JP2000081015A - Low heat expansion bolt and/or nut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate any deformation and breaking under high temperature conditions and braze a brazing joint body at a slight torque strength by using a material provided with matrices composed of Si-SiC materials between a base material composed of a prescribed quantity of C/C composite and each yarn constituting the base material. SOLUTION: In respective yarn arrangement bodies 1A, 1C, 1E and 1B, 1D, 1F of a fiber composite material 7 using C/C composite as a base material, a matrix 8A and a matrix 8B which are filled into clearances between respective yarns adjoining with each other and extend parallel along the surfaces of yarn 2A, 2B respectively are composed of silicon carbide phases 4A, 4B and Si-SiC material phases 5A, 5B. The respective matrices 8A, 8B extending along the surfaces of respective yarns into narrow, long, and linear lines and crossing at right angles with each other are continued in clearance parts between respective yarns 2A, 2B. This constitution can constitute the matrices 8A, 8B to form a three-dimensional grid as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the joining of various mechanical parts having a complicated structure, such as a radiator for an automobile, by joining a large number of structures by high-temperature joining by brazing. The present invention relates to a low-thermal-expansion bolt and / or nut useful as a tightening bolt and / or nut used in the above method.

[0002]

2. Description of the Related Art In the brazing of a radiator or the like, heat joining is performed while tightening the entire joint surface with uniform design stress. At the time of tightening, it is possible to apply a design stress using a weight, but in this case, the weight used to apply the design stress together with the workpiece to be brazed at the time of heating is also included. It is necessary to house in a heating furnace, and as a result, the furnace itself becomes large, and since the object to be heated also contains weight, it is necessary to increase the heat source for heating, and further, For uniform heating, inconveniences such as a long time are required.

[0003] When fastening is performed from both sides of the joined body using metal bolts and nuts, it is necessary to fasten the joined body in consideration of expansion due to heating of the bolts and nuts in advance. In addition, it is necessary to tighten with a large torque, and a considerable load is imposed on the tightening operation. Further, the bolt and the nut are deformed due to the difference in the coefficient of thermal expansion between the joined body and the bolt and the nut, or in the worst case, the screw thread is broken.
When such a situation occurs, the joining of the objects to be joined does not proceed according to the initial design, and defective products are generated.

[0004]

SUMMARY OF THE INVENTION In place of metal bolts and nuts, there is substantially no deformation or destruction of a brazed object even under high temperature conditions, and a small torque strength is used for the brazed object. It is an object of the present invention to provide a bolt and / or a nut which can be brazed.

[0005]

Means for Solving the Problems The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, have found that a specific amount of C / C
Bolts and / or bolts are formed by using a material in which a layer formed of a Si-SiC-based material is formed as a matrix between a matrix made of a composite and each yarn constituting the matrix.
Alternatively, it has been found that the above-mentioned problems can be solved by processing a nut, and the present invention has been completed.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a raw material for producing a low-thermal-expansion bolt and / or nut according to the present invention, a yarn containing at least a bundle of carbon fibers and a carbon component other than carbon fibers is oriented in a layer direction. A yarn assembly that is dimensionally combined and integrated so as not to be separated from each other;
A fiber composite material having a matrix made of a Si-SiC-based material and filled between the yarns constituting the yarn aggregate is used.

[0007] In the above fiber composite material used for the low thermal expansion bolt and / or nut according to the present invention, the amount of carbon constituting the yarn is from 55% by weight to the total weight of the fiber composite material.
85% by weight, more preferably 65% to 75% by weight,
The amount of Si in the Si-SiC-based material constituting the matrix is 0.1% by weight to 10% by weight, more preferably 1% by weight to 5% by weight, based on the total weight of the fiber composite material, and the amount of SiC is From 10% to 45% by weight, more preferably from 10% to 30% by weight of the total weight of If the amount of carbon is less than 55% by weight of the total weight of the fiber composite material, the toughness will be poor, and if it exceeds 85% by weight, the mechanical strength will be poor, so that it is processed into bolts and / or nuts. When this happens, it is not preferable because of the obstacle. If the amount of Si is less than 0.1% by weight of the total weight of the fiber composite material, the abrasion resistance does not reach a desired level, which causes a problem in repeated use as a bolt and / or a nut. . On the other hand, if the amount of Si exceeds 10% by weight, the toughness may decrease, and the bolts and / or nuts are not preferred because they may cause problems such as pitting during processing.

