JP3434645B2 - Desorption metal measuring device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a desorbed metal measuring device for analyzing a metal element desorbed from a sample during heating. 2. Description of the Related Art When used at high temperatures, materials used in various fields usually release metal elements contained as impurities in the materials. For example, a material used for a heating furnace is used at a temperature of about 1000 ° C. or higher, and metal impurities are desorbed from the material according to the heating temperature and the heating atmosphere. The desorbed impurities are heated in the furnace. The problem that it mixes with the sample which arises arises. Therefore, when selecting a material to be used for a heating furnace or the like, the amount of desorbed metal depending on the environment and temperature of the material is grasped in advance, and when the material is used for the heating furnace, there is no influence on the sample. You need to choose how to use it. As a method for examining the amount of metal desorbed depending on the use temperature, a thermal desorption gas analysis method is known. In this method, a sample to be measured is heated to an arbitrary temperature while maintaining a high vacuum in the closed vessel, and the amount of metal released when heated is measured. However, this method has a problem that the amount of desorbed metal depending on the environment of the sample to be measured cannot be measured because the inside of the closed vessel is kept at a high vacuum. That is, a heating furnace or the like can be used in various environments such as an oxygen atmosphere and an Ar atmosphere depending on the material of the sample to be measured. However, for example, when heating in a vacuum and when heating in an oxygen atmosphere, the amount of metal desorbed is different even when the same sample is heated to the same temperature. Cannot determine the amount of metal desorption that depends on the temperature of the material. As described above, in the conventional thermal desorption gas analysis method, the sample to be measured is heated to an arbitrary temperature and the amount of the desorbed metal at that time is measured. However, there is a problem that it is not possible to grasp a change in the amount of desorbed impurities due to the heating atmosphere. The present invention has been made in view of such a problem, and provides a method for measuring a desorbed metal capable of measuring not only a heating temperature but also a metal impurity amount desorbed from a solid sample due to a difference in a heating atmosphere. The purpose is to: Means for Solving the Problems A container on which a sample containing a metal impurity composed of at least one of ceramic, glass and platinum group metals can be placed, and a gas introduction for introducing a desired gas into the container Means, a heating means for heating the sample so as to desorb the metal element contained in the sample, and a detection means for detecting the metal element desorbed from the sample. measuring device. A container according to the present invention is a container in which a solid sample to be measured is placed. The container is a ceramic such as quartz or silicon carbide, glass or platinum, ruthenium, rhodium, palladium, or the like. Any material using a platinum group metal such as osmium or iridium can be used without any particular limitation. These materials hardly react with gases used as carrier gases such as oxygen, hydrogen, nitrogen, and Ar, and can maintain their strength even under heating at 1000 ° C. or more. Further, in order to efficiently measure the metal element generated inside the container to the detecting means described later, the container is desirably a closed system. For example, inner diameter 2-10m
In this case, both ends of the tube are connected to a detecting means and a carrier gas introducing means described later. Further, a tube in which the inner wall surface of a tube such as graphite is coated with ceramic, glass, or a high melting point metal can also be used. The heating means according to the present invention can be used without particular limitation as long as it can heat the solid sample. Although a heater or the like may be provided inside the container, impurities may be mixed into the carrier gas from the heater. Therefore, a heater is provided outside the container, and the solid sample placed inside the container is heated by heating the container, or when the container is not an insulating material such as metal, a current is applied to the container, Heating means can be used by using the heat generated at this time. [0010] The carrier gas introduction means according to the present invention is for making the inside of the closed vessel a desired atmosphere. The measurement atmosphere is determined by the carrier gas. Therefore,
Oxygen may be used as a carrier gas when it is desired to measure the desorption amount of the impurity metal when the sample is heated in an oxygen atmosphere, and Ar gas when it is desired to measure the desorption amount of the impurity metal when heated in an Ar atmosphere. May be used as a carrier gas. As described above, a desired gas can be used as the carrier gas. By connecting a gas cylinder filled with such a gas to the container via a valve, a carrier gas introducing means can be provided. The detecting means according to the present invention is not particularly limited as long as it can measure the amount of metal impurities in the closed vessel. For example, atomic absorption spectrometry, ICP (inductively coupled plasma) mass spectrometry, ICP emission spectroscopy, and the like can be used. However, when oxygen gas is used as the carrier gas, the plasma may be unstable. Also, I
When using a CP to measure the amount of metal impurities in an Ar gas atmosphere, it is desirable to add a small amount of hydrogen to Ar gas, which is a carrier gas, in order to increase analysis sensitivity. FIG. 1 is a schematic view of a desorption metal measuring apparatus according to the present invention. Hereinafter, the present invention will be described with reference to the drawings. In FIG. 1, a solid sample 3 is placed in a cylindrical closed container 9. The closed container 9 is not particularly limited as long as it can accommodate the solid sample 3. Considering that the metal impurities detached from the solid sample are smoothly discharged to the detecting means or the outside of the closed container, it is desired that the inner diameter of the closed container is at least three times larger than the diameter of the sample. ~
