CN113219148A - Carbon-containing standard substance and preparation method and application thereof - Google Patents
Carbon-containing standard substance and preparation method and application thereof Download PDFInfo
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Abstract
The invention relates to the technical field of stoichiometry, in particular to a carbon-containing standard substance and a preparation method and application thereof. The invention provides a carbon-containing standard substance, wherein the mass percent of carbon is 0.00002% -0.0005%; the standard substance has fluxing property of fluxing agent, and carbon in the standard substance is completely released under the measuring condition. The method for preparing the standard substance is provided, the standard substance is used, an extremely simple and convenient carbon-sulfur instrument initialization method is developed, the standard substance is used for analyzing a carbon-containing sample, the accuracy and precision of carbon analysis can be obviously improved, the carbon analysis speed is unexpectedly improved, and the requirement of rapid analysis in front of a furnace is met.
Description
Technical Field
The invention relates to the technical field of stoichiometry, in particular to a carbon-containing standard substance and a preparation method and application thereof.
Background
A standard substance is a substance or material that has been determined to have one or more sufficiently uniform characteristic values, as a "gauge" in the analytical measurement industry, to play an essential role in analytical work. At present, a large number of standard substances are available for selection. From the state, the standard substance is solid, liquid, gas, etc. During the analysis, carbon sulfur instrument calibration and sample measurement usually use the same or similar matrix (brand) standard substance, therefore, the standard substance is produced in combination with the corresponding product analysis requirement.
The preparation technology of the standard substance is mature and has corresponding production and management technical specifications, such as 'first-class standard substance technical specification' (JJF 1006-1994) 'and' common principle and statistical principle of standard substance valuation '(JJF 1343-2012)' and the like. However, the preparation of the standard substance involves complicated technical conditions such as mathematical statistics and manufacturing processes, and the overall performance is that the preparation cost of the standard substance is high. Only standard substances with expected yield higher than the input cost can be prepared.
The fluxing agent has the functions of reducing the melting point of a sample, providing partial heat, improving the fluidity of a melt and ensuring that carbon is completely oxidized into CO in carbon analysis2And the chemical components are metals such as tungsten, iron, tin, copper and the like, and non-metals such as vanadium pentoxide and the like. At present, a large number of fluxes have been available for alternative use. The carbon remaining in the flux is also released during the carbon analysis to form a carbon vacancy value, and of course, the lower the carbon vacancy value, the better. The measurement of low carbon in various carbon analysis methods emphasizes the necessity of subtracting blank values, specifying the relevant operations. At present, no fluxing agent with a carbon blank value of zero exists. Carbon blank values C < 0.0005% can generally be achieved. Some varieties may mark even lower carbon blanks. In the actual analysis process, it is not possible to determine how many blank values should be subtracted, but only the highest blank value noted, or according to the result of the provisional measurement.
The preparation technology of the fluxing agent is also a relatively mature technology. A plurality of manufacturers produce the fluxing agent at home and abroad. During the metallurgical production of the flux, too high a content of carbon is oxidized into carbon dioxide gas and volatilized away, but a certain content of carbon remains, which generally can achieve carbon less than 0.0005%, and some brands may mark that the carbon blank value is lower. There are many relevant documents, such as: there are many technical documents disclosed in patents such as "technical compounding multicomponent flux and method for producing the same" (patent No. 200910044800.2) and "low-gap pure iron flux and method for producing the same" (patent No. 200510012442.9). The general trend is that the lower the carbon blank value, the better the carbon blank value is on the premise of ensuring fluxing property. A ubiquitous view of flux production technicians on carbon blank technology problems is that improvements in the manufacturing process have been made to achieve reductions in, or even complete elimination of, carbon blanks in the flux. However, carbon white space values have not been completely eliminated.
The high-frequency induction combustion-infrared absorption method is the most common principle for analyzing carbon elements, and has various specific methods for analysis, wherein the specific methods have the same principle, and the specific operation steps are slightly different. Typical specific methods are: the method comprises the steps of measuring the total carbon and sulfur content of steel by an infrared absorption method after combustion of a high-frequency induction furnace (GB/T20123-. The carbon content has a great influence on the material performance, and is a key index. The material department generally requires that the carbon content is measured in advance, and if the carbon content is unqualified, other element measurement is suspended. Generally, the carbon-sulfur instrument cannot meet the requirements of stokehole analysis, and only waits.
Disclosure of Invention
The first technical problem to be solved by the invention is to provide a carbon-containing standard substance which has fluxing property of a fluxing agent and completely releases carbon under measuring conditions. The standard substance is used to open up a very simple carbon-sulfur instrument initialization method. The standard substance is used for carbon analysis, so that the accuracy and precision of carbon analysis can be obviously improved, the carbon analysis speed is unexpectedly improved, and the requirement of rapid analysis in front of a furnace is met.
In order to solve the technical problem, the invention provides a carbon-containing standard substance, wherein the mass percent of carbon is 0.00002-0.0005%.
The standard substance has fluxing property of the fluxing agent.