If the amount of SiC is less than 10% by weight of the total weight of the fiber composite material, the abrasion resistance may not be sufficiently exhibited, which causes a problem in repeated use. On the other hand, if the content exceeds 50% by weight, the toughness may deteriorate.
Problems such as occurrence of pitching appear when processing as a bolt and / or a nut, which is not preferable. The low thermal expansion material used as the bolt and / or nut according to the present invention has a thermal expansion coefficient in a direction parallel to the carbon fiber layer at 600 ° C., which is the highest temperature usually used for brazing. The ratio of the coefficient of thermal expansion in the direction perpendicular to the same layer is 1: 1 to 1: 5, and the coefficient of thermal expansion in the direction parallel to the laminating direction of the carbon fibers is 1.0 × 10 ^{−6 /} ° C. to 3.0 × 10. ⁻⁶ / ° C.

Hereinafter, a novel fiber composite material used for the bolt and / or nut of the present invention will be described. This is a material of a new concept based on a so-called C / C composite, with an improved basic configuration. As a C / C composite used as a basic material, carbon fibers having a diameter of about 10 μm are usually bundled to form a fiber bundle (yarn) by bundling hundreds to tens of thousands of carbon fibers, and this fiber bundle is two-dimensional or three-dimensional. One-way sheet (UD sheet)
Or various cloths, or by laminating the above sheets or cloths, to form a preformed body (fiber preform) having a predetermined shape, and a CV is formed inside the preformed body.
What is known as a C / C composite formed by forming a matrix made of carbon by an I method (Chemical Vapor Infiltration) or an inorganic polymer impregnation sintering method may be used. In the C / C composite used in the present invention, the carbon component other than the carbon fiber in the yarn is preferably a carbon powder, particularly preferably a graphitized carbon powder.

[0010] The fiber composite material used in the present invention uses a C / C composite as a base material,
The structure of the carbon fiber has a great feature that it is maintained without being destroyed. Moreover, it has a microstructure in which a matrix made of a Si-SiC-based material is filled between adjacent yarns in the yarn aggregate.

In the present invention, the term “Si—SiC-based material” is a general term for a material containing silicon and silicon carbide as main components, and is a material manufactured as follows. . In the present invention, silicon is impregnated into a C / C composite or a molded product thereof. At this time, the silicon contains carbon atoms constituting carbon fibers in the composite and / or free carbon remaining on the surface of the carbon fibers. Reacts with atoms and is partially carbonized.
A partially carbonized silicon is formed between the yarns made of carbon fiber and the outermost surface of the / C composite,
Thus, a matrix containing carbonized silicon is formed between the yarns. This matrix may contain several different phases, from a silicon phase with almost pure silicon remaining to a substantially pure silicon carbide phase.

In other words, this matrix is typically composed of a silicon phase and a silicon carbide phase, but the silicon content is changed between the silicon phase and the silicon carbide phase in a graded manner based on silicon. Si-SiC coexisting phase. Therefore, a Si-SiC-based material refers to such a Si-SiC
In the series, the concentration of carbon is from 0 mol% to 50 mol%
It is a generic term for materials that change to%.

[0013] In the fiber composite material used as a raw material of the bolt and / or the nut according to the present invention, it is preferable that the matrix includes a silicon carbide phase generated along the surface of the yarn. In this case, the strength of each yarn itself is further improved, and it is difficult to break. Further, the fiber composite material preferably includes a silicon phase in which the matrix is made of silicon, and a silicon carbide phase is generated between the silicon phase and the yarn. In this case, while the surface of the yarn is strengthened by the silicon carbide phase,
Since the central portion of the matrix is made of a silicon phase having a relatively low hardness, microscopic stress dispersion is further promoted.

Further, the fiber composite material preferably has a matrix having a gradient composition in which the silicon content increases as the distance from the yarn surface increases. Further, in this fiber composite material, preferably, the yarn aggregate includes a plurality of yarn arrays, and each yarn array is formed by arranging the plurality of yarns approximately two-dimensionally two-dimensionally in parallel. Each yarn array is laminated to form a yarn aggregate.
As a result, the fiber composite material has a laminated structure in which a plurality of yarn arrays are laminated in one direction.

