KR20030003501A - Method for preparing glass bead for X-Ray Flourescence - Google Patents

Abstract

PURPOSE: A method for manufacturing glass bead is provided to prevent cracking of furnace and obtain uniform specimen by preventing generation of defects at the specimen. CONSTITUTION: A method for manufacturing glass bead, comprises a first step of crushing an object specimen into powder; a second step of mixing the powder specimen with a flux and heating the mixture until the mixture reaches a semi-solid state; a third step of obtaining molten material by heating the specimen to the temperature higher than the specimen melting temperature; and a fourth step of injecting the molten specimen into a casting mold, and annealing the injected specimen in a heater having a temperature lower than the specimen melting temperature of the third step.

Description

Glass bead for fluorescence X-ray analysis {Method for preparing glass bead for X-Ray Flourescence}

The present invention relates to a method for preparing a sample for fluorescence X-ray analysis, and more particularly, to a method for producing glass beads for fluorescence X-ray analysis.

X-rays, which are short-wavelength electromagnetic waves generated by collision of high-speed electrons with a material, have been applied in various technical fields because of their unique properties.

For example, the diagnosis of various lesions and skeletal abnormalities in the medical field, the treatment of inflammation and tumors, and the nondestructive examination of materials and products in the industrial field have been a major application field since the discovery of X-rays. In particular, the use of nondestructive testing of industrial materials is a well-known application field of X-rays.

On the other hand, X-ray analysis of material structures, that is, X-ray analysis, provides a foundation for creating new materials while pioneering new facets in crystallography and solid physics. X-ray spectroscopy as a method of estimating the type and ratio of component elements in a substance from the wavelength distribution of characteristic X-rays, that is, fluorescent X-rays, which have a wavelength inherent to the elements in the substance which are emitted secondarily from the substance Also called X-Ray Flourescence.

Fluorescent X-rays are the result of X-rays in which electrons in atoms rise from a low energy level to a high energy level, and then return to their original low energy level through an intermediate energy level within a short time. The spectrum is used for elemental analysis (X-ray fluorescence analysis).

In order to perform such fluorescence X-ray spectroscopy, it is necessary to prepare a sample as a uniform mixture in solid state or a single compound in solid state in any fluorescence X-ray spectrometer. Has become a very important key factor in the speed and accuracy of the system.

Conventionally, two kinds of sample manufacturing methods used in the fluorescence X-ray spectroscopy have been introduced. One is pressurization molding, which is a method of pulverizing a sample and injecting it into a mold to sample.

The other is called glass bead (Glass Bead) method, which is a method of melting the pulverized sample is injected into the cast mold and cooled to sample.

Sample preparation methods used in the above-described fluorescence X-ray spectroscopy have advantages and disadvantages, but glass beads are frequently used. This is a factor that affects the analysis. The influence of the particle size of the analytical sample is present in the press molding using the powder state as it is, but the glass bead method that melts the analytical sample has no effect on the particle size. The effect of coexisting elements on the analytical elements in the sample mixture is known to be due to the high degree of pressure in the molding method but the small effect in the glass bead method.

This is also because the glass bead method does not have segregation (which causes some components in the sample mixture to aggregate and become nonuniform) in the prepared sample.

Therefore, the sample manufacturing method used for fluorescence X-ray spectroscopy is frequently used. As a device for melting a sample, a gas burner method, an electric furnace method, and a high frequency furnace method are used, and these pulverized sample melting apparatuses have advantages and disadvantages. This is summarized as follows.

Table 1

Melting method Melting time Advantages Disadvantages Gas burner method 20-30 minutes Low power consumption Room temperature rise during melting Electric furnace 20-30 minutes Easy maintenance Excessive power consumption High frequency furnace 4-10 minutes Short melting time Difficulty in repairing in case of breakdown

The high frequency furnace method is widely used because the melting time of the sample is short as 4 to 10 minutes, as shown above.However, when the flux and powder sample are put into a platinum crucible and the high frequency furnace is attached and melted, There is a problem that the powder flows into the apparatus, and in the crucible furnace, cracks in the crucible furnace have been frequently generated by sudden heating above the melting temperature of the sample to be analyzed.

In addition, the uniformity of each cross section of the sample when X-rays are irradiated is a large factor in the accuracy of analysis. Factors affecting the uniformity of the prepared sample include the mixing ratio of melt and sample, melting time and cooling of the melt. And the like, and defects such as crystallization, bubbles, and cracks of the prepared samples are directly related to the uniformity of the sample.

Accordingly, the present invention has been devised in view of the above-mentioned point, and an object of the present invention is to prevent the occurrence of defects such as crystallization, bubbles, cracks, etc. of the prepared sample, and thus to obtain a uniform sample. The present invention provides a method for producing glass beads.

The object of the present invention as described above is to prepare a sample for fluorescence X-ray analysis, the sample to be analyzed is preheated (melted) in a general electric furnace, etc. to a semi-solid state and then completely melted in a high-frequency furnace and below the melting point of the sample to be analyzed. It is achieved by slow cooling in a heating element of to obtain a solid state.

Specifically, the method for preparing a sample for fluorescence X-ray analysis of the present invention is a sample grinding step for powdering the sample to be analyzed: a mixture of the pulverized powder form sample with a flux is heated to prepare a semi-solid state Preheating step: A sample melting step of obtaining a melt above the sample melting temperature of the preheated sample: and after the molten sample is injected into the casting mold and characterized in that it is slowly cooled in a heating element below the melting temperature of the sample melting step It is done.

