CN104458370A - Method for preparing glow discharge mass spectrometer analysis test sample - Google Patents

Abstract

The invention discloses a method for preparing an analysis sample of a glow discharge mass spectrometer, which comprises the following steps: a) placing the refractory metal powder to be analyzed in a graphite mold coated with a release agent; molding the powder by pressing and sintering; c) turning the formed blank. Using the analysis method of the present invention: while maintaining its own impurity content as much as possible, it has a higher density and a clean surface, thereby ensuring the accuracy and precision of the glow discharge mass spectrometry analysis results. At the same time, the sample prepared by this preparation method It also has the advantages of fast analysis speed and high efficiency.

Description

A kind of preparation method of sample analyzed by glow discharge mass spectrometer

technical field

The invention relates to a method for preparing a sample analyzed by a glow discharge mass spectrometer (GDMS).

Background technique

In the purity analysis of many high-purity elements or alloys, a glow discharge mass spectrometer (GDMS) is required. Glow discharge mass spectrometer is an instrument that can directly analyze impurities in solid-state conductive samples. The principle is that the glow discharge ion source uses inert gas (usually argon) to produce ions at a voltage of thousands of volts to hit the surface of the sample. Sputtering occurs, and the sample atoms produced by sputtering diffuse into the plasma for further ionization, and then are collected and detected by a mass spectrometer. At present, the glow discharge mass spectrometer that is mainly produced and sold in the world is the Element GD glow discharge mass spectrometer produced by Thermo Electron Company of the United States. This kind of equipment can detect and quantitatively analyze almost all elements in solid samples, including carbon. , oxygen and nitrogen. Many elements can be accurate to more than ppb (parts per billion).

For powder samples, the glow discharge mass spectrometer cannot be used directly for analysis, and the powder must be prepared into a bulk sample before analysis. Requirements for samples analyzed by glow discharge mass spectrometers include high density and clean surfaces. The reason for requiring high density is to avoid adverse effects on the analysis results caused by uneven stripping of the sample due to low density and the release of gas in the sample; at the same time, there is also a risk of contamination of the analysis device when the low-density sample is decomposed.

Usually, the sample pretreatment method of GDMS includes steps such as mechanical or electric discharge cutting, mechanical grinding, acid dissolution and cleaning, but in the process of pretreatment, the surface of the sample is often easy to introduce impurities, especially Na, Fe, Ca, etc. , in order to eliminate surface contamination caused by sample preparation, it is usually necessary to perform pre-sputtering for half an hour to an hour to ensure the accuracy and stability of the collected signal. The process of this sample preparation method is relatively complicated, and the pre-sputtering time is also long, and the efficiency is low. In addition, for many powder samples, especially refractory metals, the bulk material is a material with a high melting point and is difficult to process. Therefore, how to prepare a sample that meets the analysis requirements without changing the impurity content of the sample itself is an important issue for glow discharge mass spectrometer samples. Frequently encountered problems in the analysis process.

An example of this is ruthenium powder. High-purity ruthenium is a raw material widely used in semiconductor, computer hard disk and other industries. Therefore, it is necessary to analyze the impurity content in high-purity ruthenium powder and ruthenium bulk. Due to the poor solubility of ruthenium in acid, it is impossible to use wet analysis methods such as ICP-MS. Therefore, in practical applications, a glow discharge mass spectrometer is usually used to analyze the impurity content in ruthenium. For ruthenium powder, it is necessary to prepare a high-density, high-clean ruthenium sample before analyzing ruthenium with a glow discharge mass spectrometer. Chinese invention patent 200610148577.2 discloses a method for making a ruthenium analysis sample. The method is to use a stamping mold made of yttrium-stabilized zirconia in the process of using a glow discharge mass spectrometer to analyze the quality of the ruthenium powder. Plastic ruthenium powder, use reducing gas atmosphere to calcinate ruthenium powder, so as to prepare GDMS analysis sample. The density of GDMS samples prepared by this method is low, which affects the stability of sample analysis results. At the same time, calcining ruthenium powder in a reducing atmosphere may reduce some elements originally present in the powder during the calcination process, thereby affecting the accuracy of the analysis results. Therefore, how to prepare high-density, surface-free GDMS samples and improve the efficiency and accuracy of analysis is an urgent problem to be solved.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of glow discharge mass spectrometer (GDMS) analysis sample, described sample, while keeping itself impurity content as far as possible, has higher compactness, and surface is clean simultaneously, Therefore, the accuracy and precision of the analysis results of the glow discharge mass spectrometry are guaranteed, and at the same time, the sample prepared by the preparation method has the advantages of fast analysis speed and high efficiency.

The purpose of the present invention is achieved like this:

Place the refractory metal powder to be analyzed in a graphite mold coated with a release agent, and use the method of pressure sintering to sinter the powder

Forming; turning the formed blank.

The reason for using a release agent is that on the one hand, it helps the preform to come out of the mold after molding, and on the other hand, it also prevents the sample from contacting the mold.

A chemical reaction occurs that contaminates the sample.

