JP2012254916A - Carbon fiber-reinforced carbon composite cylindrical member, method of manufacturing carbon fiber-reinforced carbon composite cylindrical member, carbon fiber-reinforced carbon composite material crucible, and method of manufacturing carbon fiber-reinforced carbon composite material crucible - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon fiber-reinforced carbon composite cylindrical member, a method of manufacturing a carbon fiber-reinforced carbon composite cylindrical member, a carbon fiber-reinforced carbon composite material crucible, and a method of manufacturing a carbon fiber-reinforced composite material crucible, the carbon fiber-reinforced carbon composite cylindrical member being composed of a carbon fiber-reinforced carbon composite material having certain physical properties and capable of suppressing wedging of a silica glass crucible during cooling, capable of being easily removed without damage to the silica glass crucible, and also capable of suppressing silicification.SOLUTION: A carbon fiber-reinforced carbon composite material crucible 20 used to support and hold a silica glass crucible that houses a molten material includes a bottom section 22 and a straight body section (cylindrical member) 21 provided above the bottom section. At least the straight body section (cylindrical member) is composed of a carbon fiber-reinforced carbon composite material containing a carbon-fiber woven fabric made using pitch-based carbon fibers having a tensile modulus of 400 GPa or more and 900 GPa or less. The average coefficient of linear thermal expansion in a circumferential direction of the straight body section within a temperature range of room temperature to 800°C is equal to or less than the average coefficient of linear thermal expansion of silica glass or less.

Description

  The present invention relates to a carbon fiber reinforced carbon composite cylindrical member, a method for manufacturing a carbon fiber reinforced carbon composite cylindrical member, a carbon fiber reinforced carbon composite material crucible, and a method for manufacturing the crucible, for example, pulling up a single crystal such as a semiconductor material. Carbon fiber reinforced carbon composite cylindrical member and carbon fiber reinforced carbon composite cylindrical member used for supporting and holding a crucible containing molten material in an apparatus or an apparatus for producing a polycrystal such as a solar cell material, and The present invention relates to a carbon fiber reinforced carbon composite material crucible and a method for producing the crucible.

For example, when producing a single crystal such as a semiconductor material, the CZ method (Czochralski method) is widely used.
In this CZ method, as shown in FIG. 9, the seed crystal P is brought into contact with the surface of the silicon melt M accommodated in the quartz glass crucible 50, the quartz glass crucible 50 is rotated, and the seed crystal P is opposed. The single crystal C is formed at the lower end of the seed crystal P by pulling upward while rotating in the direction.

As the silicon single crystal C is grown, the quartz glass crucible 50 is softened by the heat of the heater 52 surrounding it and the heat of the silicon melt M. For this reason, the quartz glass crucible 50 is accommodated and supported in the graphite crucible 51.
When the pulling of the silicon single crystal is completed, the quartz glass crucible 50 and the graphite crucible 51 are cooled. At this time, since the coefficient of thermal expansion of the graphite crucible 51 is larger than that of the quartz glass crucible 50, there is a problem that when the both are cooled in close contact with each other, the graphite crucible 51 is cracked and finally cracked. there were.

  For such a problem, for example, Patent Document 1 uses a crucible (hereinafter referred to as a carbon fiber crucible) made of a carbon fiber reinforced carbon composite material (also referred to as a C / C material) instead of the conventional graphite crucible 51. It has been proposed.

Japanese Patent Laid-Open No. 11-60373

  As the carbon fiber of the C / C material of the crucible, a PAN-based carbon fiber that is inexpensive, flexible, and easy to handle is used. The linear thermal expansion coefficient of the C / C material made of this PAN-based carbon fiber is close to the linear thermal expansion coefficient of the quartz glass crucible compared to the graphite material, and the mechanical strength is higher than that of the graphite material. Generation of cracks can be suppressed.

However, the linear thermal expansion coefficient of the C / C material made of the PAN-based carbon fiber is closer to the linear thermal expansion coefficient of the quartz glass crucible than the graphite material as described above. It is larger than the linear thermal expansion coefficient of the crucible, and the linear thermal expansion coefficient when the temperature is raised from room temperature to 1000 ° C. is about twice that of quartz glass.
Therefore, when the pulling of the silicon single crystal is completed and the quartz glass crucible and the carbon fiber crucible are cooled, the quartz glass crucible bites into the carbon fiber crucible (tightly fits) when both are in close contact with each other. There was a problem that the quartz crucible could not be removed from the carbon fiber crucible.

Further, in order to reuse the carbon fiber crucible, it is necessary to remove the quartz glass crucible from the carbon fiber crucible. However, as described above, the quartz glass crucible bites into the carbon fiber crucible (tightly fits). The crucible must be broken and the quartz glass crucible must be taken out, and there is a problem that it takes time to reuse the carbon fiber crucible.
Furthermore, when the carbon fiber of the C / C material comes into contact with the silicon oxide gas in the silicon single crystal pulling step, silicification proceeds, and the thermal expansion of the silicified portion becomes larger. As a result, when the quartz glass crucible and the carbon fiber crucible were cooled, there was a problem that the carbon fiber crucible was cracked and cracked due to the difference in thermal expansion between the quartz glass crucible and the silicified portion.

