JP2007535461A - Process for producing carbon fiber reinforced ceramic composites - Google Patents

Abstract

The present invention relates to a method for producing a carbon fiber reinforced ceramic composite, and the method for producing a carbon fiber reinforced ceramic composite according to the present invention comprises a mixture of carbon fiber and a precursor of a carbon-containing polymer. A step of producing a molded carbon fiber reinforced resin composite and a chemical vapor with a rapid thermal gradient while heat-treating the carbon fiber reinforced resin composite at a high temperature to increase the deposition rate from the inside to the outside. The step of depositing pyrolytic carbon in the step of infiltration of carbon to produce a carbon fiber reinforced carbon composite, and the step of infiltrating liquid silicon into the pores of the carbon fiber reinforced carbon composite It is characterized by. The method for producing a carbon fiber reinforced ceramic composite according to the present invention has the effect of improving the physical properties of the carbon fiber reinforced ceramic composite, compared to all conventional chemical vapor infiltration processes. Since the pyrolytic carbon layer can be deposited at a deposition rate of 5 to 10 times or more, the production process, production time, and production cost are greatly improved.

Description

  The present invention provides a carbon fiber reinforced ceramic composite that retains excellent mechanical strength at high temperatures and has excellent corrosion resistance, heat resistance, and friction / wear characteristics in harsh environments such as thermal and chemical erosion. It relates to a manufacturing method.

  Fiber-reinforced ceramic composites are lightweight and have excellent mechanical and thermal properties at high temperatures. These properties of fiber-reinforced ceramic composites require friction and wear materials such as brake disks and pads for aircraft and land vehicles, mechanical strength, corrosion resistance and heat resistance at high temperatures It has been applied to ceramic engines and ultra high temperature heat-resistant materials in rocket nozzles. Fiber reinforced ceramic composites are devised to overcome the brittle fracture shortcomings of Monolithic Ceramics, and heat the pores of preforms made of carbon or silicon carbide fibers. Manufactured by filling with refractory materials such as cracked carbon, silicon carbide, or boron nitride.

  To date, fiber reinforced ceramic composites have been manufactured in a variety of manufacturing processes, but in most cases, the fibers are damaged by mechanical and thermal shock during the manufacturing process. In order to solve such problems, a ceramic composite is prepared by introducing a gaseous precursor into a low-density porous fiber preform and then thermally decomposing it to deposit a ceramic matrix phase. Such a process is called chemical vapor infiltration, which occurs from the production of an existing ceramic composite by depositing a matrix phase at low temperature and pressure conditions. The problem of fiber damage was solved.

  However, such processes use expensive raw materials and manufacturing equipment, and the manufacturing process is complicated and requires a process time of several hundred hours or more. It is very constrained in advanced industrial fields.

  Unlike the chemical vapor infiltration process using a gaseous source gas, a process for producing a carbon fiber reinforced ceramic composite by impregnating liquid carbon with a porous carbon preform has been developed.

  Walter Krenkel et al., In Patent Document 1, Patent Document 2, and Patent Document 3, formed a mixture of cut carbon fiber, liquid phenol, and carbon powder under high-temperature and high-pressure conditions, followed by a high-temperature heat treatment process. Carbon fiber reinforced carbon composites were produced. Liquid silicon is infiltrated into the carbon fiber reinforced carbon composite manufactured in this way, and the carbon fiber reinforced ceramic composite is applied to brake disks for land vehicles and heat resistant materials in the field of space and aviation. did.

  However, the carbon fiber reinforced resin composite produced by mixing the liquid carbon precursor as described above is more efficient than the existing chemical vapor infiltration process in terms of production cost. It is difficult to form a protective layer for carbon fiber and it is difficult to prevent the reaction between liquid silicon and carbon fiber during the process of impregnation with liquid silicon, which is the mechanical property of carbon fiber reinforced ceramic composites. Was drastically reduced. In order to solve such problems, Patent Document 4, Patent Document 5, Patent Document 6, and Patent Document 7 repeatedly impregnate a liquid organic binder or change the composition of the mixture to change the carbon fiber. Although a reinforced ceramic composite was produced, it was not possible to prevent deterioration of mechanical properties due to carbon fiber erosion and to improve high-temperature friction / wear characteristics.

