JPH10281995A - Method and device for emission spectroscopic analysis - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain highly accurate analysis of an element such as oxygen liable to segregate in metal by using a metallic sample having a size capable of emitting from the whole area with one discharge. SOLUTION: An emission spectroscopic analyzer, which analyzes oxygen or the like in metal, is provided with a sample retainer 12 for supporting a rod-shaped metallic sample 1, and an electrode 2 which is fitted at a position facing the sample 1 and discharged in a space to the sample 1. The sample retainer 12 is a device for placing a plate-shape member 14 formed with a through hole 13 whose diameter is nearly equal to that of the sample 1. The through hole 13 is formed with a seal material such as a heat resisting rubber O ring for locking the sample 1 and maintaining inert atmosphere of the discharging part. Analyzed result indicates segregation in the sample 1 as one concern, therefore, the diameter of the sample 1 should be 7 mm or less which is the diameter of an ordinary discharging cross section from the electrode 2. A plurality of samples 1 are formed so as to be set at the sample electrode 12 simultaneously for sequential analysis by rotation or linear movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emission spectroscopy method and apparatus, and more particularly to a technique for accurately analyzing an oxygen element present in a metal sample.

[0002]

2. Description of the Related Art At present, for the purpose of elemental analysis in a metal sample, an emission spectrometer, particularly a spark discharge type described later, is often used. By the way, in this emission spectroscopic analysis method, usually, a so-called bomb sample obtained by cutting a metal in a molten state at a manufacturing site with a ladle, or a sample obtained by cutting a steel material into a circular cross section is used. Further, at the time of analysis, the surface is polished in advance and then set on the sample holding unit 10 shown in FIG.

[0003] However, the bomb sample often has a diameter of 20 mm or more, the cooling rate differs in the radial direction, and a concentration distribution (segregation) of component elements occurs.
This segregation is particularly significant for gas-forming elements such as oxygen. When a sample having such segregation is analyzed, a general emission spectrometer has a discharge area of about 7 mm, so that an analysis value differs depending on a discharge position, resulting in an analysis error. Therefore, the analysis of oxygen is often performed by a more traditional combustion method than the emission spectroscopy. Even a sample having segregation may be discharged over the entire area. However, the current emission spectrometer does not have a structure capable of performing the discharge, and improvement is eagerly desired.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for a spark discharge type emission spectroscopy capable of accurately analyzing even an element which is easily segregated in a sample.

[0005]

Means for Solving the Problems In order to achieve the above object, the inventor reviewed the drawbacks of the conventional analysis method and conceived of reducing the sample diameter. The present inventors have also conceived of setting a plurality of the small-diameter samples in the sample holding portion and sequentially discharging the small-diameter samples. That is, according to the present invention, in a case where a metal sample is subjected to a spark discharge treatment with a counter electrode in an inert gas atmosphere, and the element contained in the metal sample is subjected to emission spectroscopy once based on the obtained spectral lines, An emission spectroscopic analysis method characterized in that analysis is performed using a metal sample having a size capable of emitting light from the entire area by the discharge of the sample.

[0006] The present invention is also an emission spectroscopic analysis method, wherein the element is oxygen. Further, the present invention, the metal sample and the electrode facing each other in an inert atmosphere,
Performing a number of spark discharges between them, an emission spectrometer for analyzing the elements contained in the metal sample by dispersing light from the plasma generated by the discharge, at a position facing the electrode, An emission spectrometer comprising a sample holder for erecting a metal sample.

[0007] In addition, the present invention is characterized in that it comprises a sample holder for arranging a plurality of the metal samples so as to be spaced apart from each other and sequentially moving them to a position facing the electrodes.
The sample holder is a disk that is rotatable about an axis, and a plurality of through holes that stand vertically apart from the metal sample in the circumferential direction, and a gap between the through hole and the metal sample is made airtight. An emission spectrometer that is used as a sealing material.

In addition, the present invention is also an emission spectrometer characterized in that the metal sample is formed as a rod having a diameter of 7 mm or less. In the present invention, since the emission spectroscopy of a metal sample is performed with the above-described configuration, it is possible to accurately analyze even an element that is easily segregated in the sample. In particular, the present invention is effective for spectroscopic analysis of oxygen in a metal sample.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, an emission spectrometer will be described with reference to FIG. It is the metal sample 1 to be analyzed.
There is a sample holding unit 10 for supporting the sample (hereinafter, referred to as a sample) and an electrode 2 provided at a position facing the sample 1 and discharging between the sample 1 and the sample. When a discharge plasma 3 is generated from the sample 1 by the discharge, a condensing lens 5 for collecting light 4 from the plasma 3 is arranged, and a spectroscope for dispersing the condensed light through an entrance slit 7. 6 are connected. The spectroscope 6 converts the light condensed by the built-in diffraction grating 8 into a spectrum unique to each element, and measures the spectrum intensity with a photodetector 9. The measured spectrum intensity data is transferred to the computer 11 placed separately in an operation room or the like, where the element concentration is calculated and displayed.