When the quartz glass crucible and the carbon fiber crucible are cooled, the present applicant can easily remove the quartz glass crucible from the carbon fiber crucible without biting into the carbon fiber crucible. Research on carbon fiber crucible that can be suppressed.
And the crucible made of carbon fiber reinforced carbon composite material having specific physical properties can suppress the biting of the quartz glass crucible, and the quartz glass crucible can be easily taken out from the carbon fiber crucible without destroying the quartz glass crucible, The inventors have found that silicification can be suppressed and have completed the present invention.

  The present invention has been made under the circumstances as described above, can suppress the biting of the quartz glass crucible during cooling, can easily remove the quartz glass crucible without destroying the quartz glass crucible, Furthermore, a carbon fiber reinforced carbon composite cylindrical member made of a carbon fiber reinforced carbon composite material having specific physical properties capable of suppressing silicidation, a method for producing the carbon fiber reinforced carbon composite cylindrical member, a carbon fiber reinforced carbon composite crucible, and the crucible It aims at providing the manufacturing method of.

  The carbon fiber reinforced carbon composite cylindrical member according to the present invention made to solve the above-described problems is formed of a carbon fiber reinforced carbon composite material used for a crucible for supporting and holding a quartz glass crucible containing a molten material. In the carbon fiber reinforced carbon composite cylindrical member, the carbon fiber reinforced carbon composite material is a carbon fiber reinforced carbon composite material including a carbon fiber woven fabric using pitch-based carbon fibers having a tensile modulus of elasticity of 400 GPa to 900 GPa, And the average linear thermal expansion coefficient of the circumferential direction at the time of heating up from normal temperature to 800 degreeC is below the average linear thermal expansion coefficient of quartz glass, It is characterized by the above-mentioned.

The carbon fiber reinforced carbon composite cylindrical member according to the present invention is formed from a carbon fiber reinforced carbon composite material including a fiber woven fabric using pitch-based carbon fibers having a tensile elastic modulus of 400 GPa to 900 GPa.
As described above, the carbon fiber reinforced carbon composite cylindrical member is formed of a carbon fiber reinforced carbon composite material including a specific pitch-based carbon fiber woven fabric. The average linear thermal expansion coefficient when the temperature is raised from room temperature to 800 ° C. Is set to be equal to or less than the average linear thermal expansion coefficient of quartz glass.
In addition, when the carbon fiber reinforced carbon composite cylindrical member is formed of a carbon fiber reinforced carbon composite material including a PAN-based carbon fiber woven fabric and is used for a straight body portion of a crucible, an average linear thermal expansion coefficient of quartz glass is used. It is difficult to achieve an average linear thermal expansion coefficient that is approximately the same as or smaller than that, which is not preferable.

As described above, when the carbon fiber reinforced carbon composite cylindrical member is used for the straight body portion of the carbon crucible holding the quartz glass crucible, the average linear thermal expansion coefficient of the carbon fiber reinforced carbon composite cylindrical member is from room temperature. Since it is below the average linear thermal expansion coefficient of quartz glass when the temperature is raised to 800 ° C., even if the quartz glass crucible and the carbon fiber reinforced carbon composite cylindrical member are cooled in close contact, the quartz glass crucible remains in the cylindrical member ( The quartz glass crucible can be easily taken out from the crucible without biting into (straight fitting part).
Here, the average linear thermal expansion coefficient in the circumferential direction of the cylindrical member (straight body portion) is more preferably 0.5 × 10 ⁻⁶ / ° C. or less when the temperature is raised from normal temperature to 800 ° C.

  In addition, the cylindrical member (straight body portion) is configured to have a tensile elastic modulus of 400 to 900 GPa. When the tensile elastic modulus of this cylindrical member (straight barrel portion) is less than 400 GPa, the graphite orientation in the carbon fiber is not developed, and the average linear heat in the crucible circumferential direction when the temperature is raised from room temperature to 800 ° C. Since it is difficult to make the expansion coefficient substantially the same as or smaller than the average linear thermal expansion coefficient of quartz glass, it is not preferable. On the other hand, when the tensile modulus of elasticity of the cylindrical member (straight body portion) exceeds 900 GPa, the carbon fiber becomes brittle, the carbon fiber is broken inside the structure at the time of molding, and the mechanical strength accompanying the tissue destruction is lowered, which is not preferable.

The average linear thermal expansion coefficient of the cylindrical member is a negative coefficient in a range from room temperature to 400 ° C., and heat shrinks in a range from room temperature to 400 ° C. (thermal expansion in a cooling process from 400 ° C. to room temperature). Is desirable).
Thus, if the average linear thermal expansion coefficient of the cylindrical member is a negative coefficient in the range of room temperature to 400 ° C., the cylindrical member (straight body portion) is thermally contracted in the range of room temperature to 400 ° C. A gap is generated between the surface and the outer surface of the quartz glass crucible, and the quartz glass crucible can be removed more easily.

The basis weight of the pitch-based carbon fiber woven fabric is preferably 200 to 600 g / m ² . Thus, when the basis weight of the pitch-based carbon fiber woven fabric is less than 200 g / m ² , the gap between the fibers becomes large and the silicidation of the matrix portion is promoted, which is not preferable.
On the other hand, when the basis weight of the pitch-based carbon fiber woven fabric exceeds 600 g / m ² , the carbon fiber woven fabric becomes thick, so the number of laminated layers with respect to the predetermined thickness is reduced, and the matrix portion between the laminated carbon fiber woven fabrics is reduced Since the strength decreases due to the stress concentration, it is not preferable. Moreover, when it becomes a thick woven fabric, since the curvature of a fiber becomes large, a fiber is easy to break at the time of manufacture or use, and a mechanical strength falls, it is not preferable.

