JPH01290567A - Method for bonding carbon materials - Google Patents

Abstract

PURPOSE:To bond carbon materials with high bonding strength with simple operation by interposing iron (alloy) between materials to be bonded through the intervention of a bonding material contg. a specified amt. of copper at the time of bonding carbon materials contg. a specified amt. of free carbon or bonding the carbon material and a metallic material. CONSTITUTION:A bonding material 4 contg. >=25wt.% copper and other metallic components is interposed between the carbon materials 2 contg. >=0.2wt.% free carbon in an airtight vessel 1, and further iron or an iron alloy 5 is placed between the bonding materials 4. Under such conditions, the assembly is heated by a heater 3 while being pressed by a weight, a jig 6, etc. By this process, an iron-based alloy is crystallized in the bonding material 4 between the carbon material 2 and iron or the iron alloy 5. Consequently, the carbon material 2 and the bonding material 4 and the iron or the iron alloy 5 and the bonding material 4 are firmly attached by the bridging effect, and the materials are integrally bonded. In addition, symbol 7 in the figure shows an iron alloy layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for joining carbon materials, and more specifically, the present invention relates to a method for joining carbon materials, and more specifically, a method for joining carbon materials containing 0.2% by weight or more of free carbon, and the carbon material or metal material. Concerning the method of joining.

[Conventional technology]

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

Its form is defined in -a as a carbon material, but it is usually used in finer details (i.e. graphite alone, carbon alone, carbides with various metals, or composite materials containing these). be.

For example, graphite alone is used as a structural material for nuclear fuel reactors due to its excellent thermal shock resistance at high temperatures, and due to its high thermal conductivity and good lubricity,
It is used in casting molds and sleeves, in hot press molds due to its excellent high-temperature strength, and in sputtering targets due to its high conductivity.

Carbon-based materials have applications such as being used as lining materials for chemical equipment due to their corrosion resistance, and as electric brush materials due to their electrical resistance.

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, and piston heads.

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.

As described above, the uses of carbon materials are widely and steadily expanding, but problems still remain in order to actually advance industrialization.

-C. The demand for larger and more sophisticated industrial equipment is increasing day by day, and it is not always easy to create each component as a single piece due to restrictions due to the nature of the manufacturing equipment or the functions of each material. isn't it. 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 properties of carbon materials are fully utilized, there are many cases where even higher properties are required. For example, in nuclear fuel reactor structural materials, the thermal load placed on graphite as a structural material is large, and forced water cooling is required. However, water cooling of the graphite material itself is impossible due to its moisture permeability, and a combination with metal piping for water cooling is required.

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 different material than the front (back) layer.

The most common means to meet these requirements is to bond carbon materials and other metal materials, or to bond carbon materials together.
This connection provides each of the above functions and is a means for dealing with complex functions.

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

However, all of the various conventional bonding methods have insufficient bonding strength, or have limitations due to the bonding material.
Alternatively, there are many methods that require complicated operations and time, and there are currently very few methods that are satisfactory.

[Problem to be Solved by the Invention] The problem to be solved by the present invention is to bond carbon materials of this kind or carbon materials and metal materials with as simple an operation as possible and with high bonding strength, and which also has heat resistance and impact resistance. The objective is to develop a new joining method that can obtain a joining material with excellent properties and corrosion resistance.

[Means for solving the problem] This problem is solved when joining a carbon material containing 0.2% by weight or more of free carbon and the carbon material or metal material (except when joining carbon steel together), copper at least 2
Heating under vacuum, inert gas, or in the presence of flux with iron or iron alloy present between the materials to be joined with the interposition of a joining material containing 5% by weight or more and other metal components. solved by.

[Operation and configuration of the invention] In the present invention, when bonding carbon materials together or carbon materials and metal materials, iron is added to the bonding material containing at least 25% by weight of copper and other metal components. Or its alloy, preferably by interposing a thin plate or foil with a thickness of 1 mm or less and heating it under vacuum, an inert gas atmosphere, or in the presence of flux, so that iron is applied to the contact surface of the workpiece on the carbon material side. It crystallizes the alloy of the system, thereby obtaining a strong bond. Furthermore, the operation of the present invention will be explained in detail using the drawings.

