JP2023028877A - Bonded body of carbon material and tungsten material and manufacturing method thereof - Google Patents

Abstract

To provide a bonded body of carbon material and tungsten material in which the bonding strength is enhanced by bonding the carbon material and the tungsten material via a metallic intermediate material, and a method for manufacturing the same.SOLUTION: In a bonded body 10 obtained by bonding carbon material and tungsten material via a metallic intermediate material 13 which comprises one of Fe, Ti, Ti alloys, Cr, V, Mo, Cu, Re, Zr, and Ni arranged between carbon material 11 and tungsten material 12, the carbon material 11 and the tungsten material 12 are bonded by heating the carbon material 11, the tungsten material 12 and the intermediate material 13 by pulse electric current while pressurizing them using a pulsed discharge sintering device based on the spark plasma sintering method.SELECTED DRAWING: Figure 5

Description

TECHNICAL FIELD The present invention relates to a bonded body of a carbon material and a tungsten material and a manufacturing method of the bonded body.

Carbon materials such as graphite and carbon fiber composites, which are materials with excellent heat resistance, low activation characteristics, and high thermal conductivity, are applied to parts exposed to high-temperature plasma, such as the divertor plate of a nuclear fusion reactor. may occur.
However, when this carbon material is used for the divertor plate, there is a problem that the surface is easily damaged by plasma sputtering, and tritium is easily retained.

Therefore, it has been proposed to coat the surface of the carbon material with a heat-resistant metal material. The coating material has excellent sputtering resistance, low chemical affinity with hydrogen isotopes, a high melting point, and high thermal conductivity. , it is assumed that tungsten, which has a coefficient of thermal expansion close to that of the carbon material, is suitable.

Patent Document 1 discloses a joined body of a carbon material and a tungsten material in which a carbon fiber composite material layer and a tungsten layer are joined, wherein SiC, Y ₂ O ₃ and Al ₂ are interposed between the carbon fiber composite material layer and the tungsten layer. A bonded body of a carbon material and a tungsten material is disclosed in which a bonding layer containing O ₃ is arranged and bonded by a sintering method.
Patent Literature 2 discloses a joining technique for joining a tungsten material to the surface of a carbon material via a silicon layer.

Japanese Patent No. 6380756 JP 2009-51524 A

As described above, in the divertor plate of the nuclear fusion reactor, the surface of the carbon material has excellent sputtering resistance, low chemical affinity with hydrogen isotopes, high melting point, high thermal conductivity, and thermal expansion with the carbon material. It has been proposed to coat with a heat-resistant tungsten material having a similar coefficient.

However, it is difficult to directly join a carbon material and a tungsten material by a sintering method or a diffusion method. However, until now, no proposals have been made for a joint of a carbon material and a tungsten material that can demonstrate sufficient joint strength by applying a metal material with excellent heat resistance as an intermediate material. There is no proposal for a method of manufacturing a joined body of tungsten materials, which is advantageous in terms of manufacturing technology.

In the bonded body of the carbon material and the tungsten material of Patent Document 1, a ceramic bonding layer is arranged between the carbon fiber composite material layer and the tungsten powder layer, and baked at a temperature of 1700 ° C. or 1800 ° C. or higher. It is tied and joined.
For example, for pure tungsten, the temperature (recrystallization temperature) at which coarsening of grains due to secondary recrystallization (hereinafter referred to as recrystallization) begins is 1800K (1527°C).
Since the above sintering temperature greatly exceeds the recrystallization temperature of pure tungsten, tungsten tends to become brittle. Moreover, since the powder tungsten layer is used, it is not suitable for manufacturing large parts, and the manufacturing cost is high.

In the bonding technique of Patent Document 2, since the tungsten material is bonded to the surface of the carbon material via the silicon layer, the bonding portion is bonded via a non-metal such as WSi ₂ or SiC, so the bonding is performed via the metal. It is difficult to increase the bonding strength as compared with the case. Moreover, since Si slurry or powder is used for bonding, it is difficult to improve the productivity of bonding during manufacturing, and the manufacturing cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a joined body of a carbon material and a tungsten material, in which the joining strength is increased by joining the carbon material and the tungsten material through a metal intermediate material, and a manufacturing method thereof.

The first invention of the present application is a joined body of a carbon material and a tungsten material in which a carbon material and a tungsten material are joined, wherein Fe, Ti, Ti alloy, Cr, V, Mo , Cu, Re, Zr, and Ni through an intermediate member made of a metallic material.

According to the above configuration, since the carbon material and the tungsten material are joined through the metal intermediate material, the tungsten material and the metal intermediate material are firmly joined, and the carbon material and the intermediate material are made of metal carbide. is joined through Therefore, a bonded body of a carbon material and a tungsten material having excellent bonding strength can be obtained.

The following preferable forms can be adopted for the first invention described above.
In a first form, the intermediate material is an intermediate material made of titanium or a titanium alloy.
In the second mode, fine grooves are formed in the surface of the carbon material to be joined, and the carbon material and the intermediate material are joined through the fine grooves.
When the carbon material and the intermediate material are joined through a fine groove in this way, the bonding area between the carbon material and the intermediate material becomes large, and the anchor effect also acts. Because the carbon material is reinforced by, a strong joint strength can be obtained.

In a third embodiment, the fine grooves have a depth of 0.08-0.3 mm and a width of 0.1-0.3 mm.
In a fourth form, the intermediate material has a thickness of 0.05 to 0.3 mm.

In a fifth form, the carbon material is artificial graphite or a carbon fiber composite material.
In a sixth embodiment, the cemented body of carbon material and tungsten material is used for any one of a divertor plate, a limiter and a first wall of a nuclear fusion reactor.
In the seventh form, it is used for either one of a heat sink and a reflector of a high-temperature heat treatment furnace.

A second invention of the present application is a method for manufacturing a joined body in which a carbon material and a tungsten material are joined, wherein pressure is applied while an intermediate material made of titanium or a titanium alloy is arranged between the carbon material and the tungsten material. It is characterized by joining by an electric heating method.

As described above, the intermediate material made of titanium is placed between the carbon material and the tungsten material, and the intermediate material is in the form of powder or sheet (foil) instead of liquid because it is joined by the pressurized electric heating method. By adopting, a joined body of a carbon material and a tungsten material can be efficiently manufactured, and the manufacturing cost can be reduced. From the viewpoint of workability, a sheet-like intermediate material is more preferable. The pressurized current heating method is a pressurized current heating sintering method.

The following preferable forms can be adopted for the above second invention.
In the eighth embodiment, fine grooves are formed in the surface of the carbon material to be joined, and the carbon material and the intermediate material are joined through the fine grooves.

In the ninth form, the sintering temperature in the pressurized current heating method is 1600° C. or less.
Since the sintering temperature is 1600 ° C. or less and does not deviate greatly from the recrystallization temperature of tungsten (1527 ° C.), the tungsten material does not become brittle, and the carbon material and the tungsten material have sufficiently strong bonding strength. can be manufactured.

According to the first and second inventions of the present application, various effects as described above can be obtained.

1 is a perspective view of a main part of a nuclear fusion reactor incorporating a divertor plate made of a joint of a carbon material and a tungsten material according to the present invention; FIG. Figure 2 is a front view of the diverter plate of Figure 1; FIG. 3 is a view in the direction of arrow III in FIG. 2; FIG. 3 is a view in the direction of arrow IV in FIG. 2; 1 is a perspective view of an experimentally produced joined body of a carbon material and a tungsten material; FIG. FIG. 4 is a perspective view showing a carbon material and a groove pattern formed on the joint side end face thereof; FIG. 4 is a perspective view showing a carbon material and a groove pattern formed on the joint side end face thereof; FIG. 4 is an explanatory diagram showing a groove pattern including concentric circular grooves and radial grooves; FIG. 4 is an illustration showing a groove pattern including concentric square grooves and radial grooves; FIG. 4 is an explanatory diagram showing a groove pattern including spiral grooves and radial grooves; FIG. 4 is an explanatory view showing a grid-like groove pattern composed of lateral grooves and vertical grooves; It is a front view of the principal part of a pulse current sintering machine. There is an enlarged photograph of a fractured portion of the joined body of the carbon material and the tungsten material of Comparative Example 10. FIG. 11 is an enlarged photograph of a fractured portion of a joined body of a carbon material and a tungsten material of Example 10. FIG. FIG. 2 is an explanatory diagram of a carbon material made of a carbon fiber composite material and a test piece;

Embodiments for carrying out the first and second inventions of the present application will be described below. However, the invention of the present application is not limited to the following embodiments.

