JP3371993B2 - Method for producing fiber-reinforced ceramic composite material - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing a fiber-reinforced ceramic composite material, in which a matrix material is separately provided in the micro voids of the fiber bundle for forming a reinforced molded body and the space between the fiber bundles in separate steps. By impregnating and forming, and finally by impregnating and forming a matrix substance in all the pores of the molded body, it is possible to obtain a densified product in a short time.

[0002]

2. Description of the Related Art Fiber-reinforced ceramic composite materials have higher strength and lighter weight than metals, and are more resistant to heat and corrosion.
Due to its excellent wear resistance, it can be applied to high temperature equipment in the fields of aerospace, energy, environment, industrial machinery, materials, etc., and parts materials for prime movers. For example, nozzles for jet engines and engine parts for gas turbines. It is considered to be applied to.

This fiber-reinforced ceramic composite material is
It is made by forming a molded body using reinforcing fibers, and impregnating and forming this molded body with a ceramic serving as a matrix (matrix).

This reinforcing fiber has a thickness of about 10 μm in terms of strength, and since a molded body cannot be made as it is, it is bundled in the range of about 1000 to 12000 and the diameter is The fiber bundle is 2-3 mm.

Then, the fiber bundle is wound or woven into a cloth shape to form a molded body.

A fiber-reinforced ceramic composite material is produced by impregnating and forming a matrix, which becomes ceramics, in the fiber-reinforced molded body thus formed.

In the production of such a fiber-reinforced ceramic composite material, the matrix formed in the fiber-reinforced molded body is important, and conventionally, impregnation and firing are repeated using a liquid phase raw material to eliminate the voids. The matrix is formed by thermally decomposing a gas flowing under a reduced pressure using a gas raw material. Even if the shape is complicated, if a molded body can be made into a complicated shape, a fiber-reinforced ceramics It is characterized by the ability to manufacture composite material products.

[0008]

However, in the method of manufacturing a product of the fiber-reinforced ceramic composite material, the former method of repeating impregnation and firing of the liquid raw material is effective for large pores, The matrix can be formed in a relatively short time between the fiber bundles, but there is a problem that it is not easy to form the matrix in the minute voids between the fibers constituting the fiber bundle.

On the other hand, in the production method (CVI) in which a gas raw material is pyrolyzed under reduced pressure, the gas flows into the minute voids between the fibers constituting the fiber bundle, so that the surface of each fiber is Although it is possible to form a film on the surface of the product and to reduce the porosity of the product, it takes a very long time to form a matrix for large pores such as spaces between fiber bundles. There is a problem that several hundred hours are required.

Further, in the conventional fiber-reinforced ceramic composite materials, a single substance is formed as a matrix for the fiber-reinforced molded body, and a plurality of substances are used to further improve the function. It is desired to develop a manufacturing method capable of producing the same.

The present invention has been made in view of the above problems of the prior art, and it is possible to produce a densified fiber-reinforced ceramic composite material in a short time, and to use a plurality of matrix substances. An object of the present invention is to provide a method for manufacturing a reinforced ceramic composite material.

[0012]

In order to solve the above problems, a method for producing a fiber-reinforced ceramic composite material according to the present invention comprises a matrix substance in a gas phase or in a microscopic void in a fiber bundle constituting a fiber-reinforced molded article. A first step of forming by liquid phase impregnation, a second step of forming a matrix substance in the space between the fiber bundles of the fiber reinforced molded body by liquid phase impregnation method repeatedly, and then forming the fiber. The third step is the step of forming the pores formed in the reinforced molded body by impregnating the matrix material with a vapor phase impregnation method.

Further, in the method for producing a fiber-reinforced ceramic composite material according to claim 2 of the present invention, in addition to the constitution of claim 1, the matrix substance of the first to third steps is at least two different substances. It is characterized by having done.

[0014]

According to this method for producing a fiber-reinforced ceramic composite material, the microscopic voids in the fiber bundle forming the fiber-reinforced molded body are impregnated with the matrix substance in the gas phase or the liquid phase in the first step. After the formation, in the space between the fiber bundles of the fiber reinforced molded body, the matrix substance is repeatedly impregnated and baked by the liquid phase impregnation method in the second step, and finally the whole remaining pores are In the third step, the matrix material is impregnated by the vapor phase impregnation method, and the matrix is formed in different steps depending on the size of the voids and pores so that the matrix can be densified in a short time. There is.

Further, according to the method for producing a fiber-reinforced ceramic composite material of the present invention, the first to third matrix substances are made to be at least two different types of substances and have different functions. Therefore, it is possible to obtain a more excellent fiber-reinforced ceramic composite material product.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. 1 and 2 are a process diagram and an enlarged schematic diagram of the structure in each process of one embodiment of the method for producing a fiber-reinforced ceramic composite material according to the present invention.