The second technical problem to be solved by the invention is to provide a method for preparing the standard substance, which has good uniformity and melting property and can obviously improve the accuracy of carbon analysis.
In order to solve the above technical problems, the present invention provides a method for preparing the standard substance as described above, comprising the following steps
S1, preparing a fluxing agent;
s2, preparing a candidate by using a fluxing agent;
and S3, performing uniformity test, stability test, constant value determination, standard value determination and total uncertainty estimation on the candidate, and determining the mass percentage of the carbon content as the standard value of the standard substance carbon.
The step of preparing the fluxing agent in S1 comprises
SS1, selecting 1.0-2.5 parts of pure tungsten powder and 0.3-1.2 parts of pure iron powder, uniformly mixing, pressing and molding, and sintering to obtain a sinter;
SS2, crushing and sieving the prepared sinter, and taking sinter granules with the granularity of 20 meshes to 40 meshes;
and SS3, selecting 0.1-0.5 part of tin particles with the granularity of 20-60 meshes and 0.1-0.6 part of vanadium pentoxide with the granularity of 60-300 meshes, mixing the tin particles with the prepared sintered material granules, and roasting at 800-1100 ℃ to obtain the fluxing agent.
Alternatively, the step of preparing the flux in S1 includes
SS1, selecting 1.0-2.5 parts of pure tungsten powder and 0.3-1.2 parts of pure iron powder, uniformly mixing, pressing and molding, and sintering to obtain a sinter;
SS2, crushing and sieving the prepared sinter, and taking sinter granules with the granularity of 20 meshes to 40 meshes;
SS3, selecting 0.1-0.6 part of copper particles with the granularity of 20-60 meshes, mixing the copper particles with the prepared sinter particles, and roasting at 1350-1400 ℃ to obtain the fluxing agent.
The determination of the mass percent of carbon content in S3 is performed according to the method described in "general principles and statistical principles of standard substance valuation" (JJF 1343-.
The third technical problem to be solved by the present invention is to provide a method for initializing a carbon sulfur instrument by using the aforementioned standard substance, which is very simple and convenient, does not involve the special technical requirements of a pressure steel cylinder and the operations of hardware, software, etc. of the carbon sulfur instrument, can be performed without professional personnel when the carbon sulfur instrument has or may have abnormal conditions, and ensures that the carbon sulfur instrument can work in a good state at any time.
In order to solve the above technical problems, the present invention provides a method for initializing a carbon sulfur instrument using the standard substance, comprising the following steps
S1, calibrating the carbon sulfur instrument;
s2, measuring the carbon content of the standard substance by mass percent for multiple times;
s3, calculating the average value, the standard deviation and the relative standard deviation;
s4, compared with the last mean, standard deviation and relative standard deviation.
The fourth technical problem to be solved by the invention is to provide the application of the standard substance in the analysis of the carbon-containing sample, so that the accuracy, precision and analysis speed of the analysis result are improved.
In order to solve the technical problems, the invention provides the application of the standard substance in analyzing the carbon-containing sample, including the application in calibrating the carbon-sulfur instrument and the application in analyzing the sample.
The calibration carbon sulfur instrument comprises the following steps
S1, selecting a first standard substance with carbon content slightly higher than that of the sample to be detected;
s2, inputting the standard value of the standard substance carbon into a blank item of a carbon-sulfur instrument for automatic deduction;
s3, adding a standard substance as a cosolvent, and measuring the carbon content of the first standard substance for multiple times;
s4, calculating the average value, the standard deviation and the relative standard deviation of the carbon content of the first standard substance;
s5, taking the average value, the standard deviation and the relative standard deviation of the carbon content of the first standard substance as a standard carbon-sulfur instrument;
s6, selecting another second standard substance with the same or similar carbon content value as the sample to be tested, and carrying out verification measurement;
s7, adding a standard substance serving as a cosolvent, and measuring the carbon content of the second standard substance for multiple times by using a carbon sulfur instrument calibrated by the first standard substance;
s7, calculating the average value, the standard deviation and the relative standard deviation of the carbon content of the second standard substance;
and S8, verifying that the result is within the allowable difference range of the second standard substance, and completing the calibration of the carbon sulfur instrument.
The sample analysis comprises the following steps
S1, inputting the standard value of the standard substance carbon into a blank item of a carbon-sulfur instrument for automatic deduction;
s2, adding the standard substance into a carbon-containing test material, and measuring the mass percent of the carbon content for multiple times;
and S3, calculating the average value to obtain the carbon content of the carbon-containing sample.
The invention has the technical effects that:
1. the preparation method has the advantages and values that:
(1) during the metallurgical production process, too high a content of carbon is oxidized into carbon dioxide gas and volatilized, leaving a certain content of carbon. The invention can realize that C is less than 0.0005% by adopting the carbon in the general metallurgical process, does not need to pursue lower and lower carbon blank values, and reduces the preparation cost of the fluxing agent;
(2) only flux batches qualified by homogeneity inspection are prepared into standard substances. Flux batches with unqualified uniformity tests can be used as common fluxes. Namely, the smelting process of the standard substance is not specially carried out, thereby reducing the preparation cost of the standard substance.
(3) The preparation of the standard substance is to adopt necessary technical steps of uniformity measures, uniformity inspection and the like on the basis of the fluxing agent, so that the standard substance is more uniform compared with the common fluxing agent, provides more uniform heat and has better effect of improving the fluidity of the melt, namely is more beneficial to subsequent use.
2. The invention provides a novel standard substance, enriches the types of the existing standard substances, and develops an unexpected carbon-sulfur instrument initialization method.
3. The standard substance is used as a fluxing agent, so that the accuracy and precision of an analysis result are obviously improved. The effect of improving the analysis speed reaches unexpected degree, and the requirement of rapid analysis in front of the furnace is met.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Preparation of standard substance
1. Preparation of fluxing agent
Selecting 1.5 parts of pure tungsten powder and 0.5 part of pure iron powder, uniformly mixing, pressing, forming and sintering to obtain a sinter, taking sinter granules with the granularity of 20 meshes-40 meshes, selecting 0.2 part of tin granules with the granularity of 20 meshes-60 meshes and 0.2 part of vanadium pentoxide with the granularity of 60 meshes-300 meshes, mixing with the prepared sinter granules, and roasting at 800-1100 ℃ to obtain the fluxing agent.
2. And crushing, uniformly mixing and sieving the fluxing agent to obtain the candidate.
3. According to the first-class standard substance technical specification (JJF 1006-1994), uniformity test, stability test, fixed value, standard value determination and total uncertainty estimation are carried out on the candidate, the final result shows that the candidate has good uniformity and stability, and the standard value C of carbon: 0.00015% + -0.00004%.
(1) Uniformity test
Randomly draw 11 packages from 150 packages of candidate standard material, and 3 subsamples per package for inter-vial and intra-vial uniformity testing. The sampling amount is 1.0g, the carbon content is measured according to the operation steps of section 8.3.1.3 of the infrared absorption method after the combustion of the high-frequency induction furnace (GB/T20123-2006/ISO 15350:2000) for measuring the total carbon and sulfur content of steel, and the uniformity test results are shown in Table 1. Performing F-test statistical analysis according to the method in the general principle and statistical principle of standard substance valuing (JJF 1343-<F0.05(10,22). The results show that the obtained candidate targetThe quasi-substance did not differ significantly at the 95% confidence interval, i.e., the candidate standard substance was homogeneous.
TABLE 1 Standard substance homogeneity test at 0.00015% content
As can be seen from the above table, FComputing<FLook-up tableI.e. the candidate standard substance meets the homogeneity requirement.
(2) Stability verification
The candidate standard substance was examined for changes in the mass value of the standard substance after storage for 1, 3, 6, 12, and 18 months under suitable storage conditions (15-25 ℃). The carbon content is determined according to section 8.3.1.3 of the infrared absorption method after combustion of the high-frequency induction furnace for determining the total carbon and sulfur content of steel (GB/T20123-. Stability evaluation was performed using a (classical) linear model according to the standard samples specified in general and statistical principles of standard substance quantitation (JJF 1343-.
TABLE 2 stability test of 0.00015% content of standard substance
(3) Constant value
For the candidate standard substance, 11 bottles of samples are randomly extracted, each bottle is sampled once, 8 different units are entrusted to carry out value determination, and the carbon content is determined according to section 8.3.1.3 of infrared absorption method after combustion of high-frequency induction furnace for determining total carbon and sulfur content of steel (GB/T20123-. And sequentially carrying out Charpy-Wilks normal data test, Dixon and Grabbs abnormal value test, precision consistency test and comparison of significance difference of average values of different unit results on the carbon measured value, and finally obtaining a fixed value result and an uncertainty result of the standard substance. The results are shown in Table 3.
TABLE 3 Standard substance quantitative data
Two, very simple carbon-sulfur instrument initialization
An infrared carbon sulfur instrument for analyzing carbon is an electronic device, and a detector outputs an electronic signal. The electronic signal output by the detector must correspond to the chemical content, i.e. the initialization of the carbon-sulfur instrument. When the carbon-sulfur instrument is used, the carbon-sulfur instrument may have a condition that a measurement result changes after being moved. Therefore, the carbon sulfur meter was initialized before use.
The current initialization method uses a gas standard calibration, a carbon gas standard substance passes through a detector, the detector outputs an electronic signal, and the electronic signal is identified as the carbon content of the gas standard substance. The method comprises the following basic steps: with CO of known carbon content2The gas standard substance directly flows through the detector, the detector outputs an electronic signal, and the electronic signal is automatically converted and identified as the known carbon content by the computer. CO 22The gas standard is stored in a steel cylinder. Therefore, the special technical and safety requirements of the pressure steel cylinder and the hard and soft operation of the carbon sulfur instrument are involved. Generally, after the carbon sulfur instrument is shipped and a certain period of time has elapsed, it is operated by a professional.
The standard substance of the invention is a solid, has fluxing properties of a fluxing agent, and can naturally self-melt to completely release carbon. Essentially, it corresponds to CO2Gas storage in the solid standard substance of the invention, CO2The gas is generated by a carbon sulfur instrument in a normal measurement state and then flows through a detector. And determining the measurement result as the carbon content of the standard substance, and completing the initialization of the carbon-sulfur instrument.
Before and after the handling, the solid standard substance C: 0.00015% ± 0.00004% 9 measurements were made. The results are shown in Table 4.
TABLE 4 measured values of carbon of the reference substance before and after handling%
It is determined from table 4 that the accuracy and precision of the carbon measurement by the carbon sulfur instrument are not changed by moving, the carbon sulfur instrument is initialized very simply and conveniently without the special technical requirements of the pressure steel cylinder and the operations of the hard software of the carbon sulfur instrument, and therefore, when the carbon sulfur instrument has or may have abnormal conditions, the carbon sulfur instrument can be initialized without professional staff. The carbon-sulfur instrument can work in a good state at any time.
Thirdly, improving the accuracy of the analysis result
The single crystal superalloy DD6 was analyzed by the method of "high-frequency induction combustion-infrared absorption method for determining carbon content by chemical analysis of superalloy" (HB 5220.3-2008). Here, the sample was measured twice or more, and the allowable difference between the two measurements is shown in Table 5.
TABLE 5 tolerance of two measurements%
| Mass fraction of carbon | Tolerance difference |
| ＞0.001～0.010 | 0.001 |
And if the two measurements are within the allowable difference range, averaging the two measurement results, and taking the average value to send a report. If the results of the two measurements are not in the allowable difference range, a third measurement is carried out, and the average value is confirmed to be taken to send a report, or the uneven three results are taken to send a report.
1. Improving accuracy of carbon-sulfur instrument calibration result
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%, blank entry directly into carbon sulfur instrument (0.00015% + -0.00004%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
Selecting a standard substance AR 512C: 0.015% + -0.001% high value standard substance, 1.00 g (to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the results were measured 5 times as shown in Table 6.
Table 6 accuracy and precision of calibration results%
The results after calibration were all in the standard AR 512C: 0.015% ± 0.001% allowed difference.
Obviously, the precision of the calibration results is high in terms of the standard deviation and the relative standard deviation after calibration.
Then, the standard substance LECO 502-348C with a carbon content similar to that of the sample of 0.0016% + -0.00009% was used as a low-value standard substance, 1.00 g (to an accuracy of 0.001 g) was weighed, and 1.00 g of the standard substance of the present invention was added to perform verification and measurement 3 times, with the results shown in Table 7.
Table 7 verification measurement%
The verification measurement results are all within the allowable difference range of 0.0016% + -0.00009% of the standard substances LECO 502-348C. Subsequent sample measurements can be performed.
2. Improving accuracy of sample measurement results
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%, blank entry directly into carbon sulfur instrument (0.00015% + -0.00004%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
A single crystal superalloy DD6 sample (1.00 g, to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the sample was measured 2 times, and the results are shown in Table 8.
TABLE 8 measurement results of single crystal superalloy DD 6%
| Measured value | Mean value of |
| 0.0025、0.0020 | 0.0022 |
The results of the two sample measurements satisfy the requirements of the tolerance of the two measurement results in table 5, so that the single crystal superalloy DD6 sample is prepared by mixing the following components in percentage by weight: 0.0022% reports to the customer.
The standard substance of the invention has fluxing property of fluxing agent, and is used as fluxing agent, wherein the carbon blank value is accurately known, and can be directly input into a blank item (0.00015% + -0.00004%) of a carbon-sulfur instrument for automatic deduction. Compared with the blank value obtained by the original temporary analysis, the method is more accurate. Obviously, the accuracy of the sample measurement results is high.
In addition, the accuracy of the measurement result of the sample is obviously higher when the sample is measured on the premise that the accuracy of the calibration result is higher.
Fourthly, the precision of the analysis result is improved
1. Precision of carbon-sulfur instrument calibration is improved
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%, blank entry directly into carbon sulfur instrument (0.00015% + -0.00004%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
Selecting a standard substance AR 512C: 0.015% ± 0.001% high value standard substance, 1.00 g (accurate to 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the measurement was performed 5 times, and the results are shown in table 6 as the accuracy and precision of the calibration results.
The results after calibration were all in the standard AR 512C: 0.015% ± 0.001% allowed difference.
Obviously, the accuracy of the calibration results is high from the measured values and the average value after calibration.
Then, 0.0016% + -0.00009% of standard substance LECO 502-.
Clearly, the precision is high as judged from the standard deviation and relative standard deviation of the validation measurements.
2. Improving precision of sample measurement result
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%, blank entry directly into carbon sulfur instrument (0.00015% + -0.00004%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
1.00 g (accurate to 0.001 g) of a single crystal superalloy DD6 sample is weighed, 1.00 g of the standard substance of the present invention is added, and the sample is measured for 2 times, and the results are shown in Table 8 for the measurement result of the single crystal superalloy DD6 sample. The results of the two sample measurements satisfy the requirements of the tolerance of the two measurement results in table 5, so that the single crystal superalloy DD6 sample is prepared by mixing the following components in percentage by weight: 0.0022% reports to the customer.
