JP2541852B2 - Manufacturing method of fiber-reinforced ceramic composite materials - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a fiber-reinforced ceramic composite material.

(Problems to be Solved by Conventional Techniques and Inventions) A fiber-reinforced ceramic composite material is a material in which carbon fibers are used to reinforce a ceramic serving as a matrix. Fiber-reinforced ceramic composite materials are materials with high fracture toughness that compensate for the defects of monolithic ceramics that exhibit brittle fracture behavior, and are expected to be used in engine parts that require specific strength and heat resistance. . However, the manufacturing method is so-called CVI (Chemical Vapo
r Infiltration) method is the main method, which requires an extremely long processing time, resulting in high manufacturing costs.

(Means for Solving Problems) The present inventors have completed the present invention as a result of solving the above problems and studying a manufacturing process of a simple and high-performance fiber-reinforced ceramic composite material.

The present invention comprises (1) impregnating a tow consisting of a fiber bundle of long fibers of heat-resistant fibers with an organometallic polymer that is a precursor of at least one ceramic selected from the group consisting of carbide ceramics, nitride ceramics and oxide ceramics. Then, this is placed in an open container, heat-treated in a hot isostatic press, and if necessary, further heat-treated at normal pressure, and a method for producing a fiber-reinforced ceramic composite material, and (2) carbon. For a carbon fiber reinforced carbon composite material having an open porosity of 5 to 50% obtained by using a tow composed of long fiber bundles, a group consisting of carbide ceramics, nitride ceramics and oxide ceramics It is impregnated with an organometallic polymer that is a precursor of at least one selected ceramics, and this is placed in an open container and hot isostatic pressure is applied. Heat treated at location, a method for producing fiber-reinforced ceramic composite material, characterized by a heat treatment at more normal pressure if necessary.

The fiber-reinforced ceramic composite material according to the present invention will be described in detail below.

The organometallic polymer as referred to in the present invention is a precursor of at least one ceramic selected from the group consisting of carbide ceramics, nitride ceramics and oxide ceramics. Specifically, it is polycarbosilane, polysilazane, polysilazastyrene, metal alkoxide, alkyl metal, etc., and has a softening point of −50 to 400 ° C., preferably 0.
~ 350 ° C.

The heat resistant fiber referred to in the present invention means carbon fiber and ceramic fiber. Carbon fiber refers to pitch-based, polyacrylonitrile-based or rayon-based, and pitch-based carbon fiber is particularly preferable. The pitch-based carbon fiber here is a fiber obtained by melt-spinning carbonaceous pitch, infusibilizing it, carbonizing it, and graphitizing it if necessary.
The ceramic fibers are carbide ceramics such as SiC and TiC, oxide ceramics such as Al ₂ O ₃ , nitride ceramics such as Si ₃ N _4, or a mixture thereof. Further, a carbon fiber whose surface is coated with the above ceramics is also included.

The heat-resistant fiber tow is the diameter of the heat-resistant fiber 5 to 1000μ
One-dimensional laminate of 500 to 100,000 fiber bundles of m, two-dimensional woven fabric or its laminate, three-dimensional or more woven fabric, mat-like molded product, felt-shaped molded product such as two-dimensional or three-dimensional molded product Say. The fibers that make up the tow are filaments.

In the present invention, the tow of the heat-resistant fiber thus obtained is impregnated with an organometallic polymer, and the impregnated product is placed in an open container, and a hot isostatic press (HIP) device, preferably a HIP with an exhaust mechanism is used. Heat treatment in the device. The impregnation is achieved by heating and melting the organometallic polymer under vacuum and / or pressure, but it can also be cut back with a solvent to reduce the viscosity during impregnation. As the solvent, aromatic hydrocarbon, pyridine, quinoline, tetrahydrofuran, dioxane and the like can be used.

An open container is a container that does not have a sealing function. As a material, a metal such as aluminum, mild steel or stainless steel, glass, graphite, ceramics or the like can be appropriately selected according to the use temperature or purpose. The shape is not particularly limited as long as it is an open type, and it may be with or without a lid, and may wrap the object to be treated with a metal foil.