In this case, it is particularly preferable that the longitudinal directions of the yarns in adjacent yarn arrays cross each other. Thereby, the dispersion of the stress is further promoted. The longitudinal directions of the yarns in adjacent yarn arrangements are particularly preferably orthogonal. Also,
Preferably, the matrix is continuous with each other in the fiber composite material to form a three-dimensional network structure. In this case, particularly preferably, the matrix is two-dimensionally arranged substantially parallel in each yarn array,
The matrices produced in each adjacent yarn arrangement are continuous with one another, whereby the matrices form a three-dimensional lattice. Further, the gap between adjacent yarns may be filled with 100% matrix, but also includes a case where a part of the gap between yarns is filled with matrix.

A low-thermal-expansion bolt and / or nut according to the present invention provides a base material made of a specific amount of C / C composite manufactured as described above, and the above-mentioned yarn aggregate and yarn constituting the base material. It is manufactured from a fiber composite material consisting of a Si-SiC-based material formed in a three-dimensional lattice as a matrix between the fiber and the yarn. C / C as base material
By using a composite, toughness can be imparted to the bolt and the nut, so that a material having excellent impact resistance, light weight and high strength can be obtained. Therefore, even if the bolt and / or the nut are repeatedly used under a high temperature under substantially oxygen-free conditions, a long life can be exhibited.

In addition, since the fiber composite material has a structure in which a Si—SiC-based material formed in a three-dimensional lattice is provided as a matrix,
In addition to exhibiting higher abrasion resistance than the / C composite, the lubricity inherent in the C / C composite is maintained as it is. Therefore, it is very suitable for use as a bolt and / or nut.

In the case of the composite material used in manufacturing the bolt and / or nut according to the present invention, the member is provided with a Si—SiC-based material layer on its surface, so that the member has high heat resistance and creep resistance. Properties, abrasion resistance, etc., and the low thermal expansion property of the C / C composite can be used even under conditions exposed to high temperatures. By taking advantage of the extremely excellent property of not having such an element, brazing of mechanical parts such as radiators for automobiles can be performed.

The temperature used for brazing is 6
At 00 ° C., the fiber composite material used for the bolt and / or nut according to the present invention has a coefficient of thermal expansion parallel to the carbon fiber layer and a coefficient of thermal expansion perpendicular to the same layer. ratio of 1: 1 to 1: 5, in a direction parallel to the thermal expansion coefficient in the stacking direction of the carbon fibers 1.0x10 ^-6 /℃~3.0x10 ^-6 /
° C, and has the property of not being thermally expanded substantially, so if a bolt is tightened with a light torque at the time of brazing, the metal expands thermally when heated, so the stress required for brazing is naturally reduced. It is possible to significantly improve the work efficiency. The thermal expansion coefficients of 1000 ° C. is 1.5x10 ^-6 /℃~3.5x10 ^-6 / ℃ when expressed in a direction parallel to the thermal expansion coefficient in the stacking direction of the carbon fibers.

In the present invention, the reason that the layer made of the Si—SiC-based material is disposed on the surface of the C / C composite as the base material is that, in the case of the Si—SiC-based material layer,
Even if a defect occurs in a part of the Si-SiC-based material layer in an oxidizing atmosphere at a high temperature, the SiC is oxidized at a lower rate than the Si oxidization rate, so that a part of the Si-SiC layer is melted to become glass. Since the base material can be protected from oxygen and the diffusion of oxygen into the base material can be prevented, this self-repairing action allows 100 pp in the atmosphere in the brazing furnace.
Oxidation of the base material can be substantially avoided even if about m to 1000 ppm of oxygen is present, and the base material can be protected from oxidation. That is, in the case of the low thermal expansion bolt and / or nut according to the present invention, the bolt and / or the nut exhibit a self-healing property, and thus have an extremely excellent effect that they can be used for brazing with confidence.

This effect is not affected even if the fiber composite material contains a third component such as boron nitride, copper, bismuth or the like.

Further, since the thermal expansion coefficient of the Si—SiC-based material is substantially the same as the thermal expansion coefficient of the C / C composite, the influence on the service life of the bolt and / or the nut due to the difference in the thermal expansion coefficient can be ignored. There is substantially no peeling during use. As shown in FIG. 5, the cross-section of the composite material that is the raw material for producing the low thermal expansion bolt and / or nut according to the present invention is such that the fiber composite material 13 is formed on the C / C composite 15. Is preferred.