In the method of the present invention, the purpose of preheating a sample to be analyzed is to prevent the sample from being decomposed during rapid melt heating in a high frequency furnace, and to prevent the addition of the flux and the sample into a crucible (usually a platinum crucible) and to mount the high frequency furnace. When heating, the powder in the crucible flows into the inside of the instrument by high frequency oscillation at the initial stage, which makes it difficult to prepare the sample.The sample is preheated at a temperature lower than the melting temperature of the sample to prepare a semi-solid sample, and the flux is It melts in earnest in a high frequency furnace in the mixed state.

Since the preheating temperature is lower than the melting temperature of the sample to be analyzed, it is possible to use a general electric furnace.

The temperature setting in this preheating step depends on the sample to be analyzed. It should be heated above 980 ℃, but in general, it should be heated at about 980 ℃ for a proper time. But for most oxides When the preheating temperature exceeds 980 ° C, vaporization of the sample may be initiated. Therefore, the preheating temperature is preferably not to exceed 980 ° C.

In another aspect, the present invention is characterized in that the pre-heated semi-solid sample is melted in a high frequency furnace, and the molten sample is injected into a casting mold to be slowly cooled in a heating element below a melting temperature. In this way, a solid sample without bubbles, crystallization and cracking can be obtained.

On the other hand, the uniformity of the sample to be analyzed and the measurement accuracy of the analytical element prepared by adding a flux to lower the melting point during melting of the sample is closely related to the mixing ratio of the injected flux and the powder sample.

According to the experiment of the present inventors, it was confirmed that the mixing ratio of the sample powder and the flux is preferably 1:10 to 1:15. If the mixing ratio of sample powder and flux exceeds 1:15, the accuracy of analysis decreases due to overflowing from the crucible for high frequency furnace melting or excessive dilution by flux, whereas the mixing ratio of sample powder and flux is less than 1:10. If it is low, it does not melt or the size of the glass beads suitable for analysis in the casting mold is not produced.

According to the method of the present invention described above, the silicate minerals, the carbonate minerals, and the titanium minerals were pre-melted at 980 ° C. for 5 minutes in a general electric furnace to be semi-solid, and then the conditions of Table 2 in a high frequency electric furnace (trade name Mini Fuse manufactured by Philips). Melting was injected into a casting mold which is melted at 1,100 ° C. for 4 minutes and formed into beads in a small general electric furnace heated to 500 ° C., thereby slowly cooling the furnace while slowly lowering the furnace to prepare a complete glass bead.

The analytical sample prepared as described above was analyzed by a fluorescent X-ray analyzer (PW2400. Manufactured by Philips) and the analyzed value was compared with a standard sample (see Tables 3 to 5).

Table 2

Sample amount Flux Sample / Flush Peeling, defoamer Melting temperature time 0.6g? BR> 0.1mg Na ₂ B ₄ O ₇ 8.0g ± 1.0mg 1 / 13.3 Nal0.05g ± 0.1mg 1,100 ℃ 4 minutes

Table 3

SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ TiO ₂ CaO MgO K ₂ O P ₂ O ₅ Standard Sample (IPT53) 65.80 18.30 0.13 0.013 0.27 0.050 12.10 0.072 Measure 65.74 18.26 0.13 0.015 0.29 0.046 12.14 0.074

Table 4

CaO MgO SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ P S K ₂ O Standard Sample (CM1760) 37.59 15.38 0.25 0.110 0.459 0.0012 0.046 0.019 Measure 37.62 15.34 0.25 0.120 0.460 0.0015 0.044 0.020

Table 5

TiO ₂ SiO ₂ Fe ₂ O ₃ ZrO ₂ CaO MgO Cr ₂ O ₃ MnO Standard sample (X 61) 93.30 2.03 0.68 1.34 0.090 0.060 0.11 0.010 Measure 93.24 2.00 0.67 1.35 0.094 0.053 0.11 0.013

IPT53 is a standard sample of silicate mineral manufactured by Instituto De Pesquisas Technologicas Do Estado De Sao Paulo of Brazil. CM1760 is a carbonate mineral. X 61 represents a standard sample of titanium mineral prepared by Mintek, P / Bag X3015 Randburg 2125, South Africa.

The measured value was the number of times measured for each sample, and the average value was obtained.

As can be seen from the above, it can be seen that the fluorescent X-ray sample prepared according to the present invention almost matches the component ratio of the standard sample.

Although the above examples are directed to silicate minerals, carbonate minerals and titanium minerals, the method of the present invention is equally applicable to materials that can be measured in fluorescence X-ray analysis, that is, all metal or nonmetal oxides and compounds. .

According to the method of the present invention described above by applying the preheating step and the slow cooling process of the melt to the sample to be analyzed can prevent frequent cracking to the crucible that occurred during melting of the sample and also ensure the uniformity of the prepared sample More accurate fluorescence X-ray analysis is possible.

Claims (3)

In the sample production method for fluorescence X-ray analysis, Sample grinding step to powder the sample to be analyzed: Preheating step of preparing the semi-solid state by heating the mixture by mixing the pulverized powder of the sample with the flux: Sample melting step of heating the preheated sample to a sample melting temperature or more to obtain a melt: And And injecting the molten sample into a casting mold, and then slowly cooling the molten sample in a heating element below a melting temperature of the sample melting step. The method of claim 1, wherein the mixing ratio of the sample powder and flux is 1:10 to 1:15 glass beads for fluorescence X-ray analysis. The method of claim 1 or 2, wherein the sample is a silicate mineral, carbonate mineral or titanium mineral glass beads production method characterized in that the.