Method for detecting free carbon in cemented carbide mix based on pre-treatment

Abstract

The application belongs to the field of detection and analysis, and particularly relates to a method for detecting free carbon in cemented carbide mixture based on pretreatment, which comprises the following steps: S1, obtaining cemented carbide mixture, the components of the cemented carbide mixture including at least one of chromium carbide, silicon carbide and boron carbide, and grinding the cemented carbide mixture into cemented carbide mixture powder; S2, mixing, stirring and centrifugally separating the cemented carbide mixture powder and heavy liquid to obtain a mixture; taking out the upper layer liquid containing elemental carbon of the mixture and washing and solid-liquid separating to obtain an initial sample to be detected; S3, rinsing and drying the initial sample to be detected to obtain a final sample to be detected, and detecting the final sample to be detected to obtain the content of free carbon. Through the improved pretreatment detection method of free carbon in cemented carbide mixture, the accuracy and efficiency of detection are improved, the range of detection of free carbon in cemented carbide is expanded, and the method is suitable for more kinds of carbides.

Description

Technical Field

[0001] This application relates to the field of detection and analysis, specifically, to a method for detecting free carbon in cemented carbide mixtures based on pretreatment. Background Technology

[0002] Cemented carbide is widely used in industrial manufacturing due to its high hardness and wear resistance. Free carbon, as a crucial component of cemented carbide mixtures, significantly impacts the alloy's properties through its content and distribution. The free carbon content in cemented carbide mixtures often greatly influences the performance of the final product, making accurate detection of free carbon content in cemented carbide mixtures essential for ensuring product quality and performance. With the continuous expansion of cemented carbide applications, the requirements for the accuracy and efficiency of free carbon detection are also increasing. Therefore, improving the detection methods for free carbon in cemented carbide mixtures has become an important research direction in materials science.

[0003] Currently, the detection of free carbon in cemented carbide mixtures mainly relies on the GB / T 5124.2 standard. This method involves dissolving carbides in a solution, separating the free carbon (which is insoluble in acid), and then determining the free carbon content using infrared detection. While this method can provide results to some extent, it is only suitable for carbides containing tungsten, molybdenum, niobium, tantalum, titanium, hafnium, and zirconium. It has significant limitations when dealing with cemented carbide mixtures containing multiple carbides. When detecting cemented carbide mixtures containing chromium, silicon, boron, etc., these carbides cannot completely react with acid, causing free carbon to mix with them, ultimately leading to higher detection results.

[0004] Although the GB / T 5124.2 standard provides a method for detecting free carbon, it has some problems and shortcomings in practical applications. Firstly, this method cannot effectively separate carbides containing chromium, silicon, boron, etc., affecting the accuracy of the detection results. Furthermore, the method requires the use of multiple chemical reagents, raising concerns about environmental protection and safety. Therefore, developing a novel pretreatment method for detecting free carbon in cemented carbide mixtures has significant practical importance and application value. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a method for detecting free carbon in a cemented carbide mixture based on pretreatment, comprising the following steps: S1, obtaining a cemented carbide mixture, wherein the cemented carbide mixture comprises at least one of chromium carbide, silicon carbide, and boron carbide, and grinding the cemented carbide mixture into a cemented carbide mixed powder; S2, mixing, stirring, and centrifuging the cemented carbide mixed powder with a heavy liquid to obtain a mixture; removing the upper layer of the mixture containing elemental carbon and washing and separating the solid and liquid to obtain an initial sample to be tested; S3, rinsing and drying the initial sample to be tested to obtain a final sample to be tested, and detecting the free carbon content of the final sample to be tested.

[0006] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment described in this application, in step S1, the average particle size of the cemented carbide mixture powder is ≤2.5μm.

[0007] As a preferred embodiment of the method for detecting free carbon in a cemented carbide mixture based on pretreatment described in this application, the grinding method in step S1 is specifically as follows: the cemented carbide mixture is placed in an agate mortar and ground with an agate pestle to obtain the cemented carbide mixture powder.

