Method for determining blank value of carbon in fluxing agent

Abstract

The present application belongs to the field of chemical analysis, and particularly relates to a method for determining a carbon blank value in a flux, which comprises the following steps: S1, weighing a specific mass of the flux, placing the flux in a crucible, placing the crucible at an analysis position of a carbon-sulfur analyzer, running the carbon-sulfur analyzer, and obtaining a measured carbon value; S2, repeating S1 for several times to obtain measured carbon values corresponding to different masses of the flux; S3, taking the mass of the flux as an abscissa X and the measured carbon value as an ordinate Y, fitting a straight line equation Y=aX+b; and S4, taking the mass X=0 of the flux, and the corresponding Y value is the carbon blank value of the flux. The method can eliminate the interference of the carbon leached out by the crucible in the measuring process on the determination of the blank value, and obtain a more accurate carbon blank value of the flux.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical analysis, and particularly relates to a method for determining carbon blank value in flux. BACKGROUND

[0002] At present, it is a common method to measure carbon element by using carbon-sulfur analyzer made by high-frequency induction combustion-infrared absorption principle. In the process of analyzing carbon by the carbon-sulfur analyzer, flux is needed to be used; the impurity carbon in the flux is also released in the measuring process, which forms the carbon blank value. Therefore, as the flux product itself, the carbon blank value is an important product index. The lower the carbon blank value is, the better.

[0003] The current flux preparation technology cannot reduce the carbon blank value of the flux to zero, that is, the flux still contains carbon. In the analysis process, the carbon is also released to form the carbon blank value, which interferes with the measurement of carbon in the sample. Therefore, the lower the content of the carbon blank value is, the more favorable to the measurement of carbon in the sample. The carbon blank value of the flux supplied on the market is C≈0.0005%, and some flux varieties may have a lower carbon blank value. The high or low of the carbon blank value is an important index of the quality of the flux product, and accurate measurement of the carbon blank value has practical significance. At present, there are two methods for measuring the carbon blank value: 1. standard addition method: a known amount of standard substance is added to the crucible, and then the flux is added, and the carbon value under the analysis condition is measured. This method cannot be applied when the blank value is negative, because the measured value and the standard value are much larger than the blank value; 2. direct measurement method: the sample is not added to the crucible, only the flux is added, and the carbon content under the analysis condition is measured, which is the blank value. The defect of this method is that it does not consider the release of carbon in the crucible and other materials. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method for determining the carbon blank value in flux, which can eliminate the interference of the carbon released by the crucible in the measuring process on the determination of the blank value, and obtain more accurate carbon blank value.

[0005] The present application provides a method for determining the carbon blank value in flux, which comprises the following steps:

[0006] S1, a specific amount of flux is weighed and put into a crucible, the crucible is placed in the analysis position of the carbon-sulfur analyzer, the carbon-sulfur analyzer is run, and the measured carbon value is obtained;

[0007] S2, S1 is repeated for several times to measure and obtain the measured carbon value corresponding to different amounts of flux;

[0008] S3, the flux amount is taken as the horizontal coordinate X, and the measured carbon value is taken as the vertical coordinate Y, and a straight line equation Y=aX+b is fitted;

[0009] S4, taking flux quality X = 0, the corresponding Y value is the carbon blank value of the flux.

[0010] In the present application, in the linear equation Y = aX + b, Y is the measured value of carbon (unit ppm); the intercept b is the carbon blank value of the flux; the slope a represents the change of the carbon leached out by the crucible under the use of a certain crucible and a certain flux; aX represents the amount of carbon leached out by the crucible under X grams of flux.

[0011] In a preferred technical solution provided by the present application, the mass interval of the different quality fluxes is 0.50 grams. It is known that a certain amount of sample is combusted in a high-frequency induction furnace under the fluxing of a certain quality flux, and the carbon therein is completely released; generally, the amount of flux added is 1-3 grams; therefore, it is appropriate to select the mass increment interval of 0.50, 1.00, 1.50, 2.00, 2.50, 3.00 grams, the workload is appropriate, and the amount of carbon released is also within the detection limit of the instrument.

