JP2006177922A - Emission spectral analysis method and analyzing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To analyze a metal sample with accuracy, even if the metal sample obtained from severance is of low smoothness when analyzing metal samples, through the use of spark electrical discharge emission spectral analysis methods. <P>SOLUTION: In an emission spectral analysis method where plural number of times of spark electric discharges are generated in an inert gas between a metal sample 3 attached to a sample supporting stand 10 and a pair of electrodes 4 deployed facing the metal sample concerned and the element within the metal sample is quantified by implementing spectroscopy of emission for each spark discharge, let the aforementioned metal sample to attach on a protruding portion 11 prepared on the sample supporting stand to generate spark discharge. Since the metal sample contacts the protruding portion, the analysis is possible without being affected due to the ruggedness, even if the ruggedness exists on the surface of the metal sample. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an emission spectroscopic analysis method and an analysis apparatus, and more specifically, even a metal sample having a partially low-smooth portion such as a cutting burr formed at the end of a cut surface of the metal sample is accurately obtained. The present invention relates to an emission spectroscopic analysis method and an analysis apparatus that can be analyzed.

  In the steel industry, a metal sample is collected and analyzed from molten steel refined in a refining furnace such as a converter and vacuum degassing furnace, and the amount of alloy elements added or the required processing time based on the analysis value of the metal sample The component adjustment of the molten steel is performed. Therefore, in order to perform these refining quickly, it is necessary to analyze the metal sample collected during refining in a very short time.

  For this reason, spark discharge optical emission spectrometry with excellent rapidity is mainly used for this analysis, but further high-speed refining is required due to increased production and cost reduction. There is a need for further time reduction in the analysis process.

  However, in the current spark discharge emission spectrometry, for example, as disclosed in Patent Document 1, it is necessary to polish and flatten the surface of a metal sample in order to maintain the analysis accuracy. This polishing is performed for 10 seconds to 20 seconds. Was spent. If this polishing step is omitted to shorten the analysis time, and the metal sample that has been cut is analyzed, the smoothness of the surface of the metal sample is low, so when the metal sample is mounted on the sample support of the emission spectroscopic analyzer Since the analysis surface is inclined with respect to the sample support and the distance between the metal sample and the counter electrode changes from the state in which the calibration curve is created, there is a problem that the analysis accuracy is lowered.

This problem is particularly noticeable when irregularities such as burrs are present at the end of the cut surface of the metal sample. When such irregularities are present, quantitative analysis of a metal sample that has been cut is substantially impossible. It was impossible.
JP 2004-61501 A

  Even if it is a metal sample with unevenness such as burrs at the end of the cut surface, it is effective in the past even though there is a need for a means to accurately analyze this unevenness without removing it by polishing or grinding. In order to ensure analysis accuracy, the entire surface to be analyzed is polished or ground as a pre-measurement process to smooth the entire surface to be analyzed. Shortening was impossible.

  The present invention has been made in view of the above circumstances. The object of the present invention is to analyze a metal sample by spark discharge emission spectrometry, and the metal sample obtained by cutting is a metal sample having low smoothness. However, it is an object of the present invention to provide an emission spectroscopic analysis method and an analysis apparatus capable of analyzing with high accuracy even a metal sample in which irregularities such as burrs are present at the end of the cut surface of the metal sample.

  The inventors of the present invention have conducted intensive studies and studies to solve the above problems. The research and examination results are explained below.

  As shown in FIG. 6, a schematic cross-sectional view of a sample support used in a conventional spark discharge emission spectroscopic analyzer is usually equipped with a metal sample 3 for analysis in the conventional spark discharge emission spectroscopic analyzer. The sample support 10 is flat and has a circular hole 10a in a part thereof. The metal sample 3 is mounted so as to cover the hole 10a, that is, the opening 10a. Electric discharge is performed between the sample 3 and the sample 3 through the opening 10a. At this time, the contact area of the metal sample 3 with the sample support 10 is the entire analysis surface of the metal sample 3 except for the portion covering the opening 10a. By contacting the sample support 10, the metal sample 3 cannot be brought into close contact with the sample support 10, and the distance between the analysis surface of the metal sample 3 and the counter electrode 4 becomes different from the set value. Decreases. In addition, the entry of air from the gap between the contact surfaces also causes a reduction in analysis accuracy. Here, the set value of the distance is a distance when the metal sample 3 is in close contact with the sample support 10, and a calibration curve in the emission spectroscopic analysis method is usually created with this set value.