[0008] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment described in this application, in step S2, the heavy liquid is at least one of bromoform or tetrabromoethane, and the mass ratio of the cemented carbide mixture powder to the heavy liquid is 1:(5-10).

[0009] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment described in this application, in step S2, the centrifugal separation method is specifically as follows: density gradient centrifugation is performed using a centrifuge with a rotation speed of 3000-4000 r / min and a centrifugation time of 30-40 min.

[0010] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment described in this application, the washing method in step S2 is as follows: the upper layer of liquid containing elemental carbon is poured into a beaker, soaked in ethanol or acetone and stirred for 10-15 minutes to remove residual heavy liquid; after obtaining the initial test sample through solid-liquid separation, the initial test sample is washed and separated into solid and liquid again 2-3 times.

[0011] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment as described in this application, in step S2, the solid-liquid separation method is either filtration or centrifugal separation.

[0012] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment described in this application, in step S3, the rinsing method specifically involves rinsing the sample with a low-boiling-point solvent to remove high-boiling-point solvent residues, wherein the low-boiling-point solvent is one of diethyl ether or petroleum ether.

[0013] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment described in this application, in step S3, the drying method specifically involves air-drying the sample in a fume hood for 2-4 hours or drying the sample at low temperature for 2-4 hours to remove moisture and solvent residue from the sample, wherein the low temperature is <60°C.

[0014] As a preferred embodiment of the method for detecting free carbon in cemented carbide mixtures based on pretreatment as described in this application, in step S3, the detection method is infrared detection. When the standard value of the free carbon content is ≥0.05 and <0.1, the allowable error of the detection result is within 0.005%; when the standard value of the free carbon content is ≥0.1 and <0.5, the allowable error of the detection result is within 0.010%; and when the standard value of the free carbon content is ≥0.5, the allowable error of the detection result is within 0.03%.

[0015] The beneficial effects of this application are as follows: This application proposes a method for detecting free carbon in cemented carbide mixtures based on pretreatment. The traditional GB / T5124.2 standard method is applicable to carbides of tungsten, molybdenum, niobium, tantalum, titanium, hafnium, and zirconium, but it has significant limitations when processing cemented carbide mixtures containing multiple carbides. When detecting cemented carbide mixtures containing carbides such as chromium, silicon, and boron, these carbides cannot completely react with acid, causing free carbon to mix with them, ultimately leading to inflated detection results.

[0016] This application improves the accuracy and efficiency of free carbon detection in cemented carbide mixtures through an improved pretreatment method. It expands the detection range for free carbon in cemented carbide mixtures, making it applicable to more types of carbides. It also improves the repeatability and stability of the detection results, reducing errors and variability. The method involves using a density gradient centrifugation technique with a heavy liquid to separate free carbon from the cemented carbide mixture. The heavy liquid is removed by soaking and stirring the inorganic solids containing it in ethanol or acetone.

[0017] This application utilizes the significant density difference between free carbon and the cemented carbide itself in a cemented carbide mixture. After grinding, centrifugation separates the free carbon (lower density) from the cemented carbide, allowing the determination of the free carbon content. This application leverages the substantial density difference between different phases in the cemented carbide mixture. By preparing a heavy liquid of a specific density, under the influence of gravity or centrifugal force, the lighter free carbon floats while the heavier tungsten carbide sinks, thus achieving separation.

[0018] The requirements for the heavy liquid used in this application are as follows: 1. The density of the heavy liquid must be precisely between the two phases to be separated, and it should not easily volatilize during use, causing density changes. 2. The heavy liquid must not react chemically with the free carbon, tungsten carbide, etc., to be separated; otherwise, it will change the phase composition and lead to inaccurate results. 3. After separation, the heavy liquid should be easily and completely removed by evaporation or washing, leaving no residue to avoid affecting subsequent measurements.

