JPH0223499B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a method for manufacturing a bonding material between graphite and a high-melting point metal. More specifically, the present invention relates to graphite, periodic table b,
The present invention relates to a method for manufacturing a bonding material with a high melting point metal of Group B or Group B by reaction-diffusion solid phase bonding without producing a molten phase. These joining materials are
It is expected to be widely used as various high-temperature-resistant parts such as wire tube targets, laser beam reflectors, electrodes, and bearings. It is also expected to be used as the first wall component of tokamak-type fusion reactors, which are currently being researched and developed. (Prior Art) Most conventional methods for producing bonding materials between graphite and high-melting point metals are based on brazing. Examples of the brazing filler metal include Ti-Cu-Ni,
Ti-Cu-Si (for bonding graphite and copper), Ti
-78Ag-22Cu (for bonding graphite to graphite, USP, No. 2739375), Fe-36~45Ni-
Ti (for bonding graphite and graphite or Ti, Patent No. 290561), 35Au-35Ni-30Mo
(for bonding graphite and Ti), etc. are known. The usable temperature of these bonding materials is limited by the melting point of the brazing material, with the maximum usable limit being 1,000°C or less for normal materials, and 1,400°C for special cases. On the other hand, solid phase bonding methods that do not use brazing filler metals, for example,
As a method of pasting tungsten on graphite blocks, a mixed powder paste of molybdenum and rhenium (wt% 50/50) is applied to the joint surface.
A method of diffusion bonding under the conditions of 1800° C., 300 Kg/cm ² and a holding time of 30 minutes is known. This method requires the expensive precious metal rhenium and also requires a processing temperature of 1800°C.
There is a problem that high temperature of ℃ is required. (Purpose of the Invention) The present invention was made to solve the problems of the conventional methods as described above, and its purpose is to bond graphite and high-melting point metal at a relatively low temperature, requiring the use of expensive metals. Another object of the present invention is to provide a method for producing a bonding material by reaction-diffusion solid-phase bonding. (Structure of the Invention) As a result of intensive research to achieve the above-mentioned object, the present inventor has found that when joining graphite and a high-melting point metal of Groups B, B, and B of the Periodic Table that are mutually solid-solved with molybdenum or vanadium. , as the middle layer,
(1) Placing a physical vapor deposition film of molybdenum-vanadium alloy or vanadium-titanium alloy (titanium is 80% by weight or less) by ion plating, magnetron sputtering, etc. on the surface of the high-melting point metal, or (2) It has been found that when a foil of the alloy is interposed on the bonding surface and the bonding and heating is performed without melting, a strong bond can be obtained through a diffusion solid phase reaction.
The present invention was completed based on this knowledge. That is, the gist of the present invention is that periodic table b, which is a solid solution with molybdenum or vanadium,
When bonding a high-melting point metal of group B or B to graphite, solid phase bonding is performed using a physical vapor deposition layer of molybdenum-vanadium alloy or vanadium-titanium alloy (however, titanium 80% by weight or less) or alloy foil thereof. A method for producing a bonding material between graphite and a high melting point metal is provided. The thickness of the deposited film in the present invention is preferably several μm. The composition is preferably selected in consideration of the coefficient of thermal expansion of the high melting point metal base material. The ratio of the composition components may be changed to match the coefficient of thermal expansion of the base material. However, in vanadium-titanium alloys, if titanium exceeds 80% by weight, the concentration of titanium carbide in the interfacial reaction layer increases and the adhesion of the bonding surface deteriorates. It is necessary that there be. Note that it is possible to bond by disposing the above-mentioned physical vapor deposition layer on the surface of graphite, but in order to improve the adhesion of this vapor deposition layer, pretreatment such as ultrasonic cleaning is required. It is advantageous to arrange this physical vapor deposited layer on a high melting point metal surface, which allows easy attachment to the mounting device. Instead of the vapor-deposited film, a foil of an alloy thereof may be used. Preferably, the thickness of the foil is in the range 50-100 μm. Furthermore, the above-mentioned vapor-deposited film may be formed on both sides of the foil. Solid phase diffusion progresses at relatively low temperatures, resulting in a strong bond. It is preferable to buff the bonding surface of the graphite in advance and keep it as clean as possible, and the thickness of the graphite should be uniform and smooth so that the compressive load during solid phase bonding is evenly applied to the entire surface of the graphite. It is better to finish it. There are various materials for graphite, but it is best to choose one whose coefficient of thermal expansion is as close as possible to that of the metal base material to be joined, or slightly smaller than that of the metal base material to be joined. This is because thermal stress (particularly tensile stress) is not generated in the graphite layer due to differences in thermal expansion during heating or cooling. The intermediate layer is placed between graphite and a high-melting point metal, and this is sandwiched between, for example, a tungsten pressure-welding jig in a vacuum chamber, and the pressure-welding jig is pressurized with a hydraulic press or the like, and at the same time, it is heated to a predetermined value by high-frequency heating. Heat to temperature. As a result, a diffusion solid phase reaction progresses and adhesion occurs. Spraying a mold release agent such as BN powder on the tungsten pressure welding jig in advance makes it easier to release the mold from the bonding material. Typical bonding conditions are under a vacuum of 5×10 ^-6 Torr.
1300~1450℃, average pressure 7Kg/ ^mm2 , processing time 10~
It's 20 minutes. Example 1 A vapor-deposited film having a composition of vanadium-molybdenum alloy (50/50 by weight) was applied as an intermediate layer to a molybdenum base material to a thickness of about 7 μm by ion plating. thickness
A 0.4 mm Pocographite (manufactured by Pocographite, USA, A×F-5Q) was brought into close contact with the vapor-deposited layer side of the above molybdenum base material, and this was heated to 5×10 ^-6 Torr.
Under vacuum, average pressure 7Kg/mm ² and temperature 1400℃
The bonding process was performed for 10 minutes. The obtained bonding material was stretched at room temperature at a tensile rate of 0.5 mm/
A tensile test was conducted at min. The adhesion strength was 2.7 Kg/mm ² , and observation of the fracture surface showed that most of the fracture occurred within the graphite layer. That is, it shows that adhesion strength greater than the tensile strength of graphite was obtained. Example 2 A bonding material was produced under the same conditions as in Example 1, except that a vapor deposited layer having a composition of 60% by weight vanadium and 40% by weight titanium was applied as an intermediate layer to a molybdenum base material to a thickness of about 5 μm by ion plating. A thermal shock test was conducted on the obtained bonding material by irradiating the graphite surface with a low voltage, high current electron beam (beam diameter: 1 cm ² φ) generated from a hollow cathode plasma gun for a short period of time. As a result, when irradiated with a heat flux of 1.5 KW/cm ² for 1 second, blackening was observed on the graphite surface due to spot-like volatilization by the beam, but no spalling or peeling of the graphite layer occurred. This shows that it has excellent thermal shock properties. Example 3 A vapor deposited film having a composition of 90% by weight molybdenum and 10% by weight vanadium was applied to a tungsten base material to a thickness of about 60 μm using a magnetron sputtering rig. In magnetron sputtering, molybdenum target (cathode)
A film having the above composition was produced by a simultaneous sputtering method with a vanadium piece placed on top. A bonding material was prepared using graphite (IG-11 manufactured by Toyo Tanso Co., Ltd.) with a thickness of 0.25 mm under the same bonding conditions as in Example 1. The high temperature properties of the obtained bonding material were measured by the same electron beam thermal shock test as in Example 2. With a heat flux of 3.0 KW/cm ² and irradiation for 1.5 seconds, part of the graphite and base material melted in spots corresponding to the positions hit by the electron beam, as shown in Figure 1, 1 and 2. . 1 is a photomicrograph of the surface, and 2 is a photomicrograph of a cut section of the solid line portion of 1. However, the graphite layer was firmly adhered to the base material along the fused portion, indicating good bondability. Example 4 A bonding material was produced in the same manner as in Example 1 except that titanium, zirconium, hafnium, niobium, tantalum, and vanadium base materials were used in place of the molybdenum base material in Example 1. Almost the same results as in Example 1 were obtained. Example 5 Molybdenum-50% by weight vanadium alloy foil (thickness
60 μm) with a molybdenum base material and 1 mm thick graphite (manufactured by Poco Graphite, USA, A×F-
5Q), under a vacuum of 5×10 ^-6 Torr,
Bonding was performed at an average pressure of 10 Kg/mm ² and a temperature of 1400° C. for 10 minutes. The obtained bonding material was tested using an Instron tensile/compression tester at a crosshead speed of 5 mm/
A rapid bending test was performed by applying a bending load at sec.
As a result, despite the cracking of graphite,
Graphite did not peel off from the molybdenum base material. Further, when a molybdenum-vanadium (50:50) vapor deposited layer was formed on the above alloy foil and bonded in the same manner using this, good bonding similar to the above was obtained. At this time, a temperature of 1200°C was sufficient. Example 6 In the same manner as in Example 2, a vanadium-titanium alloy vapor deposited layer was formed on a tungsten base material and bonding was performed. At this time, the titanium content of the alloy layer was varied and the bondability was evaluated. Table 1 below shows the results. It can be seen that when the titanium content exceeds 80%, the desired bonding cannot be achieved. Analysis of the bonded interface using an X-ray microanalyzer confirmed that in the case of a high titanium alloy layer where peeling occurs, TiC is generated by the reaction between graphite and titanium.

