JPH0432743A - Method for dissolving sample for analysis of inclusion - Google Patents

Abstract

PURPOSE:To automate the operation for dissolution by setting control of an electron beam output, etc., in a film thickness control system of a film thickness gage provided in a vacuum vessel. CONSTITUTION:The value of the electron beam output P2 of a sample heating distribution is exactly set by building the rock crystal type film thickness gage 11 into the upper part of a hearth 3 in the vacuum vessel 2. The reason thereof lies in that the ample 6 (6a, 6b...) is heated and dissolved by the electron beam generated from an electron gun 9 and that the state just before the evaporation can be checked by the film thickness gage 11. The electron beam output P1 for preheating, the rising time T1 thereof, the preheating time T2, the rising time T3, the dissolving time T4 and the falling time T5 of the output are set by experiment, experience, etc. The data of the sample heating distribution is determined and this data is inputted to the film thickness control system 13. The control system 13 sends an output signal to a power source 10 of the electronic gun to control the electron beam output along the heating distribution data when a start button S is pushed in this state. The sample 6 is gradually heated up to the dissolving temp. in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for dissolving a metal sample before analysis in the technical field of effectively analyzing small amounts of inclusions contained in metal.

[Conventional technology] As a technique for melting metal samples, a hearth is placed in a vacuum vessel, the metal sample is placed inside the hearth, and the sample is irradiated with an electron beam to melt and float non-metallic inclusions in the sample. Separation devices are already in practical use.

By the way, when dissolving a sample to levitate minute inclusions in the sample in this way, it is necessary to levitate as many inclusions as possible without changing the shape of the minute inclusions, so ordinary electron beam melting is method requires strict control of the electron beam output. For example, if a sample is irradiated with a high-power electron beam and rapidly heated (melted), the gas accumulated in the sample will be released all at once, which may cause the sample to scatter.

Therefore, the output of the electron beam is changed in two stages, Pl and P2, to irradiate the sample, as shown in Figure 2, which shows the relationship between the heating distribution of the sample (the vertical axis is the electron beam output, and the horizontal axis is time). . In other words, after preheating the sample for a time T2 using an electron beam output of Pl, the electron beam output is changed to P2 and then T4 is heated.
It is necessary to dissolve the sample for a period of time and avoid heating the sample rapidly.

Also, when moving from the preheating state to the melting state, if the electron beam output is suddenly raised, a bumping phenomenon may occur and the sample may be scattered, so it is necessary to gradually increase the output as shown in the start-up time T3. There is.

Furthermore, the electron beam output P2 for melting the sample is as follows:
It is necessary to set the temperature to the limit where evaporation does not occur so that inclusions can be efficiently floated. At this time, the dissolution time T
If 4 becomes longer, the floating impurities will melt, so it is necessary to stop the dissolution before the inclusions melt. When stopping the sample melting, if the electron beam irradiation is stopped instantaneously, the temperature of the sample will drop rapidly, which may cause crackers to occur and the shape of the floating inclusions to collapse.

In addition, when preheating the sample, the electron beam output P
When the sample is irradiated at step 1, a current flows through the sample, which may cause the sample to move. Therefore, it is necessary to gradually increase the rise time as shown by the start-up time T1.

[Problems to be Solved by the Invention] Conventionally, since the operator controls the electron beam output shown in the figure while looking at the sample, the sample is often evaporated and wasted. Also,
Since the dissolution conditions vary from person to person, the conditions for inclusions to float cannot always be maintained constant.

SUMMARY OF THE INVENTION In order to solve this problem, it is an object of the present invention to provide a method for dissolving a sample for inclusion analysis in which the dissolution operation can be performed automatically.

[Means for Solving the Problems] In order to achieve the above object, the inclusion analysis sample dissolution method of the present invention irradiates an electron beam onto a sample on a hearth provided in a vacuum vessel to remove inclusions from the surface of the sample. In the inclusion analysis sample melting method by floating, a film thickness gauge is provided in the vacuum vessel, and control of the rise time, preheating time, melting time, and fall time of the electron beam output for melting the sample is performed. is set in the film thickness controller system of the film thickness meter, and the melting operation is automatically performed.

The principle of the present invention will be briefly explained below.

By the way, a film thickness controller system used in a film forming apparatus such as a vacuum evaporation apparatus is configured to be able to control the output of a heating source (electron gun) into two stages: a preheating mode and an evaporation mode. There is.

In other words, in order to evaporate a vapor deposited material, it is necessary to scan a narrowly focused electron beam over the vapor deposited material two-dimensionally to uniformly dissolve the entire vapor deposited material. Since only the irradiated part is instantaneously heated and scattered, the output of the electron beam is gradually increased. In addition, when the vapor deposition material is heated and evaporated all at once due to this rise, a bumping phenomenon occurs in which the gas accumulated in the vapor deposition material is suddenly released, causing the vapor deposition material to scatter. After startup, the output is kept constant and the vapor deposition material is preheated while degassing. Thereafter, the electron beam output is gradually increased to the evaporation output to evaporate the evaporated substance. Then, when a desired film thickness is reached, the output of the electron beam is gradually lowered (falling down) and the output of the electron beam is stopped.

Control of the electron beam output of such a film thickness controller system is as follows:
Focusing on the fact that it is similar to the control of the electron beam output when carrying out the sample melting method for levitating minute inclusions in a metal sample according to the present invention, the present invention utilizes a film thickness controller system to The electron beam output is controlled in accordance with the heating distribution of the sample shown in the figure.