[0019] The above-mentioned improved methods can effectively enhance the accuracy and efficiency of free carbon detection in cemented carbide mixtures, expand the detection range, simplify the detection process, improve the repeatability and stability of detection results, and reduce errors and variability. Simultaneously, this method reduces the use of chemical reagents, lowers environmental and safety risks, and has significant practical value and application potential. Compared with existing technologies, the beneficial effects of this technical solution are as follows: 1. Improved detection accuracy and efficiency: This technical solution improves the separation method by using heavy liquid density gradient centrifugation technology to effectively separate carbides and free carbon of different densities, thereby improving the accuracy and efficiency of free carbon detection in cemented carbide mixtures.

[0020] 2. Expanded detection range: This technical solution is applicable to more types of carbides, such as carbides containing chromium, silicon, boron, etc., thus expanding the range of free carbon detection in cemented carbide.

[0021] 3. Simplified testing process: This technical solution simplifies the testing process, reduces operational complexity and time costs, and testing can be completed through simple steps such as heavy liquid separation, washing and drying.

[0022] 4. Improve the repeatability and stability of test results: This technical solution reduces errors and variability by optimizing the testing process, thereby improving the repeatability and stability of test results.

[0023] 5. Environmental protection and safety: This technical solution reduces the use of chemical reagents, lowers the impact on the environment, and improves the safety of the detection process.

[0024] This application addresses the technical problems of existing free carbon detection methods failing to achieve effective separation when processing multiple carbides, thus affecting the accuracy of detection results; the technical problems of existing methods being complex in operation, requiring multiple chemical treatment steps, which increases operational complexity and time costs; and the technical problems of existing methods requiring the use of multiple chemical reagents, which poses issues in terms of environmental protection and safety. Detailed Implementation

[0025] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] This application provides a method for detecting free carbon in cemented carbide mixtures based on pretreatment, comprising the following steps: S1. Obtain a cemented carbide mixture, wherein the cemented carbide mixture comprises at least one of chromium carbide, silicon carbide, and boron carbide, and grind the cemented carbide mixture into cemented carbide mixed powder. The average particle size of the cemented carbide mixed powder is ≤2.5μm; the grinding method is as follows: the cemented carbide mixture is placed in an agate mortar and ground with an agate pestle to obtain the cemented carbide mixed powder; S2. The cemented carbide powder is mixed with heavy liquid, stirred, and centrifuged to obtain a mixture; the upper layer of the mixture containing elemental carbon is taken out, washed, and the solid-liquid separation is performed to obtain the initial sample to be tested; The heavy liquid is at least one of bromoform or tetrabromoethane, and the mass ratio of the cemented carbide mixed powder to the heavy liquid is 1:(5-10); the centrifugal separation method is specifically: density gradient centrifugation is performed using a centrifuge at a speed of 3000-4000 r / min for 30-40 min; the washing method is specifically: the upper layer of liquid containing elemental carbon is poured into a beaker, soaked in ethanol or acetone and stirred for 10-15 min to remove residual heavy liquid; after obtaining the initial test sample through solid-liquid separation, the initial test sample is washed and separated from the solid liquid 2-3 times; the solid-liquid separation method is either filtration or centrifugation.

[0027] S3. Rinse and dry the initial sample to be tested to obtain the final sample to be tested, and detect the free carbon content of the final sample to be tested; The rinsing method specifically involves rinsing the sample with a low-boiling-point solvent to remove high-boiling-point solvent residues, wherein the low-boiling-point solvent is either diethyl ether or petroleum ether. The drying method specifically involves air-drying the sample in a fume hood for 2-4 hours or drying it at a low temperature for 2-4 hours to remove moisture and solvent residues from the sample, wherein the low temperature is <60℃. The detection method is infrared detection. When the standard value of the free carbon content is ≥0.05 and <0.1, the allowable error of the detection result is within 0.005%; when the standard value of the free carbon content is ≥0.1 and <0.5, the allowable error of the detection result is within 0.010%; and when the standard value of the free carbon content is ≥0.5, the allowable error of the detection result is within 0.03%.

