JPS61183180A - Hot load resistant composite structure - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field of the invention] The present invention provides a plasma generation device that directly
This invention relates to a graphite (C)-copper (Cu)-based high heat load resistant composite structure that is used as a member that receives high heat flux loads.

[Technical background of the invention and its problems]

In general, parts that are subjected to high heat flux loads at high temperatures, such as impurity removal plates and plasma position control members of plasma generators, are directly exposed to surface parts that are subjected to high heat flux loads, and the loaded heat is effectively removed. It is a composite structure in which parts are joined together for overall cooling. Graphite is generally used as a surface material for this composite structure from the viewpoints of heat resistance, sputter resistance, thermal conductivity, and radiation loss from the plasma when dust is mixed in as an impurity in the plasma. ing.

Copper or a copper alloy is generally used as a material for the cooling part because of its excellent thermal conductivity.

The problem with such a graphite-copper composite structure is that the coefficient of thermal expansion of graphite is, for example, 6.5×10
K"-(20 to 600°C), the coefficient of thermal expansion of copper is 14.
7×10 K-(20-600°C), and there is a large difference between the two. For this reason, there is a problem in that when the temperature rises due to heat load during bond formation or during use, large thermal stress is generated at the bonded portion of both members.

Generally, methods for joining such composite structures include mechanical methods such as delt tightening, and metallurgical methods such as brazing and diffusion bonding.

In the case of the former mechanical joining method, it is possible to release the difference in thermal expansion between the two parts by taking into consideration the spacing between the two parts of the joint part, and to avoid the generation of thermal stress. Since the degree of adhesion between the two members is not good, heat conduction between the two members is not good, and effective cooling cannot be performed. Furthermore, since graphite is brittle, it cannot be tightened strongly with a delt, and the degree of adhesion is low, making it impossible to obtain a sufficient cooling effect. Therefore, for example, in a plasma generator, if excessive heat input occurs due to plasma disruption, the surface temperature of the graphite of the surface member will rise abnormally, and as a result, surface sublimation or surface Cracks often occur, leading to damage.

On the other hand, the latter metallurgical joining method has excellent adhesion between both parts, so heat is effectively removed and a smooth cooling effect is achieved.However, as the temperature rises and the difference in thermal expansion increases,
Thermal stress occurs on the joint surface.

In particular, in tokamak-type Zolazma generators that operate in an intermittent mode, thermal stress fluctuates over time, and in addition to this, electromagnetic force due to plasma is also superimposed, resulting in areas with weak bond strength and Cracks may occur in the graphite parts in close proximity to the graphite. In such a racked portion, the heat transfer efficiency deteriorates, and there is also the problem of damage such as sublimation and cracking of the graphite surface as described above.

[Purpose of the invention]

The present invention eliminates the above-mentioned drawbacks, and provides a G:7 phyto-copper-based high heat load resistant composite structure that suppresses the occurrence of thermal stress at the joint and its vicinity, and has good heat transfer and excellent cooling action. The purpose is to

[Summary of the invention]

The present inventors have focused on the problems caused by the difference in thermal expansion between the two members, and have created a product that reduces the difference in thermal expansion between the two members, has good thermal conductivity, and can withstand use at high temperatures. The high heat load resistant composite structure of the present invention was developed by interposing an intermediate layer.

That is, in the present invention, a graphite member and a copper or copper alloy member are integrally joined by interposing an intermediate layer made of a C-Cu composite, a W-Cu composite, or a Mo-Cu composite. It is characterized by this.

In the present invention, plate-shaped graphite is usually used as the graphite member.

Further, in the present invention, as the copper member, in addition to Cu alone, C
u-Ag alloy, Cu-Zn alloy, Cu-Zr alloy, etc.
A Cu alloy that has both strength and thermal conductivity is used, and these are usually formed into a plate shape, with water cooling channels provided inside.

In the present invention, the intermediate layer interposed between the graphite member and the copper member includes the C-Cu composite layer 1. or W-Cu composite layer, or Mo-Cu composite oj6.
Ru.

The first characteristic of the intermediate layer of these composites is that it has a coefficient of thermal expansion intermediate between that of graphite and copper, which have very different coefficients of thermal expansion. Furthermore, the second feature is that the intermediate layer contains Cu, so it has good thermal conductivity, and the third feature is that it can withstand use at high temperatures. Complexes are the most effective.

Further, the intermediate layer interposed between the two members is not limited to one layer, but may be two or more layers or multiple layers having different compositions.

In this case, the composition of the composite layer forming each intermediate layer is adjusted, and the intermediate layer located on the graphite side has a coefficient of thermal expansion between that of graphite and copper, and is close to that of graphite. In addition, the intermediate layer located on the copper side is made of a material whose coefficient of thermal expansion is between that of graphite and copper, and is close to that of copper, thereby gradually changing the difference in thermal expansion at the joint and preventing the generation of large thermal stress. It can be prevented.

Next, a method for manufacturing a composite structure of the present invention will be explained.

First, as a manufacturing method for the intermediate layer, the C-Cu composite is deposited, for example, by a single vapor deposition method on carbon fiber obtained by carbonizing at high temperature using polyacrylonitrile, cellulose, pitch, etc. as starting materials.

Coating copper using chemical vapor deposition, electroless plating, or electrolytic plating, weaving the resulting Cu-coated &C fibers in a cross shape, stacking them and applying heat-pressure treatment to form a C-Cu composite. Obtainable. Alternatively, a C--Cu composite can be made by processing carbon fiber into a felt shape and plasma spraying copper powder thereon.