A 50 mm ³ container is used. In FIG. 1, a sealed container 9 is inserted into a graphite tube 4 connected to a DC power supply. The graphite tube 4 is a heating means, and generates heat when a direct current is applied. In order to heat the sample 3 uniformly and efficiently, for example, as shown in the figure, it is desirable to install a graphite tube 4 so as to heat a wider area than the position where the solid sample 3 is arranged. Further, by using a heating means capable of adjusting the heating temperature, the amount of impurities desorbed due to a change in temperature can be measured. When the graphite tube 4 described above is used as the heating means, the temperature can be adjusted by changing the current value applied to the graphite. The heating at this time is usually performed with a solid sample of 800 to
What can be heated to about 2000 degreeC is used. The supply of the carrier gas into the closed container is performed by a carrier gas generating means. Specifically, a gas cylinder 5 containing a desired carrier gas may be used. Further, the carrier gas may be supplied intermittently,
It may be supplied continuously. In the case of intermittent supply, a carrier gas may be introduced into the closed vessel and the sample in the closed vessel may be heated to a desired temperature. It is desirable to shorten the heating time to a desired temperature in order to prevent the desorbed metal from adsorbing on the inner wall surface of the closed vessel, and it is desirable to heat at a heating rate of 20 ° C./sec or more. Further, in the temperature range to be measured, the desorbed metal may be desorbed by setting the heating rate to 10 ° C./sec or less, or maintaining the temperature at a desired temperature for 10 seconds or more. Keeping time is 10 seconds or less, and heating rate is 10 ° C
If it is longer than / sec, there is a possibility that the desorbed metal may not be sufficiently desorbed to the extent that it can be measured. In addition, although it varies slightly depending on the shape of the sample, the desired temperature is maintained for about one hour,
Preferably, the desorbed metal is measured. After desorbing the desorbed metal in this manner, the carrier gas in the closed vessel may be transported to the detection means, and the amount of desorbed metal in the carrier gas may be measured. When continuously introducing a carrier gas,
What is necessary is just to install a carrier gas discharge pipe connected to the closed container and set the introduction amount of the carrier gas to about 10 to 50 ml / sec. If the amount is too large, the desorbed metal may be diluted and the analytical sensitivity may be lowered. If the amount is too small, a desired atmosphere cannot be maintained. In this case, the heating of the sample is started by the heating means after the introduction of the carrier gas, and the desorbed metal contained in the carrier gas after the sample reaches a desired temperature is detected. As the means 7 for detecting the desorbed metal, those described above can be used. Specifically, for example, in atomic absorption spectrometry, light of a specific wavelength may be transmitted through the atomic vapor of the desorbed metal element, and quantification may be performed based on the absorbance. In the ICP emission spectroscopy, the desorbed metal element may be introduced into the ICP by the carrier gas, emitted light, and quantified from the emission intensity. In ICP mass spectrometry, a metal element may be similarly introduced into ICP, ionized, and quantified from the ion count. Depending on the type of the detecting means, the desorbed metal can be detected without transporting the carrier gas to the detecting means. For example, FIG. 2 shows an apparatus for measuring desorbed metals when atomic absorption spectrometry is used as a detecting means. In this case, the amount of desorbed metals in a closed container can be measured. In FIG. 1, a light source 1 emits a light beam having an absorption wavelength of an element to be measured among desorbed metals. This light beam is provided so that the optical axis passes through the carrier gas in the closed container. Atomic absorption can be detected by dispersing the light beam that has passed through the carrier gas using a spectroscope, so the carrier gas is detected. The operation of transporting to a container becomes unnecessary. In this case, it is necessary to form a window 13 made of a material that transmits light of a predetermined wavelength using quartz glass or the like in a portion of the sealed container through which light passes. Example 1 In this example, an apparatus for measuring desorbed metals using atomic absorption spectrometry as shown in FIG. 2 was used. The measuring device for the desorbed metal will be specifically described. A light source emitting a light beam having a wavelength of 324.8 nm by discharging copper was installed. A sealed vessel was obtained by providing a quartz tube having an inner diameter of 5 mm, a thickness of 1 mm, and a length of 27 mm, and quartz covers at both ends of the quartz tube. The quartz tube is washed with hydrochloric acid, nitric acid, sulfuric acid, dilute hydrofluoric acid or a mixed acid thereof, and further heated to 1200 ° C. or more, which is the maximum heating temperature in this embodiment, to heat the sample. At this time, a material in which desorption of the impurity metal from the quartz tube was prevented in advance was used. The outer diameter of the quartz tube is 6 mm in inner diameter and 25 mm in length.
A graphite tube of 1 mm was installed, and a variable DC power supply was connected to the tube to use as a heating means. Further, holes for introducing and discharging a carrier gas were provided at both ends of the quartz tube, respectively, and one of the holes was connected to a gas cylinder serving as a carrier gas generating means. Further, a gas cylinder filled with an argon gas as a carrier gas was used. The quartz tube and the light source are arranged such that the axis of the quartz tube coincides with the axis of the light beam emitted from the light source.
