JPH0141231B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a split metal container, and particularly to a split metal container that is used by connecting and integrating split containers and maintaining them under high temperature conditions and in an ultra-high vacuum. Regarding.

Generally, a large metal container such as a vacuum container for a nuclear fusion device is formed into a single piece by connecting a plurality of parts. When connecting the divided containers, an insulating material is placed at the connecting portion to provide electrical insulation between the divided containers.

By the way, metal containers such as vacuum containers for nuclear fusion devices are not only operated under high temperature conditions, but also heated to high temperatures to degas the gas adsorbed on the surface of the metal container in order to obtain an ultra-high vacuum. things will be done.
Therefore, the above-mentioned insulating material is required to be a heat-resistant inorganic material, and alumina ceramics or the like is usually used. However, in the case of conventional metal containers in which divided metal containers are connected and integrated via an insulating material such as alumina ceramics, there is a difference in thermal expansion between the divided metal containers and the insulating material, so when exposed to high temperatures, the difference in thermal expansion increases. increases, excessive stress is generated at the connection between the insulating material and the divided metal container, and there is a risk that the connection will break due to thermal stress and impair ultra-high vacuum performance. In particular, vacuum vessels for nuclear fusion devices are required to be non-magnetic, and austenitic alloys are usually used; This results in the generation of large thermal stress during the process, and the above-mentioned points are remarkable. Therefore, in the split metal container having the above-described structure, the upper limit of the heating temperature and operating temperature for degassing is limited from the viewpoint of allowable thermal stress.

This will be explained in detail using figures. FIG. 1 shows the connecting portion of the above-mentioned split metal container. In the figure, a divided metal container 1 is made of a non-magnetic alloy such as SUS304, which is an austenitic alloy. The metal containers 1 are electrically insulated from each other by high-purity alumina ceramics 2, and are integrally welded to two joining metals 4a and 4b, one end of which is brazed to the alumina ceramics 2. Alumina ceramics 2 metal container 1
On both sides of the metallized layer 3, a bonding layer is formed by reducing the surface area of the alumina ceramic 2 with molybdenum, zirconium, titanium, etc. Bonding metals 4a and 4b made of Kovar alloy, titanium, or an alloy thereof, having substantially the same modulus and a small longitudinal elastic modulus
One end is soldered in a vacuum furnace using silver solder, copper solder, or an alloy containing silver, copper, titanium, etc. as a brazing material. On the other hand, the other ends of the joining metals 4a and 4b are welded to the end of the metal container 1.
It goes without saying that the brazed portion 5 between the joining metals 4a, 4b and the metallized layer 3 and the welded portion 6 between the metal container 1 and the metal container 1 are vacuum-sealed.

When the split metal container integrated in this way is exposed to high temperatures as described above, the thermal expansion coefficient α ₁ of the metal container 1 is generally 1.4 to 1.8×10 ^-5 (1/
℃), whereas the thermal expansion coefficient α ₂ of alumina ceramics 2 and bonding metals 4a and 4b is 4.2 to 7.5×
10 ^-6 (1/°C), a difference in thermal expansion occurs between the two, and stress is generated in the brazed portion 5 and the welded portion 6 due to the difference in thermal expansion. Since this stress is proportional to temperature, the higher the temperature is used, the more likely the connection will break due to stress, and there is a risk that the ultra-high vacuum performance will be impaired. For this reason, the maximum operating temperature of a split metal container is determined by the allowable value of this thermal stress, and it cannot be used at very high temperatures.

The present invention has been made in view of the above points, and its object is to electrically insulate metal containers from each other with alumina ceramics, and to weld them together via the alumina ceramics and a joining metal to be brazed. To provide a split metal container which can be used even at higher temperatures by reducing the thermal stress generated at the joints of brazed and welded parts.

The present invention consists of two ends of a divided metal container, one end of which is brazed to the metallized layer of alumina ceramic having a metallized layer on a part of the surface, and two parts having approximately the same coefficient of thermal expansion as that of the alumina ceramic. A bonding ring formed by combining a first metal having a coefficient of thermal expansion substantially equal to that of the bonding metal and a second metal having a coefficient of thermal expansion substantially equal to that of the metal container is interposed between the bonding metal and the bonding metal. Welding the first metal and the joint ring and the second metal and the end of the metal container, respectively, or forming the end of the metal container thinner than other parts, and forming the end of the metal container with a thinner wall. and each joining metal, a first metal having a coefficient of thermal expansion approximately equal to that of the joining metal, and a second metal having a coefficient of thermal expansion approximately equal to that of the metal container and having the same thickness as the end of the metal container. interposing a joining ring formed by combining a metal, the first metal and the joining ring, and the second metal and the end of the metal container are respectively welded and joined, and the joining metal, the first metal, The intended purpose is achieved by changing the thermal expansion coefficients of the second metal and the metal container in stages.