  In the above and other processes, in Patent Document 8 and Patent Document 9, a preform made by weaving carbon fiber is subjected to isothermal / isobaric chemical vapor infiltration (ICVI) process. After vapor deposition of pyrolytic carbon, a carbon fiber reinforced ceramic composite was manufactured by proceeding a densification process of the carbon precursor again by a liquid impregnation method. Although such a process has improved the performance in terms of fiber protection, it is difficult to combine different carbon fiber reinforced ceramic composites into one structure, and it is difficult to bond carbon fiber reinforced complex shapes. The manufacture of ceramic composites is not easy. In particular, the manufacturing process is complicated, and manufacturing time of several hundred hours or more is required, resulting in an increase in manufacturing cost.

A comprehensive review of the issues related to the production of carbon fiber reinforced ceramic composites to date shows that in most cases the carbon fiber reinforced used for the production of carbon fiber reinforced ceramic composites. It can be seen that the production process of the carbon composite has a lot of production costs and has technical problems. For example, in the case of an existing chemical vapor infiltration process, it has excellent properties as a fiber protective layer, but due to the difficulty of expensive raw materials and manufacturing processes, the production of carbon fiber reinforced carbon composites Does not fit. When a carbon fiber reinforced resin composite is manufactured using an impregnation process of an organic binder containing a carbon component, a repetitive impregnation process is required, and its effectiveness is reduced in terms of fiber protection. I know you do.
US Pat. No. 6,308,808 US Pat. No. 6,358,565 US Pat. No. 5,942,064 Korean Patent Application No. 1999-7008146 Specification US Pat. No. 6,079,525 US Pat. No. 6,030,913 US Pat. No. 6,231,791 US Pat. No. 6,212,475 Korean Patent Application No. 1999-7003211 Specification

  The present invention is to solve the above-mentioned problems, and the object of the present invention is to provide a starting material necessary for producing a carbon fiber reinforced ceramic composite, and a carbon fiber reinforced carbon composite. Production of carbon fiber reinforced ceramic composites by improving the manufacturing method to improve the thermal and mechanical properties of carbon fiber reinforced ceramic composites and solving the above-mentioned problems due to expensive manufacturing costs and processes This is to provide a method.

  In order to solve the above-mentioned problems, the inventors have simplified the manufacturing process by using a carbon felt preform, a sandwich structure, or a mixture of carbon fibers as a starting material, and are uniform in a fast and inexpensive process. Applying a rapid thermal gradient chemical vapor infiltration process to produce a carbon fiber reinforced carbon composite with a fiber protective layer and using the liquid silicon infiltration process together with the carbon fiber This is to provide a method for producing a reinforced ceramic composite.

Method for producing a ceramic composite of carbon fiber reinforced according to the present invention for achieving the above object (C _f / C-SiC) was formed from a mixture obtained by mixing the pre驅体carbon fibers and carbon-containing polymer A step of producing a carbon fiber reinforced resin composite and a rapid thermal gradient chemical vapor infiltration while heat-treating the carbon fiber reinforced resin composite at a high temperature to increase the deposition rate from the inside to the outside. The method comprises the steps of: depositing pyrolytic carbon in a process to produce a carbon fiber reinforced carbon composite; and impregnating liquid silicon into pores of the carbon fiber reinforced carbon composite. To do.

Preferably, the mixture contains 10 to 60 wt% of the carbon fiber and 30 to 60 wt% of a precursor of the carbon-containing polymer.
Preferably, the mixture contains silicon carbide powder of 30 wt% or less and carbon powder of 30 wt% or less.

Preferably, the carbon fiber reinforced resin composite is characterized in that the mixture and carbon fabric are alternately laminated.
Preferably, the molded body is formed with a primary surface layer that prevents a reaction between carbon fibers and silicon by the mixture that is mixed in the mixing process, and the primary surface layer includes the liquid silicon. A ceramic base layer made of silicon carbide and silicon is formed by chemical reaction with the liquid silicon in the infiltration step.

  Preferably, the molded body is heat-treated at a temperature of 900 to 2200 ° C. in an inert gas atmosphere, and then deposited in the rapid thermal gradient chemical vapor infiltration process. A base layer of pyrolytic carbon, which is a secondary surface layer, is deposited on the surface layer.

  Preferably, in the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration step, the temperature of the pyrolysis reaction using a hydrocarbon gas is 700 to 1200 ° C., and the reaction pressure is 188 to 1130 torr. It is characterized by a range.

