Method for forming ceramic matrix composite materials

Abstract

To mold a ceramic base composite material in an appropriate manner while suppressing formation of molding defects.SOLUTION: A molding method of a ceramic base composite material by impregnating a molten metal to mold a ceramic base composite material includes the steps of: forming a laminate by laminating a plurality of fiber layers being reinforcement fibers impregnated with a base resin, as well as, arranging, between the fiber layers, matrix layers containing fibers extending in an impregnating direction of the molten metal; forming an impregnation passage in the matrix layer over the in-plane direction orthogonal to the lamination direction of the laminate by carbonizing the formed laminate; and impregnating the molten metal to the laminate where the impregnation passage are formed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method for forming a ceramic matrix composite and a ceramic matrix composite. [Background technology]

[0002] Conventionally, a method for manufacturing a ceramic matrix composite using the melt-infiltrated (MI) method has been known as a molding method for ceramic matrix composites (see, for example, Patent Document 1). In this manufacturing method, a matrix slurry containing a resin binder and a pore-forming agent is impregnated into a fiber-reinforced material to form a preform, and the preform is heated to carbonize the resin binder and promote pore formation with the pore-forming agent, thereby forming a porous preform. Thereafter, in the manufacturing method, molten silicon is filled into the pores of the porous preform to form silicon carbide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-241327 Summary of the Invention [Problem to be solved by the invention]

[0004] The matrix slurry serving as the base resin may contain a large amount of filler, such as carbon or silicon carbide. In this case, even if a porous preform is formed using a pore-forming agent as in Patent Document 1, the filler may disrupt the impregnation pathways through which the molten silicon penetrates, making it difficult to form appropriate impregnation pathways. If appropriate impregnation pathways are not formed, the impregnation of the molten silicon may stop midway, resulting in the formation of unimpregnated areas and the generation of voids or cracks. Furthermore, if large pores are formed by the pore-forming agent, even if the molten silicon is impregnated, unreacted silicon may remain unreacted with the carbon. This may result in a decrease in the strength of the molded ceramic matrix composite.

[0005] Therefore, an object of the present disclosure is to provide a method for forming a ceramic matrix composite material that can suitably form the ceramic matrix composite material while suppressing the occurrence of forming defects, and the ceramic matrix composite material. [Means for solving the problem]

[0006] The method for forming a ceramic matrix composite material disclosed herein is a method for forming a ceramic matrix composite material by impregnating it with molten metal, and includes the steps of: forming a laminate by stacking a plurality of fiber layers, which are layers of reinforcing fibers impregnated with a matrix resin, and arranging matrix layers containing fibers extending in the impregnation direction of the molten metal between the fiber layers; carbonizing the formed laminate to form impregnation paths in the matrix layers across an in-plane direction perpendicular to the stacking direction of the laminate; and impregnating the laminate with the impregnation paths formed therein with the molten metal.

[0007] The ceramic matrix composite material of the present disclosure includes a fiber layer that is a layer containing ceramic matrix reinforcing fibers, and a matrix layer that is provided between a plurality of the fiber layers stacked in a stacking direction and is formed by impregnating molten metal into impregnation paths that are formed across an in-plane direction perpendicular to the stacking direction of the fiber layers, and causing a reaction. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to suitably mold a ceramic matrix composite while suppressing the occurrence of molding defects. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing a ceramic matrix composite according to this embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of a method for forming a ceramic-based composite material according to this embodiment. [Figure 3] FIG. 3 is an explanatory diagram showing another example of the method for forming a ceramic-based composite material according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are easily replaceable by those skilled in the art, or those that are substantially identical. Furthermore, the components described below can be combined as appropriate, and if there are multiple embodiments, the respective embodiments can also be combined.

[0011] [Embodiment] Fig. 1 is a cross-sectional view showing a ceramic matrix composite according to this embodiment. Fig. 2 is an explanatory diagram showing an example of a method for forming the ceramic matrix composite according to this embodiment. Fig. 3 is an explanatory diagram showing an example of a method for forming the ceramic matrix composite according to this embodiment.

[0012] The method for forming a ceramic matrix composite according to this embodiment is a forming method using a melt infiltration method (MI method). The ceramic matrix composite is, for example, a SiC (silicon carbide) composite, specifically a SiC fiber-reinforced SiC matrix composite (SiC / SiC composite). Prior to describing the method for forming the ceramic matrix composite, a ceramic matrix composite 1, which is a SiC / SiC composite, will be described with reference to FIG. 1. The ceramic matrix composite is not particularly limited to a SiC / SiC composite, and may be any ceramic matrix composite that can be formed by the forming method of this embodiment.

[0013] (ceramic matrix composite) As shown in FIG. 1, the ceramic composite material 1 includes fiber layers 5 containing ceramic reinforcing fibers, and matrix layers 6 provided between the fiber layers 5 stacked in the stacking direction.