Further, in the single crystal pulling furnace, the generated silicon oxide gas chemically reacts with the cylindrical member (straight barrel portion) and consumes the straight barrel portion. At the same time, carbon fiber reinforced carbon composite materials using PAN-based carbon fibers tend to react more easily with silicon oxide gas than carbon fiber reinforced carbon composite materials using pitch-based carbon fibers, and this is not preferable.
Here, carbon fiber reinforced carbon composite material forming the cylindrical member (cylindrical body portion) is preferably a bulk density of ^{1.3g / cm 3 ~1.8g / cm 3} .
When the bulk density is 1.3 g / cm ³ or less, the structure is sparse, so that silicon oxide gas penetrates into the structure and promotes wear, which is not preferable.
On the other hand, when the bulk density is 1.8 g / cm ³ or more, the thermal expansion coefficient increases because the structure is dense, and the average linear thermal expansion coefficient when the temperature is raised from room temperature to 800 ° C. is Since it is difficult to make it below the average linear thermal expansion coefficient, it is not preferable.

  In the carbon fiber reinforced carbon composite cylindrical member, the carbon fiber woven fabric is bonded using a mixed adhesive of a thermosetting resin and carbon powder, and thereafter, a thermosetting treatment, a carbonization treatment, a graphitization treatment, and It is desirable to form by performing a high-purification treatment.

  A carbon fiber reinforced carbon composite crucible according to the present invention made to solve the above-described problems is used to support and hold a quartz glass crucible containing a molten material, and includes a bottom portion and an upper portion of the bottom portion. A carbon fiber reinforced carbon composite crucible in which at least the straight body portion is formed of a carbon fiber reinforced carbon composite material, and the straight body portion has a tensile modulus of 400 GPa or more and 900 GPa. The average linear thermal expansion coefficient in the circumferential direction of the straight body portion when formed from a carbon fiber reinforced carbon composite material including a carbon fiber woven fabric using the following pitch-based carbon fiber and heated from room temperature to 800 ° C, It is characterized by being below the average linear thermal expansion coefficient of quartz glass.

In the carbon fiber reinforced carbon composite material crucible according to the present invention, at least the straight body portion is formed from a carbon fiber reinforced carbon composite material including a fiber woven fabric using pitch-based carbon fibers having a tensile elastic modulus of 400 GPa to 900 GPa. Has been.
As described above, at least the straight body portion is formed of a carbon fiber reinforced carbon composite material including a specific pitch-based carbon fiber woven fabric. The average linear thermal expansion coefficient when the temperature is raised from room temperature to 800 ° C. This is because the coefficient of thermal expansion is not more than the average linear thermal expansion coefficient.
When the straight body portion is formed of a carbon fiber reinforced carbon composite material including a PAN-based carbon fiber woven fabric, the average linear thermal expansion coefficient is approximately the same as or smaller than the average linear thermal expansion coefficient of quartz glass. It is difficult to do and is not preferable.

As described above, since the straight body portion of the carbon fiber reinforced carbon composite crucible is below the average linear thermal expansion coefficient of the quartz glass when the temperature is raised from room temperature to 800 ° C., the quartz glass crucible and the carbon fiber crucible are in close contact with each other. Even if cooled in this state, the quartz glass crucible can be easily taken out from the carbon fiber reinforced carbon composite crucible without the quartz glass crucible biting into the straight body portion (tightly fitting).
Here, the average linear thermal expansion coefficient in the circumferential direction of the straight body portion of the carbon fiber reinforced carbon composite material crucible is 0.5 × 10 ⁻⁶ / ° C. or less when the temperature is raised from normal temperature to 800 ° C. More desirable.

  In addition, the straight body portion is configured to have a tensile elastic modulus of 400 to 900 GPa. When the tensile modulus of the straight body is less than 400 GPa, the graphite orientation in the carbon fiber is not developed, and the average linear thermal expansion coefficient in the circumferential direction of the crucible when the temperature is raised from room temperature to 800 ° C. It is not preferable because it is difficult to make it approximately the same or smaller than the average linear thermal expansion coefficient of glass. On the other hand, when the tensile elastic modulus of the straight body part exceeds 900 GPa, the carbon fiber becomes brittle, the carbon fiber breaks inside the structure at the time of molding, and the mechanical strength accompanying the structure destruction is lowered, which is not preferable.

Here, the bottom portion is integrally formed with the straight body portion by a carbon fiber reinforced carbon composite material including a pitch-based carbon fiber cloth, and when the temperature of the bottom portion and the straight body portion is raised from room temperature to 800 ° C. It is desirable that the average linear thermal expansion coefficient is equal to or less than the average linear thermal expansion coefficient of quartz glass and the tensile elastic modulus is 400 to 900 GPa.
That is, it is desirable that not only the straight body portion but also the bottom portion be formed in the same manner, and that the carbon fiber reinforced carbon composite material crucible be formed from a carbon fiber reinforced carbon composite material.