Preferably, the release agent is aluminum oxide, zirconia, or boron nitride. Using these release agents, the powder sample can be easily

The product comes out of the graphite mold.

Preferably, the pressure sintering method includes vacuum hot pressing, discharge plasma sintering and direct current heating sintering.

Preferably, the turning uses a diamond tool, a carbide tool or a cubic boron nitride tool, the reason for choosing these tools

The reason is that these tools have high hardness, which not only can ensure the turning of the sample, but also will not leave residue on the surface of the sample.

Preferably, the powder is ruthenium powder.

The present invention prepares an analysis blank with a density of more than 95% through the process of pressurized sintering, and makes the surface of the analysis blank have a good surface cleanliness by performing turning surface treatment on the analysis blank; at the same time, using The preparation method of pressure sintering plus mechanical processing will not bring or reduce any impurities during the preparation process, which ensures the accuracy and precision of the results of the sample used for glow discharge mass spectrometry analysis. Therefore, the prepared analysis sample has the characteristics of high density and clean surface, so as to ensure the accuracy and precision of the analysis results of glow discharge mass spectrometry. At the same time, the sample prepared by this preparation method has the advantages of fast analysis speed and high efficiency.

Description of drawings

Figure 1 is a flowchart of an embodiment of the present invention.

Fig. 2 is the relation of Fe, Ca, Na content and sputtering time in embodiment 1.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited in any way. Any changes or improvements made based on the teaching of the present invention belong to the protection scope of the present invention.

First, provide the powder to be analyzed, such as ruthenium powder. The powder is filled in a graphite mold coated with a release agent, and the powder is formed by pressure sintering; the formed blank is turned.

Preferably, the release agent is alumina, zirconia, or boron nitride. The reason for using a release agent is that on the one hand, it helps the preform to escape from the mold after molding, and on the other hand, it also prevents the sample from chemically reacting with the mold, thereby contaminating the sample.

The pressure sintering method includes vacuum hot pressing, discharge plasma sintering and direct current heating sintering. The advantage of pressure sintering is that on the one hand, it can increase the density of the sample, and at the same time, because the sintering process is in a vacuum state, it avoids external pollution, and at the same time, it can keep the original impurities of the powder unchanged.

Preferably, the turning uses a diamond tool, a carbide tool or a cubic boron nitride tool, the reason for choosing these tools

The reason is that these tools have high hardness, which can not only ensure the turning of the sample, but also will not produce residue on the surface of the sample.

Preferably, the powder is ruthenium powder.

The preparation method of the analytical sample used in the analysis of the glow discharge mass spectrometer in the present invention will be specifically described below in conjunction with specific examples.

Example 1 Put the ruthenium powder to be analyzed into a graphite mold coated with alumina. The inner diameter of the graphite mold is 30 mm. The ruthenium powder is pressurized and sintered at a temperature of 1300° C. by vacuum hot pressing, and the applied The pressure is 40MPa. After the sintering is completed, the density of the obtained ruthenium block is measured by the Archimedes method, which can reach 99% of the theoretical density of ruthenium. A polycrystalline cubic boron nitride turning tool was used to turn the ruthenium block into a ruthenium sample with a diameter of 28 mm. The ruthenium samples were ultrasonically cleaned with acetone, ethanol and ultrapure water, and dried. Put the sample into the ElementGD block sample stage, and carry out pre-sputtering for a certain period of time, with easily polluted Na, Fe, Ca as the target, start to collect data when the concentration is basically stable, record the time of pre-sputtering, and collect part of it at the same time Five sets of data of typical elements, and calculate the relative standard error (RSD%), in order to evaluate the repeatability of the analysis results. The results are shown in Table 1 and Table 2. It can be seen from Table 1 and Table 2 that the pre-sputtering time of the sample prepared in this embodiment is 10 minutes, and the surface is relatively clean. At the same time, the RSD% of the typical element content is less than 7.5%, which has good analysis repeatability.

Example 2

Put the ruthenium powder to be analyzed into a graphite mold coated with zirconia. The inner diameter of the graphite mold is 30mm. The ruthenium powder is pressure-sintered at a temperature of 1000°C by spark plasma sintering. The applied pressure is 20MPa. After the sintering is completed, the density of the obtained ruthenium block is measured by the Archimedes method, which can reach 95% of the theoretical density of ruthenium. The ruthenium block was turned into a ruthenium sample with a diameter of 28 mm using a cemented carbide turning tool. The ruthenium samples were ultrasonically cleaned with acetone, ethanol and ultrapure water, and dried. Put the sample into the Element GD block sample stage and perform pre-sputtering for a certain period of time. Taking easily polluted Na, Fe, Ca as the target, start collecting data when its concentration is basically stable, record the time of pre-sputtering, and collect five sets of data of some typical elements at the same time, and calculate their relative standard error (RSD%), This was used to evaluate the repeatability of the analysis results. The results are shown in Table 1 and Table 2. It can be seen from Table 1 and Table 2 that the pre-sputtering time of the sample prepared in this embodiment is 8 minutes, and the surface is relatively clean. At the same time, the RSD% of the typical element content is less than 8.4%, which has good analysis repeatability.