A joined body in which a carbon material and a tungsten material are joined through a metal intermediate material arranged between the carbon material and the tungsten material is manufactured.
A pressurized current heating method is used as a joining method. In the pressurized current heating method, an electric current is directly applied while pressurizing a conductive object to be heated, and the object to be heated is directly heated by Joule heat due to the internal resistance of the object to be sintered and joined.
A discharge plasma sintering method (hereinafter also referred to as an SPS method, Spark Plasma Sintering) can be suitably used as the pressurized current heating method.

The SPS method is carried out by applying a large current on-off DC pulse to the object to be heated.
Commercially available carbon materials such as artificial graphite and carbon fiber composite materials can be used.
Also, a carbon material having a coefficient of thermal expansion close to that of tungsten is preferable.
This joint of carbon material and tungsten material can be used for any one of the divertor plate, the limiter, and the first wall of the nuclear fusion reactor. is preferred. Also, this bonded body of carbon material and tungsten material can be used for either one of a heat sink and a reflector of a high-temperature heat treatment furnace. This joined body of carbon material and tungsten material can be applied to various uses other than the above uses.

FIG. 1 shows a plurality of divertor plates 1 installed in an experimental nuclear fusion reactor as heat shields against a high-temperature plasma flow.

As shown in FIGS. 2 to 4, the diverter plate 1 is a diamond-shaped plate member formed by joining a tungsten material 2 and a carbon material 3 with a titanium foil 4 interposed therebetween. The divertor plate 1 has a two-part structure, and is fastened with two bolts 6 with a cooling water pipe 5 sandwiched therebetween. Two bolts 6 are screwed into a bar nut 8 inserted into a cylindrical through hole 7 . The thick portion that holds the cooling water pipe 5 corresponds to a heat sink.

The tungsten material used for the joined body is not particularly limited, and commercially available materials can be used. Tungsten materials shall include not only tungsten but also tungsten alloys such as tungsten-rhenium alloys. Tungsten materials with a thickness of 10 mm or more can be joined.

Also, when used for a divertor plate of a nuclear fusion reactor, the tungsten material may have a thickness of about 10 mm, but it is not necessary to make the thickness thicker than necessary, and it may be about 5 mm or 1 mm. . The thickness of the carbon material may be appropriately determined depending on the application.

As the intermediate material, a metal that bonds to both the carbon material and the tungsten material is selected. Such metals include Fe, Ti, Ti alloys, Cr, V, Mo, Cu, Re, Zr, or alloys thereof.
These metals may be in the form of a sheet (foil) or powder. In consideration of manufacturability, it is preferable to use foil. It is preferable that the thickness of the foil is thin in terms of use (from the viewpoint of heat transfer, etc.), but it is necessary to select a thickness that provides sufficient bonding strength.

Among the above-mentioned various metals, those having a melting point as high as possible and having good foil availability are preferred. From this point of view, in the present embodiment, for example, titanium (including titanium alloy) is used to produce a bonded body of a carbon material and a tungsten material, and an experiment to evaluate the performance of the bonded body of a carbon material and a tungsten material. did
The thickness of the titanium foil is preferably about 0.05 mm to 0.3 mm. If the thickness is 0.05 mm or less, availability becomes a problem, and it becomes difficult to obtain sufficient bonding strength. If it exceeds 0.3 mm, the heat transfer tends to be hindered.

Fine grooves can be formed on the surface of the carbon material to be joined. This increases the contact area between the surface of the carbon material and the surface of the intermediate material, thereby increasing the bonding strength. Further, as another effect, an improvement in strength due to a so-called anchor effect can be expected.
The grooves can be, for example, 0.08-0.3 mm deep and 0.1-0.3 mm wide, but are not limited to these dimensions. The grooves can be multiple concentric circles, concentric squares, grids, spirals, or even more complex shapes.
In place of the grooves, fine shallow holes may be formed at small intervals.

In the bonding process by the SPS method, it is necessary to set the temperature, pressure and holding time. The atmosphere during bonding is a vacuum or an inert gas atmosphere such as argon gas. This is because the carbon material deteriorates due to oxidation from about 400° C. in the presence of oxygen. The temperature in the bonding process is required to be a temperature at which at least the required bonding strength is obtained.

In the divertor plate of a nuclear fusion reactor, it is desirable to join the plates under conditions that do not cause recrystallization of tungsten. Heating temperature and holding time pose a problem for recrystallization of tungsten.
At 1700° C., the tungsten crystals were coarsened and recrystallization was observed even after a holding time of 30 minutes. On the other hand, no recrystallization of tungsten was observed at 1600° C. for a holding time of 30 minutes. Further, when the temperature was maintained at 1600° C. for 120 minutes, coarsening of tungsten crystals was partially observed. Therefore, at 1600° C., it is preferable to set the holding time to about 30 minutes. The temperature is preferably 1600° C. or less.

However, as shown in Example 5 in Table 2 to be described later, even if the heating temperature is 1700 ° C. and tungsten recrystallization occurs, the shear strength required for the bonding strength of the bonded body of the carbon material and the tungsten material (for example, 5 MPa or more) can be obtained, a heating temperature of around 1700° C. is not excluded.

When a titanium intermediate material is used, the temperature is preferably 1600° C. or lower and 1450° C. or higher. If the temperature is less than 1450° C., it is difficult for elements to diffuse between the intermediate material and the tungsten material or between the intermediate material and the carbon material, making it difficult to obtain sufficient bonding strength. The pressure may be any pressure that is allowed by the apparatus, but is preferably about 10-30 MPa.

Joining of carbon material and tungsten material using titanium intermediate material by discharge plasma sintering Equipment used: pulse current sintering machine LABOX-325R (manufactured by Sinterland Co., Ltd.)
Maximum pressure 30kN, maximum pulse current output 2500A

Joined body 10 of carbon material and tungsten material: See Fig. 5 Carbon material 11: Artificial graphite Brand IG-430U (manufactured by Toyo Tanso Co., Ltd.), φ 10 × 10 tmm
Fine grooves can be formed on the joint-side surface of the carbon material.
For example, groove depth 0.08 to 0.3 mm, groove width 0.1 to 0.3 mm
Tungsten material 12: φ10×10tmm, bonding surface roughness Ra1.6
Intermediate material 13: titanium foil, intermediate material made of titanium between tungsten material 12 and carbon material 11
13 shall be provided.
A titanium foil with a thickness of 0.05 mm was used. If a thicker layer was desired, foil was overlaid.
A foil having a thickness of 0.05 mm or more can also be used.

The shape of fine grooves formed on the end face of the carbon material 11 on the joint side will be described.
Groove pattern in Figure 6:
There are four concentric grooves 15, the width of groove 15 is 0.5 mm, the width of land 16 is 0.5 mm, the depth of groove 15 is 0.1 mm, and the radius of central circular land 17 is 1.5 mm. 0 mm.
Groove pattern in Figure 7:
There are four concentric grooves 15A, the width of groove 15A is 0.5 mm, the width of land 16 is 0.5 mm, the depth of groove 15A is 0.2 mm, and the radius of central circular land 17 is 1.5 mm. 0 mm.

8 to 11 show examples of various other groove patterns, with a groove width of 0.2 mm and a groove depth of 0.1 mm. Various groove patterns other than the groove patterns described above can also be employed.
In the groove pattern of FIG. 8, the grooves 22, 23 are indicated by thick lines. This groove pattern has concentric multiple circular grooves 22 and eight radial grooves 23 .

The groove pattern of FIG. 9 has concentric multiple square grooves 24 and eight radial grooves 25 .
The groove pattern of FIG. 10 has spiral grooves 26 and eight radial grooves 27 .
The groove pattern of FIG. 11 has a plurality of equally spaced lateral grooves 28 and a plurality of equally spaced longitudinal grooves 29 .

