JP2003129199A - New composite material and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a long-life holder for an atmospheric furnace with strength equal to or higher than that of a conventionally used C/C composite, and a sliding member having high abrasion resistance. SOLUTION: The composite material comprises a carbon fiber in which 50 wt.% or more of carbon fiber has length longer than 10 mm, and a matrix component containing carbon, silicon carbide, and metallic copper. The manufacturing method is also disclosed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to lightweight, strength,
The present invention relates to a composite material having excellent wear resistance and impact resistance. In particular, it relates to a jig in an atmosphere furnace and a composite material that can be used as a member that slides at a low temperature to a high temperature.

[0002]

2. Description of the Related Art Carbon-based materials such as carbon materials and carbon fiber-in-carbon composite materials (hereinafter also referred to as C / C composites), and ceramic-based materials such as zirconia, silicon nitride, silicon carbide and alumina It is a material that is lightweight, and has excellent strength, wear resistance, impact resistance, etc., and is used as a jig in an atmosphere furnace and as a sliding material that is exposed to temperature, acid, alkali, etc. attacks. Has been. In particular, the C / C composite is unrivaled in terms of its good combination characteristics of lightness and impact resistance, and it is a furnace component and furnace that can withstand excessive thermal shocks of rapid heating and quenching. It is used as an inner jig. Further, silicon carbide is a dense material having a hardness as high as that of diamond, and its wear resistance is superior to the characteristics of other materials. It is used as a sliding material for corrosive pumps.

In the case of the C / C composite used for such a furnace constituent member or in-furnace jig, if it can be used in a stationary state, it can be used stably for a long period of time. In some cases, the thermal expansion that occurs during each heating / cooling causes friction at the contact portion to cause wear, and the abrasion powder may adversely affect the quality and yield of the material treated in the furnace. In particular, it is known that the influence is remarkable in the case of the jig in the furnace. Further, in the case of silicon carbide or silicon nitride used as a sliding material, although the wear caused by friction is small, it cannot withstand the thermal stress caused by the local thermal expansion generated by frictional heat, and further has a toughness peculiar to ceramics. It is known that a slight mechanical shock is applied due to its low height, resulting in damage. In order to solve these problems, a composite material of C / C composite and silicon carbide is disclosed in JP-A-11-
No. 292662. However,
The production method requires special equipment that uses fibers under certain conditions and complicated control, and as a result, it is considered to be an extremely expensive material, and is not an industrial general-purpose material. A composite material intended to be used as a sliding material such as a brake in which a low melting point metal such as copper is infiltrated into a C / C composite is disclosed in JP-A-62-295985. There is no description of how to infiltrate copper, which has extremely poor wettability, and it cannot be considered that it can be actually infiltrated and manufactured, and it must be called a desk material. Even if such a material exists, it can be presumed that the composite material composed of a combination of soft copper and soft carbon has good lubricity for both copper and carbon. Is low, and it can be estimated that the abrasion resistance does not exceed that of copper or carbon. At present, it has not been possible to find a substitute material in terms of these comprehensive performances, ease of manufacture, and total manufacturing cost.

Therefore, the present inventors have researched and developed a new composite material that retains the excellent impact resistance and light weight of C / C composites, while retaining the abrasion resistance of ceramics. Came to do. Furthermore, we have conducted research and development of a method for producing a new composite material by performing constant raw material control and production method control without using special equipment so that it can be used in a wider range of fields at a lower cost.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and retains the excellent impact resistance, light weight, and other advantages of C / C composites.
Furthermore, the present invention was carried out by conducting research and development of a composite material, which has the characteristics of being lightweight and having excellent strength and abrasion resistance, which is contained in ceramic materials such as zirconia, silicon nitride, silicon carbide, and alumina. Furthermore, since it is very important for the spread of the material that it is a composite material that can be mass-produced industrially at low cost, the present invention has been achieved including the production without using special equipment or expensive equipment. . The present invention proposes a material of a combination of carbon fiber, carbon, silicon carbide and metallic copper, and a method for producing the same. According to this manufacturing method, it is possible to use glass fibers, ceramic fibers, or organic fibers instead of carbon fibers, it is possible to use organic substances that carbonize instead of carbon, and silicon carbide is used. Carbide ceramics having a high hardness or ceramics such as silicon nitride can be used instead of the above, and other metal / alloys such as copper alloy, aluminum, and iron can be used as the metal copper. The material obtained by the present invention is not only effective as a jig in an atmosphere furnace where strength and impact resistance are required, but also under a high load and under an environment where it is exposed to temperature, acid, alkali, and other attacks. It has the abrasion resistance required as a sliding material, and even under high temperature conditions, it has at least the same impact resistance and abrasion resistance as C / C composites that have been used conventionally. It is an object of the present invention to provide a composite material having: and a manufacturing method thereof.