[0028] The technical solution of this application will be further described below with reference to specific embodiments.

[0029] Example 1

[0030] This application provides a method for detecting free carbon in cemented carbide mixtures based on pretreatment, comprising the following steps: S1. Obtain a cemented carbide mixture, the components of which include chromium carbide, and grind the cemented carbide mixture into cemented carbide mixed powder. The average particle size of the cemented carbide mixed powder is ≤2.5μm; the grinding method is as follows: the cemented carbide mixture is placed in an agate mortar and ground with an agate pestle to obtain the cemented carbide mixed powder; S2. The cemented carbide powder is mixed with heavy liquid, stirred, and centrifuged to obtain a mixture; the upper layer of the mixture containing elemental carbon is taken out, washed, and the solid-liquid separation is performed to obtain the initial sample to be tested; The heavy liquid was bromoform, and the mass ratio of the cemented carbide mixed powder to the heavy liquid was 1:5. The centrifugation method was as follows: density gradient centrifugation was performed using a centrifuge at a speed of 3000 r / min for 30 min. The washing method was as follows: the liquid containing elemental carbon in the upper layer was poured into a beaker, soaked in ethanol and stirred for 10 min to remove the residual heavy liquid. After obtaining the initial test sample through solid-liquid separation, the initial test sample was washed and separated twice. The solid-liquid separation method was filtration.

[0031] S3. Rinse and dry the initial sample to be tested to obtain the final sample to be tested, and detect the free carbon content of the final sample to be tested; The rinsing method is as follows: the sample is rinsed with a low-boiling-point solvent to remove high-boiling-point solvent residues, and the low-boiling-point solvent is diethyl ether; the drying method is as follows: the sample is air-dried in a fume hood for 3 hours to remove moisture and solvent residues; the detection method is infrared detection.

[0032] The standard value for free carbon content is 0.05%, and the test result for free carbon content is 0.046%. The allowable error for the test result of free carbon content is within 0.005%.

[0033] Example 2

[0034] This application provides a method for detecting free carbon in cemented carbide mixtures based on pretreatment, comprising the following steps: S1. Obtain a cemented carbide mixture, the components of which include silicon carbide, and grind the cemented carbide mixture into cemented carbide mixed powder. The average particle size of the cemented carbide mixed powder is ≤2.5μm; the grinding method is as follows: the cemented carbide mixture is placed in an agate mortar and ground with an agate pestle to obtain the cemented carbide mixed powder; S2. The cemented carbide powder is mixed with heavy liquid, stirred, and centrifuged to obtain a mixture; the upper layer of the mixture containing elemental carbon is taken out, washed, and the solid-liquid separation is performed to obtain the initial sample to be tested; The heavy liquid was tetrabromoethane, and the mass ratio of the cemented carbide mixed powder to the heavy liquid was 1:7. The centrifugation method was as follows: density gradient centrifugation was performed using a centrifuge at a speed of 3500 r / min for 35 min. The washing method was as follows: the upper layer of liquid containing elemental carbon was poured into a beaker, soaked in acetone and stirred for 12 min to remove the residual heavy liquid. After obtaining the initial test sample through solid-liquid separation, the initial test sample was washed and separated twice. The solid-liquid separation method was filtration.

[0035] S3. Rinse and dry the initial sample to be tested to obtain the final sample to be tested, and detect the free carbon content of the final sample to be tested; The rinsing method is as follows: the sample is rinsed with a low-boiling-point solvent to remove high-boiling-point solvent residues. The low-boiling-point solvent is petroleum ether. The drying method is as follows: the sample is dried at a low temperature for 2 hours to remove moisture and solvent residues. The low temperature is <60℃. The detection method is infrared detection.

[0036] The standard value for free carbon content is 0.1%, and the test result for free carbon content is 0.091%. The allowable error for the test result of free carbon content is within 0.010%.