For convenience of explanation, FIG. 1 shows a simulated explanatory diagram when carbon materials are joined together. In Figure 1, (1) is an airtight container, (
2) is carbon material, (3) is heater, (4) is bonding material, (
5) indicates iron or iron alloy. A bonding material (4) is interposed between the carbon materials (2), and iron or an iron alloy is present in this bonding material. When heated with a heater (3) while applying pressure with a weight or jig (6) as necessary, iron-based material is formed in the bonding material (4) between the carbon material (2) and iron or iron alloy (5). The alloy crystallizes, and due to the bridging bonding effect, the carbon material (2) and the bonding material (4), as well as the iron or iron alloy (5) and the bonding material (
4) is firmly joined and joined together as a whole. Figure 2 shows the joined state.
In FIG. 2, (7) is the crystallized iron alloy layer.

In this case, the inside of the airtight container (1) may be evacuated or an inert gas may be introduced. Further, when using flux or using resistance heating, it is not necessary to use the airtight container (1).

The method of the present invention will be explained in more detail below.

In the present invention, the materials to be joined are carbon materials or carbon materials and metal materials. However, this does not include the case where carbon steels are joined together, especially when carbon steels are joined together. The carbon material at this time is 0.2% by weight of free carbon, preferably 0.
．． It is a carbon material containing 5% by weight or more, and of course does not contain hydrated carbon or hydrocarbons. Here, the carbon material containing 0.2% by weight or more of free carbon refers to one containing at least 0.2% by weight or more of carbon that binds and diffuses with iron or iron alloy during heating. For example, WC, a type of cemented carbide, is stable at temperatures above 1200'C, but is unstable (
It contains about 0.4% carbon (free), which contributes to bonding, and the same goes for other carbides. In this case, if the free carbon content is less than 0.2% by weight, no bridging effect will be produced between the carbon material and the carbon material, which is not desirable. Specific examples include graphite alone, carbon alone, carbides of various metals, composites with other materials containing at least one of these as a component, and various other ceramics and metals. It may also contain a predetermined amount of free carbon. Preferred examples of carbides of various metals include titanium carbide and silicone carbide, as well as carbon steel and various alloy steels, and composite materials include carbon materials impregnated with metals, For example, carbon, iron, antimony,
Preferred specific examples include products obtained by melt-impregnating lead alloys, aluminum, etc. at high temperatures, or by mixing and press-molding them.

Further, the metal material to be joined includes a wide variety of metals, and metals also include alloys. Preferred metals include, for example, copper, tungsten, molybdenum, iron, silicon, stainless steel, Hastelloy, and carbon steel.

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

The bonding material used in the present invention contains at least 25% by weight of copper, preferably 40% by weight or more, and other metals as other components, and may be 100% copper. Typical examples are so-called gold wax, brass wax,
I can give an example of silver solder.

In this case, representative examples of other metals include gold, zinc, silver, etc., and these may be used alone or in combination of two or more. If this copper removal does not reach 25% by weight, the above-mentioned bridging bonding effect between the materials will be weak, resulting in a decrease in bonding strength, which is undesirable.

In addition, iron or iron alloy acts as a kind of core material in this joining method and remains in the joined product, so its shape is particularly suitable for thin plates, plate-like bodies, foil-like bodies, etc. Preferably, the thickness in this case is less than 1, preferably 0.5
mm or less. In this case, if it becomes too thick than the first cylinder, the impact resistance of the joint may deteriorate, which is not very desirable.

When carrying out the method of the present invention using these materials,
As already explained in FIG. 1, a thin plate or foil-like body (5) of iron or iron alloy, preferably, is used as a core material, and the materials to be joined (2) are placed above and below the core material through the joining material (4). . As the bonding conditions, either a vacuum, an inert gas atmosphere, or the presence of flux is used, or two or more of these methods are used in combination.

This is to prevent the surface of the bonding material from being oxidized. In this case, under vacuum refers to a state in which the amount of oxygen is so small that there is virtually no effect of oxygen, and it is usually 10-3 atmospheres or less, preferably about 10-4 atmospheres, and the inert atmosphere is a normal atmosphere. An inert gas such as argon or nitrogen gas may be used.

