JP6774863B2 - Manufacturing method of ceramic-based composite material - Google Patents

Description

The present invention relates to a method for producing a ceramic-based composite material.

The use of composite materials is being considered for hot parts of aircraft fuselage and engines, industrial gas turbine engines, and parts that are lightweight and require high durability. As an example of such a composite material, for example, a ceramic-based composite material (CMC: Ceramic Matrix Composites) described in Patent Document 1 below is known.

The ceramic-based composite material has a woven fabric having a plurality of fiber bundles and a reinforcing material called a matrix filled in a gap between the fiber bundles. In obtaining a ceramic-based composite material, a technique called the PIP method (Polymer Impregnation and Pyrolysis method) is used as an example. The PIP method includes a step of impregnating a woven fabric with a polymer in a solution containing a polymer serving as a precursor of a matrix, and a step of drying and firing the impregnated polymer.

Japanese Patent No. 5129997

However, in order to obtain a ceramic-based composite material having desired strength characteristics by the PIP method, it is necessary to repeat each step of impregnation, drying, and firing of the polymer a plurality of times. For this reason, it has been a problem that the manufacturing period becomes long. Further, it is also known that when the firing step is repeated a plurality of times, the strength is lowered due to the deterioration of the fiber bundle. Therefore, in order to prevent a decrease in strength, a technique for forming an interface layer on the surface of the fiber bundle has also been proposed. However, in order to form the interface layer, it is necessary to remove the sizing material adhering to the fiber bundle in advance by the dessizing step, which complicates the manufacturing process.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for producing a ceramic-based composite material, which is less likely to cause a decrease in strength and can simplify a manufacturing process.

The method for producing a ceramic-based composite material of the present invention includes a plurality of fiber bundles, a woven fabric having a sizing material surrounding the fiber bundles, and a matrix arranged in a gap between the fiber bundles. A method for producing a ceramic-based composite material, which is a step of forming a base by impregnating the woven fabric with a polymer as a precursor of the matrix to form a base, and a step of further impregnating the base with the polymer and firing. The element body forming step includes a densifying step of densifying the woven fabric in a nitrogen atmosphere to modify the sizing material to form an interface layer in the fiber bundle. Including.

According to this method, the interface layer can be formed by using the fiber bundle and the sizing material adhering to the periphery of the fiber forming the fiber bundle from the beginning. That is, the interface layer can be formed around the fiber bundle and the fiber without executing the conventional dessizing step. As a result, the man-hours can be reduced.

Further, in the method for producing a ceramics-based composite material, the sizing material is a polyurethane resin, an epoxy resin, a polybutadiene, a polyalkylene glycol, a polyolefin resin, a vinyl ester resin, a saturated polyester resin, an unsaturated polyester resin, a polyamide resin, or a polyimide resin. , Polyimideimide resin, acrylic resin, polypropylene resin, pitch-based resin may be at least one selected from the group.

According to this method, polyurethane resin, epoxy resin, polybutadiene, polyalkylene glycol, polyolefin resin, vinyl ester resin, saturated polyester resin, unsaturated polyester resin, polyamide resin, polyimide resin, polyamideimide resin, acrylic resin are used as sizing materials. , Polypropylene resin, at least one selected from the group of pitch-based resins is used. These chemical species change to a carbon-based molecular structure when heated in a nitrogen atmosphere. Therefore, according to this method, the interface layer can be easily and inexpensively formed.

Further, in the method for producing a ceramic-based composite material, the densification step includes an impregnation step of further impregnating the element body with the polymer to form an impregnated element body and a drying process of drying the impregnated element body. It may include a drying step of forming an element body and a firing step of firing the dried element body.

According to this method, the efficiency of impregnating the polymer into the element body can be increased by performing the densification step. That is, a densified ceramic-based composite material can be easily obtained.

Further, in the method for producing a ceramic-based composite material, the impregnation step and the drying step are repeated after the drying step, and the firing step is the dried step in which the impregnation step and the drying step are repeated a plurality of times. The element body may be fired.

According to this method, the efficiency of impregnating the polymer with the element body can be further increased. That is, a more densified ceramic-based composite material can be easily obtained.

According to the present invention, it is possible to provide a method for producing a ceramic-based composite material, which is less likely to cause a decrease in strength and can simplify the production process.