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings. Incidentally, the same reference numerals are used for the same parts as in the past.

FIG. 2 shows an embodiment of the present invention. In this embodiment shown in the figure, titanium bonding metal 4a, titanium bonding metal 4a,
One end of 4b is silver soldered. In this embodiment, the thermal expansion coefficient between each bonding metal 4a, 4b and the end of the metal container 1 is
The titanium-based alloy 8, which is the first metal, has a coefficient of thermal expansion almost equal to that of the bonding metal 4.
The coefficient of thermal expansion is larger than that of a, 4b and alumina ceramics 2, and forms the metal container 1.
A bonding ring 9 having a shrink-fit structure made of a combination of a high-strength non-magnetic material and a second metal, nickel-based superalloy 7, which has a coefficient of thermal expansion approximately equal to that of SUS304, is interposed, and the bonding ring 9 is made of nickel-based Super Alloy 7
and the ends of the metal container 1 are joined by welding, and the titanium-based alloy 8 and each joining alloy 4a, 4b are joined by welding.
are welded and connected. Joining ring 9
An uneven part 11 is formed at the contact area between the nickel-based superalloy 7 and the titanium-based alloy 8, which form a nickel-based superalloy 7 and the titanium-based alloy 8, and the nickel-based superalloy 7 and the titanium-based alloy 8 are fitted together by the uneven part 11, and are axially aligned with each other. Trying not to slip. Further, a lip portion 1 of the nickel-based superalloy 7 and the titanium-based alloy 8 is formed to protrude outside the container on the axial extension of the joint between the two.
2 are joined by welding, and the welded portion 6 is vacuum-sealed. In addition, the nickel-based superalloy 7 of the joining ring 9
The end portion 1a of the metal container 1 to be welded to the metal container 1 is made as thin as possible so as not to break even if the inside is placed in a vacuum state, and the welded portion 6 with the nickel-based superalloy 7 is vacuum-sealed. It has been stopped. The thicknesses of the nickel-based superalloy 7 and titanium-based alloy 8 that make up the joining ring 9 are set such that thermal stress generated in the brazed portion 5 and welded portion 6 during high-temperature use is reduced.
It is designed in consideration of each modulus of longitudinal elasticity, coefficient of thermal expansion, allowable stress, etc. That is, the joining ring 9
The amount of thermal expansion toward the outer peripheral side 13 of the bonding metals 4a, 4
The plate thicknesses of the nickel-based superalloy 7 and the titanium-based alloy 8 are formed so that the amount of thermal expansion b is approximately equal to the average value of the amount of thermal expansion of the metal container 1.

By having the configuration of this embodiment as described above,
The difference in thermal expansion between the joining metals 4a and 4b and the titanium-based alloy 8, and between the metal container 1 and the nickel-based superalloy 7 is suppressed to a low level, and at the same operating temperature, the thermal stress generated in the welded part 6 of both is compared to the conventional one. It can be reduced to about half. Therefore, since no unreasonable force is applied to the connection portion, there is no risk of breakage, and use at higher temperatures is possible without impairing ultra-high vacuum performance. The same applies to the brazed portion 5, where no thermal stress is applied. Further, since the nickel-based superalloy 7 and the titanium-based alloy 8 are prevented from sliding in the axial direction 10 by the uneven portions 11, thermal stress is not applied to the welded portion 6 of the lip portion 12 of both.

FIG. 3 shows another embodiment of the invention. In this embodiment shown in the figure, the end of the metal container 1 is made thinner than the other parts, and the end of the thin metal container 1 has a wall thickness equal to that of the thin end of the metal container 1. In addition, the length in the axial direction 10 is made as long as possible, and one end of a thin plate container 15 made of a nickel-based superalloy whose coefficient of thermal expansion is approximately equal to that of the metal container 1 is welded.
On the other hand, one end of a bonding plate 14 made of a titanium-based alloy whose coefficient of thermal expansion is approximately the same as that of the bonding metals 4a, 4b is welded to one of the bonding metals 4a, 4b made of titanium, and the bonding plate 14 and the thin plate container are further welded. 15 is also welded. That is, by joining in this way, the joining metals 4a, 4b, the joining plate 14,
The thin plate container 15 and the metal container 1 have a structure in which the coefficients of thermal expansion change in stages.