A detector comprising a spectroscope and a detector was arranged on the opposite side of the light source across the quartz tube. Using this apparatus, the desorption of metal was measured as follows. As a measurement sample, diameter 1mm, length 1c
Four m-th Kanthal wires were placed in the center of the quartz tube. Next, an argon gas was introduced into the quartz tube at a flow rate of 50 ml / min from the gas cylinder, a direct current was applied to the graphite to heat the measurement sample, and the temperature was raised to 1000 ° C. in 50 seconds, and thereafter for 20 seconds. The temperature was raised to 1100 ° C. and maintained for 20 seconds, and further raised to 1200 ° C. over 20 seconds. The change in the intensity of atomic absorption observed by the detection means at this time is shown by a solid line in FIG. Example 2 Next, the detection means was used in exactly the same manner as in Example 1 except that the measurement sample was not placed in the quartz tube and was left empty (state in which no desorbed metal was generated). The change in the intensity of the observed atomic absorption is shown by a broken line in FIG. From the broken line in FIG. 3, it can be seen that no desorbed metal is generated from the closed vessel, and it can be confirmed that the change in the atomic absorption in the example is a change due to the desorbed metal only from the measurement sample. Further, in this embodiment, it is possible to measure the amount of metal desorbed from the measurement sample between 900 ° C. and 1200 ° C. or higher. Example 3 In this example, an apparatus for measuring desorbed metals using ICP mass spectrometry as shown in FIG. 1 was used. The apparatus for measuring the desorbed metal will be specifically described. A platinum tube having the same shape as the quartz tube of Example 1 was used, a gas cylinder for introducing pure oxygen as a carrier gas was connected to the opening at one end of the platinum tube, and the other end was subjected to ICP mass spectrometry. Connected to the device. This platinum tube was also subjected to the same pretreatment (heat treatment and acid treatment) as in Example 1. Further, as a heating means, a graphite tube and a DC power supply were installed in the same manner as in Example 1. Examples were carried out using this mass spectrometer as follows. In a state where the inside of the closed vessel is empty (a state in which no desorbed metal is generated), 50 ml of pure oxygen is supplied from a gas cylinder.
/ Min at a flow rate of / min. Next, a direct current was applied to the graphite tube, and the temperature of the sealed container was raised from room temperature to 1000 ° C. for 50 seconds. Plus 900
The temperature was raised from 2.5 ° C to 1200 ° C at a rate of 2.5 ° C / sec. In this way, pure oxygen is introduced into the ICP mass spectrometer, and the amount of copper contained in the pure oxygen is
The measurement was carried out with a P mass spectrometer by measuring an ion count having a mass number of 63. FIG. 4 shows the result at this time. In FIG. 4, the measured value is constant, and it can be seen that when Cu is desorbed, the desorption amount can be detected. Comparative Example A comparative example was performed in exactly the same manner as in Example 3 except that a platinum tube was not used as a closed container, and a graphite tube as a heating means was also used as a closed container. . FIG. 5 shows the result. In FIG. 5, the background increases due to the smoke generated by the combustion of graphite, and it is impossible to measure the desorbed metal impurities. On the other hand, when a platinum tube is inserted, it is possible to measure a small amount of Cu desorbed from the solid sample without generating smoke and increasing the background. According to the present invention, since the atmosphere of the solid sample can be controlled to an arbitrary atmosphere such as oxidizing or reducing at high temperatures, a small amount of metal desorbed from the solid sample when the temperature is increased. It is possible to provide an apparatus and a method for measuring an element and evaluating a metal desorption characteristic of a material at a high temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing an example of a desorbed metal measuring device of the present invention. FIG. 2 is a schematic view showing another example of the desorbed metal measuring device of the present invention. FIG. 3 is a graph showing the relationship between the sample temperature and the absorbance of a carrier gas in Examples 1 and 2. FIG. 4 is a graph showing a relationship between a sample temperature and an absorbance of a carrier gas in Example 3. FIG. 5 is a graph showing a relationship between a sample temperature and an absorbance of a carrier gas in a comparative example. [Description of Signs] 1 ... Light source 3 ... Solid sample 4 ... Tube made of graphite 5 ... Gas cylinder 7 ... Detection means 9 ... Closed container 13 ... Window

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-267327 (JP, A) JP-A-6-300748 (JP, A) JP-A-8-248020 (JP, A) JP-A-9-208 145707 (JP, A) JP-A-9-264824 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 31/00 G01N 1/28

Claims (1)

(57) Claims: 1. A container on which a sample containing a metal impurity composed of at least one of ceramic, glass, and platinum group metals can be placed, and a desired gas is introduced into the container. Gas introducing means, heating means for heating the sample so as to desorb the metal element contained in the sample, and detecting means for detecting the metal element desorbed from the sample. Desorption metal measuring device.