Pulse current sintering machine (LABOX-325R) (see Fig. 12)
Lower fixture:
Artificial graphite first spacer 31 (φ90×30tmm), second spacer 32 (φ60×15tmm), third spacer 33 (φ30×15tmm)
Punch 34 (general-purpose synthetic graphite) (φ10×20tmm)

Upper jig:
Artificial graphite first spacer 35 (φ90×30tmm), second spacer 36 (φ60×15tmm), third spacer 37 (φ30×15tmm)
Punch 38 (general-purpose artificial graphite) (φ10×20tmm)
Casing 30: Airtightly covers the upper and lower first to third spacers 31, 32, 33, 35, 36, 37 and punches 34, 38.

Pressurizing unit: pressurizes and drives the pressurizing member 39 Pulse power supply: applies high-voltage pulses to the upper and lower punches 34 and 38 from a pair of upper and lower electrodes (not shown), and pressurizes and heats the carbon material 11 and the intermediate material 13. and the tungsten material 12 are joined.
Cooling Mechanism: At least the upper and lower punches 34, 38 are cooled by air cooling or water cooling.
Vacuum unit: evacuates the space inside the casing 30 .
Other members: Carbon sheet 0.2tmm (1 on punch 34, 1 on tungsten material 12)
Cylindrical carbon felt 40 (single layer on the side)
Temperature measurement: A radiation thermometer 41 is used to measure the side surface near the joint of the joint 10 of the carbon material and the tungsten material.

Example of Processing Conditions Atmosphere: Vacuum or Ar gas Incidentally, the degree of vacuum in a vacuum is around 20 Pa.
Applied pressure: for example 30 MPa (2.4 kN), holding time at holding temperature: for example 30 minutes Heating rate: room temperature to 600 ° C. is 200 ° C./min,
100°C/min from 600°C to 1000°C
50°C/min from 1000°C (holding temperature -50°C)
(Holding temperature -50°C) ~ Holding temperature is 25°C/min

Evaluation of Shear Strength of Joined Portion of Joined Body 10 of Carbon Material and Tungsten Material Evaluation of shear strength of the joined portion was performed using a hydraulic material testing machine (model: UH100kNNC) manufactured by Shimadzu Corporation. The joined body 10 of the carbon material and the tungsten material this time has a size of φ10×20 tmm, and the central portion in the longitudinal direction is the joining portion.
Shear strength was measured by applying stress in shear mode at a crosshead speed of 1 mm/min. The higher the shear strength, the higher the degree of bonding. Fracture at the carbon material 11 site indicates that the degree of bonding is sufficiently high.

Bonding Conditions and Measurement Results of Shear Strength of Bonded Portions Tables 1 to 9 show various data for Examples 1 to 25 and Comparative Examples 1 to 16.
"Example" indicates that the shear strength is 5 MPa (value rounded off to the nearest whole number) or more, and "Comparative Example" indicates that the shear strength is less than 5 MPa.

Table 1 shows test results of Comparative Examples 1 to 8 in which the carbon material 11 and the tungsten material 12 were directly bonded and the shear strength of the bonded portion was measured.
Intermediate material: None Grooving of carbon material joint surface: None Atmosphere: Vacuum, Holding temperature: 1000 to 2000°C, Pressure: 10 MPa, 30 MPa
Holding time: 5 minutes, 30 minutes Even at a holding temperature of 1000 to 2000°C, bonding with the required shear strength cannot be obtained.
However, there is a tendency that the higher the holding temperature, the higher the shear strength.

Table 2 shows the test results of Examples 1 to 5 and Comparative Example 9 in which the intermediate material 13 (titanium foil) was sandwiched between the carbon material 11 and the tungsten material 12 and the shear strength of the joint was measured. indicates
Intermediate material 13: 1 sheet (0.05 mm) and 3 sheets (0.15 mm) of titanium (Ti) foil
Grooving of joint surface of carbon material 11: none Atmosphere: vacuum, holding temperature 1500 to 1700°C
Pressure: 30 MPa, 60 MPa in Comparative Example 9
Holding time: 30 minutes, 120 minutes in Example 3

By arranging the titanium foil as the intermediate material 13, high shear strength was exhibited.
Comparing Examples 3 and 4, the thicker the titanium foil, the higher the shear strength.
All breaks occurred at the interface between the titanium foil and the carbon material 11 .
In Comparative Example 9, the pressure was 60 MPa, and the shear strength at that time was 2.80 MPa. Compared with Example 2, the value was considerably low.

The compressive strength (representative value) of the carbon material 11 of IG-430U is 90 MPa. For example, when a pressure of half or more of the compressive strength is applied, it is possible that the structure of the carbon material 11 is affected minutely and the strength is lowered.
In this way, when the carbon material 11 and the tungsten material 12 are joined via the intermediate material 13 of titanium foil, the strength of the joint is above the required shear strength (for example, 5 MPa) as long as the pressure is applied with an appropriate pressure. Become. Incidentally, when the test was conducted under the same conditions as in Example 2, except that the joint surface of the carbon material 11 was roughened, no significant difference in shear strength was observed.

According to an electron micrograph (not shown) of the joint interface at a magnification of 2000 times, in Example 1, the crystal grains are elongated in a fibrous shape, while in Example 5, the crystal grains are round. It's becoming This is because recrystallization of tungsten occurs at temperatures above 1700°C.

In Table 3, the intermediate material 13 is arranged between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is formed with lattice grooves (see FIG. 11), and the shear strength of the joint is measured. Test results of Examples 6-8 are shown.
Intermediate material 13: 3 sheets of titanium foil (0.15 mm)
Fine grating groove processing on the joint surface of the carbon material 11:
Grating groove (a): groove width 0.2 mm, depth 0.1 mm, interval 0.2 mm (pitch 0.4 mm)
Grating groove (b): groove width 0.2 mm, depth 0.1 mm, interval 0.4 mm (pitch 0.8 mm)
Pressure: 10 MPa, 30 MPa for grating groove (a), 30 MPa for grating groove (b)
Atmosphere: vacuum, holding temperature: 1600°C, holding time: 30 minutes

A high shear strength was exhibited by performing fine lattice groove processing on the joint surface of the carbon material 11 .
No significant difference was observed between the pressure of 10 MPa and 30 MPa.

In Table 4, the intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is subjected to fine groove processing (see FIG. 8) and joined, and the shear strength of the joint is measured. The test results of Comparative Example 10 and Examples 9 to 12 are shown.

Intermediate material 13: 3 sheets of titanium foil (0.15 mm)
Grooving of joint surface of carbon material 11: fine multiple concentric circular grooves and radial grooves Concentric circular grooves: groove width 0.2 mm, depth 0.2 mm, interval 0.2 mm (pitch 0.4 mm)
Radial groove: groove width 0.2 mm, depth 0.2 mm
Atmosphere: vacuum, pressure: 30 MPa, temperature: 1400 to 1600°C, holding time: 30 minutes

By applying fine groove processing to the joint surface of the carbon material 11, high shear strength was exhibited at a holding temperature of 1450 to 1600°C. Sufficient bonding was not achieved at 1400°C. A holding temperature of 1500° C. or higher is desirable from the standpoint of shear strength.
The fracture location was the interface between the titanium foil and the carbon material 11 in Comparative Example 10 and Example 9, the interface between the titanium foil and the carbon material 11 and the carbon material portion in Example 10, and the carbon material portion in Examples 11 and 12. .

FIG. 13 is an enlarged photograph of the fractured portion of the joined body 10 of Comparative Example 10. The groove pattern of the carbon material 11 was printed on the bulk-side fracture surface of the carbon material 11 and the bulk-side fracture surface of the tungsten material 12. . FIG. 14 is an enlarged photograph of the fractured portion of the bonded body 10 of Example 10. Since the bonding strength was high, the lower portion of the bulk of the carbon material 11 was fractured.