By having the configuration of this embodiment as described above,
Since materials whose thermal expansion coefficients change in stages are bonded, the brazed portion 5 between the metallized layer 3 and the bonding metals 4a, 4b, and the bonding plate 14 between the bonding metals 4a, 4b and the bonding plate 14.
Thermal stress generated in the welded portion 6 between the metal container 1 and the thin-walled end portion of the metal container 1 and the thin plate container 15 can be reduced in the same manner as in the above-described embodiment, and use at higher temperatures is possible. In addition, the thermal stress generated in the welded portion 6 between the joining plate 14 and the thin-walled container 15 is caused by the difference in thermal expansion between the two because the thin-walled container 15 is thin and is as long as possible in the axial direction 10. This can be absorbed and reduced by the deformation of the thin container 15, and does not pose any particular problem. It goes without saying that this deformation of the thin-walled container 15 can also reduce the thermal stress generated in the other welded parts 6 and brazed parts 5.

According to the split metal container of the present invention described above, one end is brazed to the end of the split metal container and the metallized layer of alumina ceramics having a metallized layer on a part of the surface. Between alumina ceramics and two bonding metals having substantially the same coefficient of thermal expansion, a first metal having a coefficient of thermal expansion substantially equal to the bonding metal and a second metal having a coefficient of thermal expansion substantially equal to the metal container are combined. The first metal and the joining ring are welded to each other, and the second metal and the end of the metal container are welded to each other through a joining ring formed by the metal container, and the end of the metal container is made thinner than other parts. A first metal having a coefficient of thermal expansion approximately equal to that of the joining metal and a first metal having a coefficient of thermal expansion approximately equal to that of the metal container, and a first metal having a coefficient of thermal expansion approximately equal to that of the metal container, and A joining ring formed by combining the end of the metal container and a second metal of the same thickness is interposed, and the first metal and the joining ring are connected to each other, and the second metal and the end of the metal container are connected to each other. welded and joined, the joining metal, a first metal, a second metal,
Since the coefficient of thermal expansion of the metallized layer and the metal container is changed in stages, the difference in thermal expansion of the brazed part between the metallized layer and the joining metal, the welded part between the joining ring and the joining metal, and the welded part of the metal container is reduced. Therefore, the thermal stress generated at the joint is reduced, making it possible to obtain this type of split container that can be used even at higher temperatures.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing a joint of a conventional split metal container, FIG. 2 is a cross-sectional view of a joint of a split metal container showing an embodiment of the present invention, and FIG. 3 is another embodiment of the present invention. FIG. 2 is a sectional view of a joint portion of a split metal container showing an example. 1...Metal container, 2...Alumina ceramics, 3
...metalized layer, 4a, 4b...joint metal, 5...brazed part, 6...welded part, 7...nickel-based superalloy, 8
...Titanium alloy, 9...Joining ring, 11...Irregular portion, 12...Rip portion, 14...Joining plate, 15...Thin plate container.

Claims (1)

[Claims] 1. One end of the divided metal container is brazed to the metallized layer of alumina ceramics having a metallized layer on a part of the surface, and the thermal expansion coefficient is the same as that of the alumina ceramics. In a split metal container formed by joining and integrating two joining metals having substantially equal values, a first material having a coefficient of thermal expansion approximately equal to that of the joining metal is provided between the end of the metal container and each joining metal. A bonding ring formed by combining a metal and a second metal having approximately the same coefficient of thermal expansion as the metal container is interposed, and the first metal and bonding ring are connected to the second metal and the end of the metal container. A split metal container characterized in that each of the two is welded and joined together. 2. The split metal container according to claim 1, wherein the first metal and the second metal are fitted together. 3 The first metal is a titanium-based alloy,
A split metal container according to claim 1 or 2, characterized in that the second metal is a nickel-based superalloy. 4. One end of each end is brazed to the metallized layer of alumina ceramics having a metallized layer on a part of the surface, and the thermal expansion coefficient is approximately equal to that of the alumina ceramics. In a split metal container that is joined and integrated through two joining metals, an end of the metal container is formed thinner than other parts, and a gap between the end of the thin metal container and each joining metal is formed. , formed by combining a first metal having a coefficient of thermal expansion substantially equal to that of the bonding metal and a second metal having a coefficient of thermal expansion substantially equal to that of the metal container and having the same wall thickness as the end portion of the metal container. interposed a joining ring, and the first
and a second metal and the end of the metal container by welding, respectively, and the thermal expansion coefficients of the joining metal, the first metal, the second metal, and the metal container are changed in stages. A split metal container characterized by: