JP2002168741A - Pretreatment method and apparatus for sample for analysis of trace components in metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment method for a sample for analysis of a trace component in a metal which can analyze a trace component in a metal more easily and more quickly than in the past and which can analyze with high accuracy. Provide equipment. SOLUTION: An analysis sample is exposed to an atmosphere of 10 Pa or less to remove surface contamination.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pretreatment of a sample for analyzing a trace component in a metal to prevent the occurrence of an analysis error by pretreating an analysis sample in analyzing a component in a metal, in particular, in analyzing a trace element. The present invention relates to a method and a pretreatment device for a sample for analyzing a trace component in a metal.

[0002]

2. Description of the Related Art Trace elements in metals, for example, nitrogen, carbon,
It is well known that hydrogen affects material properties such as ductility and workability, but in recent years, with the purifying of materials,
It is required to analyze these elements with extremely high accuracy. In such a high-precision analysis, the contamination of the surface of the analysis sample greatly affects the analysis result. For example,
In the analysis of nitrogen in steel, adsorption of atmospheric nitrogen and nitrogen oxides, in the analysis of carbon in steel, the adsorption of organic substances and carbon dioxide gas, and in the analysis of hydrogen in steel, the influence of adsorption of moisture and organic substances is large, causing errors. Become.

[0003] Therefore, it is extremely important to remove the surface contamination of the analysis sample prior to the analysis, and an electrolytic polishing method or a chemical dissolution method is used as a means for that. In addition, JP-A-8-211043, JP-A-10-73586 and JP-A-11-316220 disclose that, when quantifying trace components in a metal, a sample is subjected to gas analysis in an inert gas atmosphere analysis pretreatment chamber. A pretreatment method and apparatus for performing sputtering to remove a contaminated portion on a sample surface and immediately transfer the sample to an analysis reaction chamber are disclosed.

[0004]

By using these means, the contamination on the sample surface can be removed in advance, and the sample can be transferred to the analysis reaction chamber without re-contamination. However, in order to perform the inert gas sputtering, it is necessary to perform a complicated operation of sputtering the sample while keeping the sample at a certain polarity, for example, an anode, and an apparatus for the sputtering is also expensive, so that simple and quick accurate analysis can be performed. There was a need for a means to do it. The present invention has been made to solve such a problem, and it is possible to analyze a trace component in a metal more easily and quickly than in the past, and furthermore, to analyze a trace component in a metal with high accuracy. An object of the present invention is to provide a pretreatment method and apparatus for a sample for analysis.

[0005]

SUMMARY OF THE INVENTION According to the present invention, when an analysis sample is exposed to a reduced pressure, gas components adsorbed on the sample surface are easily removed, thereby causing an analysis error of trace elements in the metal. Has been resolved.

Specifically, the pretreatment method for a sample for analyzing a trace component in a metal according to the present invention removes surface contamination by exposing the sample to an atmosphere of 10 Pa or less.

The present invention is effective when applied to a metal in which the trace component in the metal is nitrogen, hydrogen or carbon. In applying the present invention, the analysis sample is previously washed with an organic solvent or chemically polished. It is preferable to remove surface deposits by polishing by a treatment or an electrochemical polishing treatment.

A pretreatment apparatus for a sample for analyzing a trace component in a metal for carrying out the method of the present invention comprises: a pretreatment chamber main body for applying a pressure of 10 Pa or less to an analysis sample; It is preferable that a sample introduction means for introducing a sample, a sample holding means for holding a sample in the main body of the pretreatment chamber, and a sample transport means for introducing the processed sample into a reaction chamber of the analyzer are additionally provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION In the pretreatment method of a sample for analyzing a trace component in a metal according to the present invention, an analysis sample is exposed to an atmosphere of 10 Pa or less. FIG. 1 shows C: 0.003%, Si: 0.01%,
After exposing a mild steel sample containing Mn: 0.01% and N: 14ppm to atmospheres of various pressures for 1 minute, immediately transfer it to the reaction chamber of the analyzer and analyze the N component by the inert gas melting method. FIG. 4 is a diagram showing the relationship between pressure and N analysis values. The analytical sample was prepared by dissolving in a laboratory by a vacuum melting method, cutting out to a mass of about 1 g with a diamond cutter after casting, and washing with an organic solvent.

As shown in FIG. 1, when the atmospheric pressure in the pretreatment chamber becomes 10 ¹ Pa (10 Pa) or less, the nitrogen analysis value stably shows 14 ppm. However, when the atmospheric pressure was higher than that, the analysis value was higher by 0.5 to 1 ppm, indicating that the influence of the contamination by the N ₂ gas adsorbed on the sample surface appeared.

