JPH03218986A - Method for joining carbon material - Google Patents

Abstract

PURPOSE:To improve bonding strength, heat, shock and corrosion resistances by interposing an insert member having iron layers at both sides and a binder contg. copper set at both sides of the member between a carbon material and a metal or a similar carbon material and joining them. CONSTITUTION:An insert member C of >=1mm thickness having iron or iron alloy layers 1, 2 of <=1mm thickness at both sides and based on a metal and/or an alloy thereof having <=7X10<-6>/ deg.C coefft. of thermal expansion and a copper or copper alloy binder D contg. >=25wt.% copper set at both sides of the member C are interposed between a carbon material A contg. >=0.2 wt.% carbon and a metal or a similar carbon material B other than carbon steel and they are joined by heating in an atmosphere of gaseous N2.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for joining carbon materials, and more specifically to carbon materials containing 0.2% by weight or more of free carbon, such as carbon materials, carbides, and metals. (hereinafter abbreviated as carbon material) and the carbon material, carbide, or metal.

[Conventional technology]

Carbon materials have a wide range of properties and are widely used in industrial applications.

Its form is generally defined as a carbon material, but more specifically, graphite alone, carbon alone, carbides with various metals, composite materials containing these, or metals containing a large amount of carbon. It is commonly used.

For example, graphite alone is used as a structural material for nuclear fission reactors and fusion reactors due to its excellent heat resistance and thermal shock resistance at high temperatures, and its high thermal conductivity and good lubricity. For this reason, it is used in mold sleeves for casting, in hot press molds due to its excellent high-temperature strength, in spuntering targets due to its high conductivity, and as a material for the internal structure of semiconductor manufacturing equipment.

Other uses for carbon alone include lining materials for chemical equipment due to its corrosion resistance, and electric brush materials commensurate with its electrical resistance.

However, in these applications, there are problems such as metal fittings for attaching the carbon material to a predetermined position and bonding with metal wiring for conducting electricity.

As carbides, for example, titanium carbide is used as a main component of hard heat-resistant alloys such as cermets due to its excellent high-temperature strength, silicon carbide is used for heat exchanger partition walls due to its corrosion resistance, and tungsten carbide is used for heat exchanger partition walls. Due to its high hardness, it is used for chip materials, cam contact parts, die materials, piston heads, etc.

Furthermore, in the case of composite materials, carbon bases are impregnated with metals with high electrical conductivity to create electric brushes that take advantage of their lubricity and conductivity, and carbon and resin are composited to create sealing materials or electrical discharge machining electrode materials. It is also used as a.

In this way, the uses of carbon materials are expanding widely and steadily.
Although it is expanding, there still remain problems in actually promoting industrialization.

In general, the demand for larger and more highly functional industrial equipment is increasing day by day.
This is not always easy due to restrictions due to the nature of the manufacturing equipment or the functions of each material. Furthermore, even when creating a casting mold with a complex shape using a so-called near shave, there are restrictions on the processing and shaping.

In addition, even if the characteristics of carbon materials are fully utilized, there are many cases where even higher characteristics are required. For example, in the structural materials of nuclear fuel reactors and nuclear fusion reactors, the thermal load applied to graphite as a structural material is large. Although forced water cooling may be required, water cooling of the graphite material itself is impossible due to its water permeability.
Requires combination with metal piping for water cooling.

In addition, there are many cases in which the expected properties of a carbon material during use are only required in the front (back) layer;
The base layer below (above) the back layer may be made of a material different from that of the front (i!) layer. Further, it may be necessary to use metal fittings to attach the carbon material to a predetermined position, or to connect it to metal wiring for passing electricity through the carbon material.

The most common means to meet such requirements is to bond carbon materials and other metal materials, or to bond carbon materials together, and this bonding provides each of the above functions and is a means of meeting the requirements through a comprehensive composite function.

In response to such demands, various methods have been proposed in the past for joining the above-mentioned materials together.

However, in many of the conventional bonding methods, the bonding strength is insufficient, or the heating temperature is limited depending on the bonding material, or the operation is complicated and time-consuming. Particularly when joining large materials, cracks may occur due to the difference in expansion coefficient between the carbon material (which generally has a small coefficient of linear expansion) and the metal material, which has a large coefficient of linear expansion. There are very few ways to do this.

