JP5927697B2 - Method for producing berylide pebble - Google Patents

Description

The present invention relates to a method for producing beryllide pebble (beryllium intermetallic compound microspheres) used as a neutron multiplication material in a blanket of a nuclear fusion reactor, for example, and in particular, two rod electrodes arranged opposite to each other. The present invention relates to a beryllide pebble manufacturing method in which a pebble is manufactured by arc discharge while rotating one or both of the above.

In a fusion reactor, much of the energy generated in the plasma collides with the reactor wall in the form of fast neutrons. Receiving these fast neutrons, the energy as furnace wall structure for the energy of the power generation in place of the heat module structure called a blanket is employed. These blanket modules are composed of a tritium breeding region where fuel is produced and a structure of beryllium intermetallic compound (berylide) which is a neutron multiplier surrounding the tritium breeding region.

  The beryllide constituting such a structure is in the form of a microsphere (pebble) for various reasons such as volume expansion and crack prevention. The rotating electrode method is widely known as one of means for producing such beryllide pebble. In these conventional rotating electrode methods, for example, as disclosed in Patent Documents 1 and 2, a consumable electrode bar made of beryllium metal and an arc fusion electrode bar made of tungsten or the like are used, and arc discharge is generated between both electrodes. While the consumable electrode rod is melted, the consumable electrode rod is rotated to scatter beryllium droplets to produce spherical particles.

  And in patent document 3, beryllium and various metals were mixed so that it might become a composition ratio of a desired intermetallic compound in the consumable electrode rod used by the above rotating electrode methods, and these were melted and solidified. After that, a method of manufacturing by machining into a predetermined shape is disclosed.

Furthermore, Patent Document 4 describes that two electrode rods used in the rotating electrode method are both consumable electrode rods.

Japanese Patent No. 2604869 Japanese Patent No. 2648655 Japanese Patent No. 3882114 JP 60-70110 A

However, the heretofore Beri ride Pebble method of manufacturing, and it was difficult to manufacture an impurity of less consumable electrode itself consisting Beriraido, and as arc melting electrode, for example, of tungsten (W) Since the electrode is used, the components constituting the arc melting electrode are captured by the manufactured beryllide pebble, and it is difficult to obtain a high-purity beryllide pebble .

An object of the present invention, compared with the conventional method of manufacturing a Beri ride pebble, with high purity can be produced in a short time a large amount of Berri ride pebble is to provide a method for producing Beri ride Pebble .

  In order to produce a large amount of beryllide pebble in a short time with a high purity, the present invention first arranges them opposite to each other without using arc melting electrode bars containing components that become impurities for the pebble as in the prior art. These two electrode rods are both consumable electrode rods, and these two consumable electrode rods rotating with each other are arc-melted and fused to obtain a beryllide pebble composed of a desired component.

More specifically, the method for producing a beryllide pebble according to one aspect of the present invention includes a hollow tube made of a metal constituting berylide and one of two consumable electrode rods and beryllium sealed therein. Created from powder, the other was made by mixing pure beryllium (Be) and pure metal powder constituting beryllide so as to achieve the target composition ratio of beryllide, and then by plasma discharge sintering. The consumable electrode rods are arranged opposite to each other in a sealed container filled with an inert gas, and then melted by arc discharge while rotating each other, and the melt is blown off by the centrifugal force generated by the rotation of the consumable electrode rods. Characterized in that a beryllide pebble with a ratio is produced.

  In the method for producing beryllide pebble of the present invention, two rod-shaped electrodes for generating arc discharge are both beryllide electrodes, and these are melted and fused to produce a beryllide pebble having a target composition ratio of beryllide. Therefore, unlike the prior art, the electrode on one side is not dedicated to a foreign material dedicated for thermionic emission for arc discharge melting, so the foreign component constituting the arc melting electrode is mixed into the berylide pebble. There is no fear of being done. Therefore, a highly pure beryllide pebble can be obtained.

It is a schematic block diagram of the manufacturing method of beryllide pebble concerning the present invention. It is structure explanatory drawing of the consumable electrode rod used with the manufacturing method shown by FIG. It is a schematic explanatory drawing of the plasma sintering method for manufacturing the consumable electrode rod of FIG. It is a photograph which shows the result of the thermal shock resistance test about the beryllide consumable electrode produced by the powder metallurgy method, and the beryllide consumable electrode produced by the plasma sintering method. It is a micrograph of the produced Beri ride pebble in the conventional manufacturing method and the manufacturing method according to the present invention.