The difference between the two measurements is 0.0005 percent, which is obviously less than the allowable difference of 0.001 percent of the two measurement results in the table 5, and the precision of the measurement results of the samples is higher.
Fifth, unexpectedly increasing the speed of analysis
The content of carbon has great influence on the single crystal superalloy DD6, and the content of carbon is a key index. Therefore, the materials department usually requires that the carbon content be measured first. If the carbon content is not qualified, the other elemental measurements are suspended. This situation places severe demands on the speed of analysis, especially in the forehearth.
1. The step of measuring the carbon blank value is eliminated, and the whole analysis speed is improved
When the carbon content in the single crystal superalloy DD6 sample is less than 0.01%, blank values in reagents and materials should be analyzed. The measured blank value is input into a blank item of a carbon-sulfur instrument for automatic deduction.
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%. Therefore, blank items (0.00015% + -0.00004%) directly inputting carbon values into the carbon-sulfur instrument are automatically deducted, the step of measuring the carbon blank values is eliminated, and the whole analysis speed is improved.
2. Improving the calibration speed of the carbon-sulfur instrument
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%, blank entry directly into carbon sulfur instrument (0.00015% + -0.00004%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
Selecting a standard substance AR 512C: 0.015% ± 0.001% high value standard substance, 1.00 g (accurate to 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the measurement was performed 5 times, and the results are shown in table 6 as the accuracy and precision of the calibration results.
The results after calibration were all in the standard AR 512C: 0.015% ± 0.001% allowed difference.
Then, 1.00 g (accurate to 0.001 g) of standard substance LECO 502-348C with the carbon content similar to that of the sample is weighed out by 0.0016% + -0.00009%, and 1.00 g of the standard substance is added to carry out verification and measurement for 3 times, and the result is shown in Table 7.
The verification measurement results are all within the allowable difference range of 0.0016% + -0.00009% of the standard substances LECO 502-348C. Subsequent sample measurements can be performed.
This carbon sulfur instrument calibration was measured 8 times, each for 60 seconds, for a total of about 8 minutes.
And (3) determining the carbon content by a high-frequency induction combustion-infrared absorption method (HB 5220.3-2008) according to the requirements of a high-temperature alloy chemical analysis method, verifying and analyzing for 3-5 times, and performing subsequent measurement until the results are within an allowable difference range, otherwise, repeatedly performing calibration. The improvement of the calibration accuracy and precision correspondingly improves the probability that the verification result meets the requirement, namely, the probability of repeated calibration is reduced.
3. Increase the speed of sample analysis
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00015% + -0.00004%, blank entry directly into carbon sulfur instrument (0.00015% + -0.00004%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
1.00 g (accurate to 0.001 g) of a single crystal superalloy DD6 sample is weighed, 1.00 g of the standard substance is added, the sample is measured for 2 times, and the result is shown in the measurement result of a variable single crystal superalloy DD6 sample in Table 8.
The results of the two sample measurements satisfy the requirements of the tolerance of the two measurement results in table 5, so that the single crystal superalloy DD6 sample is prepared by mixing the following components in percentage by weight: 0.0022% reports to the customer.
The carbon sulfur instrument calibration step can be completed before the sample measurement, and the single crystal superalloy DD6 sample is measured 2 times, the first time takes 40 seconds, the middle process takes 20 seconds, the second time takes 40 seconds, and the total time takes about 2 minutes. The requirement of rapid analysis in front of the furnace is met.
It is obvious to eliminate the step of measuring the carbon blank value to increase the analysis speed, and to reduce the number of repeated measurements. For example, measurements have been repeated many times before, requiring 2 hours of operation to complete the calibration step. Therefore, the standard substance is used as a fluxing agent, the effect of improving the analysis speed is unexpected, and the requirement of rapid analysis in front of the furnace is met.
Example 2
Preparation of standard substance
1. Preparation of fluxing agent
Selecting 2.0 parts of pure tungsten powder and 1 part of pure iron powder, uniformly mixing, pressing, forming and sintering to obtain a sinter, crushing and sieving the prepared sinter, taking sinter granules with the granularity of 20-40 meshes, selecting 0.5 part of copper granules with the granularity of 20-60 meshes, mixing with the prepared sinter granules, and roasting at 1350-1400 ℃ to obtain a fluxing agent;
2. crushing, uniformly mixing and sieving the fluxing agent to obtain a candidate;
3. according to the first-class standard substance technical specification (JJF 1006-1994), uniformity test, stability test, definite value, standard value determination and total uncertainty test are carried out on the candidate, the final result shows that the candidate has good uniformity and stability, and the standard value C of carbon: 0.00038% + -0.00008%.