The fiber composite material used in the present invention will be further described with reference to the drawings. FIG.
FIG. 2A is a schematic perspective view for explaining the concept of the yarn aggregate, FIG. 2A is a cross-sectional view taken along line IIa-IIa in FIG. 1, and FIG. 2B is a cross-sectional view taken along line IIb-IIb in FIG. is there. FIG. 3 is a partially enlarged view of FIG. The skeleton of the fiber composite material 7 is constituted by the yarn aggregate 6. The yarn aggregate 6 includes the yarn arrays 1A, 1B, 1
C, 1D, 1E and 1F are vertically stacked. In each yarn array, the yarns 3 are two-dimensionally arranged, and the longitudinal directions of the yarns are substantially parallel. The longitudinal direction of each yarn in each vertically arranged yarn array is orthogonal. That is, each yarn array 1A, 1
The longitudinal direction of each yarn 2A of C and 1E is parallel to each other, and each yarn 2 of each yarn array 1B, 1D and 1F.
B is orthogonal to the longitudinal direction.

Each yarn is composed of a fiber bundle 3 composed of carbon fibers and carbon components other than carbon fibers. The yarn assembly 6 having a three-dimensional lattice shape is formed by stacking the yarn arrays. Each yarn is crushed during a pressure forming process as described below, and has a substantially elliptical shape.

In each of the yarn arrays 1A, 1C, and 1E, a matrix 8A is provided between adjacent yarns.
And each matrix 8A extends along and parallel to the surface of the yarn 2A. In each of the yarn arrays 1B, 1D, and 1F, the gap between adjacent yarns is filled with a matrix 8B, and each matrix 8B extends along the surface of the yarn 2B and parallel thereto. In this example, the matrices 8A and 8B are respectively composed of silicon carbide phases 4A and 4B covering the surface of each yarn.
And Si-SiC-based material phases 5A and 5B having a lower carbon content than silicon carbide phases 4A and 4B. Silicon may be partially contained in the silicon carbide phase. In this example, silicon carbide phases 4A and 4B are also generated between yarns 2A and 2B that are vertically adjacent to each other.

Each of the matrices 8A and 8B is elongated, preferably linear, along the surface of the yarn, respectively, and each of the matrices 8A and 8B is orthogonal to one another. Then, the matrix 8A in the yarn arrays 1A, 1C, and 1E and the yarn array 1 orthogonal to the matrix 8A
The matrix 8B in B, 1D, and 1F is continuous at the gap between the yarns 2A and 2B, respectively. As a result, the matrices 8A and 8B form a three-dimensional lattice as a whole.

FIG. 4 is a partial sectional perspective view schematically showing a main part of another fiber composite material constituting a bolt and / or a nut according to another embodiment. In this example, a silicon carbide phase does not substantially exist between each of the yarns 2A and 2B that are vertically adjacent to each other. In each yarn arrangement, between adjacent yarns 2A and 2A or between yarns 2B and 2B
Matrixes 8A and 8B are formed between the two matrices B and B, respectively. The form of the matrices 8A and 8B is the same as the examples of FIGS. 1 to 3 except that there is no silicon carbide phase between the vertically adjacent yarns. Each matrix 8
A and 8B each include a silicon carbide phase 5C generated in contact with the surface of the yarns 2A and 2B, and a Si-SiC-based material phase 4C generated inside the yarn 2A and 2B apart from the yarn. .

The Si—SiC-based material phase preferably has a gradient composition in which the carbon concentration decreases as the distance from the yarn surface increases, or
It is preferable that it is composed of a silicon phase. As shown in FIG. 5, the bolt and / or nut materials according to the present invention include a C / C composite 15 and a C / C composite 1
5 is preferably provided with a matrix layer 13 formed by impregnation of silicon on the surface, and in particular, a silicon layer 14 formed on the matrix layer 13 is preferable. In addition, 12 is C / before impregnation with silicon.
Shows the range of the C composite body.

When the matrix layer 13 is provided,
Its thickness is preferably at least 0.01 mm. Further, it is more preferably at least 0.05 mm, more preferably at least 0.1 mm. Depending on the size of the bolts and / or nuts of the present invention, all may be constituted by the matrix layer 13 described above. Preferably, the Si concentration in the matrix layer decreases from the surface toward the inside. Preferably, the Si concentration in the matrix layer 13 is formed so as to be inclined from 90/100 to 0/100 from the surface to the inside.