FIG. 1 is a schematic view showing the configuration of a ceramic-based composite material according to the first embodiment of the present invention. FIG. 2 is an enlarged schematic view showing the configuration of the ceramic-based composite material according to the first embodiment of the present invention. FIG. 3 is an enlarged schematic view showing the fibers of the ceramic-based composite material according to the first embodiment of the present invention. FIG. 4 is a process diagram showing a method for producing a ceramic-based composite material according to the first embodiment of the present invention. FIG. 5 is an explanatory diagram showing a process of synthesis / thermal decomposition when polyurethane is used as a sizing material in the first embodiment of the present invention. FIG. 6 is a process diagram showing a method for producing a ceramic-based composite material according to the second embodiment of the present invention. FIG. 7 is an explanatory diagram showing a change in the composition of the matrix in the steam treatment step according to the second embodiment of the present invention. FIG. 8 is a graph showing the relationship between the number of firing steps in the examples of the present invention and the porosity of the matrix.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of each embodiment described below can be combined as appropriate. In addition, some components may not be used. In addition, the components in the following embodiments include those that can be easily replaced by those skilled in the art, or those that are substantially the same.

As shown in FIG. 1, the ceramic-based composite material 100 is formed in a thin plate shape as an example by laminating a plurality of fiber layers 10. In other words, the ceramic-based composite material 100 has a plurality of fiber layers 10 arranged so as to overlap each other. In the example shown in FIG. 1, the boundary line is conveniently displayed between the plurality of fiber layers 10, but in the actual ceramic-based composite material 100, such a clear boundary line is displayed between the fiber layers 10. There is no boundary line, and the plurality of fiber layers 10 are integrated with each other. Further, the shape of the ceramic-based composite material 100 is not limited to the plate shape shown in FIG. 1, and may be various shapes. In the following description, the ceramic-based composite material 100 may be abbreviated as CMC.

As shown in FIG. 2, the fiber layer 10 includes a woven fabric 1 and a matrix 3. Note that FIG. 2 schematically shows the structure of the fiber layer 10. As shown enlarged in FIG. 3, the woven fabric 1 has a plurality of fiber bundles 2, a fiber bundle 2, and an interface layer 4 that covers the outside of the fibers 2A forming the fiber bundle 2. The woven fabric 1 is a woven fabric formed by weaving a plurality of fiber bundles 2. The fiber bundle 2 according to the present embodiment is a bundle of hundreds to thousands of fibers 2A containing oxides such as alumina and mullite as main components. It is also possible to use SiC fibers as the fiber bundle 2. The woven fabric 1 can be formed by applying a plain weave or a satin weave to such a fiber bundle 2. Further, the woven fabric 1 can be formed as a non-woven fabric using the fiber bundle 2.

The interface layer 4 has a carbon-based composition such as CNO. As will be described in detail later, in forming the interface layer 4, the woven fabric 1 is heated in a nitrogen atmosphere. As a result, a chemical reaction occurs in the polyurethane-based polymer that has been attached to the fiber bundle 2 from the beginning as a sizing material. As a result, the carbon-based interface layer 4 described above is obtained. By forming the interface layer 4, the reaction between the fiber bundle 2 and the fiber 2A and the matrix 3 is suppressed, and the strength characteristics (for example, strength, toughness) of the final product CMC can be further enhanced.

The matrix 3 is arranged in the gap formed between the plurality of fiber bundles 2 and in the gap between the fibers 2A. The matrix 3 reinforces the fiber bundle 2 by impregnating the fiber bundle 2. Specifically, the matrix 3 contains an oxide such as alumina or mullite as a main component, similarly to the fiber bundle 2.

Next, a method for producing the ceramic-based composite material 100 will be described with reference to FIG. The method for producing the ceramic-based composite material 100 according to the present embodiment includes a body forming step S1 and a densification step S2. In the element body forming step S1, the woven fabric 1 is impregnated with a polymer as a precursor of the matrix 3. In the densification step S2, the density of the matrix 3 is increased by further impregnating the woven fabric 1 with the polymer.

The element body forming step S1 includes a cutting step S11, an interface layer forming step S12, a first impregnation step S13, a laminating step S14, and a temporary firing step S15. Further, in the element body forming step S1, the first impregnation step S13 and the laminating step S14 may be repeated a plurality of times. In the cutting step S11, the woven fabric 1 is cut into a predetermined desired shape and size. In the first impregnation step S13, the cut woven fabric 1 is impregnated with the polymer as a precursor of the matrix 3. The polymer as a precursor is a material that undergoes thermal decomposition in the temporary firing step S15, which will be described later, and is made into ceramics to form matrix 3.