In the case of a W-Cu composite, it is possible to produce a porous tungsten sintered body by compacting tungsten powder and sintering it at a low temperature, and then impregnating it with molten steel to obtain a W-Cu composite. can. Another method is to mix tungsten powder and copper powder, press the powder, and sinter it at a temperature near the melting point of copper.e The method for producing the Mo-Cu composite is the same as the above-mentioned W-Cu composite. As in the case of , tungsten powder can be used instead of molybdenum powder.

The blending ratio of C, W, Mo, and Cu may be selected appropriately according to the required coefficient of thermal expansion. Even if the composites have the same combination of components, multiple composites with different blending ratios may be used. A stacked intermediate layer may be interposed between the graphite member and the copper member.

Further, as a method for integrally joining the graphite member and the copper member with the intermediate layer of the composite interposed therebetween, a brazing method or a diffusion bonding method is used. When brazing is used, Ni solder, Au solder, AK solder, Cu solder, etc. are used to bond between the intermediate layers and between the intermediate layer and the copper member.
For bonding the graphite member and the intermediate layer, a brazing material containing Ti, such as 4.5% Tl-26, 7% Cu-68°8% Ag, is suitable. It is.

In addition, in the brazing process for integration, if there is a difference in brazing temperature, the parts that require high temperature are joined first and then integrated in order, and the brazing temperature is the same for all parts, A good method is to laminate the whole thing, overlap it, and braze it at a constant temperature to join the whole thing at once.

[Embodiments of the invention]

Examples of the present invention will be described below.

(Example 1) Copper was vapor-deposited on carbon fiber obtained by carbonizing polyacrylonitrile fiber, and then electroplated with copper to create Cu-coated C fiber, and the obtained fiber was woven in a cross shape, These were laminated and subjected to heat-pressure treatment to obtain a C--Cu composite with a thickness of 2 m+ and a carbon content of 42 vol. This C-Cu composite is then used as an intermediate layer, and one side of the C-Cu composite is coated with % by weight.
10 isotropic graphite plates (specific gravity 1.79.20~600℃, average thermal expansion coefficient 7. ．．
0x1o-6x-1). In addition, on the opposite side of the C-Cu composite intermediate layer, a pure copper plate with a thickness of 25 mm and a water cooling passageway of 10 m in inner diameter was placed through a thin plate of Ag solder, and the total thickness was 500 mm. ,! A load of i'/cm2 was applied, and heat treatment was performed at 840° C. for 20 minutes in a vacuum to join them together.

(Example 2) A porous tungsten sintered body was impregnated with molten steel to form a W-Cu composite having a copper content of 30% by weight, and a plate material with a thickness of 2 cm was cut from the W-Cu composite. Next, a 10 m thick graphite plate was placed on one side of the W-Cu composite with a thin plate of Ti-Cu-Ag wax as an intermediate layer, and the same as in Example 1 was placed on the other side of the intermediate layer. Ag
It was placed through the thin plate of filter 5, a load of 50,017 cm2 was applied to the whole, and heat treatment was performed in vacuum at 840° C. for 20 minutes to bond them together to obtain a composite structure.

(Example 3) A porous molybdenum sintered body was impregnated with molten steel to form a copper-containing i
Two types of Mo-Cu, 25% by weight and 40% by weight
A composite was manufactured, and plates each having a thickness of 1 m+ were cut out from it.

A thickness of 25 m with a water cooling channel formed in the same way as in Example 1.
The copper content is 4.
A Mo-Cu composite intermediate layer was placed, and a Mo-Cu composite layer with a Cu content of 25% was placed on top of the intermediate layer through an N1 thin plate.
A Cu composite intermediate layer was placed to form a two-layer structure, and a pressure of 50,017 cm2 was applied from above, and heat treatment was performed at 950° C. for 20 minutes to bond them together. After cooling the whole, a thin plate of Tl-Cu-Ag brazing filler metal is placed on top of the Mo-Cu composite intermediate layer with a Cu content of 25% by weight to a thickness of 10% by weight.
Stack m graphite plates, 50097 cm2 from above
The whole was joined together by heat treatment at 840° C. for 20 minutes to obtain a composite structure.

(Comparative example) A graphite plate with a thickness of 10+m similar to that in Example 1 and a pure copper plate with a thickness of 25 meters with a water passage formed therein were
They were stacked on top of each other with thin plates of Ag-based brazing material interposed therebetween, and heat treated at 840° C. for 20 minutes under a load of 500 yz for 20 minutes in a vacuum to bond them.

Regarding the above four types of composite structures, while cooling water (inlet temperature 20°C, flow *5J115)') was flowing through the passageway on the copper member side, the surface of the graphite plate was exposed to 50% by electron beam.
A high heat flux load cycle test was conducted in which heating-cooling was repeated 250 times by applying a heat flux of 00 W/crn2 for 60 seconds and pausing for 30 seconds.

After this test, the occurrence of cracks in and around the joints of the test pieces was examined, and the results are shown in the table below.

〔Effect of the invention〕

As explained above, according to the high heat load resistant composite structure of the present invention, an intermediate layer having a thermal expansion coefficient intermediate between the graphite member and the copper member and capable of withstanding high temperatures is integrally interposed between the graphite member and the copper member. Since the thermal stress is alleviated, there is no cracking at the joint or its vicinity even when subjected to repeated high heat flux loads, and it has excellent adhesion.
Since the intermediate layer has good thermal conductivity, it has a remarkable effect in that it can perform effective cooling.

Claims (2)

[Claims] (1) A graphite member and a copper or copper alloy member are integrally joined with an intermediate layer made of a C-Cu composite, a W-Cu composite, or a Mo-Cu composite interposed between the graphite member and the copper or copper alloy member. A high heat load resistant composite structure featuring: (2) The high heat load resistant composite structure according to claim 1, wherein the intermediate layer is composed of two or more composites having different compositions.