  Preferably, in the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration step, the vapor deposition region is divided into at least a plurality of regions from the inside to the outside, and vapor deposition is performed at different rates in each region. It is characterized by.

Preferably, the vapor deposition region is vapor-deposited from the inside to the outside within a vapor deposition rate range of 0.5 to 3.0 mm / hr.
Preferably, the carbon fiber reinforced carbon composite has an apparent density of 1.0 to 1.7 g / cm ³ and 5 to 30% of open pores used for the liquid silicon penetration path. Features.

  Preferably, the step of impregnating the liquid silicon includes laminating the carbon fiber reinforced carbon composite on the silicon powder and maintaining the interior of the reactor at 100 torr or less, and then melting the silicon. It is characterized by heating at a temperature of 1410 ° C. or higher, which is the point, to infiltrate liquid silicon into the interior of the preform, and at the same time induce chemical reactions with a plurality of carbon layers.

  In order to achieve the above-mentioned object, a method of manufacturing a carbon fiber reinforced ceramic composite according to the present invention includes a step of manufacturing a carbon felt preform, and a deposition rate of the carbon felt preform from the inside to the outside. A stage of rapid chemical vapor chemical vapor infiltration with a rapid thermal gradient to produce a carbon fiber reinforced carbon composite, and liquid silicon in the pores of the carbon fiber reinforced carbon composite. It is characterized by comprising the step of infiltration.

Preferably, the carbon felt preform is made of any one of carbon fibers such as oxypen, pen, rayon, and pitch.
Desirably, the carbon felt preform is reinforced with carbon fibers of 10 mm or less on the Z-axis, with the mat laminated being quasi-isotropic such as 0 ° / + 60 ° / -60 °. Features.

Preferably, the carbon felt preform is deposited with a pyrolytic carbon layer having a thickness of 5 to 100 μm according to the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration process. Features.

  Preferably, in the step of infiltrating the liquid silicon, the carbon fiber reinforced carbon composite is impregnated with liquid silicon, and the carbon fibers are reinforced in the three axes X, Y, and Z. Features.

  Preferably, in the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration step, the temperature of the pyrolysis reaction using a hydrocarbon gas is 700 to 1200 ° C., and the reaction pressure is 188 to 1130 torr. It is characterized by a range.

  Preferably, in the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration step, the vapor deposition region is divided into at least a plurality of regions from the inside to the outside, and vapor deposition is performed at different rates in each region. It is characterized by.

Preferably, the vapor deposition region is vapor-deposited from the inside to the outside within a vapor deposition rate range of 0.5 to 3.0 mm / hr.
Preferably, the carbon fiber reinforced carbon composite has an apparent density of 1.0 to 1.7 g / c.
m ³ , characterized in that it has 5 to 30% of open pores used in the liquid silicon permeation pathway.

  Preferably, the step of impregnating the liquid silicon includes laminating the carbon fiber reinforced carbon composite on the silicon powder and maintaining the interior of the reactor at 100 torr or less, and then melting the silicon. It is characterized in that it is heated at a temperature of 1410 ° C. or higher, which is a point, so that liquid silicon penetrates the inside of the carbon felt preform and induces a chemical reaction with a plurality of carbon layers.

  Below, the manufacturing method of the composite of the carbon fiber reinforced ceramic which concerns on this invention is demonstrated. In the following embodiments, the composition of each mixture and the production method can be modified in various ways by modifying a part of the structure. However, if the modified embodiments basically include the technical components claimed by the present invention, all of them should be considered to be included in the technical scope of the present invention.

  First, on the side of the starting material, a carbon felt preform in which carbon fibers are reinforced in the directions of three axes of X, Y and Z is used, or carbon fibers having a length of 0.3 to 150 mm (carbon fibers). ) Applying a sandwich structure made by alternately laminating a mixture of carbon-containing polymer precursor, silicon carbide powder and graphite powder and carbon fabrics, or just the above mixture Carbon fiber reinforced resin composites (CFRP) can be used.

The produced starting material is a porous carbon fiber reinforced carbon composite by depositing a pyrolytic carbon layer in a rapid thermal gradient chemical vapor infiltration process described below. Liquid silicon is infiltrated into the open pores in the carbon fiber reinforced carbon composite to produce a carbon fiber reinforced ceramic composite. The above carbon fiber reinforced ceramic composite has an apparent density of 2.2 g /
It has physical properties of cm ³ or more, apparent porosity of 1% or less, bending strength of 100 MPa or more, and thermal conductivity of 35 W / mk or more.