[Problem to be solved by the invention]

The problem to be solved by the present invention is to be able to bond carbon materials together or carbon materials and metal materials with as simple an operation as possible and with high bonding strength, heat resistance, impact resistance, and corrosion resistance, especially for large-sized materials. The aim is to develop a new joining method that can be used even if the material is not used.

[Means to solve the problem]

(A) a carbon material containing 0.2% by weight or more of carbon, and (B)
When joining metals or the above carbon materials (excluding joining carbon steel to carbon steel), (C) insert metals or (and) metal alloys with a coefficient of linear expansion of 7 × 10-”/'C or less. (D) Iron or iron alloy is interposed between the carbon material and the insert material (C); (E) Copper or copper alloy containing at least 25% copper by weight is used as a bonding material. Solved by joining.

[Function and structure of the invention]

In the present invention, when bonding carbon material (A) and carbon material (B) or carbon material (A) and metal (B), there is a linear expansion coefficient (hereinafter abbreviated as CTE) between them. 7X10-'
Use an insert material (C) in which an iron layer (film) is deposited on the surface of the following metal material, and furthermore, when bonding, at least 25% copper is coated on both sides of the insert material (C).
Bonding material made of copper or copper alloy containing % by weight or more (E)
The basic method is to join (A) and (B) by heating in the combination of A-E-D=C-E-B.

Furthermore, the operation and configuration of the present invention will be explained in detail using the drawings.

Fig. 1 is an example of joining carbon material (A) and carbon material (B), and shows an example of joining carbon material (A) and carbon material (B), and insert material (
This is a simulated example of bonding using bonding material C) with a bonding material containing copper (D) interposed on both sides thereof.

Figure 2 is an example of joining carbon material (A) and metal (B), using an insert material (C) with iron scraps (1) on the surface facing the carbon material, and copper on both sides. This is an example in which the bonding material (D) contained therein is interposed.

In this case, even if iron scraps are formed on both sides of the insert material (C), the same effect will be obtained.

In this case, the carbon materials (A) and (B) are carbon materials containing 0.2% by weight or more, preferably 0.5% by weight or more of free carbon, and of course do not contain hydrous carbon, hydrocarbons, etc. do not have. Here, a carbon material containing 0.2% by weight or more of free carbon means that substantially no free carbon is present at the time of bonding.
．． The carbon material is present in an amount of 2% by weight or more, and does not necessarily need to contain the above amount of free carbon before bonding. In order to bond, the difference in concentration from the amount of carbon in the iron foil needs to be at least 0.2% by weight, so if it is less than 0.2% by weight, no bridging effect will occur between the carbon and the carbon body. Also, since it is weak, sufficient bonding strength cannot be achieved.

Specifically, examples include those made of graphite alone, those made of carbon alone, mixtures of both, carbides of various metals, and composites with other materials that have at least one of these as a component, as well as various other ceramics. Alternatively, a metal containing a predetermined amount of free carbon may be used. Note that free carbon refers to a substance consisting of a single carbon, not a compound.

Examples of carbides of various metals include tungsten carbide,
Preferable examples include titanium carbide, silicon carbide, carbon steel, various alloy steels, etc. Composites include carbon fiber-reinforced carbon materials, so-called C/C composites, and carbon materials. Preferred specific examples include materials impregnated with metals, such as carbon materials melted and impregnated with iron, copper, etc. at high temperatures, or mixed and pressure-molded.

Next, the metal material (B) to be joined includes a wide variety of metals, and metals include alloys. Preferred metals include copper, tungsten, molybdenum,
These include iron, silicon, stainless steel, Hastelloy, Inconel, carbon steel, various alloy steels, and ferroalloys.

The shape and size of the carbon material and metal material to be joined are not limited in any way as long as the material is as described above, and any suitable shape and size may be used.

An insert material (C) is used to join these carbon materials together or to join a carbon material and a metal material.

The insert material (C) may be any metal material with a CTE of 7XlO-''C or less, such as a plate, piece, thin plate, or foil of molybdenum or iron-molybdenum alloy.
It is preferably used as a base material that has an iron layer on at least one surface. Insert material (C)
The larger the difference in expansion coefficient between the mating materials (A) and (B), the greater the thickness, and in some cases it is greater than lm/1.