According to the examination results of the inventors of the present application, in the case of heat-treating the organometallic polymer by hot isostatic pressing, the temperature inside the furnace or the temperature inside the furnace and the exhaust speed are controlled under a limited condition using an open container. It has been found that it is not necessary to use a hermetically sealed container because the shape of the object to be treated can be maintained and dust in the furnace can be suppressed to an extremely small amount if controlled. Moreover, when the open type container is used, it is possible to prevent the processed product from cracking due to the internal pressure of the generated gas.
The open container may be filled with a material for physically capturing the product, for example, carbon felt, refractory felt, fibrous material such as iron or titanium.

The HIP device with an exhaust mechanism is a device having a mechanism capable of continuously controlling and discharging the gas components generated from the object to be treated during HIP, and specifically, the generation rate and / or diffusion rate of the generated gas. It is an apparatus equipped with an exhaust mechanism capable of adjusting the removal amount according to. This gas exhaust mechanism is composed of a heat exchanger with the pressure medium gas in the furnace, a cooler outside the furnace, a pressure reducing device, a flow rate control valve, and the like. More specifically, it is an apparatus described in Japanese Patent Application No. 62-25317 already filed by one of the applicants of the present application.

Conditions of autoclaved at HIP apparatus or HIP apparatus with an exhaust mechanism, 50~10000kg / cm ² with an inert gas, preferably pressurized to 200~2000kg / cm ^2, 100~3000 ℃, preferably from 400 to 2,200 ° C. More preferably, it can be carried out at 400 to 2000 ° C. As the pressure medium gas, an inert gas such as argon, nitrogen or helium can be used. The heat treatment under normal pressure following the pressure heat treatment should be performed in an inert gas atmosphere.
It can be carried out at 400 to 2200 ° C, preferably 400 to 2000 ° C. Further, when the HIP device with an exhaust mechanism is used, it is a great feature that the operation can be performed while analyzing the gas generated during the heat treatment. It is desirable to perform the heat treatment until the above gas is substantially not generated. The term “substantially no generation” means that the concentration in exhaust gas is 10 pp.
m, preferably 5 ppm or less.

In the present invention, the respective production rates of H ₂ and CH ₄ in the exhaust gas do not exceed 10 mol / hour per 100 g of the organometallic polymer, preferably 5.0 mol / hour, more preferably 2.0 mol / hour, most preferably Preferably, the temperature profile or the temperature profile and the exhaust speed are controlled under conditions not to exceed 5.0 mol / hour, and the heat treatment is performed under hot isostatic pressing.

Further, for the densification, the cycle of impregnation and HIP treatment can be performed as many times as necessary. The volume content of the heat-resistant fiber in the composite material is arbitrarily determined depending on the purpose, but is usually 5 to 75 mol%, preferably 35 to 65 mol%.

In order to further improve the oxidation resistance of the fiber-reinforced ceramic composite material obtained by the present invention, its surface can be coated with ceramics. As the coating material,
At least one ceramic selected from the group consisting of carbide ceramics, nitride ceramics and oxide ceramics is preferable, and the coating method is CVD or PVD.
Etc. are preferred.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples.
The present invention is not limited to these.

(Example 1) Two-dimensional woven fabric (plain weave) of 2000 bundles of pitch-based carbon fibers having a diameter of 10 µm was laminated and impregnated with polysilastyrene having a softening point of 220 ° C. The impregnated material was included in carbon felt, pressurized to 1000 kg / cm ² with argon gas in a HIP apparatus, and pressure-converted at 800 ° C. The conversion yield of the impregnated polysilastyrene was about 70%, which was significantly higher than that of the normal atmospheric conversion treatment of about 25%. Following the pressure conversion, heat treatment was performed at 1700 ° C. under an atmospheric pressure and an inert atmosphere. When the carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, no cracks were found in the fiber bundles or between the fiber bundles, and the ceramics matrix was well filled. In addition, neither deformation nor damage of the carbon fiber fabric was observed.

(Example 2) Two-dimensional woven fabric (plain weave) of 2000 bundles of pitch-based carbon fibers having a diameter of 10 µm was laminated and impregnated with polysilastyrene having a softening point of 220 ° C. The impregnated material was included in carbon felt, pressurized to 1000 kg / cm ² with argon gas in a hot isostatic device with an exhaust mechanism, and pressure-converted at 800 ° C. The pumping speed was 1.0 Nm ² / hour. The softening yield of the impregnated polysilastyrene was about 70%, which was much higher than that of about 25% of that of the normal pressure conversion treatment. When the equipment was opened and inspected after operation, the inside of the furnace was found to be extremely slight. Following pressure conversion, atmospheric pressure, 1700 ° C under inert atmosphere
Was heat treated. When the carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, no cracks were found in the fiber bundles or between the fiber bundles, and the ceramics matrix was well filled. In addition, neither deformation nor damage of the carbon fiber fabric was observed.