[0006]

Means for Solving the Problems As a result of various studies to achieve the above-mentioned object, the present inventors have made it possible to impart strength and lubricity to a composite material by using a lightweight carbon fiber, and have a low specific gravity and hardness. By adding silicon carbide, which has a high thermal conductivity, to make the composite material lightweight and highly wear-resistant, and by adding carbon, a composite material with increased interlayer strength between carbon fibers can be realized, and metallic copper can be added. As a result, we have realized a composite material with excellent total balance that prevents the sliding performance from deteriorating due to the addition of silicon carbide. Here, in the production of the composite material of the present invention, a woven fabric made of carbon fibers having a desired fiber density is prepared, and a pre-mixed mixture of organic matter, silicon carbide, metallic copper and carbon is attached to the woven fabric. After that, it was heated and dried at a low temperature, and the thus-obtained forming precursor was formed into a formed sintered body having a desired density by hot pressing up to 250 ° C., and further sintered at a higher temperature if necessary. The present invention has been completed by including cooling the sintered body to room temperature while avoiding rapid thermal shock.

That is, according to the present invention, a composite material that can be used as a jig in an atmosphere furnace or a sliding material used in a harsh environment has carbon fiber, carbon, silicon carbide and metallic copper as matrix components. A composite material characterized by the fact that 50 wt% or more of the constituent carbon fibers has a length of 10 mm.
Controlled to exceed 20 to 80 wt% of carbon fiber component
%, 40 to 18 wt% carbon, 1 to 20 wt% silicon carbide
%, Metal copper is controlled to be contained in the range of 1 to 30 wt%, silicon carbide is controlled to be silicon carbide composed of α-type crystals, and silicon carbide is a fine carbonized material having an average particle size of 1 to 500 μm. It is controlled so that it is a silicon particle, and carbon is a powder having two bimodal peaks of average particle diameter, and is manufactured so that the coarse particle is controlled to be larger than the weight of the fine particle.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, 50 wt% or more of carbon fibers constituting a composite material characterized by using carbon fibers, carbon, silicon carbide and metallic copper as matrix components have a length of more than 10 mm. And manage the carbon fiber component to 2
Control so as to contain 0 to 80 wt%, carbon to 40 to 18 wt%, silicon carbide to 1 to 20 wt% and metallic copper to 1 to 30 wt%, and control so that silicon carbide is silicon carbide composed of α-type crystals. , Silicon carbide is controlled to be fine silicon carbide particles having an average particle size in the range of 1 to 500 microns, carbon is a powder having two bimodal peaks of average particle size, and coarse particles are fine particles. It is realized by managing and manufacturing so that it becomes larger than the weight. In the present invention, carbon fiber is used as one of the raw materials, but the type and brand thereof are not particularly limited, and as long as it is generally called carbon fiber, its production method, origin and the like are not limited. It can be used. Even if the fiber raw material is PAN (polyacrylonitrile), PICTH
It may be (pitch) or CVD (chemical vapor deposition). Further, as the fiber, any number of fibers such as 1K, 3K, 6K, 12K, and 24K (K means 1000) may be used. Further, the length of the fiber may be any length as long as the effect of fiber reinforcement is exhibited, and for example, if it is 10 mm or more, the effect is exhibited. Needless to say, the brands of these fibers may be fibers of any manufacturer such as Toho Rayon, Toray, and Mitsubishi Rayon. The fiber is preferably a sheet-shaped long-fiber woven fabric, more preferably a plain weave fabric, a twill weave fabric, or the like. Further, even in the case of an aggregate of single fibers, the effect is exhibited when the fibers having a length of 10 mm or more occupy 50% or more of the whole fibers.