In the present invention, it is not necessarily necessary to form iron scraps in advance, and a piece of iron foil may simply be interposed, but it is preferable in terms of work efficiency to form an iron layer on the metal in advance.

As long as this iron scrap is evenly attached,
It may be attached by any method. Examples include electroplating, chemical plating, vapor deposition, CVD, metal spraying, and the like.

The thickness of this iron scrap is usually less than III/II1, particularly preferably less than 0.2 mm/m.

It should be noted that when bonding a carbon material (low CTE) and a metal material (high CTE), it is proposed in a patent application filed in 1986 that a molybdenum foil, which has a CTE very close to that of the carbon material, be interposed as a buffer layer between the two. No. 258155. However, when only molybdenum is used as in this known method, the bonding effect is absent or weak, and is substantially impractical.

Therefore, foils, thin plates, etc. of brazing materials such as nickel, titanium, or copper are further used above and below the molybdenum to create a bridging effect, making it a practical bonding technique. In contrast, the present invention is characterized by a novel combination in which iron is used in combination with a metal having a CTE of 7x10-''C or less, such as molybdenum, and a copper layer is further provided.

Although it is technically possible to use this iron scrap in the form of foil, in order to improve work efficiency, reliability, and cost savings at the joining work site, molybdenum or It is particularly preferable to provide iron scraps. In particular, when joining curved materials, irregularly shaped materials, precisely processed materials, etc., it is extremely important to provide an iron layer in advance, and iron scrap can be reliably provided.

During the joining work, insert material (C) with iron scraps or an iron layer interposed thereon is further coated with copper such as a copper plate or copper foil.
In the presence of the bonding material (D) containing 5% or more, preferably both surfaces are sandwiched and heated under reduced pressure. That is, in the above operation, the carbon material (A) is bonded in an arrangement of one copper, one iron, one iron, one iron, one copper, and one copper (B), and in particular, between the iron scraps, [carbon one copper one iron - (copper) → The alloy crystallizes and maintains a strong bond. In this case, it is possible to use a large number of pores in the iron foil, and there is also a method in which copper flows between the Mo and the iron through the pores, directly forming a strong bonding layer. The present inventors have previously proposed that ``When bonding a carbon material containing 0.2% by weight or more of free carbon and the carbon material or metal material, the use of a bonding material containing at least 25% by weight of copper. We have invented a new joining method based on the principle of "a joining method in which iron or iron alloy is present between the materials to be joined" and have already filed an application (Japanese Patent Application No. 1105).

This invention is [carbon material, copper, iron foil, copper, carbon material or metal]
The gist of this method is to join carbon materials by arranging carbon materials, and it is extremely useful industrially. The strain caused by the difference in expansion between the metallic and carbonaceous parts cannot be fully absorbed, resulting in cracking and cracking at times.
Peeling phenomenon may occur at the bonded surface.

The present invention has been developed and improved in order to compensate for the above-mentioned drawbacks of the earlier application, which may occur at times, especially for joining large joining surfaces or materials used at relatively high temperatures. There is a difference. That is, the basic aspect of the present invention is
[Carbon material-Cu-Fe-Mo-Fe-C
u-carbon material] or [carbon material-Cu-Fe''-Mo-F
e-Cu - metal material] (However, in the case of metal material, the "Fe" layer can be omitted), and carbon material - Cu - Fe
The Mo part is an essential part of the structure of the present invention, and this part is significantly different from the previous application. The joined bodies joined by the method of the present invention or the method of the present invention are widely used in various fields. For example, the conjugate is extremely useful as a member of a nuclear fusion reactor, particularly as a first wall or limiter, or as a member for aircraft, rockets, and space equipment. In addition, the method of the present invention includes bonding copper electrodes and graphite materials, bonding carbon electrodes and copper conductive wires, attaching water cooling mechanisms to electrodes, reflectors, especially silicon carbide reflectors, submersible pumps, and mechanical seals. It is also effectively used for adhesion on sliding surfaces, etc. [Effects] According to the present invention, even in large-area bonding work, it is possible to perform strong bonding with almost no cracking or peeling phenomena on the bonded surfaces, opening up new applications. ．． [Examples] Hereinafter, embodiments of the present invention will be specifically illustrated by way of Examples.