Example 3 Two-dimensional woven fabric (plain weave) of 2000 bundles of pitch-based carbon fibers having a diameter of 10 μm was laminated and impregnated with polysilastyrene having a softening point of 220 ° C. The impregnated material was included in carbon felt, pressurized to 1000 kg / cm ² with argon gas in a hot isostatic device with an exhaust mechanism, heated up to 800 ° C at 2 ° C / min, and pressure-converted at 800 ° C. Pumping speed is 1.0 Nm ² /
It was time. The respective production rates of H ₂ and CH _{4 in} the produced gas were 0.58 mol / hr and 0.
It was 96 mol / hour. The conversion product obtained had few cracks. When the equipment was opened and inspected after operation, the inside of the furnace was found to be extremely slight. Following the pressure conversion, heat treatment was performed at 1700 ° C. under an atmospheric pressure and an inert atmosphere. When the carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, no cracks were found in the fiber bundles or between the fiber bundles, and the ceramics matrix was well filled. In addition, neither deformation nor damage of the carbon fiber fabric was observed.

(Example 4) Carbon fiber whose surface was coated with SiC (US AVCO, SCS-
6 、 diameter 14μm) is laminated in one direction and the softening point 220
The polysilastyrene at ℃ was dissolved in xylene and impregnated.
The impregnated material was included in carbon felt, pressurized to 1000 kg / cm ² with argon gas in a HIP apparatus, and pressure-converted at 1000 ° C. The conversion yield of impregnated polysilastyrene is about 70%, which is about 25% of that of ordinary atmospheric pressure conversion treatment.
Markedly improved compared to%. Following the pressure conversion, heat treatment was performed at 1200 ° C. in an inert atmosphere at normal pressure. When observing the fiber-reinforced ceramic composite material with a scanning electron microscope,
No cracks were found in the fiber bundles and between the fiber bundles, and the ceramic matrix was well filled. In addition, neither deformation nor damage of the carbon fiber fabric was observed.

Example 5 Ceramic fiber having a diameter of 11 μm (Si—C—Ti—O system,
Ube Industries, Ltd., Tyranno fiber) 1600 bundles and diameter
The same process as in Example 4 was performed on 800 bundles of 15 μm ceramic fibers (SiC-based, Nicalon manufactured by Nippon Carbon Co., Ltd.). When the obtained fiber-reinforced ceramic composite material was observed with a scanning electron microscope, no cracks were found between the fiber bundles and between the fiber bundles.
The matrix was well packed. In addition, neither deformation nor damage of the carbon fiber fabric was observed.

Example 6 2000 bundles of pitch-based carbon fibers having a diameter of 10 μm were impregnated with an optically anisotropic pitch having a softening point of 280 ° C. of a three-dimensional orthogonal woven fabric.
HI with an exhaust system that contains the impregnated material with stainless steel oil.
In equipment P, pressurize to 1000 kg / cm ² with nitrogen gas and
While evacuation was performed at Nm ³ / hour, the temperature was raised to 400 ° C. at 0.5 ° C./min and to 1000 ° C. at 2 ° C./min for carbonization under pressure. The obtained carbon / carbon composite material had a porosity of 20%. Softening point 22
It was impregnated with 0 ° C polysilastyrene, pressurized to 1000 kg / cm ² with argon gas in a HIP device, and pressure-converted at 1000 ° C. When the obtained carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, the carbon / carbon composite material had well-filled voids with the ceramics matrix, and no separation of the matrix was observed.

Example 7 2000 bundles of pitch-based carbon fibers having a diameter of 10 μm were impregnated with an optically anisotropic pitch having a softening point of 280 ° C. of a three-dimensional orthogonal woven fabric.
HI with an exhaust system that contains the impregnated material with stainless steel oil.
It was pressurized to 1000 kg / cm ² in a P apparatus and pressure carbonized at 1000 ° C. Porosity of the obtained carbon / carbon composite material
It was 20%. This is impregnated with polycarbosilane having a softening point of 232 ° C, and 1000 kg / cm 2 is applied by argon gas in a HIP device.
^It was pressurized to ² and pressure-converted at 1000 ° C. Following the pressure conversion, heat treatment was carried out at 1350 ° C. under normal pressure and an inert atmosphere. When the obtained carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, the carbon / carbon composite material had well-filled voids with the ceramics matrix, and no separation of the matrix was observed.