The method for producing a carbon fiber reinforced ceramic composite according to the present invention can be divided into two steps depending on the starting material as shown in FIG. 1 and FIG.
First, the process illustrated in FIG. 1 uses a carbon fiber cut into a size of 0.3 to 150 mm, a precursor of a carbon-containing polymer, a powder of silicon carbide, and a powder of graphite and a carbon fabric, This is a process for producing a composite of carbon fiber reinforced resin.

  The carbon fiber reinforced resin composite is manufactured by placing carbon fibers cut to a size of 0.3 to 150 mm in distilled water together with a carbon-containing polymer precursor, silicon carbide powder, and graphite powder. To produce a uniform mixture through the process of dispersion and mixing.

In this mixture, a carbon-containing polymer precursor, silicon carbide powder, and graphite powder form a primary surface layer on the surface of the carbon fiber, and the composition of the mixture is 10 to 60 wt% of the carbon fiber. The carbon-containing liquid precursor is 30 to 60 wt%. A silicon carbide powder and a carbon powder are selectively included. That is, it can be composed of 0-30 wt% silicon carbide powder and 0-30 wt% carbon powder. (S101) (S102)
The mixture thus prepared is alternately laminated with a carbon fabric to form a green body having a sandwich structure (S110). The carbon fabric can be in the form of plain weave, satin weave or twill weave. Here, in still another method of manufacturing the molded body, the carbon woven fabric is not alternately stacked, and only the mixture can be stacked and manufactured.

After that, after the produced molded body was inserted into a molding mold, heat of 80 to 250 ° C. and 1 to 20 MP
The pressure of a is simultaneously applied to produce a carbon fiber reinforced resin composite. At this time, the produced carbon fiber reinforced resin composite had an apparent density of 1.2 to 1.6 g / cm ³ and an apparent porosity of 1
It has a value of ~ 20%. (S110) (S120) (S130)
The above-described method for producing a composite of carbon fiber reinforced resin is based on the technical contents described in Korean Patent Application No. 1995-0069130 and Korean Patent Application No. 1997-0023344 filed by the present applicant. Applicable to.

  Next, the vapor deposition step (S140) in the rapid thermal gradient chemical vapor infiltration process is performed in which the produced carbon fiber reinforced resin composite is heated to 700-2200 ° C under an inert gas atmosphere. After the heat treatment, a rapid thermal gradient chemical vapor infiltration process is performed to produce a carbon fiber reinforced carbon composite.

Specifically, the rapid thermal gradient chemical vapor infiltration process of the present invention has a density of 1.3 g /
For the production of dense carbon fiber reinforced carbon composites of cm ³ or more, this rapid thermal gradient chemical vapor infiltration process divides the area to be deposited into at least three locations, It is to control the deposition rate in each section so that the deposition is performed more rapidly. At this time, the vapor deposition rate is controlled by moving a thermocouple installed in the chemical vapor deposition apparatus from the inside of the molded body to the outside at a high speed in order.

  That is, as shown in FIG. 4, a carbon fiber reinforced resin composite (500) is installed in the reactor (300), and a heating element (400) is installed in the center. And it implements, supplying hydrocarbon gas to process gas. The vapor deposition rate is controlled using a thermocouple (not shown) as described above, and vapor deposition is performed from the inside to the outside.

  And the arrow of the deposition rate illustrated in the drawing indicates that the deposition rate is slow, and that the arrow indicates that the deposition rate is fast. And the part of T1 is high temperature, the part of T2 represents low temperature, and this represents that a thermal gradient is induced | guided | derived.

In this case, the deposition rate is 0.5 to 3.0 mm / hr, and the deposition is performed from the inside to the outside. As an example, after dividing the region into the inside, the middle part, and the outside, the inside is vapor-deposited at 1.0 mm / hr, the middle part is vapor-deposited at 1.5 mm / hr, and the outside is vapor-deposited at 2.0 mm / hr. Vapor deposition should be done quickly. At this time, it is because the vapor deposition rate is relatively slower than the outside inside the molded body because the vapor deposition rate is slowed inside.

  Thus, by controlling the deposition rate, the isothermal / isobaric gas phase infiltration method, which requires high manufacturing cost due to the complicated process and long production time, pressure gradient chemical gas phase infiltration method, and existing Compared to all existing chemical vapor infiltration processes, such as chemical vapor infiltration with a constant thermal gradient, the manufacturing process and manufacturing costs can be innovatively improved.

This rapid thermal gradient chemical vapor infiltration process has a deposition rate of 5-10 compared to the thermal gradient chemical vapor infiltration process of Korean Patent No. 0198154, which is a patent right of the present applicant. By proceeding densely more than twice as fast, a pyrolytic carbon layer of about 5 to 100 μm can be formed on the surface of the carbon fiber.

At this time, the pyrolytic carbon layer thus formed acts on the reaction layer that reacts with the liquid silicon to form a silicon carbide matrix phase during the liquid silicon impregnation step.
The carbon fiber reinforced resin composite produced by the rapid thermal gradient chemical vapor infiltration process of the present invention has an apparent density of 1.0 to 1.7 g / cm ³ and an apparent porosity of 5 to 30%. Has a rate value.

Next, the liquid silicon infiltration process is a carbon fiber reinforced carbon composite produced in the rapid thermal gradient chemical vapor infiltration process, with silicon powder in the particle size range of 1 μm to 10 mm Position on top of.

  The process conditions at this time are heating at a temperature of 1410 ° C. or higher, which is the melting point of silicon, under a vacuum atmosphere. Silicon melted at a high temperature of 1410 ° C or higher fills most of the pores within a few minutes due to the capillary force of the pores existing in the carbon fiber reinforced carbon composite, and at the same time, the carbon above the carbon fiber. It reacts with the reaction layer and synthesizes into silicon carbide. Thus, the final manufactured carbon fiber reinforced ceramic composite consists of 30-60 wt% carbon, 35-60 wt% silicon carbide, and up to 5 wt% unreacted silicon.

Next, as shown in FIG. 2, a carbon fiber reinforced ceramic composite can be manufactured using a molded body made of a carbon felt preform as a starting material.
First, to manufacture a carbon felt preform reinforced in the three axis directions of X, Y, and Z (S200), specifically, carbon fibers such as oxypen, pen, rayon, pitch, etc. Is wound around a mandrel to produce a unidirectional carbon mat, and the carbon mats produced in this way are laminated. The lamination method is alternate lamination in a semi-isotropic manner such as 0 ° / + 60 ° / -60 °.

  Then, after the lamination is made into a minimum of two layers, punching is performed using a needle to reinforce each layer in the direction of the Z axis and the above process is repeated to form a felt preform having a thickness of 30 mm or more. To manufacture.

The felt preform has a fiber volume ratio of about 10 to 55%, the thickness of one layer is about 0.1 mm or less, the length of the Z-axis fiber is 10 mm or less, and the fiber ratio is , To produce about 10%. In addition, a needle having a density of 15 penetration / cm ³ can be used for the Z axis.

  Thereafter, in order to remove impurities from the carbon felt preform, heat treatment is performed in a vacuum atmosphere at 1700 ° C. or higher. The contents relating to the method for producing such a carbon felt preform are based on the embodiments of US patent application US10-180778 filed by the present applicant and Korean Patent No. 27788.

  Next, a carbon fiber reinforced carbon composite is manufactured using a rapid thermal gradient chemical vapor infiltration process (S210), which was mentioned in the first step described above. A carbon fiber reinforced carbon composite is manufactured using a rapid thermal gradient chemical vapor infiltration process (S220).

  Then, a carbon fiber reinforced ceramic composite is manufactured using a liquid silicon infiltration process. This liquid silicon impregnation step is applied in the same manner as in the first embodiment described above.

Hereinafter, preferred embodiments of the above method will be described.
<Example 1>
30 wt% carbon fiber cut to 30 mm, phenolic resin 40 wt%, carbon powder 5 wt%, and silicon carbide powder 5 wt% mixture to form a 20 wt% satin weave carbon A molded body was produced by alternating lamination with a woven fabric. Put the manufactured molded body into a molding mold and set 2MPa
A carbon fiber reinforced resin composite was produced by curing simultaneously with pressurization at a pressure of 10 minutes.

  The carbon fiber reinforced resin composite was subjected to high temperature heat treatment in an inert gas atmosphere. Then, pyrolytic carbon was vapor-deposited under the conditions of chemical vapor infiltration with a rapid thermal gradient to produce a carbon fiber reinforced carbon composite.