[Table] (Effects of the invention) According to the method of the present invention, molybdenum-vanadium or vanadium-titanium alloy is used as the intermediate layer, so the temperature is higher than that in the case of using a low melting point brazing filler metal in the conventional method. endure,
In addition, compared to conventional solid-phase bonding methods, this method has an excellent effect in that extremely strongly bonded bonding materials can be obtained at lower temperatures without using noble metals.

[Brief explanation of drawings]

FIG. 1 is an electron micrograph of the bonding material obtained by the method of Example 3, where 1 shows the surface and 2 shows the cut section of the solid line portion of 1.

Claims (1)

[Claims] 1. When bonding graphite with a high-melting point metal of Groups b, b, b of the periodic table that is mutually solid-solved with molybdenum or vanadium, molybdenum-vanadium alloy or vanadium-titanium alloy (however, titanium 1. A method for producing a bonding material between graphite and a high-melting point metal, which comprises disposing a physical vapor deposition layer of 80% by weight or less on the surface of the high-melting point metal and performing solid phase bonding. 2. When bonding graphite with a high-melting point metal of group b, b, or b of the periodic table that is a solid solution with molybdenum or vanadium, a molybdenum-vanadium alloy or a vanadium-titanium alloy (however, titanium 80% by weight or less) A method for producing a bonding material between graphite and a high-melting point metal, characterized by solid phase bonding via an alloy foil.