In the interface layer forming step S12, the cut woven fabric 1 is heated in a nitrogen atmosphere. As a result, the sizing material can be modified to form the carbon-based interface layer 4. Specifically, as shown in FIG. 5, when polyurethane is used as the sizing material, CNO as the interface layer 4 is generated through the synthesis and thermal decomposition of polyurethane.

As the sizing material, polyurethane resin, epoxy resin, polybutadiene, polyalkylene glycol, polyolefin resin, vinyl ester resin, saturated polyester resin, unsaturated polyester resin, polyamide resin, polyimide resin, polyamideimide resin, acrylic resin, polypropylene resin , At least one selected from the group of pitch resins can be used. In other words, if at least one chemical species in the above group is contained as a sizing material, the interface layer 4 can be easily formed by heating in a nitrogen atmosphere.

In the first impregnation step S13, the polymer is impregnated in a part of the woven fabric 1 by immersing the woven fabric 1 in the slurry containing the polymer powder.

In the laminating step S14, a plurality of woven fabrics 1 impregnated with the polymer are laminated until the desired thickness is reached. In addition, when the woven fabric 1 is laminated, the running direction of the fibers is different for each layer, so that the laminated woven fabric 1 can be given pseudo-isotropic property. Specifically, when the n-layer woven fabric 1 is laminated, pseudo-isotropic property can be realized by changing the traveling direction of the fibers of each layer for each (360 / n) °. In the temporary firing step S15, the laminated woven fabric 1 is fired. The woven fabric 1 in the state of being fired in the temporary firing step S15 is hereinafter referred to as a "elementary body". As described above, the element body forming step S1 is completed. The density of the element body obtained in the element body forming step S1 is increased by executing the densification step S2.

The densification step S2 includes a second impregnation step S21 (impregnation step), a drying step S22, a firing step S23, and a determination step S24. In the densification step S2, the second impregnation step S21, the drying step S22, the firing step S23, and the determination step S24 are executed in this order. In the densification step S2, a part of the steps can be repeatedly executed.

In the second impregnation step S21, the element body is further impregnated with the polymer as a precursor of the matrix 3. In the element body before executing the second impregnation step S21, the matrix 3 is arranged only in a part of the gap between the fiber bundles 2. In other words, at this stage, the density of the element body, that is, the filling rate of the matrix 3 is not sufficiently increased, and there is room for further forming the matrix 3. Therefore, by executing the second impregnation step S21, the laminated element body is further impregnated with the polymer as the precursor of the matrix 3. The impregnated element body is formed by the second impregnation step S21.

After the second impregnation step S21, the drying step S22 is performed. The element body further impregnated with the polymer in the second impregnation step S21 contains a large amount of solvent and water of the slurry used for impregnation. In the drying step S22, the solvent component is volatilized and the water content is evaporated. As a result, a dried element body is formed. The volume of the dried element body is smaller than the volume of the impregnated element body.

After the drying step S22, the firing step S23 is executed. In the firing step S23, the dried element body is fired. By executing the firing step S23, a chemical reaction occurs between the polymer as the precursor described above and the woven fabric 1. By the chemical reaction, the polymer becomes a matrix 3 and is in a state of being impregnated in the fiber bundle 2 of the woven fabric 1.

Specifically, in the firing step S23, the OH group contained in the polymer becomes an oxo group (O group) by the dehydration reaction, and the polymer as a precursor becomes the matrix 3. Therefore, in the polymer after the firing step S23, intermolecular condensation occurs between adjacent oxo groups. In addition, intramolecular condensation due to oxo groups also occurs in the polymer.

After the firing step S23, the determination step S24 is executed. In the determination step S24, it is determined whether or not the processed element body satisfies the predetermined characteristics and conditions. When it is determined in the determination step S24 that the predetermined characteristics and conditions are satisfied, it is determined that the CMC having the desired characteristics has been completed. On the other hand, if it is determined that the predetermined characteristics and conditions are not satisfied, the second impregnation step S21, the drying step S22, and the firing step S23 are performed again. That is, the second impregnation step S21, the drying step S22, and the firing step S23 are repeated until the predetermined characteristics and conditions are satisfied in the determination step S24. In the present embodiment, the determination is executed in the determination step S24, but the number of repetitions of the second impregnation step S21, the drying step S22, the firing step S23, and the determination step S24 that satisfy the predetermined characteristics and conditions is tested in advance. Etc., and the determined number of times may be repeated. As described above, all the steps of the method for manufacturing the ceramic-based composite material 100 are completed.