In Table 5, an intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the bonding surface of the carbon material 11 is finely grooved and bonded (at a holding temperature of 1500 ° C., pressure and titanium foil The test results are shown for Comparative Example 11 and Examples 10 and 13 in which the shear strength of the joint portion was measured.
Intermediate material: 3 sheets (0.15 mm) and 5 sheets (0.25 mm) of titanium foil
Groove processing of carbon material joint surface: formation of fine multiple concentric circular grooves and radial grooves (same as groove processing in Table 4)

When the holding temperature was 1500° C. and the thickness of the titanium foil was 0.15 mm, a high shear strength was obtained even at a pressure of 20 MPa.
In Comparative Example 11, the breaking point was the interface between the carbon material 11 and titanium. In Example 13, it was the carbon material portion.

In Table 6, the intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the bonding surface of the carbon material 11 is subjected to fine groove processing and bonded (tested by changing the pressure and the thickness of the titanium foil), Test results of Comparative Examples 12 to 14 and Examples 12 and 14 to 20 in which the shear strength of the joint was measured are shown.
Intermediate material: 1, 2, 3, 4, 5 titanium foils (thickness 0.05 mm) Processing of carbon material joint surface: Fine multiple concentric circular grooves and radial groove formation (groove processing and groove processing in Table 4 same)
Atmosphere: vacuum, pressure: 10 to 40 MPa, temperature: 1600°C, holding time: 30 minutes

When the titanium foil had a thickness of 0.15 mm, the shear strength was a substantially constant high value in the pressure range of 10 to 40 MPa (see Examples 12, 14, 15 and 20).
In Comparative Example 9 shown in Table 2, when the pressure is 60 MPa, the shear strength is remarkably low. Considering this, it is presumed that if the pressure is further increased from 40 MPa, the shear strength will drop below the required shear strength.

When fine grooving is applied, the shear strength is low when the thickness of the titanium foil is 0.05 mm (see Comparative Example 12 and Example 17). All fractured portions were at the interfaces between the carbon material 11 and the titanium foil.
When fine grooves were applied and the titanium foil was 0.25 mm, Example 16 had a high shear strength when the pressure was 20 MPa, but Comparative Example 13 had a low shear strength when the pressure was 30 MPa. . In the case of Comparative Example 11 shown in Table 5, the strength was low under the conditions of a titanium foil of 0.25 mm, a holding temperature of 1500° C. and a holding temperature of 30 MPa.
In the cases of Examples 14, 16 and 18, the broken portion was the carbon material portion.

Table 7 shows comparative examples 15 and 16 and examples 21 and 22 in which the intermediate material 13 was placed between the carbon material 11 and the tungsten material 12 made of carbon fiber composite material and joined, and the shear strength of the joint was measured. Test results are shown.

Here, as shown in FIG. 15, the carbon fiber composite material is produced by laminating felt 45 made of carbon fiber while applying pressure in the vertical direction in FIG. The term “felt cross section” as the joint surface in Table 7 indicates that the longitudinal direction of the test piece a is parallel to the felt surface, such as the test piece a, which is a joined body, and the joint surface is a “felt plane”. indicates that the longitudinal direction of the test piece b is oriented in the lamination direction of the felt, like the test piece b.

Carbon fiber composite material: trade name TCC-123U (manufactured by Toyo Tanso Co., Ltd.)
Carbon fiber felt impregnated with pyrolytic carbon by chemical vapor infiltration and graphitized.
Bulk density: 1.49 g/ ^cm3
Intermediate material: 3 sheets of titanium foil (0.15 mm)
Processing of joint surface of carbon material: None

A good joined body was obtained under the conditions of 1600° C. and 10 MPa of pressure. The breaking point was the interface between the carbon material 11 and the titanium foil in Example 21, and the carbon material portion in Example 22.
When the pressure was increased to 30 MPa, the shear strength decreased. The breaking point was the interface between the carbon material and the titanium foil in both Comparative Examples 15 and 16.

Table 8 shows Example 23 in which the intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is subjected to fine shallow hole processing to join, and the shear strength of the joint is measured. -25 test results are shown. Two specimens were tested for each example.
Intermediate material: 3 sheets of titanium foil (thickness 0.05 mm) Machining of bonding surface of carbon material 11: Forming fine shallow holes in a fine pattern Hole machining (a) Holes with a diameter of 0.2 mm and a depth of 0.2 mm (b) Holes with a pitch of 0.2 mm and a depth of 0.1 mm are formed on the entire surface with a pitch of 0.4 mm. (c) Holes with a diameter of 0.2 mm and a depth of 0.2 mm. is formed on the entire surface at a pitch of 0.8 mm Atmosphere: vacuum, pressure: 30 MPa, temperature: 1600°C, holding time: 30 minutes

Examples 23 to 25 were carried out under the same conditions as Example 4 in Table 2, except that the joint surface of the carbon material 11 was drilled, but the shear strength was higher than that of Example 4, 8.78 MPa. Only one specimen of Example 24 yielded shear strength. No effect of drilling the joint surface of the carbon material 11 was observed.

Table 9 is a reference example in which titanium foil and titanium brazing or titanium brazing are placed between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is joined without groove processing, and the shear strength of the joint is measured. 1 to 3 test results are shown. Titanium brazing material manufactured by Tokyo Blaze Co., Ltd. was used.
It is presumed that it is difficult to sufficiently increase the shear strength by brazing as in Reference Examples 1 to 3.

The following can be understood from Examples 1 to 25 and Comparative Examples 1 to 16 described above.
In joining the carbon material 11 and the tungsten material 12 by the discharge plasma sintering method, in order to enable joining, a metal intermediate material 13 is arranged at the interface between the carbon material 11 and the tungsten material 12 and sintered. is desirable.

As the intermediate material 13, an intermediate material made of any one of metal materials such as Fe, Ti, Ti alloy, Cr, V, Mo, Cu, Re, Zr, and Ni is preferable. is particularly preferred.
The suitable thickness of the titanium foil varies depending on the type of carbon material 11, the processing of the interface, and the bonding conditions.

When the carbon material 11 is artificial graphite, the shear strength can be increased by grooving the joint surface. The width, depth, pitch (interval) and shape of the grooves must be set appropriately.
Fine grooving is more preferred. Roughening the joint surface of the carbon material 11 was ineffective. Even if fine hole processing was performed on the joint surface of the carbon material 11, the effect was small.
When the carbon material 11 was a carbon fiber composite material, fine groove processing rather lowered the shear strength.

Among the parameters for bonding, the holding temperature is preferably 1450° C. or higher. When the carbon material 11 was artificial graphite, substantially the same shear strength was obtained at 1500 to 1600° C., and substantially the same shear strength was obtained at a pressure of 10 to 40 MPa. If the pressure is too high, the shear strength will rather decrease.
For the carbon fiber composite material with low material strength, the shear strength was good at about 10 MPa, and the shear strength was low at 30 MPa.

The holding time may be about 30 minutes. It is considered that adjustment is necessary depending on conditions such as the type and size of the material and the holding temperature.
At a holding temperature of 1600° C., coarsening of the structure due to recrystallization of tungsten was observed in some cases and not in other cases.

In the above-described embodiment, a bonded body of a carbon material and a tungsten material applied to a divertor plate of a nuclear fusion reactor has been described. It can also be applied to joints of various carbon materials and tungsten materials used for the purpose of.
Those skilled in the art can add various modifications to the above-described embodiment without departing from the scope of the present invention, and the present invention also includes such modifications.

10 Joined body of carbon material and tungsten material 11 Carbon material 12 Tungsten material 13 Intermediate material

TECHNICAL FIELD The present invention relates to a bonded body of a carbon material and a tungsten material and a manufacturing method of the bonded body.

Carbon materials such as graphite and carbon fiber composites, which are materials with excellent heat resistance, low activation characteristics, and high thermal conductivity, are applied to parts exposed to high-temperature plasma, such as the divertor plate of a nuclear fusion reactor. may occur.
However, when this carbon material is used for the divertor plate, there is a problem that the surface is easily damaged by plasma sputtering, and tritium is easily retained.

Therefore, it has been proposed to coat the surface of the carbon material with a heat-resistant metal material. The coating material has excellent sputtering resistance, low chemical affinity with hydrogen isotopes, a high melting point, and high thermal conductivity. , it is assumed that tungsten, which has a coefficient of thermal expansion close to that of the carbon material, is suitable.