  A carbon fiber reinforced carbon composite produced as described above is laminated on a silicon powder and heated at a temperature of 1550 ° C. in a vacuum atmosphere to impregnate liquid silicon to form a carbon fiber reinforced carbon composite. A carbon ceramic composite was produced. At this time, the physical properties of the produced carbon fiber reinforced ceramic composite are as shown in Table 1.

<Example 2>
A molded body was manufactured by making a mixture of 55 wt% of carbon fibers cut to a size of 30 mm, 35 wt% of phenol resin, 5 wt% of carbon powder, and 5 wt% of silicon carbide powder. In Example 2, alternating lamination using carbon fabric was not performed. The produced molded body was put in a molding mold and cured simultaneously with pressurization at a pressure of 2 MPa for 10 minutes to produce a carbon fiber reinforced resin composite.

  The carbon fiber reinforced resin composite was subjected to high temperature heat treatment in an inert gas atmosphere. Then, pyrolytic carbon was vapor-deposited under the conditions of chemical vapor infiltration with a rapid thermal gradient to produce a carbon fiber reinforced carbon composite.

  A carbon fiber reinforced carbon composite produced as described above is laminated on a silicon powder and heated at a temperature of 1550 ° C. in a vacuum atmosphere to impregnate liquid silicon. A carbon ceramic composite was produced. Table 1 shows the physical properties of the carbon fiber reinforced ceramic composites produced.

<Example 3>
A unidirectional carbon mat was manufactured by winding 320K oxypen fiber around a mendrel, and the carbon mat manufactured by the above method was laminated. The lamination was carried out alternately by the 0 ° / + 60 ° / -60 ° method.

  After the lamination was made into a minimum of two layers, punching was performed using a needle to reinforce each layer in the direction of the Z axis, and the above process was repeated to produce a preform having a thickness of 30 mm. The volume ratio of the preformed oxypen fibers was made to about 45%, the thickness of one layer was made to about 0.9 mm, and the fiber ratio of the z axis was made to about 10%.

The preform manufactured as described above was heat-treated at 1700 ° C. in a vacuum atmosphere to remove impurities.
The produced carbon felt preform was vapor deposited with pyrolytic carbon under the conditions of rapid thermal gradient chemical vapor infiltration to produce a carbon fiber reinforced carbon composite.

  A carbon fiber reinforced carbon composite produced as described above is laminated on a silicon powder and heated at a temperature of 1550 ° C. in a vacuum atmosphere to impregnate liquid silicon. A carbon ceramic composite was produced. Table 1 shows the physical properties of the carbon fiber reinforced ceramic composites produced.

<Comparative Example 1>
Mix 54 wt% of carbon fiber cut to 130 mm size with 36 wt% of phenolic resin and 10 wt% of carbon powder to make a mixture, put in a molding mold and cure at the same time with pressure of 3 MPa A carbon fiber reinforced resin composite was produced.

  The carbon fiber reinforced resin composite was heat-treated at 900 ° C. in an inert gas atmosphere to produce a carbon fiber reinforced carbon composite. In this way, the produced carbon fiber reinforced carbon composite is laminated on the silicon powder and heated at a temperature of 1600 ° C. in a vacuum atmosphere to impregnate the liquid silicon. A carbon ceramic composite was produced. Table 1 shows the physical properties of the carbon fiber reinforced ceramic composites produced.

  The method of manufacturing a carbon fiber reinforced ceramic composite according to the present invention as described above, the carbon fiber of the carbon fiber reinforced carbon composite manufactured in a rapid thermal gradient chemical vapor infiltration process is uniform. In the process of impregnation with liquid silicon, such a pyrolytic carbon layer is synthesized into silicon carbide by reacting with silicon during the liquid silicon impregnation process. The layer has not only a role as a fiber protective layer that prevents carbon fiber erosion, which is the most problematic in the liquid silicon impregnation process, but also has excellent properties as a reaction layer for synthesizing silicon carbide. A new interface is formed between the fiber and the silicon carbide matrix phase to improve the mechanical properties of the carbon fiber reinforced ceramic composite.

  The microstructure of the carbon fiber reinforced ceramic composite produced by the production method of the present invention is as shown in FIG. 3, in which the dark gray area around the carbon fiber is a pyrolytic carbon layer (102). The light gray part is the silicon carbide layer (103) and the brightest part is the residual silicon layer (104). It can be seen that there was almost no erosion of the carbon fiber by the pyrolytic carbon layer around the carbon fiber, and that silicon carbide was synthesized around the pyrolytic carbon layer.