Further, the average linear thermal expansion coefficient of the straight body part and the bottom part is a negative coefficient in a range from room temperature to 400 ° C., and heat shrinks in a range from room temperature to 400 ° C. (cooling from 400 ° C. to room temperature) Thermal expansion in the process) is desirable.
Thus, if the average linear thermal expansion coefficient of the straight body part and the bottom part is a negative coefficient in the range of room temperature to 400 ° C., the inner surface of the crucible is thermally shrunk in the range of room temperature to 400 ° C. And a gap between the outer surface of the quartz glass crucible and the quartz glass crucible can be removed more easily.

The basis weight of the pitch-based carbon fiber woven fabric is preferably 200 to 600 g / m ² . Thus, when the basis weight of the pitch-based carbon fiber woven fabric is less than 200 g / m ² , the gap between the fibers becomes large and the silicidation of the matrix portion is promoted, which is not preferable.
On the other hand, when the basis weight of the pitch-based carbon fiber woven fabric exceeds 600 g / m ² , the carbon fiber woven fabric becomes thick, so the number of laminated layers with respect to the predetermined thickness is reduced, and the matrix portion between the laminated carbon fiber woven fabrics is reduced Since the strength decreases due to the stress concentration, it is not preferable. Moreover, when it becomes a thick woven fabric, since the curvature of a fiber becomes large, a fiber is easy to break at the time of manufacture or use, and a mechanical strength falls, it is not preferable.

Further, in the single crystal pulling furnace, the generated silicon oxide gas chemically reacts with the crucible and consumes the crucible. At the same time, carbon fiber reinforced carbon composite materials using PAN-based carbon fibers tend to react more easily with silicon oxide gas than carbon fiber reinforced carbon composite materials using pitch-based carbon fibers, and this is not preferable.
Here, carbon fiber reinforced carbon composite material forming the crucible is preferably a bulk density of ^{1.3g / cm 3 ~1.8g / cm 3} .
When the bulk density is 1.3 g / cm ³ or less, the structure is sparse, so that silicon oxide gas penetrates into the structure and promotes wear, which is not preferable.
On the other hand, when the bulk density is 1.8 g / cm ³ or more, the thermal expansion coefficient increases because the structure is dense, and the average linear thermal expansion coefficient when the temperature is raised from room temperature to 800 ° C. is Since it is difficult to make it below the average linear thermal expansion coefficient, it is not preferable.

  Also, the carbon fiber reinforced carbon composite crucible is bonded to the carbon fiber woven fabric using a mixed adhesive of a thermosetting resin and carbon powder, and then a thermosetting treatment, a carbonization treatment, a graphitization treatment, and It is desirable to form by performing a high-purification treatment.

  According to the present invention, the biting of the quartz glass crucible during cooling is suppressed, the quartz glass crucible can be easily removed without destroying the quartz glass crucible, and further, the carbon fiber can suppress silicification. A method for producing a reinforced carbon composite cylindrical member and a carbon fiber reinforced carbon composite cylindrical member, a carbon fiber reinforced carbon composite crucible, and a method for producing the crucible can be obtained.

FIG. 1 is a plan view of a carbon fiber woven fabric used in a carbon fiber reinforced carbon composite crucible according to the present invention. FIG. 2 is a cross-sectional view showing a first embodiment of a carbon fiber reinforced carbon composite crucible according to the present invention. FIG. 3 is a cross-sectional view showing a modification of the first embodiment. FIG. 4 is a conceptual diagram of a carbon fiber woven fabric used in the straight body portion of the carbon fiber reinforced carbon composite material crucible shown in FIGS. 2 and 3. FIG. 5 is a diagram for explaining a manufacturing process of the straight body portion of the carbon fiber reinforced carbon composite material crucible shown in FIGS. 2 and 3. FIG. 6 is a view showing a second embodiment of the carbon fiber-reinforced carbon composite crucible according to the present invention, and is a perspective view showing the bottom part upward. FIG. 7 is a schematic cross-sectional view of the carbon fiber reinforced carbon composite crucible (including a molding die) shown in FIG. FIG. 7 is a diagram for explaining a manufacturing process of the carbon fiber-reinforced carbon composite material crucible shown in FIG. 6. FIG. 9 is a diagram for explaining a crucible used in a silicon single crystal pulling apparatus.

Hereinafter, embodiments of a carbon fiber reinforced carbon composite crucible according to the present invention will be described with reference to the drawings.
First, based on FIG. 1, the carbon fiber woven fabric used for this carbon fiber reinforced carbon composite material crucible will be described.
The carbon fiber woven fabric 1 is a pitch-based carbon fiber woven fabric, and 1000 to 36000 pitch-based carbon fibers having a diameter of 5 μm to 20 μm are used as warps 1a, and 1000 pitch-based carbon fibers having a diameter of 5 to 20 μm. It is a carbon fiber woven fabric that is woven alternately with ˜36,000 wefts 1b, and has a basis weight of 200 g / m ^{2 to} 600 g / m ² and a thickness of 0.1 mm to 0.6 mm.