Patent Document 1 discloses a joined body of a carbon material and a tungsten material in which a carbon fiber composite material layer and a tungsten layer are joined, wherein SiC, Y ₂ O ₃ and Al ₂ are interposed between the carbon fiber composite material layer and the tungsten layer. A bonded body of a carbon material and a tungsten material is disclosed in which a bonding layer containing O ₃ is arranged and bonded by a sintering method.
Patent Literature 2 discloses a joining technique for joining a tungsten material to the surface of a carbon material via a silicon layer.

Japanese Patent No. 6380756 JP 2019-51524 A

As described above, in the divertor plate of the nuclear fusion reactor, the surface of the carbon material has excellent sputtering resistance, low chemical affinity with hydrogen isotopes, high melting point, high thermal conductivity, and thermal expansion with the carbon material. It has been proposed to coat with a heat-resistant tungsten material having a similar coefficient.

However, it is difficult to directly join a carbon material and a tungsten material by a sintering method or a diffusion method. However, until now, no proposals have been made for a joint of a carbon material and a tungsten material that can demonstrate sufficient joint strength by applying a metal material with excellent heat resistance as an intermediate material. There is no proposal for a method of manufacturing a joined body of tungsten materials, which is advantageous in terms of manufacturing technology.

In the bonded body of the carbon material and the tungsten material of Patent Document 1, a ceramic bonding layer is arranged between the carbon fiber composite material layer and the tungsten powder layer, and baked at a temperature of 1700 ° C. or 1800 ° C. or higher. It is tied and joined.
For example, for pure tungsten, the temperature (recrystallization temperature) at which coarsening of grains due to secondary recrystallization (hereinafter referred to as recrystallization) begins is 1800K (1527°C).
Since the above sintering temperature greatly exceeds the recrystallization temperature of pure tungsten, tungsten tends to become brittle. Moreover, since the powder tungsten layer is used, it is not suitable for manufacturing large parts, and the manufacturing cost is high.

In the bonding technique of Patent Document 2, since the tungsten material is bonded to the surface of the carbon material via the silicon layer, the bonding portion is bonded via a non-metal such as WSi ₂ or SiC, so the bonding is performed via the metal. It is difficult to increase the bonding strength as compared with the case. Moreover, since Si slurry or powder is used for bonding, it is difficult to improve the productivity of bonding during manufacturing, and the manufacturing cost increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a joined body of a carbon material and a tungsten material, in which the joining strength is increased by joining the carbon material and the tungsten material through a metal intermediate material, and a manufacturing method thereof.

A first invention of the present application is a joined body of a carbon material and a tungsten material in which a carbon material and a tungsten material are joined, wherein the carbon material and the tungsten material are joined via an intermediate material made of titanium disposed between the carbon material and the tungsten material. It is characterized by having

According to the above configuration, since the carbon material and the tungsten material are joined through the intermediate material made of titanium , the tungsten material and the intermediate material made of titanium are firmly joined, and the carbon material and the titanium intermediate material are joined together. are bonded via metal carbide. Therefore, a bonded body of a carbon material and a tungsten material having excellent bonding strength can be obtained.

The following preferable forms can be adopted for the first invention described above .
In the first mode, fine grooves are formed on the surface of the carbon material to be joined, and the carbon material and the intermediate material are joined through the fine grooves.
When the carbon material and the intermediate material are joined through a fine groove in this way, the bonding area between the carbon material and the intermediate material becomes large, and the anchor effect also acts. Because the carbon material is reinforced by, a strong joint strength can be obtained.

In a second form, the fine groove has a depth of 0.08-0.3 mm and a width of 0.1-0.3 mm.
In a third form, the intermediate material has a thickness of 0.05 to 0.3 mm.

In a fourth form, the carbon material is artificial graphite or a carbon fiber composite material.
In a fifth embodiment, the carbon-tungsten composite is used for any one of a divertor plate, a limiter, and a first wall of a nuclear fusion reactor.
In a sixth embodiment, the bonded body of carbon material and tungsten material is used for either one of a heat sink and a reflector of a high-temperature heat treatment furnace.

The second invention of the present application is a method for manufacturing a joined body in which a carbon material and a tungsten material are joined, and in a state in which a titanium intermediate material is arranged between the carbon material and the tungsten material, a pressurized electric heating method is performed. It is characterized by joining.

As described above, the intermediate material made of titanium is placed between the carbon material and the tungsten material, and the intermediate material is in the form of powder or sheet (foil) instead of liquid because it is joined by the pressurized electric heating method. By adopting, a joined body of a carbon material and a tungsten material can be efficiently manufactured, and the manufacturing cost can be reduced. From the viewpoint of workability, a sheet-like intermediate material is more preferable. The pressurized current heating method is a pressurized current heating sintering method.

The following preferable forms can be adopted for the above second invention.
In a seventh embodiment, fine grooves are formed in the surface of the carbon material to be joined, and the carbon material and the intermediate material are joined through the fine grooves.

In the eighth form, the sintering temperature in the pressurized current heating method is 1600° C. or less.
Since the sintering temperature is 1600 ° C. or less and does not deviate greatly from the recrystallization temperature of tungsten (1527 ° C.), the tungsten material does not become brittle, and the carbon material and the tungsten material have sufficiently strong bonding strength. can be manufactured.

According to the first and second inventions of the present application, various effects as described above can be obtained.

1 is a perspective view of a main part of a nuclear fusion reactor incorporating a divertor plate made of a joint of a carbon material and a tungsten material according to the present invention; FIG. Figure 2 is a front view of the diverter plate of Figure 1; FIG. 3 is a view in the direction of arrow III in FIG. 2; FIG. 3 is a view in the direction of arrow IV in FIG. 2; 1 is a perspective view of an experimentally produced joined body of a carbon material and a tungsten material; FIG. FIG. 4 is a perspective view showing a carbon material and a groove pattern formed on the joint side end face thereof; FIG. 4 is a perspective view showing a carbon material and a groove pattern formed on the joint side end face thereof; FIG. 4 is an explanatory diagram showing a groove pattern including concentric circular grooves and radial grooves; FIG. 4 is an illustration showing a groove pattern including concentric square grooves and radial grooves; FIG. 4 is an explanatory diagram showing a groove pattern including spiral grooves and radial grooves; FIG. 4 is an explanatory view showing a grid-like groove pattern composed of lateral grooves and vertical grooves; It is a front view of the principal part of a pulse current sintering machine. There is an enlarged photograph of a fractured portion of the joined body of the carbon material and the tungsten material of Comparative Example 10. FIG. 11 is an enlarged photograph of a fractured portion of a joined body of a carbon material and a tungsten material of Example 10. FIG. FIG. 2 is an explanatory diagram of a carbon material made of a carbon fiber composite material and a test piece;

Embodiments for carrying out the first and second inventions of the present application will be described below. However, the invention of the present application is not limited to the following embodiments.

A joined body in which a carbon material and a tungsten material are joined through a metal intermediate material arranged between the carbon material and the tungsten material is manufactured.
A pressurized current heating method is used as a joining method. In the pressurized current heating method, an electric current is directly applied while pressurizing a conductive object to be heated, and the object to be heated is directly heated by Joule heat due to the internal resistance of the object to be sintered and joined.
A discharge plasma sintering method (hereinafter also referred to as an SPS method, Spark Plasma Sintering) can be suitably used as the pressurized current heating method.

The SPS method is carried out by applying a large current on-off DC pulse to the object to be heated.
Commercially available carbon materials such as artificial graphite and carbon fiber composite materials can be used.
Also, a carbon material having a coefficient of thermal expansion close to that of tungsten is preferable.
This joint of carbon material and tungsten material can be used for any one of the divertor plate, the limiter, and the first wall of the nuclear fusion reactor. is preferred. Also, this bonded body of carbon material and tungsten material can be used for either one of a heat sink and a reflector of a high-temperature heat treatment furnace. This joined body of carbon material and tungsten material can be applied to various uses other than the above uses.

FIG. 1 shows a plurality of divertor plates 1 installed in an experimental nuclear fusion reactor as heat shields against a high-temperature plasma flow.