Hereinafter, an example of the present invention will be explained in detail based on the drawings.

[Example] FIG. 1 is a schematic diagram showing an example of an inclusion analysis sample dissolution apparatus using the method of the present invention. In the figure, 1 is a main body of the apparatus, and 2 is a vacuum vessel removably placed on the upper surface of the apparatus in an airtight manner.The inside of this vacuum vessel is connected to a vacuum pump (not shown) to maintain a vacuum. Further, a circular hearth 3 made of copper is provided within this vacuum vessel. The hearth has a rotating shaft 4 passing through the main body 1 in an airtight manner.
A large number of recesses 5a, 5b, . . . are formed at equal intervals on the same circumference around the rotation center on the upper surface of the /XX soot. Samples 6g, 6b, . . . are accommodated in each of the recesses. 7 is a motor for rotating the rotating shaft 4, and 8 is a driving power source thereof. Although not shown, water cooling means for circulating cooling water is provided inside the hearth 3.

Reference numeral 9 denotes an electron gun provided near the hearth 3, and the generated electron beam E is deflected by about 180 degrees by a deflection means (not shown) to irradiate the sample set at the melting position on the hearth 3. 10 is a power source for this electron gun. Although not shown, the electron gun 9 has a built-in deflection system for two-dimensionally scanning the electron beam over the sample.

11 is a crystal film thickness gauge placed above the hearth 3 in the vacuum vessel 2, and a holding rod 12 passing through the vacuum vessel 2;
is held at the tip of the Reference numeral 13 denotes a controller system for this film thickness meter, and this controller system controls the motor power source 8 and the electron gun power source 9, respectively, using its output signals. Reference numeral 14 is a display section for the evaporation rate counted by this controller system.

By incorporating the film thickness gauge 11 in this manner, it is possible to accurately set the value of the electron beam output P2 for the sample heating distribution shown in FIG. This is because an electron beam is generated from the electron gun 9 on the sample to heat and melt it, and the state on the verge of evaporation can be confirmed using a film thickness meter. Furthermore, since the electron beam output P1 for preheating is less than P2, it can be easily set by experience or the like by repeating experiments without actually measuring it. Furthermore, the rise time TI until the other sample melts, the preheating time T2. Rise time T3. Similarly, the dissolution time T4 and the fall time T5 can be easily set by repeating experiments or by experience. Data on the sample heating distribution is then input to the controller system 13.

In this state, when you press the start button S, the controller system 13
First, an output signal is sent to the motor power source 7 and the first sample 6a is set at the melting position for heating. Thereafter, the controller system sends an output signal to the electron gun power supply 10 to control the electron beam output generated from the electron gun along the distribution shown in FIG. As a result, the sample 6a is heated gradually without being heated rapidly, and when the entire sample uniformly reaches a certain temperature, it is gradually heated to the melting temperature, so that the inclusions are separated and floated and solidified. Then, when the electron beam output from the electron gun 9 is stopped, the controller system 13 sends a melting end signal to the motor power source 8 to rotate the motor 7 by a certain angle. This rotation causes the hearth 3 to rotate via the rotating shaft 4, and the next four parts are set at the melting position. Thereafter, the above-described operations are repeated, and each sample accommodated in the recess on the hearth is automatically and sequentially melted by the electron beam, and the inclusions are floated and solidified.

By doing so, the electron beam power for dissolving the sample can be set accurately, so that inclusions can be efficiently levitated and the sample can be prevented from being wasted.

In addition, since evaporation can be confirmed with a film thickness meter while the sample is being melted, it is possible to check for abnormalities in the measurement sample, and at the same time, it is possible to immediately check for abnormal heating due to aging of the filament in the electron gun. It is possible to prevent waste of samples due to Furthermore, the dissolution (floating of inclusions) of a large number of samples can be automated easily and with a simple configuration.

It should be noted that the above description is an example of the present invention, and many modifications can be made in implementing the present invention. For example, in the above embodiment,
Although a crystal type film thickness meter was used, the present invention is not limited thereto, and any known type such as an electron impact type film thickness meter may be used.

[Effect] By doing the above, the operator can automatically control the levitation of inclusions without having to observe the heating state of the sample each time, unlike in the past, so the sample is not evaporated and wasted. You can prevent this from happening. In addition, the accuracy of the conditions under which inclusions float can be further improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of an inclusion analysis sample dissolving apparatus using the method of the present invention, and FIG. 2 is a diagram showing the heating distribution of the sample. 1: Mounting body 2: Vacuum vessel 3: Hearth 4: Rotating shaft 5a, 5b: Recesses 6a, 6b: Sample 7: Motor 8: Motor power supply 9: Electron gun 102 Electron gun power supply 11: Crystal film thickness meter 12: Holding rod 13: Controller system

Claims (1)

[Claims] In an inclusion analysis sample dissolution method in which a sample on a hearth provided in a vacuum vessel is irradiated with an electron beam to cause inclusions to float to the surface thereof, a film thickness gauge is provided in the vacuum vessel to dissolve the sample. An intervention characterized in that the control of the rise time of the electron beam output, the preheating time, the melting time, and the fall time of the output is set in the film thickness controller system of the film thickness meter, and the melting operation is automatically performed. Physical analysis sample dissolution method.