Further, although silicon carbide powder is used in the present invention, its crystal form must be α type. Generally, there are low temperature β-type silicon carbide and high temperature type α-type silicon carbide in silicon carbide. Since β-type silicon carbide contains unreacted residual carbon and residual silicon inside, it does not exhibit the original hardness of silicon carbide and is not suitable for the present invention. On the other hand, α-type silicon carbide contains almost no residual carbon or residual silicon inside the particles, and therefore exhibits the original hardness of silicon carbide, and at the same time, the particles have a blocky shape with sharp corners. It can be preferably used in the invention.

The carbon to be added has an average particle size of 1 to 1
The range of 000 microns is preferable, for example, carbon having an average particle size of 10 microns is used in a ratio of 40% and carbon of 200 microns is used in a ratio of 60%, and the particle size distribution is bimodal, and the ratio of coarse particles is high. Is good. As a result, it is possible to obtain a composite material having a high interlaminar strength by forming a close-packed structure inside the molded body.

The metallic copper added exerts its effect whether it is in a powder state or a wire state. According to the production method of the present invention, a woven fabric or a fiber sheet made of carbon fibers having a desired fiber density is prepared, and a mixture of organic matter, silicon carbide, metallic copper, and carbon prepared in advance is attached to the woven fabric. After that, it is heated and dried at a low temperature, and the thus-obtained forming precursor is formed into a formed sintered body having a desired density by hot pressing up to 250 ° C., and if necessary, sintered at a higher temperature to obtain a sintered body. By cooling the bonded body to room temperature while avoiding rapid thermal shock, a composite material composed of carbon fibers and a matrix composed of carbon, silicon carbide and metallic copper can be manufactured.

A method of preparing a woven fabric or a fiber sheet and applying a mixture of an organic substance, silicon carbide, metallic copper and carbon prepared in advance to the woven fabric is as follows. That is, a resin having a relatively high residual carbon ratio such as a phenol resin (either a resole type or a novolak type) or a furan resin is used as an organic substance, and methyl alcohol, ethyl alcohol, octyl alcohol, acetone or kerosene is appropriately used to adjust the viscosity of the solution. And the like are prepared, and carbon having an average particle size in the range of 1 to 1000 μm (for example, carbon having an average particle size of 10 μm is added at a ratio of 40% and carbon of 200 μm at a ratio of 60%) is added. In addition to having a modal particle size distribution, the average particle size of α-type crystals is 1 to 5
A solution is prepared by adding fine silicon carbide particles in the range of 00 microns and adding metallic copper in the form of powder or wire to the fibers. Here, the concentration of the liquid is 40 to 18 w for carbon when the carbon fiber component is 20 to 80 wt%.
t%, 1 to 20 wt% of silicon carbide, 1 to 30 w of metallic copper
Include t%. The prepared liquid is uniformly applied to a woven fabric or a fiber sheet by a roller or the like. Here, the prepared liquid is a mixture of substances with different specific gravities, so it is preferable to always stir it. Furthermore, since air will be entrained during mixing, it should be thoroughly degassed in a vacuum chamber etc. immediately before coating. It is better to carry out, and when using a phenol resin, in order to control the hardness of the resin, 20 ° C to 40 ° C.
It is better to keep the liquid temperature in the range.

When the metallic copper is added in the form of a wire, it is not mixed in the above-mentioned liquid, but is uniformly applied after applying a liquid containing only metallic copper to the woven fabric or the fiber sheet with a roller or the like. It is also possible to disperse and attach a fixed amount to the. The woven fabric or fiber sheet coated with the liquid is press-molded after being naturally dried at 100 ° C. or lower or dried by heating. The pressing is performed in a temperature range of up to 180 ° C. while sufficiently exhausting gas decomposed and generated from organic substances such as phenolic resin for several minutes until the curing of the resin is completed. The pressure applied during pressing is 1 MPa or more and 100
M or less, preferably 5 MPa or more and 20 MPa or less, more preferably 10 MPa or more, 15 MP
It is a or less. In this case, the application time of the pressure is 10 seconds or more and 60 minutes or less, preferably 2 minutes or more and 20 minutes or less. This has a material thickness of 30m when the press is completed.
The same is true when the wall thickness exceeds m. Also, in order to heat the material, it is preferable to use a press equipped with a heater inside both the upper mold and the lower mold.