(1) Uniformity test
Randomly draw 11 packages from 150 packages of candidate standard material, and 3 subsamples per package for inter-vial and intra-vial uniformity testing. The sampling amount is 1.0g, the carbon content is measured according to section 8.3.1.3 of the infrared absorption method after the combustion of the high-frequency induction furnace (GB/T20123-2006/ISO 15350:2000) for measuring the total carbon and sulfur content of steel, and the uniformity test results are shown in Table 9. Performing F-test statistical analysis according to the method in the general principle and statistical principle of standard substance valuing (JJF 1343-<F0.05(10,22). The results indicate that the resulting candidate standard substance does not differ significantly at the 95% confidence interval, i.e., the candidate standard substance is homogeneous.
TABLE 9 Standard substance homogeneity test at 0.00038% level
(2) Stability verification
The candidate standard substance was examined for changes in the mass value of the standard substance after storage for 1, 3, 6, 12, and 18 months under suitable storage conditions (15-25 ℃). Measuring carbon content according to high-frequency induction combustion-infrared absorption method, taking 5 packages each time, taking a sample for each package, measuring for 3 times, calculating average value, and taking the measured average value of 5 packages of standard substances as detection result. Stability evaluation was performed using a (classical) linear model according to the standard samples specified in general and statistical principles of standard substance quantitation (JJF 1343-.
TABLE 10 stability test of 0.00038% content of standard substance
(3) Constant value
For the candidate standard substance, 11 bottles of samples are randomly extracted, each bottle is sampled once, 8 different units are entrusted to carry out value determination, and the carbon content is determined according to section 8.3.1.3 of infrared absorption method after combustion of high-frequency induction furnace for determining total carbon and sulfur content of steel (GB/T20123-. And for the carbon measurement value, sequentially carrying out Charpy-Wilker normal data test, Dixon and Grabbs abnormal value test, precision consistency test and comparison of significance difference of average values of different unit results on the data, and finally obtaining a fixed value result and an uncertainty result of the standard substance. The results are shown in Table 11.
TABLE 11 Standard substance quantitative data
Two, very simple carbon-sulfur instrument initialization
After the carbon sulfur instrument was initialized in example 1, the carbon sulfur instrument was continuously used for one month, and the carbon sulfur instrument was initialized again in order to observe whether the carbon sulfur instrument fluctuated.
For solid standard substance C: 0.00038% ± 0.00008% 9 measurements were made. The results of the last and the current measurements are as follows:
TABLE 12 measured values of carbon of the last and present standards%
As judged by the table 12, the accuracy and precision of the carbon sulfur instrument for measuring carbon are not changed after the instrument is continuously used for one month, and the instrument can work at any time without requiring a professional to debug.
Thirdly, improving the accuracy of the analysis result
The stainless steel plate is analyzed according to the method of the infrared absorption method after the combustion of the high-frequency induction furnace (GB/T20123-.
1. Improving accuracy of carbon-sulfur instrument calibration result
The standard substance of the present invention has fluxing properties for fluxing and is used herein as a fluxing agent, wherein the standard value C for carbon: 0.00038% + -0.00008%, blank entry directly into the carbon sulfur instrument (0.00038% + -0.00008%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
Selecting a standard substance AR 512C: 0.015% + -0.001% of the highest point standard substance, 1.00 g (to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the results were measured 5 times as shown in Table 13.
Table 13 accuracy and precision of calibration results%
The results after calibration were all in the standard AR 512C: 0.015% ± 0.001% allowed difference.
Selecting standard substances LECO 502-:
table 14 minimum point standard substance measurement%
Obviously, the precision of the calibration results is high in terms of the standard deviation and relative standard deviation after calibration of the highest point standard substance and the lowest point standard substance.
Then, 0.0036% + -0.0003% of YSBC 281121-2015C, which is a standard substance with similar carbon content to the sample, is added to the sample, and 1.00 g of the standard substance of the present invention is weighed out to the nearest 0.001 g, and the results are verified and measured for 3 times, as shown in Table 15.
Table 15 verification measurement%
The results of the verification measurements are all within the range of the allowable difference of 0.0036% + -0.0003% for the standard YSBC 281121-2015C. Subsequent sample measurements can be performed.
2. Improving accuracy of sample measurement results
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00038% + -0.00008%, blank entry directly into the carbon sulfur instrument (0.00038% + -0.00008%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
A stainless steel plate sample (1.00 g, to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the sample was measured 2 times, and the results were as follows:
TABLE 16 test results of stainless steel plate sample%
| Measured value | Mean value of |
| 0.0053、0.0051 | 0.0052 |
Taking an average value C of two sample measurement results: 0.0052% reports to the customer.
The standard substance of the invention has fluxing property of fluxing agent, and is used as fluxing agent, wherein the carbon blank value is accurately known, and can be directly input into a blank item (0.00038% + -0.00008%) of a carbon-sulfur instrument for automatic deduction. Compared with the blank value obtained by the original temporary analysis, the method is more accurate. Obviously, the accuracy of the sample measurement results is high.
In addition, the accuracy of the measurement result of the sample is obviously higher when the sample is measured on the premise that the accuracy of the calibration result is higher.