Example 1 (Example of joining graphite material and copper) The joining operation was performed in the following two steps. (a) First, carbon material (isotropic graphite material manufactured by Toyo Tanso 2rrG-
43J) and a metal molybdenum plate were joined via a copper (acid-free copper) foil and an iron plate, as shown in Figure 3. However, the sizes of these are as follows.

Carbon material: 28X28X15m/m, OD copper foil in Figure 3: 0.1m/s, 02) Iron plate in Figure 3: 0.1■
/1, 0 in Fig. 3 Molybdenum plate: 0.6 m/m, (b) in Fig. 3 Overlap the above and place a weight of about 500 g above the carbon material 00,
The temperature was raised to 1200°C in a nitrogen atmosphere, held for 4 minutes, and then slowly cooled.

(Example) Next, as shown in Figure 4, the sample obtained in (a) above was soldered to a copper plate 06) (30x30x25
Ill/lI1), the temperature was raised to 950°C under a nitrogen atmosphere, maintained for 4 minutes, and slowly cooled. After heating the bonded body of carbon material 00 and copper plate (10) obtained by the operations (a) and (b) above to about 500°C, it was put into water and quenched, but no peeling or cracking occurred. There were no cracks, and the joint was strong. The gold solder used in the step (1) is an alloy with a composition of (Cu 66 /^U 34% by weight) and has a melting point of 950 to 990°C. Therefore, the melting point of pure copper (1040°C) The temperature is 50 to 100°C lower than that of 100°C, and the bonding can be performed without damaging the copper plates that are the objects to be bonded. This takes into account the above.

Example 2 Composite material (carbon/carbon) as carbon material [rCX manufactured by Toyo Tanso Co., Ltd.
-2002J), a zygote was obtained under almost the same conditions and operations as in Example 1. However, in this example, carbon material: 28X28X15 gg/m (material to be joined rC
X-2002J) Residual wax foil: 0.1 m/II (Cu 66X.
Au 34 weight χ) Iron foil: 0.1 m/s Molybdenum foil: 0.6 m/m Gold solder foil: 0.1 m/m (same as above) Copper: 28x28x25 Joining operation in the order of II/II (materials to be joined) The temperature was raised to 950°C in nitrogen gas at once, held for 4 minutes, and then slowly cooled to complete the bonding operation without dividing into two steps. The obtained bonded body was left at room temperature for about one month, but there was no deterioration such as peeling, and even when it was heated to 500°C and placed in water, no peeling or cracking was observed. ．． Comparative Example 1 A bonded body obtained by performing the same process as in Example 2 except for the Mo layer was peeled off and broken at the bonded surface on the carbon side when the bonded body was taken out at room temperature.

This is a (carbon/carbon) composite r CX-2002
The coefficient of thermal expansion (CTE) of J is 2 × 10-'/''C
This is because the CTE of copper is 17X10-h/''C, which is a significant difference between the two. Example 3 In the same manner as in Example 2, stainless steel (200X5
A conjugate of (0X10 −/s, SOS 316) and a (carbon/carbon) composite r CM-2002 J was obtained.

However, in this example, since the metal side, which is the material to be joined, is stainless steel with a relatively high melting point (approximately 1400°C), copper (acid-free copper) (
(melting point 1080°C) can be used.

Therefore, the order of the joining materials is as follows. Carbon material:
180x50x20 m/m (material to be joined rcX-200
2J) Molybdenum foil: 0.6 mm/@ Stainless steel: 200 x 50 x 30 m/m (joint material SOS 316) However, *l is iron foil as it is, $2 is iron foil coated with copper in advance by electroplating method I used something.

The samples were stacked in the above order, a weight was placed on top, a nitrogen atmosphere was created in the furnace, the temperature was raised, the temperature was held at 1100°C for 4 minutes, and then the temperature was slowly cooled.

This example is an example of bonding between materials that are relatively long and have a large CTE difference, and in many experiments using conventional methods, peeling and cracking phenomena have occurred. By the method of the invention, it was possible to perform bonding without any peeling or cracking.