After that, 600 ° C. in an atmosphere with a small amount of oxygen
The organic matter is carbonized at a moderate temperature, and at the same time, volatile components and decomposed components are removed. Further, in order to sufficiently remove volatile components and decomposed components, heat treatment is performed at a temperature of about 1000 ° C. in an atmosphere with a small amount of oxygen. These heated materials are 10
It is better to cool to 100 ° C at a temperature slower than 00 ° C / hour. Cooling at a rate exceeding this rate may cause cracks or delamination inside the composite material.

The term "composite material" as used herein means a press-molded product which is formed in a temperature range of up to 180 ° C., and carbonizes organic matter at a temperature of about 600 ° C. in an atmosphere with a small amount of oxygen, and at the same time removes volatile components and decomposed components. Needless to say, both the sintered body, the sintered body in which the volatile components and the decomposed components are sufficiently removed at a temperature of about 1000 ° C. in an atmosphere with a small amount of oxygen, and the sintered body which is further heat-treated at a high temperature.

[0016]

EXAMPLES Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The properties of the composite materials obtained in each example were evaluated by the methods described below. (Composite material strength evaluation method) 8 mm width, 6 mm thickness,
A material having a length of 80 mm was cut out from the composite material to obtain a test piece. This was installed on a beam-supported jig with a distance between fulcrums of 60 mm, the container with hooks was hung down to the center of the test piece, and sand was gradually put into the container to break the test piece. The strength of the material was measured and calculated by measuring the weight of the sand and the container. (Evaluation Method of Amount of Abrasion of Composite Material) Diameter 40 mm, Thickness 30
A mm-shaped cylindrical material was cut out from the composite material to obtain a test piece. The test pieces were fixed to the top and bottom of the milling machine, a certain amount of load was applied to the Z-axis moving arm of the milling machine, and the test pieces were pressed against each other while rotating at 200 rpm for 10 minutes to evaluate the amount of wear. The amount of wear was measured by measuring the mass Wa (mg) of the cylindrical test piece before the test and the mass Wb (mg) after the test, and measuring this and the density ρ of the test piece.
The wear amount V (mm ³ ) was calculated from (g / cm ³ ) by the following formula. Amount of wear V = (Wa-Wb)
/ Ρ (Example 1) A PAN (polyacrylonitrile) system was used as the raw material system of the fiber and further 12K (where K is 100).
A bundle number of fibers (meaning 0) was used. Further, as the fiber, a plain weave fabric of long fibers made by Toho Rayon was used. Here, 800 g of fabric having a basis weight of 500 g / m 2 after plain weaving was used.
As the silicon carbide powder, the crystal form was α type and the average particle size was selected to be 1 micron. In addition, as the added carbon, carbon having an average particle size of 10 microns was used at a ratio of 30% and carbon having an average particle size of 200 was used at a ratio of 70% to obtain a bimodal particle size distribution. As the metallic copper to be added, powder having an average particle size of 10 μm was used.

Using 300 g of a phenol resin (resole-type residual carbon ratio of 50%) as an organic substance, a solution prepared by appropriately adding ethyl alcohol for adjusting the viscosity of the solution is prepared, and 10 g of the above-mentioned silicon carbide and 30 g of carbon are added thereto. And 10 g of copper were added and mixed to prepare a mixed solution. The entire amount of the prepared liquid was uniformly applied to a carbon fiber woven fabric by a roller. Here, the prepared liquid was constantly stirred, and immediately before coating, it was deaerated in a vacuum chamber for 10 minutes. The temperature of the preparation liquid was kept at 25 ° C.