[0037] Example 3

[0038] This application provides a method for detecting free carbon in cemented carbide mixtures based on pretreatment, comprising the following steps: S1. Obtain a cemented carbide mixture, the components of which include boron carbide, and grind the cemented carbide mixture into cemented carbide mixed powder. The average particle size of the cemented carbide mixed powder is ≤2.5μm; the grinding method is as follows: the cemented carbide mixture is placed in an agate mortar and ground with an agate pestle to obtain the cemented carbide mixed powder; S2. The cemented carbide powder is mixed with heavy liquid, stirred, and centrifuged to obtain a mixture; the upper layer of the mixture containing elemental carbon is taken out, washed, and the solid-liquid separation is performed to obtain the initial sample to be tested; The heavy liquid was bromoform, and the mass ratio of the cemented carbide powder to the heavy liquid was 1:10. The centrifugation method was as follows: density gradient centrifugation was performed using a centrifuge at a speed of 4000 r / min for 40 min. The washing method was as follows: the upper layer of liquid containing elemental carbon was poured into a beaker, soaked in acetone and stirred for 15 min to remove the residual heavy liquid. After obtaining the initial test sample through solid-liquid separation, the initial test sample was washed and separated into solid and liquid three times. The solid-liquid separation method was centrifugation.

[0039] S3. Rinse and dry the initial sample to be tested to obtain the final sample to be tested, and detect the free carbon content of the final sample to be tested; The rinsing method is as follows: the sample is rinsed with a low-boiling-point solvent to remove high-boiling-point solvent residues. The low-boiling-point solvent is petroleum ether. The drying method is as follows: the sample is dried at a low temperature for 4 hours to remove moisture and solvent residues. The low temperature is <60℃. The detection method is infrared detection.

[0040] The standard value for free carbon content is 0.5%, and the test result for free carbon content is 0.478%. The allowable error for the test result of free carbon content is within 0.03%.

[0041] Comparative Example 1 The mixture in Example 1 was tested using GB / T 5124.2, and the free carbon content was found to be 0.064%. Since chromium carbide is insoluble, the actual test result was much higher than the standard value; therefore, the national standard testing method is not feasible.

[0042] Comparative Example 2 The mixture in Example 2 was tested using GB / T 5124.2, and the free carbon content was found to be 0.15%. Since silicon carbide is insoluble, the actual test result was much higher than the standard value; therefore, the national standard testing method is not feasible.

[0043] Comparative Example 3 The mixture in Example 3 was tested using GB / T 5124.2, and the free carbon content was found to be 0.64%. Since boron carbide is insoluble, the actual test result was much higher than the standard value; therefore, the national standard testing method is not feasible.

[0044] Comparative Example 4 The difference between this comparative example and Example 1 is that the average particle size of the cemented carbide mixed powder is >2.5 μm, while the other steps are the same as in Example 1; The standard value for free carbon content is 0.05%, and the test result for free carbon content is 0.039%. The allowable error for the test result of free carbon content is not within 0.005%.

[0045] Comparative Example 5 The difference between this comparative example and Example 1 is that the heavy liquid is ethanol, while the other steps are the same as in Example 1. As a result, free carbon was not separated from the cemented carbide mixture.

[0046] Comparative Example 6 The difference between this comparative example and Example 1 is that the centrifugation time is 20 minutes, while the other steps are the same as in Example 1. The standard value for free carbon content is 0.05%, and the test result for free carbon content is 0.035%. The allowable error for the test result of free carbon content is not within 0.005%.

[0047] Comparative Example 7 The difference between this comparative example and Example 1 is that rinsing and drying were not performed; the other steps are the same as in Example 1. The standard value for free carbon content is 0.05%, and the test result for free carbon content is 0.062%. The allowable error for the test result of free carbon content is not within 0.005%.

[0048] As can be seen from the above embodiments and comparative examples: Example 1, in conjunction with Comparative Example 1, shows that using national standards to test chromium carbide-containing cemented carbide mixtures has a large error, with results that differ significantly and cannot accurately detect the contents.