[0030] The fiber composite material used as the bolt and / or the nut according to the present invention has a carbon fiber of 10 to 70%.
% By weight, for example, boron nitride, boron,
It may contain elements other than carbon such as copper, bismuth, titanium, chromium, tungsten, molybdenum, and the like. These substances such as boron nitride, boron, copper, bismuth, titanium, chromium, tungsten, and molybdenum are 2
More than one kind may be contained. Since these substances have lubricity, the lubrication of the fibers can be maintained even in the part of the base material impregnated with the Si-SiC-based material by being contained in the base material made of the C / C composite,
Physical properties can be prevented from deteriorating.

For example, the content of boron nitride is
With respect to 100% by weight of the base material composed of C / C composite,
Preferably it is 0.1 to 40% by weight. If the content is less than 0.1% by weight, the effect of imparting lubricity by boron nitride cannot be sufficiently obtained, and if it exceeds 40% by weight, the brittleness of boron nitride appears in the composite material.

The fiber composite material of the present invention can be preferably produced by the following method. That is, for the bundle of carbon fibers, powdered binder pitch, which eventually becomes free carbon and acts as a matrix of the bundle of carbon fibers, includes cokes, and further contains phenol resin powder and the like as necessary. This produces a carbon fiber bundle. A flexible coating made of a plastic such as a thermoplastic resin is formed around the carbon fiber bundle to obtain a flexible intermediate material. This flexible intermediate material is made into a yarn shape,
As described in Japanese Patent No. 231791, the required amount is laminated and then hot-pressed at 300 to 2000 ° C.,
A molded article is obtained by molding under the condition of 0 kg / cm ² . Alternatively, the molded body may be replaced with 700
Carbonized at ~ 1200 ° C and graphitized at 1500-3000 ° C to obtain a sintered body.

The carbon fiber is obtained by adjusting pitch for spinning, melt-spinning, infusibilizing and carbonizing, and carbonizing pitch-based carbon fiber and acrylonitrile (co) polymer fiber using petroleum pitch or coal tar pitch as a raw material. Any of the obtained PAN-based carbon fibers may be used. Thermosetting resins such as phenolic resins and epoxy resins and tars and pitches are used as carbon precursors necessary for the formation of the matrix, and these include cokes, metals, metal compounds, inorganic and organic compounds, and the like. You may go out.

Next, the compact or sintered compact produced as described above and Si are held in a temperature range of 1100 to 1400 ° C. and a furnace pressure of 0.1 to 10 hPa for 1 hour or more.
Preferably, at this time, 0.1 NL (normal liter: 1 kg) per kg of the total weight of the molded body or the sintered body and the silicon
In the case of 200 ° C. and a pressure of 0.1 hPa, an Si—SiC layer is formed on the surface of the molded body or the sintered body while flowing an inert gas of 5065 liters or more. Then the temperature 14
The temperature is raised to 50 to 2500 ° C., preferably 1700 to 1800 ° C., and silicon is melted and impregnated into the compact or the sintered open pores to form a Si—SiC material. In this process, when a molded body is used, the molded body is also baked to produce a fiber composite material.

[0035] The molded body or the sintered body and Si are
The temperature is maintained at 1400 ° C. and the pressure of 0.1 to 10 hPa for 1 hour or more, and at that time, the inert gas is 0.1 NL or more, preferably 1 NL or more per 1 kg of the total weight of the compact or sintered body and Si, More preferably, it is desirable to control so as to flow at 10 NL or more. As described above, by setting the atmosphere to an inert gas at the time of firing (that is, the stage before melting and impregnation of Si), the generated gas such as CO accompanying the change of the inorganic polymer or inorganic substance into ceramics is removed from the firing atmosphere. Also, by preventing contamination of the firing atmosphere from the outside by O2 or the like in the atmosphere, the porosity of the composite material obtained by subsequently melting and impregnating Si can be kept low.

In addition, Si is welded to a molded body or a sintered body,
When impregnating, the ambient temperature is 1450-2500 ° C,
Preferably, the temperature is raised to 1700 to 1800 ° C. In this case, the firing furnace internal pressure is preferably in the range of 0.1 to 10 hPa.

As described above, when the flexible intermediate material is used and combined with silicon impregnation and melting, elongated open pores tend to remain in the gaps between the yarns in the formed or sintered body. Silicon easily penetrates deep into the sintered body or the formed body along the pores. During this infiltration process, the silicon reacts with the carbon of the yarn and gradually carbonizes from the yarn surface side, so that the fiber composite material used in the present invention can be produced. Note that, depending on the application, the fiber composite material having such a configuration may be formed as a so-called fiber composite material layer only on a part of the surface layer portion of the base material made of the C / C composite.