[0012] In another preferred technical solution provided by the present application, the mass interval of the different quality fluxes is <0.50 grams. The above mass interval is suitable for the flux with a relatively high carbon blank value.

[0013] In a preferred technical solution provided by the present application, the determination method specifically comprises the following steps:

[0014] S1, a plurality of groups of the same flux with specific quality are weighed and placed in corresponding crucibles, the crucibles are placed at the analysis position of the carbon-sulfur analyzer, the carbon-sulfur analyzer is run, and the measured value of carbon is obtained;

[0015] S2, S1 is repeated for several times, and the measured values of carbon corresponding to the plurality of groups of fluxes with different quality are obtained;

[0016] S3, taking the quality of the flux as the horizontal coordinate X and the measured value of carbon as the vertical coordinate Y, a linear equation Y = aX + b corresponding to the different groups of fluxes is fitted;

[0017] S4, taking the quality of the flux X = 0, the corresponding Y value is the carbon blank value of the different groups of fluxes;

[0018] S5, the carbon blank values of the different groups of fluxes are added and divided by the number of groups, and the average carbon blank value of the flux is obtained.

[0019] In the above preferred technical solution provided by the present application, the carbon content result is averaged, and the influence of accidental factors on the measurement of carbon content is eliminated.

[0020] In another preferred technical solution provided by the present application, the determination method specifically comprises the following steps:

[0021] S1, a plurality of groups of the same flux of a certain mass are weighed, and are respectively placed in corresponding crucibles, the crucibles used by different groups of fluxes are different; the crucibles are placed in a position to be analyzed of a carbon-sulfur analyzer, the carbon-sulfur analyzer is run, and a measured value of carbon is obtained;

[0022] S2, S1 is repeated for several times, and the measured values of carbon corresponding to a plurality of groups of fluxes of different masses are obtained;

[0023] S3, the mass of the flux is taken as an abscissa X, and the measured value of carbon is taken as an ordinate Y, and a linear equation Y=aX+b corresponding to different groups of fluxes is fitted;

[0024] S4, a linear equation with the smallest slope a is selected from the linear equations corresponding to different groups of fluxes, and the Y value corresponding to the mass X=0 of the flux in the linear equation is the carbon blank value of the flux.

[0025] In the above preferred technical scheme provided by the present application, the linear equation with a small slope corresponds to a crucible with a small leaching rate, the carbon leaching amount under the same test condition is small, the carbon leaching interference is small, and the measurement of the carbon blank value is more favorable.

[0026] In one preferred technical scheme provided by the present application, the crucible is an ultra-low carbon crucible. The carbon leached by the ultra-low carbon crucible is very small, and the measured carbon blank value is more accurate.

[0027] In one preferred technical scheme provided by the present application, the oxygen used when the carbon-sulfur analyzer is running has a purity of ≥99.999%. The purity of ordinary oxygen is usually ≥99.2%, and the impurity carbon in high-purity oxygen is less, and the measured carbon blank value is more accurate.

[0028] Compared with the prior art, the method for determining the carbon blank value in the flux provided by the present application has the following beneficial effects:

[0029] Since the carbon release amount of crucible leaching is positively correlated with the quality of the molten body, the interfering carbon released by the crucible can be reduced by reducing the amount of flux, and when the amount of flux tends to zero, the amount of interfering carbon released by the crucible also tends to zero, thereby excluding the interference of crucible leaching carbon on the determination of the carbon blank value of the flux. Based on the above technical concept, the method provided by the present application first uses a carbon-sulfur analyzer to detect crucibles with different quality fluxes, then fits a straight line equation Y=aX+b with the quality of the flux as the abscissa and the measured carbon concentration as the ordinate, and finally takes the Y value corresponding to the quality X=0 of the flux as the carbon blank value of the flux. The method excludes the interference of the carbon released by the crucible, measures the carbon blank value of the flux itself, overcomes the defects in the prior art method for measuring the carbon blank value, provides a new solution for the determination of the carbon blank value of the flux in the carbon analysis process, and also provides a practical method for measuring the carbon blank value in the production of the flux.