  For this reason, in the quantitative analysis in the spark discharge optical emission spectrometer, it was essential to attach the metal sample 3 to the sample support 10 after polishing or grinding the metal sample to smooth the entire analysis surface. .

  However, as a result of observing the cut surface of the metal sample cut by a high-speed cutting machine (circular saw cutting machine) widely used in obtaining the metal sample 3 for analysis, unevenness occurs on the entire surface of the metal sample cut surface. However, irregularities are mainly generated at the edge of the cut surface, and most of the cut surface is a flat area that can be discharged, and this flat area can be sufficiently quantitatively analyzed without polishing or grinding. The knowledge that there is.

  Therefore, as a result of studying the use of this flat region, quantitative analysis is possible if the metal sample 3 is mounted on the sample support 10 so that the uneven portion of the cut surface of the metal sample does not contact the sample support 10. I got the knowledge. In other words, by providing a protrusion on the sample support and contacting only the flat region formed on a part of the cut surface with the protrusion, sufficient quantitative analysis can be performed without being affected by the uneven portion of the cut surface. The knowledge that it is possible was obtained.

  The present invention has been made on the basis of the above knowledge, and an emission spectroscopic analysis method according to a first invention includes a metal sample mounted on a sample support and a counter electrode disposed to face the metal sample. In an emission spectroscopic analysis method in which a number of spark discharges are generated in an inert gas atmosphere and the light emission of each spark discharge is analyzed to quantify the elements in the metal sample, the metal sample is supported on the sample. It is characterized in that the spark discharge is carried out by mounting on a protrusion provided on the table.

  In the emission spectroscopic analysis method according to a second aspect of the present invention, in the first aspect, the protrusion is provided in an annular shape so as to surround the opening of the sample support, and has a height of 0.5 mm or more. The width of the surface on which the sample is mounted is 0.5 mm or more and 3 mm or less.

  An emission spectroscopic analysis method according to a third invention is characterized in that, in the first or second invention, a distance between the metal sample and the counter electrode is 1 mm or more and 3 mm or less.

  An emission spectroscopic analysis method according to a fourth invention is characterized in that, in the first or second invention, a spark discharge region in the metal sample has a diameter of 4 mm or less.

  According to a fifth aspect of the present invention, there is provided an emission spectroscopic analyzer between a metal sample mounted on a sample support so as to cover an opening of the sample support and a counter electrode disposed opposite to the metal sample. In an emission spectroscopic analyzer that generates a number of spark discharges in an inert gas atmosphere and quantifies the elements in the metal sample by spectroscopically analyzing the light emission of each spark discharge, the sample support base surrounds the opening. An annular protrusion is provided, and the metal sample is mounted on the sample support in contact with the tip portion of the protrusion.

  In the emission spectroscopic analyzer according to a sixth invention, in the sixth invention, the protrusion has a height of 0.5 mm or more and a width of a surface in contact with the metal sample is 0.5 mm or more and 3 mm or less. It is characterized by.

  The emission spectroscopic analyzer according to a seventh invention is characterized in that, in the fifth or sixth invention, a distance between the metal sample and the counter electrode is 1 mm or more and 3 mm or less.

  According to the present invention, the projection is provided on the sample support for mounting the metal sample, and the metal sample for analysis is supported at the tip portion of the projection. Even if there are irregularities, the convex part of the metal sample does not come into contact with the sample support table by bringing a relatively smooth part other than these irregularities into contact with the projection, and the metal sample is placed at a predetermined position on the sample support table. Can be worn. As a result, the distance between the metal sample and the counter electrode is always kept constant, and the metal sample can be quantitatively analyzed with high accuracy based on a calibration curve prepared in advance. In addition, in the quantitative analysis where the analysis surface was polished and ground, this polishing and grinding process can be omitted, and the laboratory time and the analytical work load can be greatly reduced compared to the conventional method. In addition, the refining time of the converter and the vacuum degassing furnace is shortened, and an industrially beneficial effect is brought about.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an example of the overall configuration of a spark discharge emission spectrometer according to the present invention, and FIG. 2 is an example of a sample support used in the spark discharge emission spectrometer according to the present invention. It is a schematic sectional drawing which shows.