As described above, according to the method for producing the ceramic-based composite material 100 according to the present embodiment, by executing the interface layer forming step S12, the interface is formed around the fiber bundle 2 without removing the sizing material. Layer 4 can be formed. Thereby, the material adhering as the sizing material around the fiber bundle 2 of the woven fabric 1 can be removed, and the interface layer 4 can be formed in the interface layer forming step S12 without forming the interface. Thereby, the CMC having the interface layer 4 can be obtained without complicating and lengthening the process. Further, since it is not necessary to separately prepare the material for forming the interface layer 4, the cost can be reduced.

Further, according to the method for producing the ceramics-based composite material 100 according to the present embodiment, the sizing material is a polyurethane resin, an epoxy resin, a polybutadiene, a polyalkylene glycol, a polyolefin resin, a vinyl ester resin, a saturated polyester resin, or an unsaturated polyester resin. , Polyimide resin, Polyimide resin, Polyamideimide resin, Acrylic resin, Polypropylene resin, Pitch resin At least one selected from the group is used. These chemical species change to a carbon-based molecular structure when heated in a nitrogen atmosphere. Therefore, according to this method, the interface layer can be easily and inexpensively formed.

[Second Embodiment]
Next, the second embodiment of the present invention will be described with reference to FIGS. 6 to 8. As shown in FIG. 6, the method for producing the ceramic-based composite material 200 according to the present embodiment is different from the above-described first embodiment in that the steam treatment step S223 and the preliminary determination step S224 are further included.

Specifically, the steam treatment step S223 is executed after the drying step S222. In the steam treatment step S223, the dried element is placed under saturated steam pressure. Specifically, the dried body is sealed in a processing container. The temperature inside the processing container is preferably 30 to 200 ° C. More preferably, the temperature inside the processing vessel is 80-150 ° C, most preferably 100-130 ° C. The period for performing the steam treatment step S223 is appropriately selected from several minutes to several hours, and the nominal value is about 1 hour.

In the steam treatment step S223, a part of the polymer contained in the dried element (that is, the polymer as a precursor of the matrix 3) is hydrolyzed. Specifically, when the steam treatment step S223 is executed on the polymer, a chemical reaction as shown in FIG. 7 occurs. In FIG. 7, “L” represents a predetermined leaving group. As shown in the figure, by executing the steam treatment step S223, the L group in the polymer is replaced with the OH group. By executing the steam treatment step S223, the treated element body is formed.

After the steam treatment step S223, the preliminary determination step S224 is executed. In the preliminary determination step S224, it is determined whether or not the processed element body satisfies the predetermined characteristics and conditions. If it is determined in the preliminary determination step S224 that the predetermined characteristics and conditions are satisfied, the process proceeds to the subsequent firing step S225. On the other hand, if it is determined that the predetermined characteristics and conditions are not satisfied, the second impregnation step S221, the drying step S222, and the steam treatment step S223 are executed again. That is, the second impregnation step S221, the drying step S222, and the steam treatment step S223 are repeated until the preliminary determination step S224 satisfies the predetermined characteristics and conditions. In the present embodiment, the determination is executed in the preliminary determination step S224, but the number of repetitions of the second impregnation step S221, the drying step S222, and the steam treatment step S223 that satisfy the predetermined characteristics and conditions is determined in advance by an experiment or the like. It may be decided and the determined number of times may be repeated.

In the method for producing the ceramic-based composite material 200 according to the present embodiment, the efficiency of impregnating the polymer into the element body can be increased by executing the steam treatment step S223. That is, the ceramic-based composite material 200 having desired characteristics can be obtained without executing the subsequent firing step S225 many times. Therefore, it is possible to avoid a decrease in strength due to heat and a prolongation of the production period that occur when the firing step S225 is repeated.