The thickness of the matrix layer is adjusted by adjusting the open porosity and the pore size of the compact or sintered body. For example, when the thickness of the Si—SiC material layer is 0.01 to 10 mm, the open porosity at least in the vicinity of the surface of the formed body or the sintered body is 5 to 50%, and the average pore diameter is 1 μm or more. . Open porosity of molded or sintered body is 10-50%
It is preferable that the average pore diameter be 10 μm or more. If the open porosity is less than 5%, the binder in the molded body or the sintered body cannot be completely removed, and 50%
If it is larger, Si-SiC is deeper inside the base material.
This is because the material is impregnated and the impact resistance of the composite material is reduced.

In order to form the matrix layer on the surface of the carbon fiber of the yarn, it is necessary to use a molded body adjusted so that the open porosity at least near the surface becomes 0.1 to 30% during sintering. preferable.

In order to reduce the open porosity of the molded body or the sintered body from the surface toward the inside, a plurality of preformed sheets made of preformed yarns having different binder pitches are formed from the inside to the surface layer side. This is carried out by arranging and molding such that the binder pitch increases toward.

When a gradient is provided in the silicon concentration in the matrix layer, the sintered body is adjusted so that the open porosity near the surface decreases from the surface toward the inside, or at least the open porosity near the surface increases. Using a compact that has been adjusted to decrease from the surface to the inside during sintering,
Manufacture of composite materials.

[0042]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In addition, the thermal expansion property of the low thermal expansion bolt according to the present invention was evaluated by the following method. The coefficient of thermal expansion between room temperature and 1000 ° C. is measured in an argon atmosphere using a thermal dilatometer manufactured by Rigaku Corporation.

(Production Example) A carbon fiber aligned in one direction was impregnated with a phenol resin to obtain a carbon fiber having a diameter of 7 μm.
Approximately 10,000 carbon long fibers are bundled, and prepreg sheets as fiber bundles (yarns) are laminated so that the carbon fibers are orthogonal to each other, and are hot-pressed at 180 ° C. and 10 kg / cm ^2.
To cure the resin. Next, the mixture was fired at 2000 ° C. in nitrogen to obtain a C / C composite. The density of the obtained C / C composite was 1.0 g / cm ³ , and the open porosity was 50%.
Met.

Next, the obtained C / C composite is
It was set up in a carbon crucible filled with Si powder having a purity of 99.8% and an average particle size of 1 mm. Next, the carbon crucible was moved into the firing furnace. The temperature inside the firing furnace was 1300
° C, the flow rate of argon gas as an inert gas is 20 NL /
Min, the furnace pressure was set to 1 hPa, and the holding time was set to 4 hours. Then, while maintaining the pressure in the firing furnace, the furnace temperature was increased to 1600 ° C., thereby increasing the amount of Si in the C / C composite. Was impregnated with Si so that the amount of SiC was 7% by weight and the amount of SiC was 45% by weight, and a member in which a matrix layer made of a Si-SiC-based material was disposed on a C / C composite base material having a thickness of 100 mm Manufactured. Si
-The thickness from the surface of the layer in which the base material was impregnated with the SiC-based material was 50 mm.

The coefficient of thermal expansion of the obtained member was 600 ° C., and the coefficient of thermal expansion in the direction parallel to the carbon fiber layer and the coefficient of thermal expansion in the direction perpendicular to the layer were 1.3 × 10 5
⁻⁶ / ° C., 2.9 × 10 ⁻⁶ / ° C. 6 and 7 show an example of a chart showing the relationship between the obtained temperature and the coefficient of thermal expansion at the time of measurement. FIG. 6 is a chart showing the coefficient of thermal expansion in the direction parallel to the carbon fiber layer, and FIG. 7 is a chart showing the coefficient of thermal expansion in the direction perpendicular to the carbon fiber layer. The two lines shown in FIGS. 6 and 7 indicate that the hysteresis of the temperature rise and the hysteresis of the cool are well matched. Using this, tightening bolts for radiator assembly (diameter: 10 mm, length: 1
00 mm) and a nut (inner diameter: 10 mm).