As shown in FIGS. 2 to 4, the diverter plate 1 is a diamond-shaped plate member formed by joining a tungsten material 2 and a carbon material 3 with a titanium foil 4 interposed therebetween. The divertor plate 1 has a two-part structure, and is fastened with two bolts 6 with a cooling water pipe 5 sandwiched therebetween. Two bolts 6 are screwed into a bar nut 8 inserted into a cylindrical through hole 7 . The thick portion that holds the cooling water pipe 5 corresponds to a heat sink.

The tungsten material used for the joined body is not particularly limited, and commercially available materials can be used. Tungsten materials shall include not only tungsten but also tungsten alloys such as tungsten-rhenium alloys. Tungsten materials with a thickness of 10 mm or more can be joined.

Also, when used for a divertor plate of a nuclear fusion reactor, the tungsten material may have a thickness of about 10 mm, but it is not necessary to make the thickness thicker than necessary, and it may be about 5 mm or 1 mm. . The thickness of the carbon material may be appropriately determined depending on the application.

As the intermediate material, a metal that bonds to both the carbon material and the tungsten material is selected. Such metals include Fe, Ti, Ti alloys, Cr, V, Mo, Cu, Re, Zr, or alloys thereof.
These metals may be in the form of a sheet (foil) or powder. In consideration of manufacturability, it is preferable to use foil. It is preferable that the thickness of the foil is thin in terms of use (from the viewpoint of heat transfer, etc.), but it is necessary to select a thickness that provides sufficient bonding strength.

Among the above-mentioned various metals, those having a melting point as high as possible and having good foil availability are preferred. From this point of view, in the present embodiment, for example, titanium (including titanium alloy) is used to produce a bonded body of a carbon material and a tungsten material, and an experiment to evaluate the performance of the bonded body of a carbon material and a tungsten material. did
The thickness of the titanium foil is preferably about 0.05 mm to 0.3 mm. If the thickness is 0.05 mm or less, availability becomes a problem, and it becomes difficult to obtain sufficient bonding strength. If it exceeds 0.3 mm, the heat transfer tends to be hindered.

Fine grooves can be formed on the surface of the carbon material to be joined. This increases the contact area between the surface of the carbon material and the surface of the intermediate material, thereby increasing the bonding strength. Further, as another effect, an improvement in strength due to a so-called anchor effect can be expected.
The grooves can be, for example, 0.08-0.3 mm deep and 0.1-0.3 mm wide, but are not limited to these dimensions. The grooves can be multiple concentric circles, concentric squares, grids, spirals, or even more complex shapes.
In place of the grooves, fine shallow holes may be formed at small intervals.

In the bonding process by the SPS method, it is necessary to set the temperature, pressure and holding time. The atmosphere during bonding is a vacuum or an inert gas atmosphere such as argon gas. This is because the carbon material deteriorates due to oxidation from about 400° C. in the presence of oxygen. The temperature in the bonding process is required to be a temperature at which at least the required bonding strength is obtained.

In the divertor plate of a nuclear fusion reactor, it is desirable to join the plates under conditions that do not cause recrystallization of tungsten. Heating temperature and holding time pose a problem for recrystallization of tungsten.
At 1700° C., the tungsten crystals were coarsened and recrystallization was observed even after a holding time of 30 minutes. On the other hand, no recrystallization of tungsten was observed at 1600° C. for a holding time of 30 minutes. Further, when the temperature was maintained at 1600° C. for 120 minutes, coarsening of tungsten crystals was partially observed. Therefore, at 1600° C., it is preferable to set the holding time to about 30 minutes. The temperature is preferably 1600° C. or less.

However, as shown in Example 5 in Table 2 to be described later, even if the heating temperature is 1700 ° C. and tungsten recrystallization occurs, the shear strength required for the bonding strength of the bonded body of the carbon material and the tungsten material (for example, 5 MPa or more) can be obtained, a heating temperature of around 1700° C. is not excluded.

When a titanium intermediate material is used, the temperature is preferably 1600° C. or lower and 1450° C. or higher. If the temperature is less than 1450° C., it is difficult for elements to diffuse between the intermediate material and the tungsten material or between the intermediate material and the carbon material, making it difficult to obtain sufficient bonding strength. The pressure may be any pressure that is allowed by the apparatus, but is preferably about 10-30 MPa.

Joining of carbon material and tungsten material using titanium intermediate material by discharge plasma sintering Equipment used: pulse current sintering machine LABOX-325R (manufactured by Sinterland Co., Ltd.)
Maximum pressure 30kN, maximum pulse current output 2500A

Joined body 10 of carbon material and tungsten material: See Fig. 5 Carbon material 11: Artificial graphite Brand IG-430U (manufactured by Toyo Tanso Co., Ltd.), φ 10 × 10 tmm
Fine grooves can be formed on the joint-side surface of the carbon material.
For example, groove depth 0.08 to 0.3 mm, groove width 0.1 to 0.3 mm
Tungsten material 12: φ10×10tmm, bonding surface roughness Ra1.6
Intermediate material 13: titanium foil, intermediate material made of titanium between tungsten material 12 and carbon material 11
13 shall be provided.
A titanium foil with a thickness of 0.05 mm was used. If a thicker layer was desired, foil was overlaid.
A foil having a thickness of 0.05 mm or more can also be used.

The shape of fine grooves formed on the end face of the carbon material 11 on the joint side will be described.
Groove pattern in Figure 6:
There are four concentric grooves 15, the width of groove 15 is 0.5 mm, the width of land 16 is 0.5 mm, the depth of groove 15 is 0.1 mm, and the radius of central circular land 17 is 1.5 mm. 0 mm.
Groove pattern in Figure 7:
There are four concentric grooves 15A, the width of groove 15A is 0.5 mm, the width of land 16 is 0.5 mm, the depth of groove 15A is 0.2 mm, and the radius of central circular land 17 is 1.5 mm. 0 mm.

8 to 11 show examples of various other groove patterns, with a groove width of 0.2 mm and a groove depth of 0.1 mm. Various groove patterns other than the groove patterns described above can also be employed.
In the groove pattern of FIG. 8, the grooves 22, 23 are indicated by thick lines. This groove pattern has concentric multiple circular grooves 22 and eight radial grooves 23 .

The groove pattern of FIG. 9 has concentric multiple square grooves 24 and eight radial grooves 25 .
The groove pattern of FIG. 10 has spiral grooves 26 and eight radial grooves 27 .
The groove pattern of FIG. 11 has a plurality of equally spaced lateral grooves 28 and a plurality of equally spaced longitudinal grooves 29 .

Pulse current sintering machine (LABOX-325R) (see Fig. 12)
Lower fixture:
Artificial graphite first spacer 31 (φ90×30tmm), second spacer 32 (φ60×15tmm), third spacer 33 (φ30×15tmm)
Punch 34 (general-purpose synthetic graphite) (φ10×20tmm)

Upper jig:
Artificial graphite first spacer 35 (φ90×30tmm), second spacer 36 (φ60×15tmm), third spacer 37 (φ30×15tmm)
Punch 38 (general-purpose artificial graphite) (φ10×20tmm)
Casing 30: Airtightly covers the upper and lower first to third spacers 31, 32, 33, 35, 36, 37 and punches 34, 38.

Pressurizing unit: pressurizes and drives the pressurizing member 39 Pulse power supply: applies high-voltage pulses to the upper and lower punches 34 and 38 from a pair of upper and lower electrodes (not shown), and pressurizes and heats the carbon material 11 and the intermediate material 13. and the tungsten material 12 are joined.
Cooling Mechanism: At least the upper and lower punches 34, 38 are cooled by air cooling or water cooling.
Vacuum unit: evacuates the space inside the casing 30 .
Other members: Carbon sheet 0.2tmm (1 on punch 34, 1 on tungsten material 12)
Cylindrical carbon felt 40 (single layer on the side)
Temperature measurement: A radiation thermometer 41 is used to measure the side surface near the joint of the joint 10 of the carbon material and the tungsten material.