Fourthly, the precision of the analysis result is improved
1. Precision of carbon-sulfur instrument calibration is improved
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00038% + -0.00008%, blank entry directly into the carbon sulfur instrument (0.00038% + -0.00008%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
Selecting a standard substance AR 512C: 0.015% ± 0.001% of the highest point standard substance, 1.00 g (to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the measurement was performed 5 times, and the results are shown in table 13 as the accuracy and precision of the calibration results.
The results after calibration were all in the standard AR 512C: 0.015% ± 0.001% allowed difference.
Obviously, the accuracy of the calibration results is high from the measured values and the average value after calibration.
Then, 0.0036% + -0.0003% of YSBC 281121-2015C, which is a standard substance with similar carbon content to the sample, is used for weighing 1.00 g (accurate to 0.001 g), 1.00 g of the standard substance is added, and the verification and measurement are carried out for 3 times, wherein the results are verified as shown in Table 15.
It is clear that the precision is high as judged by verifying the standard deviation and the relative standard deviation of the measurement results from table 15.
2. Improving precision of sample measurement result
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00038% + -0.00008%, blank entry directly into the carbon sulfur instrument (0.00038% + -0.00008%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
A stainless steel plate sample (1.00 g, to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the sample was measured 2 times, and the results are shown in Table 16. Stainless steel plate samples were prepared according to the following formula C: 0.0052% reports to the customer.
The difference between the two measurements is 0.0002%, and obviously, the precision of the measurement result of the sample is higher.
According to the requirements of an infrared absorption method (GB/T20123-2006/ISO 15350:2000) for measuring the total carbon and sulfur content of steel after combustion of a high-frequency induction furnace, subsequent measurement can be carried out only when the result is within an allowable difference range after verification and analysis for 3 times, otherwise, calibration is carried out repeatedly. The improvement of the calibration accuracy and precision correspondingly improves the probability that the verification result meets the requirement, namely reduces the probability of repeated calibration.
Fifth, unexpectedly increasing the speed of analysis
The carbon content has a great influence on the stainless steel plate, and is a key index. Therefore, the materials department usually requires that the carbon content be measured first. If the carbon content is not qualified, the other elemental measurements are suspended. This situation places severe demands on the speed of analysis, especially in the forehearth.
1. The step of measuring the carbon blank value is eliminated, and the whole analysis speed is improved
When the carbon content in the stainless steel plate sample is less than 0.01%, the blank value in the reagent and the material should be analyzed. The measured blank value is input into a blank item of a carbon-sulfur instrument for automatic deduction.
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00038% + -0.00008%. Therefore, blank items (0.00038% + -0.00008%) directly inputting carbon values into the carbon-sulfur instrument are automatically deducted, the step of measuring the carbon blank values is eliminated, and the whole analysis speed is improved.
2. Improving the calibration speed of the carbon-sulfur instrument
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00038% + -0.00008%, blank entry directly into the carbon sulfur instrument (0.00038% + -0.00008%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
Selecting a standard substance AR 512C: 0.015% ± 0.001% of the highest point standard substance, 1.00 g (to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the measurement was performed 5 times, and the results are shown in table 13 as the accuracy and precision of the calibration results.
The results after calibration were all in the standard AR 512C: 0.015% ± 0.001% allowed difference.
Then, 1.00 g (to the accuracy of 0.001 g) of the standard substance LECO 502-712C with the content similar to that of the sample is weighed out by 0.0014% + -0.0002%, and 1.00 g of the standard substance of the invention is added to verify and measure for 3 times, and the result is shown in Table 15.
The verification measurement results are all in the range of the allowable difference of 0.0014% + -0.0002% of the standard substances LECO 502-712C. Subsequent sample measurements can be performed.
This carbon sulfur instrument calibration was performed 13 times, each for 60 seconds, for a total of about 13 minutes.
3. Increase the speed of sample analysis
The standard substance of the present invention has fluxing properties of a flux, and is used herein as a flux, wherein the standard value C of carbon: 0.00038% + -0.00008%, blank entry directly into the carbon sulfur instrument (0.00038% + -0.00008%) was automatically subtracted. Compared with the blank value obtained by the original temporary analysis, the method is more accurate.
A stainless steel plate sample (1.00 g, to the nearest 0.001 g) was weighed, 1.00 g of the standard substance of the present invention was added, and the sample was measured 2 times, and the results are shown in Table 16.
The difference between the two measurements is 0.0002%, and obviously, the precision of the measurement result of the sample is higher. Therefore, the stainless steel sheet sample was prepared in the following manner: 0.0052% reports to the customer.
The carbon sulfur instrument calibration step may be completed before the sample measurement, and this time the stainless steel plate sample measurement takes 2 times, the first time takes 40 seconds, the middle process takes 20 seconds, the second time takes 40 seconds, and the total time takes about 2 minutes. The requirement of rapid analysis in front of the furnace is met.