By repeating such an experiment, the sample is exposed to a reduced-pressure atmosphere having a pressure of 10 Pa or less.
It was clarified that the gas substance adsorbed on the sample surface was removed and the analysis error was eliminated. By such processing, typical gas components that eliminate analysis errors include:
Examples of nitrogen include N ₂ , hydrogen include H ₂ O (steam), and carbon include hydrocarbon solvents such as organic solvents. However, the present invention is not restricted to these components and can be applied to the removal of all gas components that are adsorbed on the surface and cause analysis errors. When the content of the element to be analyzed in the sample is several ppm, it is preferable to further reduce the influence of the gas component adsorbed on the sample surface. In such a case, the reduced pressure atmosphere is preferably set to 10 ⁻⁶ Pa or less.

By exposing the analysis sample to the reduced-pressure atmosphere in this manner, the influence of the adsorbed gas on the surface of the analysis sample can be removed. However, it is necessary to pay attention to the conditions other than the pressure as follows. is there. First, the exposure time is preferably kept at least 30 seconds. In addition, the shape of the sample is desirably as small as possible in surface area in order to minimize the influence of contamination. In addition, it is necessary to transfer the processed sample directly to the reaction chamber of the analytical instrument without exposing it to, for example, air or other polluting gases.

It is preferable that the surface of the sample is removed from the surface of the sample by an organic solvent washing, a chemical polishing or an electrochemical polishing before the exposure to the reduced pressure atmosphere. This is because contaminants such as abrasives cannot be removed only by reduced pressure. This processing enables more accurate analysis.

As described above, it is preferable to use an apparatus as shown in FIG. 2 when exposing the analysis sample to a reduced pressure atmosphere. In this example, a pretreatment device for a sample for analyzing a trace component in a metal according to the present invention is installed above a reaction chamber of the device for analyzing a component in a metal.

The pretreatment apparatus includes a pretreatment chamber main body 4 for applying a pressure of 10 Pa or less to an analysis sample, a sample introducing means 18 for introducing the analysis sample 2 into the pretreatment chamber main body 4, and a preprocessed analysis sample 2 And sample transport means 22 for introducing the sample into the reaction chamber 16 of the analyzer main body.

In the main body 4 of the pretreatment chamber, an analysis sample 2 is provided.
An analytical sample holder having a sharp tip is provided as a sample holding means 20 for supporting the analytical sample 2, so that the analytical sample 2 can be supported by an extremely small supporting area.
Thereby, contamination on the surface of the analysis sample 2 can be removed without being hindered by the sample holder.

Further, in the case of FIG. 2, the helium gas is supplied from the helium gas source 6 to the pretreatment chamber main body 4 so as to supply the helium gas. This piping is also provided to the reaction chamber 16 of the main body of the analyzer, so that the helium gas can be supplied to both the pretreatment chamber main body 4 and the reaction chamber 16 by switching the valve 8.

The type of gas used for the pretreatment chamber main body 4 and the reaction chamber 16 may be determined depending on the type of the element to be analyzed and the like, and may be replaced with another gas, for example, argon gas. Further, a pipe that can supply gas to both the pretreatment chamber 4 and the reaction chamber 16 using the valve 8 is not essential. That is, a dedicated gas source and piping may be provided in each of the pretreatment chamber 4 and the reaction chamber 16.

The pretreatment device for a sample for analyzing a trace component in a metal configured as described above operates as follows.
First, the sample 2 is inserted into the pretreatment chamber main body 4 from the sample introduction means 18 at the upper part of the pretreatment chamber main body 4, and after being fixed by the holding means 20, the sample introduction means 18 is closed airtightly and the exhaust pump 10 is operated. To reduce the pressure inside the pretreatment chamber main body 4.

After reducing the pressure to a predetermined pressure for a predetermined time, a gas (helium gas in this case) similar to the atmosphere of the reaction chamber 16 of the analyzer main body is introduced from the gas source 6 into the pre-processing chamber 4 via the valve 8. . Subsequently, the analysis sample 2 is directly moved from the main body 4 of the pretreatment chamber to the reaction chamber 16 without being exposed to the atmosphere by the sample transport means 22. More specifically, the sample transfer means 22 is constituted by a slide valve, which is released, the holding means 20 is loosened, and the analysis sample 2 is transferred to the pretreatment chamber main body 4.
From the reaction chamber 16.

Thus, the metal analysis sample is transferred to the reaction chamber of the analyzer main body without re-contamination with the adsorbed gas on the surface removed, and a predetermined component analysis is performed there. The component analyzer main body is not particularly limited, and may be any device that can analyze a trace element in a metal.

