JPH0460436A - Melting method of sample for analysis of inclusion - Google Patents

Abstract

PURPOSE:To heat the whole of a sample uniformly irrespective of movement of the sample and thereby to keep a melted state invariable and to enable accurate execution of measurement of the qualtity of an interposition and identification thereof by making an electron beam scan two-dimensionally in a prescribed sphere. CONSTITUTION:A toroidal deflecting coil 10 is provided just in front of an electron gun 8, an electron beam E, irradiating a sample 6 is made to scan two-dimensionally over a prescribed sphere by the coil 10, as indicated by an alternate long and short dash line, and thereby the sample is heated to be melted. On the occasion, the radius of the electron beam irradiating the sample 6 is made equal to the size of the sample 6. By making the electron beam scan two-dimensionally in this way, the whole of the sample can be irradiated by the electron beam even when the sample 6 moves in a melting chamber 5, and therefore the sample 6 can be melted evenly without nonuniformity. As for a scanning area of the electron beam, an optimum melted state can be obtained when the area is made twice as large as the surface area of the sample 6 at the time when the sample is viewed from the direction of irradiation of the electron beam. According to this constitution, measurement of the quantity of an inclusion and identification thereof can be executed accurately.

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.

"Prior Art" As an apparatus for melting such a metal sample, one shown in FIG. 2 is in practical use.

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 interior of this vessel is connected to a vacuum pump (not shown) to maintain a vacuum.

Moreover, a circular hearth 3 made of copper and cooled is installed inside the vessel 1. The bars are rotatably held by a rotary shaft 4 that penetrates the earthen wall of the apparatus body 1 in an airtight manner, and the upper surface of the hearth has a melting chamber 5 formed in the shape of many recesses. They are formed at equal intervals around the same circumference around the center of rotation. A sample 6 is accommodated in each of the dissolution chambers. 7 is a motor for rotating the rotating shaft 4. Reference numeral 8 denotes an electron gun installed near the hearth, and the generated electron beam E is deflected by a magnetic field between two pole pieces 9a and 9b (see FIG. 1 for 9b) arranged to face each other. Irradiates the sample inside the lysis chamber.

In such an apparatus, if the motor 7 is repeatedly rotated and stopped by a motor control circuit (not shown) and each sample 6 placed on the hearth 3 is sequentially set at the electron beam irradiation position,
The sample is melted by the electron beam E, and inclusions are floated and separated.

[Problem to be solved by the invention] By the way, in a sample dissolving device that dissolves and floats minute inclusions in a sample, it is difficult to identify the inclusions based on their shape or measure their amount. Therefore, it is desirable to maintain a constant state of dissolution in each sample. However, with such a conventional device, it is difficult to maintain a constant state of dissolution of each sample, and it is inevitable that the measurement results will be adversely affected.

As a result of experiments on this point, the present inventor found that the cause was movement within the melting chamber when the sample was set at the electron beam irradiation position. This is a pair of pol pieces 9a for electron beam deflection.

Since the tip of 9b extends above the melting chamber 5 of the hearth 3, the sample moves under the influence of the magnetic field from this pole piece. On the other hand, the spot diameter of the electron beam that irradiates the sample is selected to be approximately the same size as the sample. As a result, when the sample is set at the electron beam irradiation position, the center of the electron beam and the center of the sample are blurred. If the centers of the two are misaligned in this way, the intensity distribution of the electron beam has a Gaussian distribution, so it is only possible to uniformly heat the entire sample, and it is not possible to maintain a constant melting state.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide an apparatus that can uniformly heat the entire sample and maintain a constant melting state regardless of the movement of the sample.

[Means for Solving the Problem] In order to achieve the above object, the inclusion analysis sample melting method of the present invention melts a sample held on a hearth provided in a vacuum vessel with an electron beam, and dissolves the sample in the sample. In the method for dissolving a sample for inclusion analysis in which inclusions are floated to the surface thereof, the sample is dissolved by the electron beam by scanning the electron beam two-dimensionally within a certain area.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

[Example] FIG. 1 is an enlarged plan view of essential parts showing an example of an apparatus for carrying out the method of the present invention, and the same numbers as in FIG. 2 indicate the same components.

That is, in this embodiment, a toroidal deflection coil 10 is provided immediately before the electron gun 8, and the electron beam E that irradiates the sample 6 is two-dimensionally scanned over a certain area by this coil as shown by the dashed line A. It is characterized by heating and melting the sample.

At this time, the diameter of the electron beam that irradiates the sample is equal to the size of the sample, similar to the conventional apparatus.

If the electron beam is scanned two-dimensionally in this way, the sample 6
Since the entire sample can be irradiated with the electron beam even if the sample moves within the dissolution chamber 5, the sample can be dissolved uniformly and evenly unlike the conventional method.

Here, as a result of experiments, an optimal melting state was obtained when the electron beam scanning area was twice the surface area of the sample when viewed from the electron beam irradiation direction.

According to the present invention described in detail above, each sample can be heated uniformly regardless of the movement of the sample in the melting chamber, so the melting conditions can be kept constant and the amount of inclusions can be measured and identified. Can be done accurately.

[Brief explanation of drawings]

FIG. 1 is an enlarged plan view of essential parts showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a schematic diagram of the configuration for explaining a conventional example. 1: Equipment body, 2: Vacuum vessel 3: Hearth
4: Rotating shaft 5, melting chamber 6: Sample 7: Motor 8: Electron gun 9a, 9b: Pole piece 10: Deflection coil

Claims (1)

[Claims] In an inclusion analysis sample melting method in which a sample held on a hearth provided in a vacuum vessel is melted by an electron beam and inclusions in the sample float to the surface, the melting of the sample by the electron beam is A method for dissolving a sample for inclusion analysis, characterized in that the method is carried out by scanning a beam two-dimensionally within a certain area.