This pitch-based carbon fiber woven fabric is produced by a general manufacturing method. First, the viscosity and molecular weight are adjusted so that the pitch of the purified raw material can be heated and spun, and then heated to give fluidity, and a fiber having a predetermined diameter (for example, 10 μm) is formed through a nozzle.
In this state, pitch-based carbon fibers can be produced by performing an infusibilization treatment for adding oxygen and performing a carbonization treatment in an inert atmosphere.
Then, as described above, warp yarns and weft yarns are knitted to form a pitch-based carbon fiber woven fabric as shown in FIG. As this pitch-based carbon fiber, for example, trade name XN-80 manufactured by Nippon Graphite Fiber Co., Ltd. can be used. Generally, the linear thermal expansion coefficient of this pitch-based carbon fiber woven fabric is −1.5 × 10 ⁻⁶ / ° C. at room temperature, and the tensile elastic modulus is 780 GPa.

Next, a first embodiment of a carbon fiber reinforced carbon composite crucible 10 (hereinafter referred to as a carbon fiber crucible) according to the present invention will be described with reference to FIG.
The carbon fiber crucible 10 is a crucible used to support and hold a quartz glass crucible containing a silicon melt, for example, in a single crystal pulling apparatus (not shown) for pulling a single crystal such as a semiconductor material. It is.

The carbon fiber crucible 10 has a straight body portion (cylindrical member) 11 and a bottom portion 12, and the straight body portion (cylindrical member) 11 is attached to the upper surface of the bottom portion 12. Further, a ring-shaped spacer 13 is provided in contact with the lower inner peripheral surface of the straight body portion (cylindrical member) 11 and the inner peripheral edge of the bottom portion 12.
The bottom portion 12 and the spacer 13 are formed of a graphite material as in the conventional case, and the straight body portion 11 is formed of a pitch-based carbon fiber woven fabric.
As described above, when the bottom 12 and the spacer 13 are formed of a graphite material as in the prior art, the coefficient of thermal expansion is larger than that of the carbon fiber reinforced carbon material, so that the bottom 12 and the spacer 13 do not bite into the end of the straight body portion during cooling. Can be removed and is preferred.

In addition, as shown in FIG. 3, you may integrally form the bottom part 12 and the spacer 13 with a graphite material. Further, as in a second embodiment to be described later, the bottom 12 and the spacer 13 may be formed of a carbon fiber reinforced carbon material, particularly a pitch-based carbon fiber reinforced carbon material. Moreover, you may integrally form the bottom part 12 and the spacer 13 with a carbon fiber reinforced carbon material.
Further, the lower outer peripheral surface of the straight body portion 11 of the carbon fiber reinforced carbon composite crucible 10 shown in FIG. 2 is fitted to the inner periphery of the rising portion 12 a of the bottom portion 12, and the straight body portion 11 is connected to the bottom portion 12. Fixed. On the other hand, as shown in FIG. 3, the lower inner peripheral surface of the straight body portion 11 of the carbon fiber reinforced carbon composite crucible 10 is fitted to the outer periphery of the rising portion 12 a of the bottom portion 12. May be fixed to the bottom 12.

Further, it is desirable that the inner peripheral side of the upper end portion of the straight body portion 11 is R-chamfered (chamfered to a curved surface shape) or C-chamfered (chamfered).
Thus, when the inner peripheral side of the upper end portion of the straight body portion 11 is R-chamfered (chamfered into a curved surface shape) or C-chamfered (chamfered), the quartz glass crucible should be Even when the quartz glass crucible needs to be broken and removed, the crack or chipping on the inner peripheral side of the upper end portion of the straight barrel portion 11 can be suppressed, and the straight barrel portion can be suppressed. 11 can be used for reuse.

This carbon fiber reinforced carbon composite crucible 10 carries a plurality of the above-mentioned carbon fiber woven fabrics 1 and carries a mixed adhesive (not shown) of a thermosetting resin and carbon powder (for example, graphite powder) and bonded together. Then, it is formed by subjecting to thermosetting, carbonization, graphitization and purification treatment.
Specifically, the sheet-like carbon fiber woven fabric 1 shown in FIG. 4 is bonded to a plurality of layers on a crucible molding die 14 as shown in FIG. 5, and is thermoset, carbonized, graphitized, and high. It is formed by a purification treatment. A specific manufacturing method will be described later.

The tensile elastic modulus of the straight body part (cylindrical member) 11 of the carbon fiber reinforced carbon composite crucible 10 is configured to be 400 to 900 GPa. When the tensile elastic modulus of the straight body portion (cylindrical member) 11 is less than 400 GPa, the graphite orientation in the carbon fiber is not developed, and the linear heat in the crucible circumferential direction when the temperature is raised from room temperature to 800 ° C. Since it is difficult to make the expansion coefficient smaller than the linear thermal expansion coefficient of quartz glass, it is not preferable.
When the temperature of the quartz glass crucible rises, deformation occurs along the inner diameter of the carbon fiber reinforced carbon composite material crucible 10 due to the softening of the silica glass, so that the tensile stress generated in the circumferential direction of the carbon fiber reinforced carbon composite material crucible 10 is increased. Considering this, it is preferable that the tensile elastic modulus of the straight body portion (cylindrical member) 11 is 400 GPa or more.
On the other hand, when the tensile elastic modulus of the straight body part exceeds 900 GPa, the carbon fiber becomes brittle, the carbon fiber breaks inside the structure at the time of molding, and the mechanical strength accompanying the destruction of the structure decreases, which is not preferable.