This method for producing a fiber-reinforced ceramic composite material can be widely applied to an inorganic ceramic composite material which is reinforced by fibers and has a higher order structure control. For example, carbon fiber for reinforcement and carbon matrix are used. It is applied to a carbon fiber reinforced carbon composite material that forms a carbon fiber, a ceramics composite material that forms a matrix of silicon carbide on carbon fiber, and the like.

First, a fiber-reinforced molded body 2 having a shape (near net shape) corresponding to the shape of a product is made from a fiber bundle 1 such as carbon fiber.

This fiber-reinforced molded body 2 is a molded body in which the fiber bundle 1 such as carbon fiber is uniaxially oriented, two-dimensionally oriented or three-dimensionally oriented according to the shape of the product, and the higher order structure is controlled. The fiber-reinforced molding 2 usually has a porosity of about 50%.

The fiber-reinforced molded body 2 molded in this way is
As shown in FIG. 2A, in the first step, the matrix 4 is formed in the minute voids 3 between the fibers of the fiber bundle 1.

The formation of the matrix 4 in the first step is aimed at the minute voids 3 between the fibers of the fiber bundle 1, and the minute voids 3 have a diameter of about 10 μm, and the gas raw material The matrix 4 is formed by causing a thermochemical reaction to form a film on the surface of the fiber using the vapor phase impregnation method (CVI) used. This CVI is, for example, 1
The matrix 4 is formed in the minute voids 3 by performing the operation for about 100 hours.

The matrix 4 in the minute voids 3
The formation of is not limited to the case of CVI, but the thermochemical reaction may be caused by a liquid phase impregnation method using a liquid raw material to form the matrix substance 4.

As a concrete matrix material 4 of this first step, for example, a mixed gas of methane and hydrogen can be cited, and CVI is carried out using this mixed gas as a raw material to form carbon in the minute voids 3.

In the second step, the fiber-reinforced molded body 5 in which the matrix 4 is formed in the minute voids 3 inside the fiber bundle 1 forms the matrix 7 in the space 6 between the fiber bundles 1 in the second step (FIG. 2). (See (b)).

Since the fiber bundle 1 has a diameter of about 2 to 3 mm, the space 6 between the fiber bundles 1 has a size of several mm in accordance therewith, and thus the micro voids in the first step. Compared to 3, it is much larger.

Therefore, the space 6 between the fiber bundles 1 is repeatedly impregnated with the liquid raw material, and a thermochemical reaction is caused to repeat the firing for forming the matrix substance 7.

In this liquid phase impregnation method, when impregnation and firing are performed, pores 8 are formed due to shrinkage and degassing, so it is necessary to repeat the impregnation and firing until a predetermined porosity is reached. Repeat about once.

As a specific matrix material 7 used in the liquid phase impregnation method in the second step, for example, when carbon is used as a matrix, impregnation and firing of pitch are repeated or silicon carbide is used as a matrix. In this case, the polycarbosilane impregnation and firing are repeated, or after the carbon fiber voids are impregnated with polycarbosilane, heating is performed in the air to crosslink the polycarbosilane before direct firing, and then the By repeating the firing in the active gas atmosphere under the same firing conditions as before so that the polycarbosilane is crosslinked with oxygen in advance, degassing and shrinkage are reduced and the yield of the matrix is increased.

In this way, the space 6 between the fiber bundles 1 is repeatedly impregnated with the matrix substance 7 and fired. In any case, the fiber-reinforced molded body 8 which has completed the second step is not contracted. A state in which minute cracks 9 and the like due to degassing have occurred.

Therefore, as the third step, the matrix 10 is further formed in the fine cracks 9 of the matrix 7 formed in the second step and the pores 9 remaining in the spaces between the fiber bundles (FIG. 2). (See (c)).

In the third step, a thermochemical reaction is caused by a vapor phase impregnation method (CVI) using a gas raw material to form a matrix 10 in the fine cracks 9 and the residual pores 9 between the fiber bundles 1. To do. This CVI is performed, for example, for several tens of hours to form the matrix 10 in the fine cracks 9 and the like.

As the concrete matrix material 10 in the third step, for example, a mixed gas of methane and hydrogen can be used as in the CVI in the first step, and CVI is performed using this mixed gas as a raw material. Form carbon.

The fiber-reinforced ceramic composite material produced as described above can form a dense product in a shorter time as compared with the case where the conventional fiber-reinforced molded body is subjected to CVI to form a matrix. Compared with the case of repeating impregnation and firing of the matrix material in the fiber-reinforced molding by the liquid phase impregnation method, it is possible to form a matrix up to minute voids in the fiber bundle and manufacture a dense product with a small porosity in a short time. it can.