Example of Processing Conditions Atmosphere: Vacuum or Ar gas Incidentally, the degree of vacuum in a vacuum is around 20 Pa.
Applied pressure: for example 30 MPa (2.4 kN), holding time at holding temperature: for example 30 minutes Heating rate: room temperature to 600 ° C. is 200 ° C./min,
100°C/min from 600°C to 1000°C
50°C/min from 1000°C (holding temperature -50°C)
(Holding temperature -50°C) ~ Holding temperature is 25°C/min

Evaluation of Shear Strength of Joined Portion of Joined Body 10 of Carbon Material and Tungsten Material Evaluation of shear strength of the joined portion was performed using a hydraulic material testing machine (model: UH100kNNC) manufactured by Shimadzu Corporation. The joined body 10 of the carbon material and the tungsten material this time has a size of φ10×20 tmm, and the central portion in the longitudinal direction is the joining portion.
Shear strength was measured by applying stress in shear mode at a crosshead speed of 1 mm/min. The higher the shear strength, the higher the degree of bonding. Fracture at the carbon material 11 site indicates that the degree of bonding is sufficiently high.

Bonding Conditions and Measurement Results of Shear Strength of Bonded Portions Tables 1 to 9 show various data for Examples 1 to 25 and Comparative Examples 1 to 16.
"Example" indicates that the shear strength is 5 MPa (value rounded off to the nearest whole number) or more, and "Comparative Example" indicates that the shear strength is less than 5 MPa.

Table 1 shows test results of Comparative Examples 1 to 8 in which the carbon material 11 and the tungsten material 12 were directly bonded and the shear strength of the bonded portion was measured.
Intermediate material: None Grooving of carbon material joint surface: None Atmosphere: Vacuum, Holding temperature: 1000 to 2000°C, Pressure: 10 MPa, 30 MPa
Holding time: 5 minutes, 30 minutes Even at a holding temperature of 1000 to 2000°C, bonding with the required shear strength cannot be obtained.
However, there is a tendency that the higher the holding temperature, the higher the shear strength.

Table 2 shows the test results of Examples 1 to 5 and Comparative Example 9 in which the intermediate material 13 (titanium foil) was sandwiched between the carbon material 11 and the tungsten material 12 and the shear strength of the joint was measured. indicates
Intermediate material 13: 1 sheet (0.05 mm) and 3 sheets (0.15 mm) of titanium (Ti) foil
Grooving of joint surface of carbon material 11: none Atmosphere: vacuum, holding temperature 1500 to 1700°C
Pressure: 30 MPa, 60 MPa in Comparative Example 9
Holding time: 30 minutes, 120 minutes in Example 3

By arranging the titanium foil as the intermediate material 13, high shear strength was exhibited.
Comparing Examples 3 and 4, the thicker the titanium foil, the higher the shear strength.
All breaks occurred at the interface between the titanium foil and the carbon material 11 .
In Comparative Example 9, the pressure was 60 MPa, and the shear strength at that time was 2.80 MPa. Compared with Example 2, the value was considerably low.

The compressive strength (representative value) of the carbon material 11 of IG-430U is 90 MPa. For example, when a pressure of half or more of the compressive strength is applied, it is possible that the structure of the carbon material 11 is affected minutely and the strength is lowered.
In this way, when the carbon material 11 and the tungsten material 12 are joined via the intermediate material 13 of titanium foil, the strength of the joint is above the required shear strength (for example, 5 MPa) as long as the pressure is applied with an appropriate pressure. Become. Incidentally, when the test was conducted under the same conditions as in Example 2, except that the joint surface of the carbon material 11 was roughened, no significant difference in shear strength was observed.

According to an electron micrograph (not shown) of the joint interface at a magnification of 2000 times, in Example 1, the crystal grains are elongated in a fibrous shape, while in Example 5, the crystal grains are round. It's becoming This is because recrystallization of tungsten occurs at temperatures above 1700°C.

In Table 3, the intermediate material 13 is arranged between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is formed with lattice grooves (see FIG. 11), and the shear strength of the joint is measured. Test results of Examples 6-8 are shown.
Intermediate material 13: 3 sheets of titanium foil (0.15 mm)
Fine grating groove processing on the joint surface of the carbon material 11:
Grating groove (a): groove width 0.2 mm, depth 0.1 mm, interval 0.2 mm (pitch 0.4 mm)
Grating groove (b): groove width 0.2 mm, depth 0.1 mm, interval 0.4 mm (pitch 0.8 mm)
Pressure: 10 MPa, 30 MPa for grating groove (a), 30 MPa for grating groove (b)
Atmosphere: vacuum, holding temperature: 1600°C, holding time: 30 minutes

A high shear strength was exhibited by performing fine lattice groove processing on the joint surface of the carbon material 11 .
No significant difference was observed between the pressure of 10 MPa and 30 MPa.

In Table 4, the intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is subjected to fine groove processing (see FIG. 8) and joined, and the shear strength of the joint is measured. The test results of Comparative Example 10 and Examples 9 to 12 are shown.

Intermediate material 13: 3 sheets of titanium foil (0.15 mm)
Grooving of joint surface of carbon material 11: fine multiple concentric circular grooves and radial grooves Concentric circular grooves: groove width 0.2 mm, depth 0.2 mm, interval 0.2 mm (pitch 0.4 mm)
Radial groove: groove width 0.2 mm, depth 0.2 mm
Atmosphere: vacuum, pressure: 30 MPa, temperature: 1400 to 1600°C, holding time: 30 minutes

By applying fine groove processing to the joint surface of the carbon material 11, high shear strength was exhibited at a holding temperature of 1450 to 1600°C. Sufficient bonding was not achieved at 1400°C. A holding temperature of 1500° C. or higher is desirable from the standpoint of shear strength.
The fracture location was the interface between the titanium foil and the carbon material 11 in Comparative Example 10 and Example 9, the interface between the titanium foil and the carbon material 11 and the carbon material portion in Example 10, and the carbon material portion in Examples 11 and 12. .

FIG. 13 is an enlarged photograph of the fractured portion of the joined body 10 of Comparative Example 10. The groove pattern of the carbon material 11 was printed on the bulk-side fracture surface of the carbon material 11 and the bulk-side fracture surface of the tungsten material 12. . FIG. 14 is an enlarged photograph of the fractured portion of the bonded body 10 of Example 10. Since the bonding strength was high, the lower portion of the bulk of the carbon material 11 was fractured.

In Table 5, an intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the bonding surface of the carbon material 11 is finely grooved and bonded (at a holding temperature of 1500 ° C., pressure and titanium foil The test results are shown for Comparative Example 11 and Examples 10 and 13 in which the shear strength of the joint portion was measured.
Intermediate material: 3 sheets (0.15 mm) and 5 sheets (0.25 mm) of titanium foil
Groove processing of carbon material joint surface: formation of fine multiple concentric circular grooves and radial grooves (same as groove processing in Table 4)

When the holding temperature was 1500° C. and the thickness of the titanium foil was 0.15 mm, a high shear strength was obtained even at a pressure of 20 MPa.
In Comparative Example 11, the breaking point was the interface between the carbon material 11 and titanium. In Example 13, it was the carbon material portion.

In Table 6, the intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the bonding surface of the carbon material 11 is subjected to fine groove processing and bonded (tested by changing the pressure and the thickness of the titanium foil), Test results of Comparative Examples 12 to 14 and Examples 12 and 14 to 20 in which the shear strength of the joint was measured are shown.
Intermediate material: 1, 2, 3, 4, 5 titanium foils (thickness 0.05 mm) Processing of carbon material joint surface: Fine multiple concentric circular grooves and radial groove formation (groove processing and groove processing in Table 4 same)
Atmosphere: vacuum, pressure: 10 to 40 MPa, temperature: 1600°C, holding time: 30 minutes

When the titanium foil had a thickness of 0.15 mm, the shear strength was a substantially constant high value in the pressure range of 10 to 40 MPa (see Examples 12, 14, 15 and 20).
In Comparative Example 9 shown in Table 2, when the pressure is 60 MPa, the shear strength is remarkably low. Considering this, it is presumed that if the pressure is further increased from 40 MPa, the shear strength will drop below the required shear strength.