The method for producing a beryllide pebble according to the present invention basically comprises one of two consumable electrode rods made of a hollow tube made of a metal constituting beryllide and a beryllium powder enclosed therein, The other was prepared by mixing pure beryllium (Be) and pure metal powder constituting beryllide so as to achieve the target composition ratio of beryllide, and then sintering by plasma discharge sintering. A beryllide having a target composition ratio is disposed in an airtight container filled with an inert gas, and then melted by arc discharge while rotating each other, and the melt is blown away by centrifugal force due to rotation of the consumable electrode rod. Manufacturing pebble

  As these consumable electrode rods, for example, (1) one of the two consumable electrode rods is composed of a hollow tube made of metal constituting beryllide and beryllium powder sealed therein, and the other is pure beryllium. (Be) and pure metal powder constituting beryllide mixed so as to have a target composition ratio of beryllide, (2) a hollow tube in which one of the two consumable electrode rods is made of metal constituting berylide And a beryllide rod formed by plasma discharge sintering of a low-temperature synthetic beryllide powder synthesized at a temperature lower than the melting point of each material.

  Also, the two consumable electrode bars can have the same structure. For example, (3) both of the two consumable electrode rods are composed of a hollow tube made of a metal constituting beryllide and beryllium powder enclosed therein, and (4) two of the consumable electrode rods Both may be beryllide rods obtained by mixing pure beryllium (Be) and pure metal powder constituting beryllide so as to achieve the target composition ratio of beryllide and performing plasma discharge sintering.

  The thickness of the metal hollow tube can be designed based on the thickness derived from the stoichiometric ratio of the metal constituting the beryllide. As a material of the hollow tube, titanium (Ti) is preferable.

Hereinafter, an embodiment of a method for producing a beryllide pebble according to the present invention in which the metal constituting beryllide is titanium (Ti) will be described in detail with reference to the accompanying drawings.

  Please refer to FIG. FIG. 1 shows an example in which two opposing electrodes are used as a consumable electrode bar. Reference numeral 11 is a sealed container filled with helium gas (He), and 12a and 12b are rod-shaped consumable electrodes. The two consumable electrode rods 12a and 12b are fixed by electrode chucks 13a and 13b, respectively. Further, the tips of the two consumable electrode rods 12a and 12b are arranged to face each other at the central portion of the sealed container 11 in a state where they are separated from each other by a certain distance. The two electrode chucks 13a and 13b are configured to rotate in the forward direction or the opposite direction. For this reason, electrode drive units 14a and 14b for rotating the electrode chucks 13a and 13b are provided outside the sealed container 11. The electrode drive units 14a and 14b also have a function of moving the electrode chucks 13a and 13b in the axial direction thereof as necessary to keep the distance between the tips of the two consumable electrode rods 12a and 12b constant. Have.

FIG. 1 schematically shows an apparatus for manufacturing a beryllide pebble for carrying out the manufacturing method of the present invention for convenience of explanation. The two consumable electrode rods 12a and 12b are arranged so as to face each other in the vertical direction, and the produced beryllide pebble is collected along the side wall of the hermetic container 11 to the lower consumable 12b side by gravity, and the hermetic container 11 is taken out.

  Next, the operation of the beryllide pebble manufacturing apparatus having the above-described configuration will be described. After the two consumable electrode rods 12a and 12b are attached by the electrode chucks 13a and 13b, respectively, the sealed container is replaced and sealed with He gas, and the electrode chuck units 13a and 14b are provided by the electrode drive units 14a and 14b provided outside. And 13b are rotated in opposite directions to apply a maximum DC current of 300 A to the consumable electrode rods 12a and 12b. Thereby, arc discharge is caused between these consumable electrode rods, and the consumable electrode rods 12a and 12b are melted. The melted consumable electrode rods 12a and 12b are scattered as spherical droplets, and the scattered droplets are collected by the berylide pebble collection unit 15. Since the consumable electrode rods 12a and 12b are melted and consumed, the electrode chucks 13a and 13b are moved in the axial direction by the electrode drive units 14a and 14b, and the berylide pebble is continuously maintained while keeping the distance of the arc discharge part 10 constant. Manufacturing.

Here, the thermoelectrons for arc melting flow from the negative electrode ( − ) to the positive electrode (+) in the electrode bar, and the electrode bar is heated and partially melted by the impact of the thermoelectrons. While being scattered and beveled by surface tension, it is cooled in a He gas atmosphere, and as a result, a beryllide pebble is produced. Therefore, the electrode potential is an alternating potential “± E” as shown in FIG.

With reference to FIG. 2, the structure of the consumable electrode used in the beryllide pebble manufacturing apparatus shown in FIG. 1 will be described. As shown in the figure, the consumable electrode rod 12a is a titanium (Ti) hollow tube filled with beryllium (Be) powder and enclosed. When the diameter of the consumable electrode rod used in the beryllide pebble manufacturing apparatus shown in FIG. 1 is φ5 mm to φ20 mm, when the stoichiometric composition of Be ₁₂ Ti is obtained, the consumable electrode rod diameter φ5 mm is made of this titanium. The wall thickness of the hollow tube is 0.125 mm, and when the diameter is 20 mm, the wall thickness is 0.5 mm.