Therefore, it is possible to densify and fabricate an inorganic material, which is reinforced by fibers and has a higher order controlled structure, in a short time, and has a high strength in the fields of aerospace, energy, environment, industrial machinery, materials and the like. It can be used as a high toughness and heat resistant material.

Next, an embodiment according to claim 2 of the present invention will be described. In this method for producing a fiber-reinforced ceramic composite material, the matrix substances 4, 7, in the first to third steps of the invention described in claim 1 have already been described.
There are at least two kinds of 10 and they are changed in each step, and those which are changed in all the steps or some of which are the same are included.

For example, in the first step, when forming the matrix substance 4 between the fiber bundles 1, the material is selected so that the fiber bundles 1 can be made rigid and hard.

Then, in the second step, the liquid raw material is selected so as to increase the rigidity of the space 6 between the fiber bundles 1, and the impregnation and firing are repeated.

In the final third step, the matrix material 10 is formed by CVI in the pores 9 such as fine cracks.

Alternatively, in the case of producing the environment-resistant material and the oxidation-resistant material, even when the fiber-reinforced molded body 2 is produced by using the fiber having low oxidation resistance, the fiber itself is used as the first step. A material for protection is formed as the matrix 4 by CVI or the like.

In the second step, the matrix material 7 is formed to fill the space 6 between the fiber bundles 1. The matrix material 7 is used to protect the fibers from oxidation.
The matrix material 7 itself is oxidized so that oxygen does not reach the fibers.

In the final third step, the matrix 10 is formed so as to prevent the fine cracks 9 and the like from having a higher oxidation resistance of the entire molded body.

Since the matrix materials 4, 7 and 10 are formed separately in the first to third steps, the matrix materials 4, 7 and 10 in each step can be changed and the matrix materials 4, 7 and 10 can be changed. Matrix material 4,7,10
It is possible to produce a more excellent fiber-reinforced ceramic composite material by selecting the function of, and it is possible to obtain an inorganic material reinforced by fibers and having a higher order structure controlled.

The present invention is not limited to the above-mentioned embodiments, and each constituent element may be modified within the scope of the invention.

[0044]

As described above in detail with reference to the embodiments, according to the method for producing a fiber-reinforced ceramic composite material of the present invention, the minute voids in the fiber bundle constituting the fiber-reinforced molded body are After the matrix material is formed by impregnating the matrix material in the gas phase or the liquid phase in the first step, the matrix material is impregnated and baked in the space between the fiber bundles of the fiber reinforced molded article by the liquid phase impregnation method in the second step. The entire remaining pores that were formed repeatedly were formed by impregnating the matrix material with the vapor phase impregnation method in the third step, so it is optimal depending on the size of the voids and pores. The matrix can be formed in various steps, and the fiber-reinforced ceramic composite material can be densified in a shorter time than ever.

Further, according to the method for producing a fiber-reinforced ceramic composite material of the present invention, the first to third matrix substances are made to be at least two different types of substances, so that the respective matrix substances are different. Can have different functions, and a more excellent fiber-reinforced ceramic composite material can be manufactured.

Therefore, according to these inventions, it is possible to obtain an inorganic material having a controlled structure of higher order.

[Brief description of drawings]

FIG. 1 is a process chart according to an example of a method for producing a fiber-reinforced ceramic composite material of the present invention.

FIG. 2 is a schematic view showing an enlarged structure in each step according to one example of the method for producing a fiber-reinforced ceramic composite material of the present invention.

[Explanation of symbols]

1 fiber bundle 2 Fiber reinforced molding 3 micro voids 4 Ceramic matrix 5 Fiber-reinforced molded product after the first step 6 Space between fiber bundles 7 Ceramic matrix 8 holes 9 Residual holes such as fine cracks 10 Ceramic matrix

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-223179 (JP, A) JP-A-5-330933 (JP, A) JP-A-3-28177 (JP, A) JP-A-3- 223178 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C04B 35/80 C04B 35/76

Claims (2)

(57) [Claims] 1. A first step of forming a matrix substance in a gas phase or a liquid phase by impregnating minute voids in a fiber bundle constituting a fiber-reinforced molded product, and then a space between fiber bundles of the fiber-reinforced molded product. A second step of repeatedly forming and impregnating a matrix material with a liquid phase impregnation method, and then a third step of impregnating the pores formed in the fiber-reinforced molded article with the matrix material by a vapor phase impregnation method. The method for producing a fiber-reinforced ceramics composite material, comprising: 2. The method for producing a fiber-reinforced ceramic composite material according to claim 1, wherein the matrix substances used in the first to third steps are at least two different substances.