  And, in the present invention, the rapid thermal gradient chemical vapor infiltration process is more than 10 times compared with the existing chemical vapor infiltration process when considering the production time of the carbon fiber reinforced carbon composite Compared to the conventional thermal gradient chemical infiltration process, the pyrolysis carbon layer can be deposited at a deposition rate of 5 times or more, so that the production cost of carbon fiber reinforced carbon composite can be significantly reduced.

  In addition, a carbon fiber reinforced resin composite can be obtained in a single step without the need for repeated densification steps such as the manufacturing process of a carbon fiber reinforced resin composite using a liquid precursor containing carbon. Simplify the manufacturing process of carbon fiber reinforced ceramic composites by combining the rapid thermal gradient chemical vapor infiltration process and liquid silicon impregnation process, significantly reducing manufacturing costs Therefore, it is possible to apply carbon fiber reinforced ceramic composites in various fields.

  Then, a carbon fiber having a size of 0.3 to 150 mm is mixed with a carbon-containing polymer precursor, silicon carbide powder, and carbon powder, and then alternately laminated with a carbon woven fabric, or a molded body produced only by the mixture. Is homogeneous in dispersion and mixing and has excellent properties for forming the primary surface layer of carbon fibers and carbon fabrics. In addition, since shrinkage hardly occurs during high-temperature heat treatment at 1000 ° C. or higher, there is no change in dimensions, and the cost required for processing of dimensions and shapes can be greatly reduced.

  As described above, the method for producing a carbon fiber reinforced ceramic composite according to the present invention has the effect of improving the physical properties of the carbon fiber reinforced ceramic composite, and all conventional chemical vapor infiltration processes. Compared with, it is possible to deposit a pyrolytic carbon layer at a deposition rate of 5 to 10 times or more, so that the manufacturing process, manufacturing time, and manufacturing cost are greatly improved.

FIG. 1 is a block diagram showing a method for producing a composite of a carbon fabric and a carbon fiber reinforced ceramic using a mixture of carbon fibers according to the present invention. FIG. 2 is a block diagram showing a method for producing a carbon fiber reinforced ceramic composite using a carbon felt preform according to the present invention. FIG. 3 is a photograph of the microstructure of a carbon fiber reinforced ceramic composite according to the present invention. FIG. 4 is a conceptual diagram showing a rapid thermal gradient chemical vapor infiltration method according to the present invention.

Explanation of symbols

101: carbon fiber, 102: carbon of pyrolysis, 103: silicon carbide, 104: residual silicon

Claims (21)