Next, a second embodiment of the carbon fiber reinforced carbon composite material crucible will be described with reference to FIG.
In the second embodiment, the same pitch-based carbon fiber woven fabric as that of the first embodiment is used, and the straight body portion 21 and the bottom portion 22 are integrated as a crucible 20. In the second embodiment, the spacer 13 in the first embodiment is omitted.

  The manufacturing process of the carbon fiber crucible 20 shown in FIG. 6 will be described with reference to FIGS. In addition, since the carbon fiber crucible 20 in the second embodiment and the carbon fiber reinforced carbon composite material crucible 10 in the first embodiment are basically manufactured by the same manufacturing process, the case of the second embodiment A description will be given and the case of the first embodiment will be described as necessary.

First, as shown in FIG. 5, a crucible molding die 14 is prepared, and a mixed adhesive of a thermosetting resin (for example, phenol resin) and carbon powder (for example, graphite powder) is provided on the die straight body portion 14a. A carbon fiber woven fabric 1 carrying (not shown) is wound (step S1 in FIG. 8).
Further, the axial direction of the carbon fibers of the carbon fiber woven fabric 1 (the axial direction of the warp 1a and the weft 1b) is a direction orthogonal to the circumferential direction T of the crucible (the axial direction of the crucible).
At this time, the carbon fiber woven fabric 1 does not extend in a direction parallel to the crucible circumferential direction T indicated by an arrow in FIG. 5 and does not extend in the direction orthogonal to the crucible circumferential direction T (the crucible axial direction). Since the diameter of the mold straight body portion 14a does not change, the carbon fiber woven fabric 1 can be adhered to the mold straight body portion 14a without any defects.

In the first embodiment, steps S2 and S3 in FIG. 8 are omitted, and the carbon fiber woven fabric 1 is affixed a plurality of times and laminated to a predetermined thickness (see FIG. 8). 8 step S4). At this time, a plurality of short carbon fiber woven fabrics 1 may be used by being wound around the die straight body portion 14a a plurality of times, or a single long carbon fiber woven fabric 1 may be formed as a mold. The straight body portion 14a may be wound a plurality of times.
When all the carbon fiber woven fabrics are pasted (laminated), thermosetting, carbonization, graphitization, and high-purification treatment are performed, and a cylindrical straight body portion 11 made of carbon fiber is manufactured. (Steps S6 to S10 in FIG. 8).
The cylindrical straight body portion 11 is attached to a bottom portion made of graphite and serves as a carbon fiber reinforced carbon composite crucible 10 including a pitch-based carbon fiber woven fabric. In addition, the bottom part 12 and the spacer 13 may be formed with a graphite material by a conventional manufacturing method, and may be formed with a carbon fiber reinforced carbon composite material.

  In the second embodiment, as shown in FIG. 7, the mixed adhesive is supported on the bottom 14b of the crucible molding die 14, and the circular carbon fiber woven fabric 2 is attached and covered to form the bottom. (Step S2 in FIG. 8). This circular carbon fiber woven fabric 2 is obtained by making the outer shape of the carbon fiber woven fabric 1 into a circular shape. And the boundary part of the carbon fiber woven fabric 1 that forms the straight body portion 21 of the carbon fiber crucible 20 and the carbon fiber woven fabric 2 that forms the bottom portion 22 is affixed so as not to overlap and to create a gap. Is done.

In attaching the circular carbon fiber woven fabric 2, the carbon fiber woven fabric 2 can be attached while being stretched in a direction different from the axial direction of the carbon fibers. Thereby, even the curved part is stuck without a wrinkle.
Then, the above-mentioned mixed adhesive is carried on the bonded carbon fiber woven fabrics 1 and 2, and the straight body portion 21 (the straight portion of the molding die 14) formed by the carbon fiber woven fabric 1 as shown in FIG. The carbon fiber woven fabric 3 is attached so as to cover the trunk portion 14a) and the curved portion formed by the carbon fiber woven fabric 2 (step S3 in FIG. 8). At this time, the axial direction of the carbon fiber of the carbon fiber woven fabric 3 is inclined with respect to the circumferential direction T of the crucible.

  Such a carbon fiber woven fabric 1, 2, and 3 affixing step is repeated a plurality of times as shown in the cross-sectional view of FIG. 7 (three times in FIG. 7), and laminated to a predetermined thickness. (Step S4 in FIG. 8). When all the carbon fiber woven fabrics 1, 2 and 3 are attached (laminated), the lower end portion 1A (the upper end portion when the crucible is used) of the innermost carbon fiber woven fabric 1 is folded in the direction of the arrow shown in FIG. Bending and pasting so as to cover the end of the crucible, an end molding process is performed (step S5 in FIG. 8).

Thus, when a crucible-type preform is obtained, it is placed in a vacuum furnace in a state of being attached around the crucible molding die 14 and is thermally cured at a temperature of 100 ° C. to 300 ° C. ( Step S6 in FIG.
Next, the crucible molding die 14 is removed (step S7 in FIG. 8), and the resulting molded body is carbonized at a temperature of about 1000 ° C. in an inert atmosphere (step S8 in FIG. 8). Depending on the condition, the resin is impregnated with phenol resin, tar pitch or the like, and carbonized again.
After the carbonization treatment, heating is performed at a temperature of 2000 ° C. or higher to perform graphitization treatment (step S9 in FIG. 8).
Then, the crucible obtained by graphitization is usually heated to a temperature of 1500 ° C. to 2500 ° C. and subjected to a high purification treatment to obtain a carbon fiber crucible 20 including a pitch-based carbon fiber woven fabric (FIG. 8). Step S10).