The carbon fiber woven fabric coated with the liquid is naturally dried in the atmosphere for 12 hours, and further heated and dried at 80 ° C. for 3 hours.
After time, it was press molded. The press performs degassing 5 times within 3 minutes until the curing of the resin is completed.
Heated to 80 ° C. The press pressure was 5 MPa, and the pressure application time was 20 minutes.

Then, at 600 ° C. in an atmosphere containing a small amount of oxygen.
After heat treatment for 1 hour at 100 ° C at a rate of 500 ° C / hour
It cooled to 0 degreeC and obtained the composite material. (Example 2) A PAN (polyacrylonitrile) system was used as a raw material system of the fiber, and a short fiber 20 having a length of 25 mm was used.
0 g was used. Further, as the silicon carbide powder, the crystal form was α type, and the average particle size was selected to be 500 μm. In addition, as the added carbon, 40 carbon with an average particle size of 70 microns is used.
%, 100 micron carbon was used at a ratio of 60% to obtain a bimodal particle size distribution. As the metallic copper, a wire rod having an average diameter of 100 μm was used.

Using 300 g of a phenol resin (resole-type residual carbon ratio of 50%) as an organic substance, a solution was prepared by appropriately adding ethyl alcohol for adjusting the viscosity of the solution. To this, 200 g of silicon carbide and 250 g of carbon were prepared. , Copper 200g
Was added and mixed, and short fibers were further mixed with this to obtain a liquid. The liquid was made into a fibrous sheet having a uniform thickness with a roller. The fibrous sheet was naturally dried in the atmosphere for 12 hours, further heated and dried at 80 ° C. for 3 hours, and then press-molded. The press was degassed 5 times during 3 minutes until the curing of the resin was completed, and heated to 180 ° C. The press pressure was 5 MPa, and the pressure application time was 20 minutes.

After that, 600 ° C. in an atmosphere with a small amount of oxygen
After heat treatment for 1 hour, it was cooled to 100 ° C. at 500 ° C./hour to obtain a composite material. (Example 3) A PAN (polyacrylonitrile) system was used as a raw material system for fibers, and further 12K (where K is 100).
A bundle number of fibers (meaning 0) was used. Further, as the fiber, a plain weave fabric of Toray long fibers was used. Here, 700 g of plain weave having a basis weight of 500 g / m 2 was used. Further, the silicon carbide powder has an α-type crystal form and an average particle size of 5
Micron was selected. The added carbon has an average particle size of 10
30% micron carbon, 70% 200 micron carbon
% And used as a bimodal particle size distribution. As the metallic copper to be added, powder having an average particle size of 30 μm was used.

300 g of a phenol resin (resole-type residual carbon ratio of 50%) was used as an organic substance, and ethyl alcohol was appropriately added to adjust the viscosity of the solution. A solution was prepared, and 50 g of the above-mentioned silicon carbide and 50 g of carbon were prepared. And 50 g of copper were added and mixed to prepare a mixed solution. The entire amount of the prepared liquid was uniformly applied to a carbon fiber woven fabric by a roller. Here, the prepared liquid was constantly stirred, and immediately before coating, it was deaerated in a vacuum chamber for 15 minutes. The temperature of the preparation liquid was kept at 25 ° C.

The carbon fiber woven fabric coated with the liquid is naturally dried in the atmosphere for 12 hours, and further heated and dried at 80 ° C. for 3 hours.
After time, it was press molded. The press vents 8 times during 3 minutes until the curing of the resin is completed.
Heated to 60 ° C. The press pressure is 10 MPa,
The pressure application time was 30 minutes.

After that, 1000 in an atmosphere with a small amount of oxygen
After heat treatment at 1 ° C. for 1 hour, it was cooled to 100 ° C. at 250 ° C./hour to obtain a composite material. (Comparative Example) A PAN (polyacrylonitrile) system was used as the raw material system of the fiber and further 12K (where K is 1000).
(Meaning of book) The number of fibers of the bundle was used. Further, as the fiber, a plain weave fabric of Toray long fibers was used. Here, 700 g of plain weave having a basis weight of 500 g / m 2 was used. As the carbon, carbon having an m average particle diameter of 10 microns was used. A solution was prepared by using 300 g of a phenol resin (resol type residual carbon ratio of 50%) as an organic substance, and appropriately adding ethyl alcohol to adjust the viscosity of the solution. To this, 150 g of the above carbon was added and mixed to prepare a preparation liquid. . The entire amount of the prepared liquid was uniformly applied to a carbon fiber woven fabric by a roller.