Example 4 This Example 4 is an example of manufacturing a test member for evaluating whether or not the joined body obtained by the method described in Example 3 can be used as a material for a nuclear fusion reactor. When used as a heat-resistant interior material in a furnace, especially the first wall, which requires the most severe heat resistance, properties such as strength at high temperatures, low outgassing, and resistance to chemical erosion caused by H2 gas are required. Ru.
Carbon fiber/carbon matrix composite (rCX-200
2": Toyo Tanso) is used by attaching it to the furnace body with the metal (stainless steel) side facing the reaction atmosphere and the back facing the metal (stainless steel) side. The above-mentioned composite material itself has the above-mentioned properties and has traditionally been used for this first wall.
Since the joined body of Example 3 has metal firmly joined to it, it is easy to attach other members when used as the first wall. That is, since the back surface of the joined body obtained by the method of Example 3 is made of metal, it is possible to freely and firmly attach the mounting vault to the main body, and it is also possible to weld water cooling piping to this metal. , drilling, etc. can be carried out freely. The method of attaching this water cooling pipe is based on Example 7.

Example 5 The joined body obtained by the method described in Example 3 can be used as an aircraft member.

In other words, carbon fiber/carbon matrix composite materials are recently being used as space equipment and aircraft components due to their ultra-light weight and high strength properties, but the most technically problematic material at present is: This is a method of attaching this type of composite material to a strength structure.

Figure 5 (a) shows some examples of where they are used for aircraft, and (21) in the figure is the external tail plate (Ou
t Board Tail), (22) is the lavatory
Module part (Lavatory Module), (
23) is the inboard flap part (Inboard Fl
ap), and the joining method of the present invention can be effectively applied to attaching these members.

Figure 5 (mouth) shows an example of how to install it.
When attaching the carbon fiber/carbon matrix composite material (32) to the strong structural frame member (31), metal is used for the bonding surface (33), and the method of the present invention is applied to this bonding. . Note that (34) indicates a mounting bolt.

The method of the present invention enables strong, large-area bonding, making it possible for the first time to apply it to aircraft, which require the highest level of safety.

Example 6 (Example of joining electrode copper and graphite material) Graphite material is used as an electrode for metal smelting (for example, aluminum) or for electrolysis of hydrogen halides (for example, hydrogen chloride, hydrogen fluoride).

The main reason why carbon materials are used for this purpose is that carbon materials have high heat resistance, high corrosion resistance against chemicals, and high electrical conductivity. However, connectivity with steel, which is the wiring material, has often been a problem in the past.

Traditionally, carbon and steel materials were polished together and then brought together.
Mechanical integration using bolts and nuts is generally used, but this has the disadvantage that chemical vapor and water droplets can enter the mating surfaces with continuous use, gradually increasing contact resistance. By the method of the present invention, the bonding area can be increased, and the carbon material and the metal material are completely and firmly integrated, so that the connection resistance is low and there are few failures due to continuous use.

FIG. 6 shows an example of joining a carbon material (t-pole) and a steel material (wiring wire).

In Fig. 6, (41) is steel material (wiring), (42) is copper bolt, (43) is flexible graphite sheet (Toyo Tanso RPP SO J), (44) is graphite material (graphite electrode, Toyo Tanso rlG-11 J), (45
) indicates the joint surface.

In the form shown in FIG. 6, the graphite material (44) and the steel material (wiring) (41) were joined by the method of Example 2.

In order to accommodate the expansion and contraction of the copper bolt (42), a flexible graphite sheet (43) was interposed.

Example 7 (Example of joining SiC and copper material) A reflecting mirror for short wavelength light (wavelength of 100 nanometers or less) is particularly required to have heat resistance. Since the theoretical reflectance is low in this wavelength range, unreflected light remains on the mirror body, so a material with high heat resistance (for example, silicon carbide) is used as the material for forming the mirror body, but in addition, the mirror body itself In order to avoid optical axis distortion due to temperature rise, a water cooling mechanism is provided on the surface opposite to the mirror surface. An example of this is shown in FIG. However, (51) in Fig. 7 is a material for a reflecting mirror, with the inside being a carbon material and the outside being covered with SiC. Also (52)
is a joint surface, and (53) is a cooling mechanism, which is entirely made of copper. (53-1) indicates a steel pipe for cooling water, and (53-2) indicates a strain absorption groove.