Example 8 2000 bundles of pitch-based carbon fibers having a diameter of 10 μm were impregnated with an optically anisotropic pitch having a softening point of 280 ° C. of a three-dimensional orthogonal woven fabric.
HI with an exhaust system that contains the impregnated material with stainless steel oil.
It was pressurized to 1000 kg / cm ² in a P apparatus and pressure carbonized at 1000 ° C. Porosity of the obtained carbon / carbon composite material
It was 20%. This was impregnated with polysilazane having a softening point of 87 ° C, pressurized to 1000 kg / cm ² with argon gas in a HIP device, and pressure-converted at 1000 ° C.

Following the pressure conversion, heat treatment was carried out at 1350 ° C. under normal pressure and an inert atmosphere. When the obtained carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, the carbon / carbon composite material had well-filled voids with the ceramics matrix, and no separation of the matrix was observed.

Example 9 A two-dimensional plain weave of 2000 bundles of pitch-based carbon fibers having a diameter of 10 μm was impregnated with a phenol resin. After the impregnated product was dried, it was cured at 150 ° C. to obtain a CFRP primary molded body.
This primary molded body was carbonized in nitrogen at 1500 ° C. for 1 hour,
A carbon / carbon composite material having a porosity of 25% was obtained. Softening point
Impregnated with polycarbosilane at 232 ° C and included with a stainless steel foil, 1000k in HIP device with exhaust mechanism
It was pressurized to g / cm ² and pressure-converted at 1000 ° C. The obtained carbon / carbon composite material had a porosity of 20%. Following the pressure conversion, heat treatment was carried out at 1350 ° C. under normal pressure and an inert atmosphere. When the obtained carbon fiber reinforced ceramics composite material was observed with a scanning electron microscope, the carbon / carbon composite material had well-filled voids with the ceramics matrix, and no separation of the matrix was observed.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshinori Nakamura 1-1 Kawasaki-cho, Akashi-shi, Hyogo, Kawasaki Heavy Industries, Ltd. Technical Research Institute (72) Takeshi Suemitsu 1-1 Kawasaki-cho, Akashi-shi, Hyogo Kawasaki (56) Reference JP-A-63-288974 (JP, A) JP-A-57-27746 (JP, A)

Claims (6)

(57) [Claims] 1. A tow consisting of a bundle of heat-resistant long fibers is impregnated with an organometallic polymer which is a precursor of at least one ceramic selected from the group consisting of carbide ceramics, nitride ceramics and oxide ceramics, A method for producing a fiber-reinforced ceramics composite material, which comprises placing this in an open-type treated product container and heat-treating it in a hot isostatic press to turn the polymer into a ceramic. 2. The method for producing a fiber-reinforced ceramic composite material according to claim 1, wherein the hot isostatic device has an exhaust mechanism. 3. The heat treatment in the hot isostatic press is carried out under the condition that the production rates of H ₂ and CH _{4 in} the produced gas do not exceed 10 mol / hour per 100 g of the organometallic polymer. A method for producing a fiber-reinforced ceramic composite material according to claim 1. 4. A carbon fiber-reinforced carbon composite material having an open porosity of 5 to 30% obtained by using a tow composed of long fiber bundles of carbon fibers, in addition to carbide ceramics, nitride ceramics and oxides. At least one kind of ceramics selected from the group consisting of ceramics is impregnated with organometallic polymy, which is a precursor of the ceramics, and this is placed in an open-type processed material container and heat-treated in a hot isostatic device to convert the polymer into a ceramic A method for producing a fiber-reinforced ceramic composite material, comprising: 5. The method for producing a fiber-reinforced ceramic composite material according to claim 4, wherein the hot isostatic device has an exhaust mechanism. 6. The heat treatment in a hot hydrostatic pressure device is performed under conditions such that the production rates of H ₂ and CH _{4 in} the produced gas do not exceed 10 mol / hour per 100 g of the organometallic polymer. The method for producing the fiber-reinforced ceramic composite material according to claim 4.