  As shown in FIG. 1, a spark discharge optical emission spectrometer 1 includes a discharge device 2, an analysis metal sample (also an electrode) 3 and a counter electrode 4, and the discharge device 2 in an inert gas atmosphere such as Ar gas. Comprising a light emitting part that generates a spark discharge between the metal sample 3 and the counter electrode 4 in response to a signal from the light source, a slit 5, a diffraction grating 6, and a detector 7. A spectroscopic unit, a photometric device 8 for processing spectral lines detected by the detector 7 of the spectroscopic unit, and data for obtaining the element content of the metal sample 3 based on the spectral line intensity input from the photometric device 8 And a processing device 9.

  As shown in FIG. 2, the sample support 10 for mounting the metal sample 3 in the spark discharge optical emission spectrometer 1 has a planar shape along the periphery of the opening 10 a provided in the sample support 10. An annular protrusion 11 that is circular is provided, and the metal sample 3 is mounted on the sample support 10 in a state of being placed on the protrusion 11. That is, the metal sample 3 is mounted on the sample support 10 so as to be in contact only with the tip portion of the protrusion 11. The metal sample 3 is configured to perform a spark discharge with the counter electrode 4 in this state. The periphery of the counter electrode 4 is an inert gas atmosphere such as Ar gas. In FIG. 1, the sample support 10 is omitted.

  Thus, since the contact surface between the metal sample 3 and the sample support 10 is limited to a very narrow range of only the tip portion of the protrusion 11, even if the metal sample 3 remains cut and cut, Even if there is unevenness on a part of the analysis surface of the metal sample 3 by bringing the flat portion of the cut surface into contact with the protrusion 11 without removing unevenness such as cutting burrs by polishing or grinding, etc. The distance between the analysis surface of the metal sample 3 and the counter electrode 4 is equal to the set value without being affected by the unevenness, and the analysis surface of the metal sample 3 and the sample support 10 are in close contact with each other without any gap. Alternatively, quantitative analysis can be performed with the same accuracy as the ground analysis surface.

  In this case, in order to minimize the influence of unevenness such as cutting burrs, it is preferable that the height of the protrusion 11 is 0.5 mm or more and the width of the tip portion of the protrusion 11 is 0.5 mm or more and 3 mm or less. . When the height is less than 0.5 mm, the convex portion of the metal sample 3 comes into contact with the sample support base 10 around the protrusion 11 and the metal sample 3 and the protrusion 11 do not adhere to each other, which may reduce the analysis accuracy. Occurs. The upper limit of the height of the protrusion 11 need not be particularly limited, but about 5 mm is sufficient if judged from the state of occurrence of unevenness in the metal sample 3. Also, if the width of the protrusion 11 is less than 0.5 mm, the protrusion 11 may be deformed when the metal sample 3 is held, and at the same time, air is mixed from the gap formed by the deformation and the analysis accuracy is lowered. On the other hand, if the width of the protrusion 11 exceeds 3 mm, the contact area between the analysis surface of the metal sample 3 and the protrusion 11 becomes large, and the analysis accuracy is lowered due to being easily affected by the unevenness of the metal sample 3. There is a fear.

  In analyzing the metal sample 3 that has been cut, it is desirable that the smoothness of the cut surface serving as the analysis surface is high. Therefore, when the present invention is carried out, a relatively high smoothness of the cut surface can be obtained. It is preferable to cut with a high-speed cutter having a rotary blade having a circular outer shape.