Bonding conditions: SiC material for reflector (SiC 12 manufactured by Toyo Tanso as core material)
A silicon carbide layer was deposited on the surface by CVD method of about 300p) (100x50xl5/-) However, the intermediate layer was joined in the same order as in Example 1, and a two-step joining method was used. 140x50x50s/
m) Oxygen-free copper bonding reaction conditions are also the same as in Example 1. Results: When the bonded product was heated to approximately 700°C, placed in water, and rapidly cooled, it was found that it did not peel or crack, and was extremely resistant to thermal shock. However, after carefully examining the deviation of the optical axis on the reflective surface after cooling, we found that
Since a slight arching change in the joined body was observed due to the difference in thermal expansion between the carbon material and the steel material, a strain absorbing groove (53-2) was provided in the direction transverse to the long axis, as shown in Figure 7. In the end, I was able to prevent this.

[Brief explanation of drawings]

Figures 1 and 2 show simulated structural diagrams for explaining the method of the present invention, and Figures 3 and 4 also show similar structural diagrams. FIG. 5 is an explanatory diagram when the method of the present invention is applied to aircraft parts, and FIG.
The figure shows a drawing for explaining an example of bonding electrode copper and graphite material. Furthermore, Fig. 7 shows an explanatory diagram of a case where a cooling device is bonded to a reflecting mirror using the method of the present invention. 11... Carbon material 41... Steel material (for wiring) 12... Copper foil 42... Copper bolt 13... Iron plate 43... Flexible graphite sheet 14... Molybdenum plate 44 ...graphite material (electrode) 15...gold solder 45...
・Joint surface 16...Copper plate 2l...External tail plate 22...Lavatory module 23...Inboard flap 3l...Strength structural frame material 32...Composite material 33...Joint surface 34 ···bolt

Claims (14)

[Claims] (1) In joining (A) a carbon material containing 0.2% by weight or more of carbon and (B) metal or the above-mentioned carbon material (excluding the joining of carbon steels), (C) Linear expansion A metal or (and) metal alloy with a coefficient of 7 × 10^-^6/℃ or less is used as the insert material, and (D) iron or iron alloy is used between the carbon material (A) and the insert material (C). (E) A method for joining carbon materials, characterized in that the joining is performed by interposing copper or a copper alloy containing at least 25% by weight of copper as a joining material. (2) A metal or (and) whose coefficient of linear expansion is 7×10^-^6/℃ or less in the joining method in claim (1).
At least one side of the metal alloy (C) is coated with iron or iron alloy (E).
) A joining method characterized by using a layer formed in advance. (3) In the joining method in claim (1), iron or an iron alloy (D) and a copper or copper alloy layer (E) containing at least 25% copper by weight are used. A joining method characterized by: (4) In at least one of claims (1) to (3), the metal or (and) metal alloy (C) having a coefficient of thermal expansion of 7 x 10^-^6/°C or less is molybdenum. A joining method characterized by: (5) A method for joining carbon materials, characterized in that the copper or copper alloy (E) containing at least 25% copper by weight as set forth in claim (1) is gold solder or (and) silver solder. (6) In claim (1), the carbon material (A) or (B) containing 0.2% by weight or more of carbon includes an isotropic carbon material, an anisotropic carbon material, and free carbon. Bonding characterized by being at least one of metal carbide, cemented carbide, cermet, etc., a carbon fiber-carbon matrix composite, a composite of carbon mixed with or impregnated with metal, and a composite of ceramic mixed with carbon. Method. (7) Claim (1) is characterized in that the metal (B) is at least one of copper, tungsten, molybdenum, iron, silicon, stainless steel, Hastelloy, Inconel, various alloy steels, and iron alloys. joining method. (8) A joined body joined by the joining method of claim (1). (9) A nuclear fusion reactor using the zygote according to claim (8) as an internal heat-resistant member. (10) An aircraft using the joined body according to claim (8) as at least a part of its members. (11) An electrode member using the conjugate according to claim (8) in at least a part of the member. (12) A reflecting mirror using the conjugate according to claim (8) as at least a part thereof. (13) A reflecting mirror body using the bonded body according to claim (8) on two sides. (14) A pump using the bonded body according to claim (8) as a sliding member of its liquid seal portion.