It is obvious to eliminate the step of measuring the carbon blank value to increase the analysis speed, and to reduce the number of repeated measurements. For example, measurements have been repeated many times before, requiring 4 hours of operation to complete the calibration step. Therefore, the standard substance is used as a fluxing agent, the effect of improving the analysis speed is unexpected, and the requirement of rapid analysis in front of the furnace is met.
The foregoing is merely a detailed description of the embodiments of the present invention, and some of the conventional techniques are not detailed. The scope of the present invention is not limited thereto, and any changes or substitutions that can be easily made by those skilled in the art within the technical scope of the present invention will be covered by the scope of the present invention. The protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (9)
1. The carbon-containing standard substance is characterized by being a fluxing agent with fluxing performance, wherein the fluxing agent is a standard substance with the carbon content of 0.00002-0.0005 mass percent.
2. The carbon-containing standard substance according to claim 1, wherein the flux is formed by sintering 1.0-2.5 parts of pure tungsten powder, 0.3-1.2 parts of pure iron powder, 0.1-0.5 part of tin particles and 0.1-0.6 part of vanadium pentoxide, or is formed by sintering 1.0-2.5 parts of pure tungsten powder, 0.3-1.2 parts of pure iron powder and 0.1-0.6 part of copper particles, wherein the content uniformity of carbon as flux impurities meets the requirement of the content uniformity of the standard substance.
3. A method of preparing a standard substance according to claim 1, comprising the steps of
S1, preparing a fluxing agent;
s2, preparing a candidate by using a fluxing agent;
and S3, performing uniformity test, stability test, constant value determination, standard value determination and total uncertainty estimation on the candidate, and determining the mass percentage of the carbon content as the standard value of the standard substance carbon.
4. The method for preparing standard substance according to claim 3, wherein the step of preparing the flux in S1 comprises
SS1, selecting 1.0-2.5 parts of pure tungsten powder and 0.3-1.2 parts of pure iron powder, uniformly mixing, pressing and molding, and sintering to obtain a sinter;
SS2, crushing and sieving the prepared sinter, and taking sinter granules with the granularity of 20 meshes to 40 meshes;
and SS3, selecting 0.1-0.5 part of tin particles with the granularity of 20-60 meshes and 0.1-0.6 part of vanadium pentoxide with the granularity of 60-300 meshes, mixing the tin particles with the prepared sintered material granules, and roasting at 800-1100 ℃ to obtain the fluxing agent.
5. The method for preparing standard substance according to claim 3, wherein the step of preparing the flux in S1 comprises
SS1, selecting 1.0-2.5 parts of pure tungsten powder and 0.3-1.2 parts of pure iron powder, uniformly mixing, pressing and molding, and sintering to obtain a sinter;
SS2, crushing and sieving the prepared sinter, and taking sinter granules with the granularity of 20 meshes to 40 meshes;
SS3, selecting 0.1-0.6 part of copper particles with the granularity of 20-60 meshes, mixing the copper particles with the prepared sinter particles, and roasting at 1350-1400 ℃ to obtain the fluxing agent.
6. Use of the standard substance of claim 1 in material analysis, including for carbon-sulfur instrument initialization, carbon-sulfur instrument calibration, and carbon-containing sample analysis.
7. Use of the standard substance in material analysis according to claim 6, for initialization of a carbon sulfur instrument, comprising the following steps
S1, calibrating the carbon sulfur instrument;
s2, measuring the carbon content of the standard substance by mass percent for multiple times;
s3, calculating calibration parameters at least comprising a mean value, a standard deviation and a relative standard deviation;
s4, comparing with the last calibration parameter.
8. Use of a standard substance according to claim 6 in material analysis, wherein the procedure for calibrating the application of a carbon sulfur instrument is as follows:
s1, selecting a first standard substance with carbon content slightly higher than that of the sample to be detected;
s2, inputting the standard value of the standard substance carbon into a blank item of a carbon-sulfur instrument for automatic deduction;
s3, adding a standard substance as a cosolvent, and measuring the carbon content of the first standard substance for multiple times;
s4, calculating the average value, the standard deviation and the relative standard deviation of the carbon content of the first standard substance;
s5, taking the average value, the standard deviation and the relative standard deviation of the carbon content of the first standard substance as a standard carbon-sulfur instrument;
s6, selecting another second standard substance with the same or similar carbon content value as the sample to be detected;
s7, adding a standard substance serving as a cosolvent, and measuring the carbon content of the second standard substance for multiple times by using a carbon sulfur instrument calibrated by the first standard substance;
s7, calculating the average value, the standard deviation and the relative standard deviation of the carbon content of the second standard substance;
and S8, verifying that the result is within the allowable difference range of the second standard substance, and completing the calibration of the carbon sulfur instrument.
9. Use of the standard substance according to claim 6 in sample analysis, wherein the sample analysis comprises the following steps
S1, inputting the standard value of the standard substance carbon into a blank item of a carbon-sulfur instrument for automatic deduction;
s2, adding the standard substance into a carbon-containing test material, and measuring the mass percent of the carbon content for multiple times;
and S3, calculating the average value to obtain the carbon content of the carbon-containing sample.
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