Further, by executing the steam treatment step S223, adjacent oxo groups in the polymer are intermolecularly condensed. In addition, intramolecular condensation due to oxo groups also occurs in the polymer. That is, the polymers form a three-dimensional network. As a result, the strength of the matrix 3 after the firing step S225 can be increased. In other words, by executing the steam treatment step S223, it is possible to obtain a CMC having a desired strength with a smaller number of repetitions as compared with the case where only the firing step S225 is repeated a plurality of times. Therefore, the number of firing steps S225 can be reduced, and the possibility of strength reduction or weight loss due to heat can also be reduced.

Further, the steam treatment step S223 is executed under saturated steam of 30 ° C. or higher and 200 ° C. or lower. Since the treatment can be performed at a relatively low temperature in this way, the efficiency of impregnating the polymer into the element body can be increased without using large-scale equipment.

The second embodiment of the present invention has been described above. It is possible to make various changes to the above configuration and method as long as the gist of the present invention is not deviated.

For example, in the second embodiment, the second impregnation step S221, the drying step S222, and the steam treatment step S223 are repeatedly executed, but it may be performed only once. Similarly, in the second embodiment, the second impregnation step S221, the drying step S222, the steam treatment step S223, the preliminary determination step S224, and the firing step S225 are repeatedly executed, but it may be performed only once.

The second embodiment of the present invention has been described above. It is possible to make various changes to the above configuration and method as long as the gist of the present invention is not deviated.

Next, examples of the present invention will be described with reference to FIG. FIG. 8 is a graph showing the relationship between the presence / absence of the steam treatment step S223 described in the second embodiment, the number of repetitions of the densification step S2, and the porosity (porosity) of the matrix 3. The horizontal axis of the graph represents the number of repetitions of the firing step S25. The vertical axis of the graph represents the porosity value when the porosity of the initial matrix 3 is 1. That is, the lower the porosity value, the higher the impregnation rate of the matrix 3 and the more densified it is. Further, since low porosity can be achieved while the number of repetitions of the firing step S25 is suppressed to a small number, it is possible to suppress a decrease in fiber strength, and it is possible to realize cost reduction and shortening of construction period. That is, as shown in this embodiment, by repeatedly executing the steam treatment step S223, it is possible to reduce the number of firing steps S25 and reduce the porosity.

As shown in FIG. 8 as a comparative example, when the steam treatment step S223 was not executed, it was necessary to repeat the densification step S2 eight times in order to reduce the porosity to about 0.85. On the other hand, when the steam treatment was executed once, the desired porosity was reached only by repeating the densification step S2 five times. Further, when the steam treatment was executed twice, the desired porosity was reached only by repeating the densification step S2 three times. In addition, when the steam treatment was performed three times, the desired porosity was reached only by repeating the densification step S2 twice.

As described above, it can be seen that the number of times the densification step S2 is executed can be reduced by executing the steam treatment step S223. Further, it can be seen that as the number of times the steam treatment step S223 is executed increases, the number of times the densification step S2 is executed can be reduced.

1 Woven fabric 2 Fiber bundle 2A Fiber 3 Matrix 4 Interface layer 10 Fiber layer 100, 200 Ceramic-based composite material

Claims (3)

A method for producing a ceramic-based composite material, which comprises a plurality of fiber bundles, a woven fabric having a sizing material that covers the periphery of the fiber bundles, and a matrix arranged in a gap between the fiber bundles.
A body forming step of impregnating the woven fabric with a polymer as a precursor of the matrix to form a body,
A densification step of further impregnating the element body with the polymer and firing it,
Including
The element body forming step, the woven fabric by heating in a nitrogen atmosphere, saw including an interface layer formation step of forming an interface layer on the fiber bundle by modifying the sizing member,
The sizing material is a ceramic group which is at least one selected from the group of polybutadiene, polyalkylene glycol, polyolefin resin, vinyl ester resin, saturated polyester resin, unsaturated polyester resin, acrylic resin, polypropylene resin, and pitch resin. Method of manufacturing composite material. The densification step is
An impregnation step of further impregnating the element body with the polymer to form an impregnated element body,
A drying step of drying the impregnated body to form a dried body,
The firing step of firing the dried body and
The method for producing a ceramic-based composite material according to claim 1. After the drying step, the impregnation step and the drying step are repeated.
In the firing step, the dried element body obtained by repeating the impregnation step and the drying step a plurality of times is fired.
The method for producing a ceramic-based composite material according to claim 2 .

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