When the average linear thermal expansion coefficient in the circumferential direction of the straight body portion thus formed and the average linear thermal expansion coefficient in the circumferential direction and radial direction of the bottom portion are raised from room temperature to 800 ° C., 0.5% × 10 ⁻⁶ / ° C. or less. In particular, it is 0.0 × 10 ⁻⁶ / ° C. or less in the range from room temperature to 400 ° C., and heat shrinks in the range from room temperature to 400 ° C. That is, it expands when it is cooled from 400 ° C. to room temperature.
On the other hand, quartz glass constituting the quartz glass crucible has an average linear thermal expansion coefficient at 800 ° C. from room temperature is ^{0.5 × 10 -6 /℃~0.6×10 -6 / ℃} , approximately in the temperature range The average linear thermal expansion coefficient of the straight body portion and the bottom portion is a value close to or less than the average linear thermal expansion coefficient of quartz glass.

In this way, the quartz glass crucible and the carbon fiber crucible are cooled because the straight body portion of the crucible is made of a material having a small thermal expansion coefficient that is close to or less than the average linear thermal expansion coefficient of quartz glass. At this time, the quartz glass crucible can be easily removed from the carbon fiber reinforced carbon composite crucible without the quartz glass crucible biting into the straight body part (even if it is cooled in a state where both are in close contact). Can be taken out.
In particular, if the average linear thermal expansion coefficient of the straight body part and the bottom part is a negative value in the range of room temperature to 400 ° C., that is, less than 0.0 × 10 ⁻⁶ / ° C., the cooling process from 400 ° C. to room temperature Since the carbon fiber reinforced carbon composite material crucible expands, a gap is formed between the carbon glass crucible and the quartz glass crucible, and can be removed more easily.

[Example 1]
A carbon fiber woven fabric having a basis weight of 400 g / m ² was woven from commercially available pitch-based carbon fibers having a tensile modulus of 780 GPa, and a mixed adhesive of graphite powder and phenol resin was supported on the woven fabric to obtain a prepreg. This was attached to a cylindrical mold having a diameter of 500 mm and laminated and cured at 150 ° C. to obtain a cylindrical molded body. This was embedded in carbon powder and fired at about 1000 ° C., followed by secondary firing and purification at 2100 ° C. The bulk density of the obtained carbon fiber reinforced carbon composite cylinder was 1.55 g / cm ³ , and the average linear thermal expansion coefficient when the temperature was raised from room temperature to 800 ° C. was 0.31 × 10 ⁻⁶ / ° C.
The obtained carbon fiber reinforced carbon composite cylinder was attached to a receiving tray made of a graphite material to form a crucible. A quartz glass crucible filled with polycrystalline silicon was put into these carbon fiber reinforced carbon composite crucibles, heat-treated at 1550 ° C. for 5 hours and gradually cooled to confirm the state of fitting with the quartz glass crucible. As a result, the quartz glass crucible could be removed relatively easily.

[Example 2]
A carbon fiber woven fabric having a basis weight of 400 g / m ² was woven from commercially available pitch-based carbon fibers having a tensile modulus of 780 GPa, and a mixed adhesive of graphite powder and phenol resin was supported on the woven fabric to obtain a prepreg. This was attached to a cylindrical mold having a diameter of 500 mm and laminated and cured at 150 ° C. to obtain a cylindrical molded body. This was embedded in carbon powder, baked at about 1000 ° C., impregnated with a phenol resin and baked again, and then subjected to secondary baking and purification treatment at 2100 ° C. The bulk density of the obtained carbon fiber reinforced carbon composite cylinder was 1.55 g / cm ³ , and the average linear thermal expansion coefficient when the temperature was raised from room temperature to 800 ° C. was 0.49 × 10 ⁻⁶ / ° C.
The obtained carbon fiber reinforced carbon composite cylinder was attached to a receiving tray made of a graphite material to form a crucible. A quartz glass crucible filled with polycrystalline silicon was put into these carbon fiber reinforced carbon composite crucibles, heat-treated at 1550 ° C. for 5 hours and gradually cooled to confirm the state of fitting with the quartz glass crucible. As a result, the quartz glass crucible could be removed relatively easily.

[Comparative Example 1]
A carbon fiber reinforced carbon composite cylinder was obtained in the same manner as in Example 1 except that the carbon fiber used was a commercially available PAN-based carbon fiber having a tensile modulus of 240 GPa. The bulk density was 1.44 g / cm ³ , and the average linear thermal expansion coefficient when the temperature was raised from room temperature to 800 ° C. was 0.81 × 10 ⁻⁶ / ° C.
In the same manner as in Example 1, the obtained carbon fiber reinforced carbon composite cylinder was attached to a tray made of a graphite material to form a crucible. A quartz glass crucible filled with polycrystalline silicon was put into these carbon fiber reinforced carbon composite crucibles, heat-treated at 1550 ° C. for 5 hours and gradually cooled to confirm the state of fitting with the quartz glass crucible.
As a result, it was difficult to remove the quartz crucible from the cylinder, and when it was to be removed, the carbon fiber reinforced carbon composite cylinder was broken and cracked.