[0010] In such an emission spectrometer, the present invention provides:
The sample holder 10 was modified. That is, the metal sample 1 having a size capable of emitting light from the entire area by one discharge can be used. Usually, the discharge between the electrode 2 and the sample 1 has a circular cross section with a diameter of about 7 mm. Therefore, the sample 1 is a rod-shaped body having the cross-sectional area. If the thickness is 7 mm or more, segregation becomes a problem in the analysis result. And
A sample holder 12 for fixing and supporting the sample 1 has been devised.

As shown in FIG. 1, a plate-like member 14 having a through hole 13 having a diameter substantially equal to the diameter of the sample 1 is provided.
This is mounted on the hole 15 of the sample holding unit 10. The rod-shaped sample 1 is inserted into the through hole 13.
If the airtightness is not maintained when inserting the air,
The inert atmosphere of the sample holder 10 cannot be maintained. For this purpose, the through hole 13 of the holder 12 is provided with a sealing material 16 which also serves to lock the sample 1. As the sealing material 16, for example, an O-ring made of heat-resistant rubber is suitable.

Further, according to the present invention, the sample holder 12 can set a plurality of samples 1 at the same time. Specifically, as shown in the plan view of FIG. 3, a plurality of through holes 13 are provided, each of which is a disk that is rotatable around a shaft 18, and that stands apart from the metal sample 1 in the circumferential direction. A seal member 16 for sealing the gap between the through hole 13 and the metal sample 1 is provided. In this way, the sample is sequentially opposed to the electrode without breaking the inert atmosphere of the sample holding unit 10,
Analysis becomes possible. That is, the analysis value was easily obtained as an average value of the values from the plurality of samples. In the present invention, the sample holder 12 does not need to be limited to the disk 17 but may be of a linear movement type or of various types. The number of through holes 13 may be arbitrarily selected in accordance with the number required for analysis.

[0013]

EXAMPLE A sample for analysis was pumped from molten steel at substantially the same position in a converter during refining, and the diameter was 6 mm and 20 m.
m carbon steel sample. A sample whose diameter is 6 mm is 8
After the surface was polished, four of them were set on the disk-shaped holder 12 and placed on the sample holder 10 shown in FIG. Then, a vacuum pump (not shown) was operated to evacuate the inside of the decompression chamber (not shown), and then argon gas was introduced to maintain the sample holder 10 at a constant pressure. Then, discharge was performed between the first sample 1 and the electrode 2, and oxygen analysis was performed. Next, the sample holder 12 was rotated by 90 ° about the axis 18, the second sample 1 was moved to a position facing the electrode 2, and discharge and analysis were performed. By repeating this operation, oxygen analysis of Sample 1 was performed.

On the other hand, the remaining four tubes having a diameter of 6 mm were analyzed by the conventional combustion method, and the sample having a diameter of 20 mm was analyzed by the emission spectroscopy at four locations in the same plane of the sample. Table 1 shows the results of each analysis. From Table 1, the results obtained by the emission spectroscopy according to the present invention were almost the same as those obtained by the conventional combustion method. On the other hand, 20mm
The value of the sample was different from the value of the combustion method, and the variation was large.

[0015]

[Table 1]

[0016]

As described above, according to the present invention, a metal sample can be analyzed with high accuracy by reducing the diameter of a sample used in an emission spectrometer to a smaller diameter than in the prior art. In addition, since a plurality of samples can be analyzed in one set, not only the reliability of the analysis value is improved, but also an effect can be expected for rapid analysis.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a sample holder used in an emission spectrometer according to the present invention.

FIG. 2 is a longitudinal sectional view showing a spark type emission spectrometer.

FIG. 3 is a plan view showing a sample holder which can analyze a plurality of samples in one set.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sample (metal sample) 2 Electrode 3 Discharge plasma (plasma) 4 Light 5 Condensing lens 6 Spectroscope 7 Incident slit 8 Diffraction grating 9 Photodetector 10 Sample holder 11 Computer 12 Sample holder 13 Through hole 14 Plate member 15 hole 16 sealing material 17 disk 18 axis

Claims (6)

[Claims] In an inert gas atmosphere, a metal sample is subjected to a spark discharge treatment with a counter electrode, and the emission spectrum analysis of elements contained in the metal sample is performed once based on the obtained spectral lines. An emission spectroscopic analysis method characterized in that analysis is performed using a metal sample having a size capable of emitting light from all areas by discharge. 2. The method according to claim 1, wherein the element is oxygen. 3. A metal sample and an electrode are opposed to each other in an inert atmosphere, a number of spark discharges are performed between the metal sample and the electrode, and light from plasma generated by the discharge is dispersed to separate the elements contained in the metal sample. An emission spectroscopy apparatus for analyzing a light emission spectrum, comprising: a sample holder for erecting a metal sample at a position facing the electrode. 4. A plurality of metal samples are erected at a distance from each other,
4. An emission spectrometer according to claim 3, further comprising a sample holder for sequentially moving them to a position facing said electrodes. 5. The sample holder is a disk that is rotatable about an axis, a plurality of through-holes that stand vertically apart from the metal sample in the circumferential direction, and a plurality of through-holes for the metal sample. 5. A sealing material for airtightly sealing a gap.
An emission spectrometer according to the above. 6. The emission spectrometer according to claim 3, wherein the metal sample is a rod having a diameter of 7 mm or less.