The carbon fiber woven fabric coated with the liquid is naturally dried in the atmosphere for 12 hours, and further heated and dried at 80 ° C. for 3 hours.
After time, it was press molded. The press vents 8 times during 3 minutes until the curing of the resin is completed.
Heated to 60 ° C. The press pressure is 10 MPa,
The pressure application time was 30 minutes.

After that, 1000 in an atmosphere with a small amount of oxygen
After heat treatment at 1 ° C. for 1 hour, it was cooled to 100 ° C. at a rate of 1500 ° C./hour or more to obtain a composite material. Example 1,
From the composite materials obtained in Examples 2, 3 and Comparative Example, a material having a width of 8 mm, a thickness of 6 mm and a length of 80 mm, and a diameter of 40 mm,
A cylindrical material having a thickness of 30 mm was cut out, and the strength and the amount of wear were measured by the above method.

The three-point bending strength of the composite material was measured in Example 1,
The values of 2 and 3 are 150 MPa, 105 MPa,
It was 130 MPa, whereas the comparative example was 60 MPa. In each of Examples 1, 2, and 3, the composite material exceeded 100 MPa and had high strength. The wear amount of the composite material is
2,3 Each value is 30mm ^3, 8mm ³ 15mm ³
In contrast, the comparative example had a size of 120 mm ³ . In each of Examples 1, 2 and ³ , the composite material had a wear resistance of less than 50 mm ³ and high abrasion resistance.

The densities of the composite materials obtained in Examples 1, 2 and 3 were 1.65 g / cm ³ and 1.75 g, respectively.
/ Cm ³ , 1.70 g / cm ³ and lightweight.

[0029]

EFFECTS OF THE INVENTION Since the composite material according to the present invention exhibits practical strength and has a small amount of wear, it can be seen that it is an extremely promising jig for atmosphere furnaces or a sliding member. Also,
It contains a certain amount of carbon fiber with low specific gravity, high toughness and high strength, and the added material is carbon and a small amount of silicon carbide and copper, so it is lightweight and has little energy loss. In line with the demands of the age of energy conservation. Furthermore, the manufacturing method is simple, and it is not necessary to use expensive equipment or a special control device, and a large amount of composite material can be provided at low cost.

Therefore, as is clear from the above results, the composite material and the method for producing the same according to the present invention are extremely promising techniques as jigs for atmospheric furnaces and sliding members.

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Claims (7)

[Claims] 1. A composite material comprising carbon fiber, carbon, silicon carbide and metallic copper as matrix components. 2. The composite material according to claim 1, wherein 50 wt% or more of the constituent carbon fibers exceeds 10 mm in length. 3. The composite material according to claim 1, which comprises 20 to 80 wt% of a carbon fiber component, 40 to 18 wt% of carbon, 1 to 20 wt% of silicon carbide, and 1 to 30 wt% of metallic copper. 4. The composite material according to claim 1, wherein the silicon carbide is silicon carbide composed of α-type crystals. 5. The composite material according to claim 1, wherein the silicon carbide is fine silicon carbide particles having an average particle size of 1 to 500 μm. 6. The composite material according to claim 1, wherein the carbon is a powder having two peaks of bimodal average particle diameter, and coarse particles are larger than weight of fine particles. 7. A woven fabric or fiber sheet made of carbon fibers having a desired fiber density is prepared, and a mixture of an organic substance, silicon carbide, metallic copper, and carbon prepared in advance is attached to the woven fabric, and then the mixture is heated at a low temperature. The shaped precursor thus obtained is dried by heating to obtain a shaped sintered body having a desired density by hot pressing up to 250 ° C., and if necessary, further sintered at a high temperature to obtain a sintered body. A method for producing a composite material comprising carbon fibers and a matrix composed of carbon, silicon carbide and metallic copper, characterized in that cooling is performed while avoiding rapid thermal shock.