Further, any flux may be used as long as it can cover the bonding material well and block contact with oxygen, and representative examples include borax, boric acid, borofluoride, and mixtures thereof. When using this flux, it may be carried out in the air or in the above atmosphere. Note that the flux is volatilized by evaporation, decomposition, etc. under heated bonding conditions and does not remain on the bonding surface.

Heating conditions can be determined appropriately depending on the materials to be joined and the type of material to be joined, and in principle, the temperature is such that the iron alloy can crystallize in the material to be joined, and is usually higher than the softening point of the material to be joined. The temperature is high, preferably around 50°C.

At this time, in the present invention, a slight load may be applied as necessary. As a result, the bonding material melts and flows, uniformly wetting the entire surface of the bonding surface, and also prevents the formation of cavities on the bonding surface.

〔Example] The method of the present invention will be explained in more detail with reference to Examples below.

Example 1 The procedure shown in FIG. 1 was followed. The carbon material (2) used at this time was 99.9% free carbon and had a bulk specific gravity of 1.77.
, coefficient of thermal expansion 4. OX 10-6/”C (room temperature ~ 400°
C), block body with anisotropy ratio of 1.02 (size 0.6 cm
'XO, 6cm x 2.25cm). As the bonding material (4), residual wax rAu-IJ (37.0 to 38.0% gold and remaining copper) according to JIS-Z-3266 is used in an amount that gives a thickness of 0.1 mm. Iron foil (thickness: 0.1 mm) (5) was used as the core material. The conditions are to introduce N2 gas into the container (1) and seal it.
The mixture was heated at 050°C for 4 minutes using a heater (3).

Due to this heating, an iron-based alloy crystallizes in the bonding material (4) between the carbon material (2) and the core iron foil (5), and the carbon material (2)
and the bonding material (4) are firmly bonded, and as shown in FIG. 2, the alloy (7) crystallizes and maintains a strong bond.

The joint between the carbon materials thus obtained has sufficient strength. For example, the hot four-point bending strength of this bonding material is shown in FIG. 4, using the relative temperature with the melting point of the bonding material as 1 on the horizontal axis and the four-point bending strength on the joint axis.

From this result, the bending strength of the bonding material is almost the same as that of the carbon material, and the relative temperature with the melting point of the bonding material being 1 is 0.6.
It has been shown that it has sufficient heat resistance.

Example 2 Instead of joining the carbon materials together in Example 1, only one of them is made of metal (electrolytic copper, 100% copper steel material for electrical conductor)
The rest was done in the same way. As a result, as shown in FIG. 3, a strong bond was achieved as in Example 1.

Example 3 Instead of bonding the carbon materials together in Example 1, only one of them was made of metal (carbon w4 containing 0.8% carbon), and the rest was carried out in the same manner. As a result, as in Example 1, strong bonding was achieved.

〔Effect of the invention〕

According to the method of the present invention, a bonding material containing 25% or more copper and iron or an iron alloy are interposed between the materials to be joined, which is an extremely simple operation, and it can be made strong and heat resistant in an extremely short time. A rich zygote can be obtained, and its industrial value is extremely high.

Furthermore, this bonding method allows carbon materials or carbon materials to be bonded to metal materials firmly and with sufficient heat resistance, resulting in the effect that the bonded product can be used in a wide variety of fields.

[Brief explanation of the drawing]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIGS. 2 and 3 are both simulated structural diagrams of a bonded product obtained by the method of the present invention. FIG. 4 is a graph showing the strength of the bonded product obtained in Example 1. 1...Airtight container 2...Carbon material 3...Heater 4...Joining material 5...Iron or its alloy 6... ... Weight 7 ... Crystallized alloy 8 ... Metal material (or more)

Claims (2)

[Claims] (1) When joining a carbon material containing 0.2% by weight or more of free carbon with the carbon material or metal material (excluding the case of joining carbon steel together), the carbon material must contain at least 25% by weight of copper. A method for joining carbon materials, characterized in that iron or iron alloy is present between the materials to be joined in the presence of a joining material consisting of a carbon material, and heating is performed under vacuum, inert gas, or in the presence of flux. (2) Claim 1 wherein the iron or iron alloy is in the form of a thin plate or foil.
The joining method described in .