[0030] In addition, in the method provided by the present application, aX in the straight line equation Y=aX+b represents the leaching amount of carbon, and therefore the method provided by the present application also provides a practical solution for measuring the leaching amount of carbon of the crucible. The lower the leaching amount of carbon, the smaller the interference of the impurity carbon of the crucible on the analysis process, that is, the better the quality of the crucible, and therefore the method provided by the present application can also be applied to judge the quality of the crucible. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0032] Figure 1 The figure is a schematic diagram of the quality of the flux and the measured value of carbon in Example 1 of the present application.

[0033] Figure 2 The figure is a schematic diagram of the quality of the flux and the measured value of carbon in Example 2 of the present application.

[0034] Figure 3 The figure is a schematic diagram of the quality of the flux and the measured value of carbon of the ordinary crucible in Example 3 of the present application.

[0035] Figure 4 The figure is a schematic diagram of the quality of the flux and the measured value of carbon of the special crucible for carbon-sulfur analysis measured in Example 3 of the present application. DETAILED DESCRIPTION

[0036] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of the present application.

[0037] In the following described embodiments of the present application, the carbon-sulfur analyzer used is a CS844ES type carbon-sulfur analyzer of LECO Corporation, USA, and the key condition parameters are as follows: (1) Analysis Time (carbon analysis time, carbon release time under combustion condition), standard mode: 40 seconds, ES mode (enhanced sensitivity mode): 130 seconds; (2) Cycle Time (including crucible entering device time + purification system time + analysis time + crucible leaving device time after analysis, i.e. the whole analysis process of one crucible takes time), standard mode: 130 seconds, enhanced sensitivity mode: 270 seconds; (3) Carrier Flow (standard mode: 3 liters / minute, enhanced sensitivity mode: 0.8 liters / minute); if not otherwise specified, the oxygen purity used when the carbon-sulfur analyzer is running is all ≥ 99.999%.

[0038] Embodiment 1

[0039] The determination of the carbon blank value of the pure iron fluxing agent and the determination of the carbon amount leached out from the crucible by 2.0 grams of the fluxing agent are as follows:

[0040] The pure iron fluxing agent shown in Table 1 is weighed and placed in a crucible, and the crucible is placed in the position to be analyzed in the carbon-sulfur analyzer;

[0041] The run key is pressed, and the carbon-sulfur analyzer is automatically run (the impurity carbon content in the pure iron fluxing agent is high, and the carbon-sulfur analyzer is used in the standard mode for measurement); the result is automatically output in ppm, and the measured carbon value is obtained;

[0042] The measured carbon values corresponding to different masses of the fluxing agent are continuously measured and obtained;

[0043] The mass of the fluxing agent is used as the horizontal coordinate X, and the measured carbon value is used as the vertical coordinate Y, and an EXCEL is used to fit a straight line equation, and the result is Y = 0.292X + 5.064, as shown in Figure 1

[0044] X = 0 is taken, and the corresponding Y value is the carbon blank value, and the result is Y = 5.06 ppm.

[0045] ​2.0 grams of fluxing agent is added during sample measurement, so the leaching carbon amount of the crucible caused by 2.0 grams of fluxing agent needs to be measured to accurately deduct during sample measurement; the leaching carbon amount aX=Y-b=5.60-5.06=0.54 ppm; that is, the leaching carbon amount of the crucible caused by 2.0 grams of pure iron fluxing agent is 0.54 ppm.