Example 3

Put the ruthenium powder to be analyzed into a graphite mold coated with boron nitride. The inner diameter of the graphite mold is 30 mm. The ruthenium powder is pressure sintered at a temperature of 1200 by direct current heating and sintering, and the applied pressure is 30 MPa. . After the sintering is completed, the density of the obtained ruthenium block is measured by the Archimedes method, which can reach 97% of the theoretical density of ruthenium. A diamond turning tool was used to turn the ruthenium block into a ruthenium sample with a diameter of 28 mm. The ruthenium samples were ultrasonically cleaned with acetone, ethanol and ultrapure water, and dried. Put the sample into the Element GD block sample stage and perform pre-sputtering for a certain period of time. Taking easily polluted Na, Fe, Ca as the target, start collecting data when its concentration is basically stable, record the time of pre-sputtering, and collect five sets of data of some typical elements at the same time, and calculate their relative standard error (RSD%), This was used to evaluate the repeatability of the analysis results. The results are shown in Table 1 and Table 2. It can be seen from Table 1 and Table 2 that the pre-sputtering time of the sample prepared in this embodiment is 10 minutes, and the surface is relatively clean. At the same time, the RSD% of the typical element content is less than 7.2%, which has good analysis repeatability.

Comparative example 1

Put the ruthenium powder to be analyzed into the yttrium-stabilized zirconia mold, the inner diameter of the mold is 30 mm, and sinter the ruthenium powder at a temperature of 1000 by using the common sintering method. After the sintering is completed, the density of the obtained ruthenium block is measured by the Archimedes method, which can reach 80% of the theoretical density of ruthenium. The ruthenium samples were ultrasonically cleaned with acetone, ethanol and ultrapure water, and dried. Put the sample into the Element GD block sample stage and perform pre-sputtering for a certain period of time. Taking easily polluted Na, Fe, Ca as the target, start collecting data when its concentration is basically stable, record the time of pre-sputtering, and collect five sets of data of some typical elements at the same time, and calculate their relative standard error (RSD%), This was used to evaluate the repeatability of the analysis results. The results are shown in Table 1 and Table 2. It can be seen from Table 1 and Table 2 that the pre-sputtering time of the sample prepared in Comparative Example 1 is 24 minutes, and there may be contamination in the sample preparation process. At the same time, the maximum RSD% of the typical element content is 11.8%, and its analytical repeatability is worse than that of the comparative example.

The impurity content and corresponding standard deviation of measured ruthenium powder in embodiment and comparative example in table 1

Table 2 embodiment and comparative example pre-sputtering time and standard deviation statistical data

Claims (6)

1. a preparation method for glow discharge mass spectroscopy analytical sample, is characterized in that, comprises the following steps:

A) powder of Water demand being positioned over inwall scribbles in the graphite jig of release agent;

B) method of pressure sintering is used to carry out shaping to described powder;

C) surperficial turning is carried out to shaping material base;

D) material base described in carries out cleaning-drying.

2. the method for the preparation of glow discharge mass spectroscopy analytical sample according to claim 1, is characterized in that, described release agent is aluminium oxide, zirconia or boron nitride.

3. the method for the preparation of glow discharge mass spectroscopy analytical sample according to claim 1, is characterized in that, described pressure sintering method comprises vacuum hotpressing, discharge plasma sintering and DC heating sintering.

4. the method for the preparation of glow discharge mass spectroscopy analytical sample according to claim 1, is characterized in that, described turning adopts carbide-tipped tool, diamond cutter or cubic boron nitride cutting tool.

5. the method for the preparation of glow discharge mass spectroscopy analytical sample according to claim 1, is characterized in that, described powder is ruthenium powder.

6. a preparation method for glow discharge mass spectroscopy analytical sample ruthenium powder, is characterized in that, comprise the following steps:

Loaded in the middle of the graphite jig scribbling aluminium oxide by ruthenium powder to be analyzed, the internal diameter of graphite jig is 30mm, and adopt the method for vacuum hotpressing, by the pressure sintering of ruthenium powder at the temperature of 1300 DEG C, institute's applied pressure is 40MPa;

Sinter rear employing Archimedes method and density has been surveyed to gained ruthenium block, 99% of ruthenium solid density can have been reached;

Polycrystalline cubic boron nitride lathe tool is adopted ruthenium block to be lathed the ruthenium sample that diameter is 28mm;

With acetone, ethanol and ultrapure water, ultrasonic cleaning is carried out to ruthenium sample respectively, and dry;

Sample is put into Element GD bulk sample platform, and carry out the pre-sputtering of certain hour, with Na, Fe, Ca of easily polluting for target, image data is started time basicly stable with concentration, the time of record pre-sputtering, five groups of data of collecting part typical element simultaneously, and calculate its relative standard deviation (RSD%), the repeatability of evaluation analysis result is carried out with this.