  The consumable electrode rod 12b is a berylide sintered rod obtained by forming and firing a mixed powder obtained by mixing pure Be and pure Ti powders, which are raw materials, so as to have a target composition ratio of beryllide. Low-temperature synthetic beryllide powder synthesized at a temperature lower than the melting point of each material can also be used.

  Low-temperature synthetic beryllide powder is a Be (melting point 1285 ° C) powder and Ti (melting point 1660 ° C) powder, weighed (target composition ratio) and mixed, and then heated in an inert atmosphere (eg Ar gas) at a heating rate of 200 ° C / Heat to 1200 ° C., which is below the melting point of each metal powder, and hold for 24 hours, cool to room temperature in 12 hours, and then pulverize to eliminate particle fusion.

  The consumable electrode rods 12a and 12b are formed by mixing and sintering a powder of pure Be and pure Ti so as to have a target composition ratio of beryllide, or a sintered beryllide rod or a melting point of each material. Although it is a beryllide rod formed and sintered at low temperature synthesized beryllide powder synthesized at low temperature, the sintering may be performed in a general electric furnace etc., but it should be sintered by plasma discharge sintering method Is desirable.

Like the above-mentioned consumable electrode rod, an electrode rod made by filling and encapsulating Be powder in a Ti hollow tube, or a mixture of pure Be and pure Ti powder to achieve the target composition ratio of berylide Alternatively, consumable electrode rods made from beryllide rods, which are synthesized by plasma discharge sintering of low-temperature synthetic beryllide powder synthesized at a temperature lower than the melting point of each material, are compared to consumable electrode rods manufactured by conventional arc melting. Since there is no contamination with impurities, a high-purity beryllide pebble is obtained, and since it is superior in thermal shock resistance to a beryllide rod manufactured by a high temperature melting method, it is difficult to be destroyed even by a thermal shock caused by arc discharge.

  Next, with reference to FIG. 3, the production of the consumable electrode rod by the plasma sintering method will be described. FIG. 3 shows a state where raw material powder is put into a carbon punch and die and uniaxially compressed. The raw material powder is molded in this punch and die apparatus, the surface thereof is activated by a pulse current, and then sintered by direct current heating. The beryllide consumable electrode produced by such a plasma sintering method has excellent thermal shock resistance as described below.

FIG. 4 shows the results of the thermal shock resistance test for the beryllide consumable electrode produced by the powder metallurgy method and the beryllide consumable electrode produced by the plasma sintering method used in the beryllide pebble manufacturing apparatus shown in FIG. Indicates. FIG. 4 (a) is a photograph showing the result of a Be12Ti consumable electrode produced by powder metallurgy, and FIG. 4 (b) is a test result of the Be12Ti consumable electrode produced by plasma sintering. From these photographs, it can be seen that the electrode rod produced by the powder metallurgy method is destroyed by the thermal shock during the arc discharge, but the electrode rod produced by the plasma sintering method can withstand the thermal shock. In these experiments, a conventional tungsten (W) arc fusion electrode rod was used as the opposed electrode rod.

Next, FIG. 5 shows a photomicrograph of the fabricated Beri ride pebble in the conventional manufacturing method and the manufacturing method according to the present invention. 5A is a photomicrograph of beryllide pebble manufactured by the conventional method , and FIG. 5B is a photomicrograph of beryllide pebble manufactured by the above-described method according to the present invention.

  As mentioned above, although the optimal Example of this invention was described, this invention is not limited to this. For example, the cross section of the consumable electrode rod is not necessarily circular, but may be a point-symmetric shape such as a polygon or a star. In addition, in order to generate arc discharge between the consumable electrodes at all times, in the above-described embodiment, the motor rotation of the electrode driving unit is controlled by visual observation and manually controlled. It is clear that the motor rotation may be automatically controlled by parameters such as the arc discharge current value and the voltage value that change in such a manner, and such replacement is obvious to those skilled in the art.

11 Airtight container
12a, 12b Consumable electrode rod
13a.13b Electrode chuck
14a, 14b Electrode drive unit

Claims (3)

One of the two consumable electrode rods is made of a hollow tube made of metal constituting beryllide and beryllium powder sealed therein, and the other is made of pure beryllium (Be) and pure metal constituting beryllide. After the powder is mixed to the desired composition ratio of beryllide, it is created by plasma discharge sintering, and the two consumable electrode rods created are placed oppositely in a sealed container filled with inert gas. Then, they are melted by arc discharge while rotating each other, and the melt is blown off by centrifugal force due to rotation of the consumable electrode rod to produce a beryllide pebble having a target composition ratio. Manufacturing method . 2. The manufacturing method according to claim 1, wherein the thickness of the hollow tube made of the metal constituting the beryllide is set based on the thickness derived from the stoichiometric ratio of the metal constituting the beryllide. Manufacturing method of berylide pebble. The method of manufacture according to claim 1 or 2, Beri ride Pebble manufacturing method, wherein the metal constituting the Beriraido is titanium (Ti).

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