[0046] Table 1 Fluxing agent mass-carbon measurement value table of pure iron fluxing agent

[0047] Flux mass / gram 0.50 1.0 1.50 2.00 2.50 3.00 Carbon measurement / ppm 5.23 5.38 5.48 5.60 5.76 6.00

[0048] Example 2

[0049] Determination of carbon blank value of tungsten particle fluxing agent and measurement of leaching carbon amount of the crucible caused by 1.5 grams of fluxing agent, as follows:

[0050] Weigh the tungsten particle fluxing agent as shown in Table 2 and place it in the crucible, which is placed in the analysis position of the carbon-sulfur analyzer;

[0051] Press the run key, and the carbon-sulfur analyzer automatically runs (the impurity carbon content in the tungsten particle fluxing agent is low, so the carbon-sulfur analyzer needs to be in enhanced sensitivity mode for measurement); the result is automatically output in ppm, and the measured carbon value is obtained;

[0052] Continue to measure the measured carbon values corresponding to different masses of fluxing agent;

[0053] Use EXCEL to fit a straight line equation with the fluxing agent mass as the horizontal coordinate X and the measured carbon value as the vertical coordinate Y, and the result is Y=0.2937X+1.1693, as shown in Figure 2 .

[0054] Take X=0, and the corresponding Y value is the carbon blank value, which is Y=1.17 ppm.

[0055] 1.5 grams of fluxing agent is added during sample measurement, so the leaching carbon amount of the crucible caused by 1.5 grams of fluxing agent needs to be measured to accurately deduct during sample measurement; the leaching carbon amount aX=Y-b=1.54-1.17=0.37 ppm; that is, the leaching carbon amount of the crucible caused by 1.5 grams of tungsten particle fluxing agent is 0.37 ppm.

[0056] Table 2 Fluxing agent mass-carbon measurement value table of tungsten particle fluxing agent

[0057] Flux mass / gram 0.50 1.0 1.50 2.00 2.50 3.00 Carbon measurement / ppm 1.38 1.46 1.54 1.67 1.98 2.07

[0058] Example 3

[0059] Comparison of the mass of a general crucible and a carbon-sulfur analysis special crucible

[0060] (1) Measure the leaching carbon amount of the general crucible, as follows:

[0061] Take the tungsten tin iron fluxing agent as shown in Table 3, put it into the crucible, and place the crucible in the position to be analyzed by the carbon-sulfur analyzer;

[0062] Press the run key, and the carbon-sulfur analyzer automatically runs (the impurity carbon blank value in the tungsten tin iron fluxing agent is high, and the carbon-sulfur analyzer standard mode is used for measurement) ; the result is automatically output in ppm, and the measured carbon value is obtained;

[0063] Continue to measure to obtain the measured carbon values corresponding to different masses of the fluxing agent;

[0064] Use EXCEL to fit a straight line equation with the mass of the fluxing agent as the abscissa X and the measured carbon value as the ordinate Y, and the result is Y = 0.4126X + 2.8047, as shown in Figure 3 ;

[0065] Take X = 0, and the corresponding Y value is the carbon blank value, and the result is Y = 2.80 ppm;

[0066] When the sample is measured, 2.0 grams of fluxing agent are added, so the amount of carbon leached out of the crucible caused by 2.0 grams of fluxing agent needs to be measured to accurately deduct it when the sample is measured; the amount of carbon leached out of the crucible aX = Y - b = 3.65 - 2.80 = 0.85 ppm; that is, the amount of carbon leached out of the crucible caused by 2.0 grams of tungsten tin iron fluxing agent is 0.85 ppm.

[0067] Table 3 Mass of fluxing agent-carbon measurement value table when a general crucible is used

[0068] Flux mass / gram 0.50 1.0 1.50 2.00 2.50 3.00 Carbon measurement / ppm 3.05 3.13 3.45 3.65 3.87 4.01

[0069] (2) Measure the amount of carbon leached out of the carbon-sulfur analysis special crucible, as follows:

[0070] Take the tungsten tin iron fluxing agent as shown in Table 4, put it into the crucible, and place the crucible in the position to be analyzed by the carbon-sulfur analyzer;

[0071] Press the run key, and the carbon-sulfur analyzer automatically runs (the impurity carbon blank value in the tungsten tin iron fluxing agent is high, and the carbon-sulfur analyzer standard mode is used for measurement) ; the result is automatically output in ppm, and the measured carbon value is obtained;

[0072] Continue to measure to obtain the measured carbon values corresponding to different masses of the fluxing agent;

