purge time of 40 s, a pre-integration time of 10 s, and an analysis time of 45 s to 60 s. Step 2: Immerse the sample in anhydrous ethanol for 3-5 minutes and then dry it. Step 3: Input the carbon and sulfur standard values ​​corresponding to the standard substance. Place a ceramic crucible on the analytical balance, take 50% of the total weight of tungsten particles and spread it at the bottom layer, spread the standard substance evenly, cover the standard sample layer with tin particles, mix lithium carbonate and copper oxide in proportion and sprinkle evenly on the surface of the tin particle layer, then spread the remaining tungsten particles evenly. Measure at least once to obtain the carbon and sulfur standard values ​​of the standard substance. The test results are expressed as a percentage. Step 4: Select the tested standard substance, select "Calibrate", and the infrared carbon-sulfur analyzer will automatically calibrate and save the coefficients; Step 5: Repeat the test on the standard substance at least once. If the result does not meet the carbon and sulfur standard value range of the standard substance, return to step 3 until the test result meets the carbon and sulfur standard value range of the standard substance. Step 6: Place a ceramic crucible on the analytical balance, take 50% of the total weight of tungsten particles and spread it at the bottom layer, spread 0.3-0.8g of the sample to be tested, cover the standard sample layer with tin particles, mix lithium carbonate and copper oxide in proportion and sprinkle them evenly on the surface of the tin particle layer, then spread the remaining tungsten particles, and determine the carbon and sulfur content of the sample according to the working conditions selected by the infrared carbon and sulfur analyzer. Step 7: Input the carbon and sulfur standard values ​​corresponding to the standard substance. Place a ceramic crucible on the analytical balance, take 50% of the total weight of tungsten particles and spread it at the bottom layer, spread the standard substance evenly, cover the standard sample layer with tin particles, mix lithium carbonate and copper oxide in proportion and sprinkle evenly on the surface of the tin particle layer, then spread the remaining tungsten particles evenly. Measure at least once to obtain the carbon and sulfur standard values ​​of the standard substance, and determine whether the test results meet the carbon and sulfur standard value range. Step 8: Read the detection data of carbon and sulfur content of the sample.

9. The method according to claim 8, characterized in that, The standard values ​​of the reference materials used, expressed as a percentage by mass, range as follows: C 0.0100%~0.0200%, S 0.0010%~0.0100%.

10. The method according to claim 8, characterized in that, The anhydrous ethanol used was of analytical grade, with an ethanol concentration of 99.0% to 99.9% by mass percentage.

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