Producing a carbon fiber reinforced resin composite formed from a mixture of carbon fiber and a precursor of a carbon-containing polymer;
The carbon fiber reinforced resin composite is heat-treated at a high temperature to increase the deposition rate from the inside to the outside. Producing a carbon composite;
A method for producing a carbon fiber reinforced ceramic composite comprising the step of impregnating liquid silicon into pores of the carbon fiber reinforced carbon composite.   2. The composite of carbon fiber reinforced ceramic according to claim 1, wherein the mixture contains 10 to 60 wt% of the carbon fiber and 30 to 60 wt% of a precursor of the carbon-containing polymer. Method.   3. The method for producing a composite of carbon fiber reinforced ceramic according to claim 2, wherein the mixture contains silicon carbide powder of 30 wt% or less and carbon powder of 30 wt% or less.   4. The method for producing a carbon fiber reinforced ceramic composite according to claim 2, wherein the carbon fiber reinforced resin composite is formed by alternately laminating the mixture and a carbon fabric.   In the molded body, a primary surface layer that prevents a reaction between carbon fibers and silicon is formed by the mixture that is mixed in the mixing process, and the primary surface layer is in a stage of infiltrating the liquid silicon. 5. The method for producing a carbon fiber reinforced ceramic composite according to claim 4, wherein the composite is formed from a ceramic base layer made of silicon carbide and silicon by chemical reaction with the liquid silicon.   The molded body is heat-treated at a temperature of 900 to 2200 ° C. in an inert gas atmosphere, and then deposited in the chemical vapor infiltration process of the rapid thermal gradient. 2. A method for producing a carbon fiber reinforced ceramic composite according to claim 1, wherein a pyrolytic carbon base layer as a secondary surface layer is deposited on the surface.   The temperature of the pyrolysis reaction using a hydrocarbon gas is 700 to 1200 ° C. and the reaction pressure is in the range of 188 to 1130 torr in the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration process. A method for producing a carbon fiber reinforced ceramic composite according to claim 1.   In the step of depositing in the rapid thermal gradient chemical vapor infiltration step, the deposition region is divided into at least a plurality of regions from the inside to the outside, and the regions are deposited at different rates. A method for producing a carbon fiber reinforced ceramic composite according to claim 1. 2. The method for producing a carbon fiber reinforced ceramic composite according to claim 1, wherein the vapor deposition region is vapor-deposited from the inside to the outside within a vapor deposition rate range of 0.5 to 3.0 mm / hr. The carbon fiber reinforced carbon composite has an apparent density of 1.0 to 1.7 g / cm ³ and 5 to 30% of open pores used for the liquid silicon infiltration path. Item 8. A method for producing a carbon fiber reinforced ceramic composite according to Item 1. The step of infiltrating the liquid silicon comprises laminating the carbon fiber reinforced carbon composite on the silicon powder and maintaining the inside of the reactor at 100 torr or less, and then the melting point of silicon is 1410 ° C. 2. The carbon fiber reinforced ceramic composite according to claim 1, wherein said composite is heated at the above temperature so that liquid silicon penetrates into the preform and induces a chemical reaction with a plurality of carbon layers. Production method. Producing a carbon felt preform;
Vaporizing the carbon felt preform from the inside to the outside while increasing the deposition rate in a chemical vapor infiltration process with a rapid thermal gradient to produce a carbon fiber reinforced carbon composite;
A method for producing a carbon fiber reinforced ceramic composite comprising the step of impregnating liquid silicon into pores of the carbon fiber reinforced carbon composite.   13. The method for producing a carbon fiber reinforced ceramic composite according to claim 12, wherein the carbon felt preform is made of any one of carbon fibers such as oxypen, pen, rayon, and pitch.   The carbon felt preform is characterized in that a mat laminate is quasi-isotropic such as 0 ° / + 60 ° / -60 °, and carbon fibers of 10 mm or less are reinforced on the Z axis. 12. A process for producing a carbon fiber reinforced ceramic composite according to 12. 13. The carbon felt preform is deposited with a pyrolytic carbon layer having a thickness of 5 to 100 [mu] m according to the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration process. A method for producing a carbon fiber reinforced ceramic composite as described.   The carbon fiber is reinforced in three axes of X, Y and Z by impregnating the carbon fiber-reinforced carbon composite with liquid silicon in the step of infiltrating the liquid silicon. 12. A process for producing a carbon fiber reinforced ceramic composite according to 12.   In the step of vapor deposition in the rapid thermal gradient chemical vapor infiltration process, the temperature of the pyrolysis reaction using a hydrocarbon gas is 700-1200 ° C., and the reaction pressure is in the range of 188-1130 torr. 13. A method for producing a carbon fiber reinforced ceramic composite according to claim 12.   In the step of depositing in the rapid thermal gradient chemical vapor infiltration step, the deposition region is divided into at least a plurality of regions from the inside to the outside, and the regions are deposited at different rates. A method for producing a carbon fiber reinforced ceramic composite according to claim 12. 13. The method of manufacturing a carbon fiber reinforced ceramic composite according to claim 12, wherein the vapor deposition region is vapor-deposited from the inside to the outside within a range of a deposition rate of 0.5 to 3.0 mm / hr. The carbon fiber reinforced carbon composite has an apparent density of 1.0 to 1.7 g / cm ³ and 5 to 30% of open pores used for the liquid silicon infiltration path. Item 13. A method for producing a carbon fiber reinforced ceramic composite according to Item 12.   The step of infiltrating the liquid silicon comprises laminating the carbon fiber reinforced carbon composite on the silicon powder and holding the interior of the reactor at 100 torr or less, and then the melting point of silicon is 1410 ° C. or higher The carbon fiber reinforced ceramic according to claim 12, wherein the carbon fiber reinforced ceramic is heated at a temperature of about 10 μm to infiltrate liquid silicon into the carbon felt preform and induce a chemical reaction with the plurality of carbon layers. A method for producing a composite.

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