  However, since the metal sample 3 remains cut, there are minute uneven portions on the analysis surface. In order to avoid the influence of the minute uneven portions, it is preferable that the distance between the metal sample 3 and the counter electrode 4 is 1 mm or more and 3 mm or less. The influence of the minute uneven portions can be efficiently avoided by narrowing the discharge region on the analysis surface of the metal sample 3. FIG. 4 (detailed description of FIG. 4 will be described later in the column of Examples) is a result of investigating the discharge region in the metal sample 3 at the time when the distance between the metal sample 3 and the counter electrode 4 was changed. By setting the distance between the metal sample 3 and the counter electrode 4 to 1 mm or more and 3 mm or less, the diameter of the discharge region can be reduced to about 5 mm or less. In other words, by setting the distance between the metal sample 3 and the counter electrode 4 to 1 mm or more and 3 mm or less, it is possible to avoid the influence of minute uneven portions on the analysis surface and perform analysis of a minute region with high accuracy. It becomes.

  In particular, by setting the discharge area in the metal sample 3 to a diameter of 4 mm or less, it becomes possible to analyze a minute area of ¼ to 1/10 compared to the conventional discharge area, and the influence of minute uneven portions on the analysis surface. Can be avoided even more. In this case, the diameter of the opening 10a provided in the sample support 10 is sufficient to be 7 mm or less.

  In addition, this invention is not limited to the range demonstrated above, In the range which does not deviate from the summary, it can be variously changed. For example, in the above description, the annular protrusion 11 is installed along the periphery of the opening 10a, but may be installed at a position away from the opening 10a as long as it is installed so as to surround the opening 10a. Moreover, the annular protrusion 11 may have any shape as long as it is a circular shape such as a quadrangle, a polygon, or an ellipse, as well as a circular shape. The “annular” in the present invention means “circulating shape”.

  Using the spark discharge optical emission spectrometer shown in FIG. 3, the position of the metal sample 3 and the position of the counter electrode 4 are changed to affect the discharge region in the metal sample 3 and the background equivalent concentration of each element. And the influence of the distance (L). Here, the installation position of the metal sample 3 was changed using a spacer 12 that can change the thickness in place of the protrusion. In addition, the thickness of the sample support 10 is made as thin as possible, and the distance (L) can be up to about 1 mm. The position of the counter electrode 4 is based on the position where the tip of the counter electrode 4 is 1 mm from the upper surface of the sample support 10, but the position of the counter electrode 4 can also be adjusted up and down, and in some tests it may be downward. Moved. As shown in FIG. 3, the position of the metal sample 3 and the position of the counter electrode 4 were based on the position of the upper surface of the sample support 10.

  FIG. 4 shows the results of investigating the discharge region in the metal sample 3 when the distance (L) between the metal sample and the counter electrode is changed with the electrical conditions of the discharge being constant. As is clear from FIG. 4, the discharge region becomes smaller as the distance (L) is decreased, and the diameter of the discharge region is set to about 5 mm by setting the distance between the metal sample 3 and the counter electrode 4 to 1 mm or more and 3 mm or less. I found out that I can: In other words, by setting the distance between the metal sample 3 and the counter electrode 4 to 1 mm or more and 3 mm or less, the influence of the minute uneven portions on the analysis surface of the metal sample 3 can be avoided and the analysis of the minute region can be performed with high accuracy. It turns out that it is possible.

  FIG. 5 is a diagram showing the results of investigating the influence of C, Si, P, and S on the background equivalent concentration by changing the position and distance (L) of the metal sample 3. In FIG. 5, the sample position of 0 mm indicates a state in which the spacer 12 is not used and the metal sample 3 is directly placed on the sample support 10. The sample position is 1 mm, 2 mm, and 3 mm. The case of 1 mm, 2 mm, and 3 mm is shown. Further, the conventional (2 mm) is a case where the conventional thick sample support 10 is used. In this case, the position of the metal sample is 2 mm when the position of the metal sample 3 is represented by the positional relationship of the metal sample 3 shown in FIG. It means to correspond to a position.

  A lower background equivalent concentration is generally more advantageous in terms of accuracy, and as is clear from FIG. 5, by making the distance (L) 1 mm or more and 3 mm or less, a highly accurate analysis is achieved while miniaturizing the discharge region. Was found to be possible. In particular, it was found that a highly accurate analysis is possible by setting the thickness of the spacer 12 to 1 mm and the distance (L) to 3 mm or less.