[0049] Example 2, in conjunction with Comparative Example 2, shows that using national standards to test silicon carbide-containing cemented carbide mixtures has a large error, with results that differ significantly and cannot accurately detect the contents.

[0050] Example 3, in conjunction with Comparative Example 3, shows that using national standards to test boron carbide-containing cemented carbide mixtures has a large error, with results that differ significantly and cannot accurately detect the contents.

[0051] Example 1, in conjunction with Comparative Example 4, shows that when the average particle size of the cemented carbide mixed powder is too large, the results obtained differ somewhat from the standard value.

[0052] Example 1, in conjunction with Comparative Example 5, shows that free carbon cannot be separated from a solution with an incompatible density.

[0053] Example 1, in conjunction with Comparative Example 6, shows that the results of insufficient centrifugation differ from the standard values.

[0054] Example 1, in conjunction with Comparative Example 7, shows that without rinsing and drying, residual organic carbon can affect the detection of free carbon.

[0055] Examples 1-3, together with Comparative Examples 1-7, demonstrate that the patented method solves the technical problem that existing free carbon detection methods cannot achieve effective separation when processing multiple carbides, thus affecting the accuracy of the detection results.

[0056] The above description is only a preferred embodiment of this application and does not limit the patent scope of this application. All equivalent structural transformations made using the content of this application's specification under the inventive concept of this application, or direct / indirect applications in other related technical fields, are included within the patent protection scope of this application.

Claims

1. A method for detecting free carbon in cemented carbide mixtures based on pretreatment, characterized in that, Includes the following steps: S1. Obtain a cemented carbide mixture, wherein the cemented carbide mixture comprises at least one of chromium carbide, silicon carbide, and boron carbide, and grind the cemented carbide mixture into cemented carbide mixed powder. S2. The cemented carbide powder is mixed with heavy liquid, stirred, and centrifuged to obtain a mixture; the upper layer of the mixture containing elemental carbon is taken out, washed, and the solid-liquid separation is performed to obtain the initial sample to be tested; S3. Rinse and dry the initial sample to be tested to obtain the final sample to be tested, and detect the free carbon content of the final sample to be tested.

2. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S1, the average particle size of the cemented carbide mixed powder is ≤2.5μm.

3. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S1, the grinding method specifically involves placing the cemented carbide mixture into an agate mortar and grinding it with an agate pestle to obtain the cemented carbide mixture powder.

4. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S2, the heavy liquid is at least one of bromoform or tetrabromoethane, and the mass ratio of the cemented carbide mixed powder to the heavy liquid is 1:(5-10).

5. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S2, the centrifugal separation method is as follows: density gradient centrifugation is performed using a centrifuge with a rotation speed of 3000-4000 r / min and a centrifugation time of 30-40 min.

6. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S2, the washing method is as follows: the upper layer of liquid containing elemental carbon is poured into a beaker, soaked in ethanol or acetone and stirred for 10-15 minutes to remove the residual heavy liquid; after solid-liquid separation to obtain the initial test sample, the initial test sample is washed and solid-liquid separated 2-3 times.

7. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S2, the solid-liquid separation method is either filtration or centrifugal separation.

8. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S3, the rinsing method specifically involves rinsing the sample with a low-boiling-point solvent to remove high-boiling-point solvent residues. The low-boiling-point solvent is either diethyl ether or petroleum ether.

9. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S3, the drying method specifically involves air-drying the sample in a fume hood for 2-4 hours or drying it at a low temperature for 2-4 hours to remove moisture and solvent residue from the sample, wherein the low temperature is <60℃.

10. The method for detecting free carbon in cemented carbide mixtures based on pretreatment according to claim 1, characterized in that, In step S3, the detection method is infrared detection. When the standard value of the free carbon content is ≥0.05 and <0.1, the allowable error of the detection result is within 0.005%. When the standard value of the free carbon content is ≥0.1 and <0.5, the allowable error of the detection result is within 0.010%. When the standard value of the free carbon content is ≥0.5, the allowable error of the detection result is within 0.03%.