When fine grooving is applied, the shear strength is low when the thickness of the titanium foil is 0.05 mm (see Comparative Example 12 and Example 17). All fractured portions were at the interfaces between the carbon material 11 and the titanium foil.
When fine grooves were applied and the titanium foil was 0.25 mm, Example 16 had a high shear strength when the pressure was 20 MPa, but Comparative Example 13 had a low shear strength when the pressure was 30 MPa. . In the case of Comparative Example 11 shown in Table 5, the strength was low under the conditions of a titanium foil of 0.25 mm, a holding temperature of 1500° C. and a holding temperature of 30 MPa.
In the cases of Examples 14, 16 and 18, the broken portion was the carbon material portion.

Table 7 shows comparative examples 15 and 16 and examples 21 and 22 in which the intermediate material 13 was placed between the carbon material 11 and the tungsten material 12 made of carbon fiber composite material and joined, and the shear strength of the joint was measured. Test results are shown.

Here, as shown in FIG. 15, the carbon fiber composite material is produced by laminating felt 45 made of carbon fiber while applying pressure in the vertical direction in FIG. The term “felt cross section” as the joint surface in Table 7 indicates that the longitudinal direction of the test piece a is parallel to the felt surface, such as the test piece a, which is a joined body, and the joint surface is a “felt plane”. indicates that the longitudinal direction of the test piece b is oriented in the lamination direction of the felt, like the test piece b.

Carbon fiber composite material: trade name TCC-123U (manufactured by Toyo Tanso Co., Ltd.)
Carbon fiber felt impregnated with pyrolytic carbon by chemical vapor infiltration and graphitized.
Bulk density: 1.49 g/ ^cm3
Intermediate material: 3 sheets of titanium foil (0.15 mm)
Processing of joint surface of carbon material: None

A good joined body was obtained under the conditions of 1600° C. and 10 MPa of pressure. The breaking point was the interface between the carbon material 11 and the titanium foil in Example 21, and the carbon material portion in Example 22.
When the pressure was increased to 30 MPa, the shear strength decreased. The breaking point was the interface between the carbon material and the titanium foil in both Comparative Examples 15 and 16.

Table 8 shows Example 23 in which the intermediate material 13 is placed between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is subjected to fine shallow hole processing to join, and the shear strength of the joint is measured. -25 test results are shown. Two specimens were tested for each example.
Intermediate material: 3 sheets of titanium foil (thickness 0.05 mm) Machining of bonding surface of carbon material 11: Forming fine shallow holes in a fine pattern Hole machining (a) Holes with a diameter of 0.2 mm and a depth of 0.2 mm (b) Holes with a pitch of 0.2 mm and a depth of 0.1 mm are formed on the entire surface with a pitch of 0.4 mm. (c) Holes with a diameter of 0.2 mm and a depth of 0.2 mm. is formed on the entire surface at a pitch of 0.8 mm Atmosphere: vacuum, pressure: 30 MPa, temperature: 1600°C, holding time: 30 minutes

Examples 23 to 25 were carried out under the same conditions as Example 4 in Table 2, except that the joint surface of the carbon material 11 was drilled, but the shear strength was higher than that of Example 4, 8.78 MPa. Only one specimen of Example 24 yielded shear strength. No effect of drilling the joint surface of the carbon material 11 was observed.

Table 9 is a reference example in which titanium foil and titanium brazing or titanium brazing are placed between the carbon material 11 and the tungsten material 12, and the joint surface of the carbon material 11 is joined without groove processing, and the shear strength of the joint is measured. 1 to 3 test results are shown. Titanium brazing material manufactured by Tokyo Blaze Co., Ltd. was used.
It is presumed that it is difficult to sufficiently increase the shear strength by brazing as in Reference Examples 1 to 3.

The following can be understood from Examples 1 to 25 and Comparative Examples 1 to 16 described above.
In joining the carbon material 11 and the tungsten material 12 by the discharge plasma sintering method, in order to enable joining, a metal intermediate material 13 is arranged at the interface between the carbon material 11 and the tungsten material 12 and sintered. is desirable.

As the intermediate material 13, an intermediate material made of any one of metal materials such as Fe, Ti, Ti alloy, Cr, V, Mo, Cu, Re, Zr, and Ni is preferable. is particularly preferred.
The suitable thickness of the titanium foil varies depending on the type of carbon material 11, the processing of the interface, and the bonding conditions.

When the carbon material 11 is artificial graphite, the shear strength can be increased by grooving the joint surface. The width, depth, pitch (interval) and shape of the grooves must be set appropriately.
Fine grooving is more preferred. Roughening the joint surface of the carbon material 11 was ineffective. Even if fine hole processing was performed on the joint surface of the carbon material 11, the effect was small.
When the carbon material 11 was a carbon fiber composite material, fine groove processing rather lowered the shear strength.

Among the parameters for bonding, the holding temperature is preferably 1450° C. or higher. When the carbon material 11 was artificial graphite, substantially the same shear strength was obtained at 1500 to 1600° C., and substantially the same shear strength was obtained at a pressure of 10 to 40 MPa. If the pressure is too high, the shear strength will rather decrease.
For the carbon fiber composite material with low material strength, the shear strength was good at about 10 MPa, and the shear strength was low at 30 MPa.

The holding time may be about 30 minutes. It is considered that adjustment is necessary depending on conditions such as the type and size of the material and the holding temperature.
At a holding temperature of 1600° C., coarsening of the structure due to recrystallization of tungsten was observed in some cases and not in other cases.

In the above-described embodiment, a bonded body of a carbon material and a tungsten material applied to a divertor plate of a nuclear fusion reactor has been described. It can also be applied to joints of various carbon materials and tungsten materials used for the purpose of.
Those skilled in the art can add various modifications to the above-described embodiment without departing from the scope of the present invention, and the present invention also includes such modifications.

10 Joined body of carbon material and tungsten material 11 Carbon material 12 Tungsten material 13 Intermediate material

Claims (11)

A bonded body of a carbon material and a tungsten material in which a carbon material and a tungsten material are bonded, wherein Fe, Ti, Ti alloy, Cr, V, Mo, Cu, Re, Zr, and the like are placed between the carbon material and the tungsten material. A joined body of a carbon material and a tungsten material, characterized in that they are joined via an intermediate material made of any one of Ni metal materials. 2. A joined body of a carbon material and a tungsten material according to claim 1, wherein said intermediate material is an intermediate material made of titanium or a titanium alloy. 3. The carbon material according to claim 1 or 2, wherein fine grooves are formed on the surface of said carbon material to be joined, and said carbon material and said intermediate material are joined through these fine grooves. and tungsten material. 4. The joint of carbon material and tungsten material according to claim 3, wherein the fine groove has a depth of 0.08 to 0.3 mm and a width of 0.1 to 0.3 mm. A joined body of a carbon material and a tungsten material according to any one of claims 1 to 4, wherein the intermediate material has a thickness of 0.05 to 0.3 mm. A joined body of a carbon material and a tungsten material according to any one of claims 1 to 5, wherein the carbon material is artificial graphite or a carbon fiber composite material. 7. The carbon material-tungsten joint body according to any one of claims 1 to 6, wherein the joint body of the carbon material and the tungsten material is used for any one of a divertor plate, a limiter, and a first wall of a nuclear fusion reactor. A bonded body of carbon material and tungsten material. The joined body of carbon material and tungsten material according to any one of claims 1 to 6, characterized in that it is used for either one of a heat sink and a reflector of a high-temperature heat treatment furnace. A method for manufacturing a bonded body in which a carbon material and a tungsten material are bonded, wherein the bonding is performed by a pressure current heating method in a state in which an intermediate material made of titanium or a titanium alloy is arranged between the carbon material and the tungsten material. A method for producing a joined body of a carbon material and a tungsten material, characterized by: 10. The carbon material and tungsten according to claim 9, wherein fine grooves are formed in the surface of the carbon material to be joined, and the carbon material and the intermediate material are joined through the fine grooves. A method for manufacturing a joined body of lumber. 11. The method for producing a joined body of a carbon material and a tungsten material according to claim 9 or 10, wherein the sintering temperature in the pressurized current heating method is 1600[deg.] C. or less.

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