  A metal sample for analysis is cut out from a low alloy steel with a known element concentration measured using a wet quantitative analysis method, etc. using a high-speed cutting machine, and the sample is converted into a sample for emission spectroscopic analysis without polishing and grinding the cut surface. Provided. The emission spectroscopic analysis apparatus used is an emission spectroscopic analysis apparatus according to the present invention provided with a sample support having a protrusion shown in FIG. 2, and a conventional emission spectroscopic analysis apparatus provided with a sample support shown in FIG. The type was used. The analysis was performed three times on the same cut surface of the metal sample. A case where analysis is performed using the emission spectroscopic analyzer according to the present invention is referred to as an example of the present invention, while a case where analysis is performed using a conventional emission spectroscopic analyzer is referred to as a comparative example. Table 1 shows the results of analysis performed three times. In the example of the present invention, the distance between the metal sample and the counter electrode was 2 mm. In the comparative example, the distance between the metal sample and the counter electrode is 4 mm.

  As shown in Table 1, in the comparative example, the analysis results of the three times vary, and the absolute value of the concentration deviates significantly from the concentration quantitatively analyzed in advance. There was little variation in the analysis results, and the absolute value of the concentration was in good agreement with the concentration quantitatively analyzed in advance. From this result, it was confirmed that even a metal sample as cut could be quantitatively analyzed with high accuracy by applying the present invention.

It is the schematic which shows one example of the whole structure of the spark discharge emission-spectral-analysis apparatus based on this invention. It is a schematic sectional drawing which shows an example of the sample support stand used in the spark discharge optical emission spectrometer which concerns on this invention. 1 is a schematic cross-sectional view of a sample support base portion of a spark discharge optical emission spectrometer used in Example 1. FIG. It is a figure which shows the result of having investigated the discharge area | region in the metal sample at the time of changing the distance of a metal sample and a counter electrode. It is a figure which shows the result of having investigated the influence on the background equivalent density | concentration of C, Si, P, and S by changing the position of a metal sample, and the distance of a metal sample and a counter electrode. It is a schematic sectional drawing of the sample support stand used in the conventional spark discharge emission-spectral-analysis apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spark discharge emission-spectral-analysis apparatus 2 Discharge apparatus 3 Metal sample 4 Counter electrode 5 Slit 6 Diffraction grating 7 Detector 8 Photometry apparatus 9 Data processing apparatus 10 Sample support stand 10a Opening part 11 Protrusion part 12 Spacer

Claims (7)

  A number of spark discharges are generated in an inert gas atmosphere between a metal sample mounted on the sample support and a counter electrode disposed opposite to the metal sample, and light emission for each spark discharge is spectroscopically analyzed. Then, in the emission spectroscopic analysis method for quantifying the elements in the metal sample, the metal sample is mounted on a protrusion provided on the sample support and spark discharge is performed.   The protrusion is provided in an annular shape so as to surround the opening of the sample support, and has a height of 0.5 mm or more and a width of a surface on which the metal sample is mounted is 0.5 mm or more and 3 mm or less. The emission spectroscopic analysis method according to claim 1, wherein   The emission spectroscopic analysis method according to claim 1 or 2, wherein a distance between the metal sample and the counter electrode is 1 mm or more and 3 mm or less.   The emission spectroscopic analysis method according to claim 1 or 2, wherein a spark discharge region in the metal sample has a diameter of 4 mm or less.   A number of spark discharges are generated in an inert gas atmosphere between a metal sample mounted on the sample support base so as to cover the opening of the sample support base and a counter electrode disposed opposite to the metal sample. In the emission spectroscopic analyzer that quantifies the element in the metal sample by analyzing the light emission of each spark discharge, the sample support is provided with an annular protrusion surrounding the opening, An emission spectroscopic analyzer characterized in that a sample is attached to a sample support in contact with a tip portion of the protrusion.   The emission spectroscopic analyzer according to claim 3, wherein the protrusion has a height of 0.5 mm or more and a width of a surface in contact with the metal sample is 0.5 mm or more and 3 mm or less.   The emission spectroscopic analyzer according to claim 5 or 6, wherein a distance between the metal sample and the counter electrode is 1 mm or more and 3 mm or less.

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