For example, as shown in FIG. 2, a reaction chamber 14 containing a graphite crucible 14 and a graphite crucible 14
A helium gas source for introducing a carrier gas into the reaction chamber 16 and a helium gas source for introducing a carrier gas into the reaction chamber 16, and a thermal conductivity detection device for receiving and analyzing the analysis component gas together with the carrier gas from the reaction chamber 16 can be used. .

As described above, the configuration of the main body of the component analyzer is not limited to the above example, and the configuration of the main body varies depending on the target component or element to be analyzed. For example, when analyzing carbon in steel, a graphite crucible cannot be used, so an alumina crucible was installed instead, oxygen was used as the carrier gas, the high-frequency induction heating power supply was used as the heating power supply, and the infrared radiation was used as the detector. It becomes an absorption device.
The carrier gas and the analysis component detection device can be appropriately changed depending on the analysis target component.

[0024]

EXAMPLES Tables 1 to 3 show the results of analyzing nitrogen, carbon and hydrogen in steel by pretreating a metal analysis sample using the method of the present invention and inert gas sputtering. Here, the conventional method is a case where the analysis sample is not exposed to a reduced pressure state, or a preliminary treatment by inert gas sputtering is not performed. The analysis sample was prepared in the same manner as in the experiment shown in FIG.
30 s was set to ^-1 Pa. For samples A, B, D, E, G, H, 1
30 sec at 0 ^-1 Pa, and 30 sec at 10 ^-6 Pa for samples C, F, and I.

The test results are shown in Tables 1 to 3. As can be seen from these tables, in the case of the conventional method, the analysis values are clearly higher than those of the present invention and the inert gas sputtering method. On the other hand, in the case of the present invention, an analysis value equivalent to that obtained when the contaminated portion was removed by inert gas sputtering was obtained. On the other hand, when the pretreatment was performed according to the present invention, the time was shortened by about 20 min per measurement as compared with the case where the inert gas sputtering was used. That is, in the case of the present invention, it can be seen that the gas component adsorbed on the sample surface can be completely removed and the analysis time including the contamination removal of the sample surface can be greatly reduced.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

[Table 3]

[0029]

According to the present invention, it is possible to easily and reliably remove surface adsorbed substances without using a special apparatus such as an inert gas sputtering method when analyzing trace elements in metals. High-precision analysis of trace elements can be performed easily and quickly.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between an atmospheric pressure of a pretreatment chamber and an N analysis value when an N component is analyzed by an inert gas melting method.

FIG. 2 is a schematic sectional view showing a typical example of a pretreatment apparatus for a sample for analyzing a trace component in a metal according to the present invention.

[Explanation of symbols]

 2: Analytical sample 4: Pretreatment chamber body 6: Helium gas source 8, 12: Valve 10: Exhaust pump 14: Graphite crucible 16: Reaction chamber 18: Sample introduction means 20: Sample holding means 22: Sample transport means 30: Heating Power supply

 ──────────────────────────────────────────────────の Continued on the front page (71) Applicant 591121959 Japan Analyst Co., Ltd. 3-9-23 Nishigotanda, Shinagawa-ku, Tokyo (72) Inventor Hisao Yasuhara 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel (72) Inventor Makoto Shimura 1st Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Pref. 72) Inventor Hideo Iwai Inside ULVAC-PHI Co., Ltd. 370, Enzo, Chigasaki-shi, Kanagawa (72) Inventor Takashi Niida F-term in Japan Analyst Co., Ltd. 3-7-23 Nishigotanda, Shinagawa-ku, Tokyo (reference) 2G055 AA01 CA22 CA23 EA10

Claims (4)

[Claims] 1. A pretreatment method for a sample for analyzing a trace component in a metal, wherein the sample is exposed to an atmosphere of 10 Pa or less to remove surface contamination. 2. The method according to claim 1, wherein the trace component in the metal is nitrogen, hydrogen or carbon. 3. A trace amount of metal in a metal according to claim 1, wherein the analytical sample is one in which the surface deposits have been removed in advance by washing with an organic solvent, a chemical polishing treatment or an electrochemical polishing treatment. Pretreatment method for sample for component analysis. 4. A pre-processing chamber main body for applying a pressure of 10 Pa or less to an analysis sample, a sample introducing means for introducing an analysis sample into the pre-processing chamber main body, a sample holding means for holding a sample in the pre-processing chamber main body, And a sample transporting means for introducing the processed sample into a reaction chamber of the analyzer main body.