(Example of Use) Eight copper pipes having an inner diameter of 10 mm, a thickness of 1 mm, and a length of 100 mm were prepared, and four pipes each of which were perpendicular to each other were closely stacked in two stages. A copper brazing paste was applied to the contact points between the pipes. The thus-prepared Ni was 140 mm long and 5 mm wide and 5 mm thick.
The two superalloy plates were sandwiched between two plates, and the four corners of each plate were fixed using the above-mentioned bolts and nuts. If the copper pipe was strongly caulked in this state, the copper pipe would be crushed, so it was tightened so that the distance between the two plates was exactly 20 mm. After the tightening operation was completed, this was heated to 1000 ° C. in a heating furnace, then cooled to room temperature, and the state of connection between the copper pipes was inspected. Since the bolt and the nut according to the present invention were used, the pipes were firmly connected to each other.

On the other hand, as a comparative example, a bolt and a nut made of Ni-based superalloy were used for fixing, but in this case, the connection of the copper pipes was not recognized, and they were easily separated during the checking operation. The cause is that in the case of bolts and nuts made of Ni-based superalloys, the coefficient of thermal expansion is higher than that of copper pipes, so they expand in the heating furnace and cannot be tightened for fixing. is there.

[0048]

The low thermal expansion bolt and / or the low thermal expansion bolt according to the present invention
Alternatively, even if the nut is not substantially tightened at the time of assembly before heating, the metal material expands at the time of heating due to its low thermal expansion property, so that a tightening force corresponding to the difference in expansion rate between the two is applied, so the radiator In the case of metal objects that are relatively weak to pressure such as caulking force, etc., brazing can be performed without applying caulking force before heating. Compared to bolts and nuts, the work of assembling before heating does not require any particular experience or know-how, and has the effect that joining can be performed in an extremely good state.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a structure of a yarn aggregate which is a basic structure of one fiber composite material used for a bolt and / or a nut of the present invention.

2A is a sectional view taken along line IIa-IIa in FIG. 1, and FIG. 2B is a sectional view taken along line IIb-IIb in FIG.

FIG. 3 is a partially enlarged view of FIG.

FIG. 4 is a partial cross-sectional perspective view schematically showing a main part of another embodiment of a fiber composite material usable for a bolt and / or a nut according to the present invention.

FIG. 5 is a schematic diagram showing a cross-sectional structure of one fiber composite material used for the bolt and / or nut of the present invention.

FIG. 6 shows a chart of a measurement example of a thermal expansion coefficient in a direction parallel to a carbon fiber layer.

FIG. 7 shows a chart of a measurement example of a coefficient of thermal expansion in a direction perpendicular to a carbon fiber layer.

[Explanation of symbols]

1A, 1B, 1C, 1D, 1E, 1F...
2A: yarn, 2B: yarn, 3: fiber bundle (yarn),
4A: Silicon carbide phase, 4B: Silicon carbide phase, 4C: Silicon carbide phase, 5A: Si-SiC material phase, 5B: Si-SiC
5C: Si-SiC-based material phase, 6: Yarn aggregate, 7: Fiber composite material, 8A: Matrix, 8B:
Matrix, 11: fiber composite material, 12: range of C / C composite body before impregnation with silicon, 13: matrix layer, 14: silicon layer, 15: C / C composite.

Claims (3)

[Claims] 1. A yarn containing at least a bundle of carbon fibers and a carbon component other than carbon fibers is oriented in a layer direction.
Fiber comprising a yarn assembly that is dimensionally combined and integrated so as not to be separated from each other, and a matrix made of a Si-SiC-based material filled between the yarns constituting the yarn assembly A low thermal expansion bolt and / or nut, comprising a composite material. 2. The fiber composite material according to claim 1, wherein a matrix layer is formed on a surface of a C / C composite, which is a base material of the fiber composite material, and a direction parallel to the carbon fiber layer at 600 ° C. The ratio of the coefficient of thermal expansion to the layer perpendicular to the same layer is 1: 1 to 1: 5, and the coefficient of thermal expansion in the direction parallel to the laminating direction of the carbon fibers is 1.0 × 10 ⁻⁶ / ° C. ~ 3.0x
Low thermal expansion bolts and / or nuts having a temperature of 10 ⁻⁶ / ° C. 3. The method according to claim 1, wherein the thickness of the matrix layer is at least 0.01 mm.
A low thermal expansion bolt and / or nut according to item 1.