[0073] Use EXCEL to fit a straight line equation with the mass of the fluxing agent as the abscissa X and the measured carbon value as the ordinate Y, and the result is Y = 0.2914X + 2.8033, as shown in Figure 4 ;

[0074] Take X = 0, and the corresponding Y value is the carbon blank value, and the result is Y = 2.80 ppm;

[0075] 2.0 grams of fluxing agent is added during sample measurement, so the amount of carbon leached out of the crucible caused by 2.0 grams of fluxing agent needs to be measured to accurately deduct during sample measurement; the amount of carbon leached out aX=Y-b=3.29-2.80=0.49 ppm; that is, the amount of carbon leached out of the crucible caused by 2.0 grams of tungsten tin iron fluxing agent is 0.49 ppm.

[0076] Table 4: Mass-flux carbon measurement values when using special crucibles

[0077] Flux mass / gram 0.50 1.0 1.50 2.00 2.50 3.00 Carbon measurement / ppm 3.00 3.13 3.20 3.29 3.45 3.81

[0078] It can be seen that 2.0 grams of tungsten tin iron fluxing agent causes the amount of carbon leached out of the ordinary crucible to be 0.85 ppm, and causes the amount of carbon leached out of the carbon-sulfur analysis special crucible to be 0.49 ppm; therefore, when measuring the sample to be tested, the carbon-sulfur analysis special crucible has less interference, and is more conducive to the measurement of carbon.

[0079] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for determining the carbon blank value in a flux, characterized in that, Includes the following steps: S1. Weigh a certain mass of flux, put it into a crucible, place the crucible in the position to be analyzed of the carbon-sulfur analyzer, run the carbon-sulfur analyzer, and obtain the measured carbon value. In step S1, the mass of the flux is not zero; S2, repeat S1 several times to measure and obtain the carbon values ​​corresponding to different masses of flux; S3, with flux mass as the x-axis and carbon measured value as the y-axis, the linear equation Y=aX+b is obtained by fitting; S4, take flux mass X=0, the corresponding Y value is the carbon blank value of flux.

2. The determination method according to claim 1, characterized in that, The mass interval between the different masses of flux is 0.50 grams.

3. The determination method according to claim 1, characterized in that, The mass interval of the different masses of flux is <0.50 g.

4. The determination method according to claim 1, characterized in that, Includes the following steps: S1. Weigh out multiple groups of the same flux of a certain mass and put them into the corresponding crucibles. Place the crucibles in the position to be analyzed in the carbon-sulfur analyzer and run the carbon-sulfur analyzer to obtain the carbon measurement value. S2, repeat S1 several times, and measure and obtain the carbon values ​​corresponding to multiple sets of fluxes of different masses; S3, with flux mass as the abscissa X and carbon measurement value as the ordinate Y, the linear equation Y=aX+b corresponding to different groups of flux is obtained by fitting. S4, take flux mass X=0, the corresponding Y value is the carbon blank value of different groups of flux; S5. Add the carbon blank values ​​of different groups of fluxes together and divide by the number of groups to obtain the average carbon blank value of the flux.

5. The determination method according to claim 1, characterized in that, Includes the following steps: S1. Weigh out multiple groups of the same flux of a certain mass and place them into corresponding crucibles. Different types of crucibles are used for different groups of flux. Place the crucibles in the position to be analyzed on the carbon-sulfur analyzer, run the carbon-sulfur analyzer, and obtain the carbon measurement value. S2, repeat S1 several times, and measure and obtain the carbon values ​​corresponding to multiple sets of fluxes of different masses; S3, with flux mass as the abscissa X and carbon measurement value as the ordinate Y, the linear equation Y=aX+b corresponding to different groups of flux is obtained by fitting. S4. Select the linear equation with the smallest slope a from the linear equations corresponding to different groups of fluxes. In this linear equation, take the flux mass X=0, and the corresponding Y value is the carbon blank value of the flux.

6. The determination method according to claim 1, characterized in that, The oxygen used in the operation of the carbon-sulfur analyzer has a purity of ≥99.999%.

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