1 (pitch-based) carbon fiber woven fabric 2 (pitch-based) carbon fiber woven fabric (circular carbon fiber woven fabric)
3 (pitch-based) carbon fiber woven fabric 10 pitch-based carbon fiber reinforced carbon composite crucible (carbon fiber crucible)
11 Straight body (cylindrical member)
14 Mold for crucible molding 20 Pitch-based carbon fiber reinforced carbon composite crucible (carbon fiber crucible)
21 Straight body part 22 Bottom part

Claims (13)

In a carbon fiber reinforced carbon composite cylindrical member formed of a carbon fiber reinforced carbon composite material used for a crucible for supporting and holding a quartz glass crucible containing a molten material,
The carbon fiber reinforced carbon composite material is a carbon fiber reinforced carbon composite material including a carbon fiber woven fabric using pitch-based carbon fibers having a tensile modulus of 400 GPa or more and 900 GPa or less,
And the average linear thermal expansion coefficient of the circumferential direction at the time of heating up from normal temperature to 800 degreeC is below the average linear thermal expansion coefficient of quartz glass, The carbon fiber reinforced carbon composite cylindrical member characterized by the above-mentioned. 2. The carbon fiber according to claim 1, wherein the carbon fiber reinforced carbon composite material has an average linear thermal expansion coefficient of 0.5 × 10 ⁻⁶ / ° C. or less when the temperature is raised from normal temperature to 800 ° C. 3. Reinforced carbon composite cylindrical member.   3. The carbon according to claim 1, wherein the average linear thermal expansion coefficient is a negative coefficient in a range from room temperature to 400 ° C., and is thermally expanded in a cooling process from 400 ° C. to room temperature. Fiber reinforced carbon composite cylindrical member. Carbon fiber reinforced carbon composite cylindrical member according to any one of claims 1 to 3 weight per unit area of the pitch-based carbon fiber woven fabric is characterized in that it is a 200 to 600 g / m ^2. 5. The carbon fiber reinforced carbon according to claim 1, wherein the carbon fiber reinforced carbon composite material has a bulk density of 1.3 g / cm ³ or more and 1.8 g / cm ³ or less. Composite cylindrical member. A method for producing a carbon fiber reinforced carbon composite cylindrical member according to any one of claims 1 to 5,
The carbon fiber woven fabric is bonded using a mixed adhesive of a thermosetting resin and carbon powder, and then formed by performing a thermosetting treatment, a carbonization treatment, a graphitization treatment and a high purification treatment. A method for producing a carbon fiber reinforced carbon composite cylindrical member. Used to support and hold a quartz glass crucible containing molten material, and has a bottom portion and a straight body portion provided above the bottom portion, at least the straight body portion being a carbon fiber reinforced carbon composite material. Formed carbon fiber reinforced carbon composite crucible,
The straight body when the straight body is formed from a carbon fiber reinforced carbon composite material including a carbon fiber woven fabric using pitch-based carbon fibers having a tensile modulus of 400 GPa or more and 900 GPa or less, and the temperature is raised from room temperature to 800 ° C. The carbon fiber-reinforced carbon composite crucible, wherein the average linear thermal expansion coefficient in the circumferential direction of the portion is equal to or less than the average linear thermal expansion coefficient of quartz glass. The bottom part and the straight body part are carbon fiber reinforced carbon composite crucibles formed of a carbon fiber reinforced carbon composite material,
The bottom portion is integrally formed with the straight body portion by a carbon fiber reinforced carbon composite material including a carbon fiber woven fabric using pitch-based carbon fibers having a tensile modulus of 400 GPa or more and 900 GPa or less, and the temperature rises from room temperature to 800 ° C. The carbon fiber-reinforced carbon composite material according to claim 7, wherein an average linear thermal expansion coefficient in the circumferential direction of the bottom part and the straight body part when heated is equal to or less than an average linear thermal expansion coefficient of quartz glass. Crucible. The average linear thermal expansion coefficient when the temperature of the carbon fiber reinforced carbon composite material is raised from normal temperature to 800 ° C is 0.5 × 10 ^-6 / ° C or less. Carbon fiber reinforced carbon composite crucible.   The average linear thermal expansion coefficient of the straight body part and the bottom part is a negative coefficient in a range from room temperature to 400 ° C, and thermally expands in the cooling process from 400 ° C to room temperature. The carbon fiber reinforced carbon composite crucible according to claim 9. 11. The carbon fiber-reinforced carbon composite crucible according to claim 7, wherein the pitch-based carbon fiber woven fabric has a basis weight of 200 to 600 g / m ² . 12. The carbon fiber reinforced carbon according to claim 7, wherein the carbon fiber reinforced carbon composite material has a bulk density of 1.3 g / cm ³ or more and 1.8 g / cm ³ or less. Composite crucible. A method for producing a carbon fiber reinforced carbon composite crucible according to any one of claims 7 to 12,
The carbon fiber woven fabric is bonded using a mixed adhesive of a thermosetting resin and carbon powder, and then formed by performing a thermosetting treatment, a carbonization treatment, a graphitization treatment and a high purification treatment. A method for producing a carbon fiber reinforced carbon composite crucible.

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