[0014] The fiber layer 5 is a layer mainly composed of fibers, and SiC fibers are used as ceramic-based reinforcing fibers. The fiber layer 5 is formed by laminating and curing prepregs in which carbon fibers are impregnated with a matrix resin to form a preform, carbonizing the preform, and impregnating and reacting it with molten silicon as a molten metal. For example, a unidirectional material in which the fiber direction of the SiC fibers is unidirectional is used as the prepreg, and the prepregs are laminated with different fiber directions. For example, a thermosetting resin such as an epoxy resin is used as the matrix resin. The matrix resin also contains a filler, which is at least one of powdered carbon and powdered silicon carbide. In this way, the matrix resin is a thermosetting resin containing a filler.

[0015] The matrix layer 6 is a layer containing silicon carbide. The matrix layer 6 is formed by carbonizing fibers 11 (see FIG. 2 ), which will be described later, to form impregnation paths 8, and then impregnating and reacting molten silicon into these impregnation paths 8. The impregnation paths 8 formed in the matrix layer 6 are formed so that the spaces filled with molten silicon are connected across the in-plane direction perpendicular to the lamination direction of the fiber layers 5. Then, as the molten silicon is impregnated into these impregnation paths 8, the matrix layer 6 becomes a layer in which silicon carbide is formed along the impregnation paths 8.

[0016] (Method for forming ceramic matrix composite materials) Next, a method for forming the ceramic matrix composite material 1 will be described with reference to FIG. 2. In the method for forming the ceramic matrix composite material 1, first, a laminate is formed by stacking fiber layers 5 and matrix layers 6 to form a preform (step S1). In step S1, multiple prepregs, each of which is an integrated fiber layer 5 and a matrix layer 6 that does not contain fibers 11, are stacked, and fibers 11 are placed between the prepreg layers. That is, in step S1, prepregs and fibers 11 are alternately stacked. Note that in step S1, the prepregs and fibers 11 may be further integrated into sheets, and multiple sheets may be stacked repeatedly. Thereafter, in step S1, the stacked prepregs are heated to melt the matrix layers 6 and integrate them with the fibers 11, and further heating is performed to thermally cure the fiber layers 5 and matrix layers 6, thereby forming a laminate. As a result, matrix layers 6 containing fibers 11 extending in the in-plane direction of the laminate are formed. The fibers 11 used in the matrix layer 6 are inorganic fibers such as carbon fibers with a binder resin attached or SiC fibers with a binder resin attached, or organic fibers. Note that a binder resin may also be attached to the organic fibers. The fibers 11 used in the matrix layer 6 are nonwoven fabric, woven fabric, or unidirectional material. Therefore, the fiber direction of the fibers 11 used in the matrix layer 6 is aligned with the in-plane direction of the laminate.

[0017] When the matrix layer 6 is carbonized, impregnation paths 8 are formed along the fiber direction (in-plane direction) of the fibers 11 by carbonizing the binder resin in the case of carbon fibers and SiC fibers, or by carbonizing the fibers themselves in the case of organic fibers. At this time, the binder resin and organic fibers are resins with a lower decomposition temperature than the matrix resin of the fiber layer 5. For example, when an epoxy resin is used as the matrix resin, PVC (polyvinyl chloride), PMMA (Poly Methyl Methacrylate), or the like is used as the binder resin and organic fiber.

[0018] The fiber 11 of the matrix layer 6 has a fiber diameter of 0.5 to 20 μm, more preferably 1 to 7 μm, and even more preferably 1 to 5 μm. The fiber 11 of the matrix layer 6 has a basis weight of 20 g / m 2 Preferably, the basis weight is 8 g / m or less. 2 The details are as follows.

[0019] Next, in the method for forming the ceramic matrix composite 1, the formed laminate is carbonized to form impregnation paths 8 in the matrix layer 6 across the in-plane direction of the laminate (step S2). In step S2, the laminate is carbonized to form a laminate with impregnation paths 8 formed therein, as a precursor of the ceramic matrix composite 1. In step S2, if the fibers 11 of the matrix layer 6 are carbon fibers and SiC fibers, the binder resin attached to the fibers 11 is carbonized to form impregnation paths 8 through which the molten silicon is impregnated, and carbon is formed within the impregnation paths 8. In step S2, if the fibers 11 of the matrix layer 6 are organic fibers, the fibers 11 themselves are carbonized to form impregnation paths 8 through which the molten silicon is impregnated, and carbon is formed within the impregnation paths 8. The impregnation paths 8 formed in step S2 also function as degassing paths for decomposition gases generated by carbonization of the matrix resin, thereby suppressing cracking of the laminate.

[0020] Thereafter, in the method for forming the ceramic matrix composite 1, the laminate in which the impregnation paths 8 serving as precursors are formed is impregnated with molten silicon (step S3). In step S3, the molten silicon is impregnated along the impregnation paths 8 formed in step S2. The impregnated molten silicon reacts with the carbon in the impregnation paths 8, the carbon contained in the carbonized matrix resin, and the carbon of the filler contained in the matrix resin to form silicon carbide. Note that if the fibers 11 in the matrix layer 6 are carbon fibers, the molten silicon reacts with the carbon fibers to produce SiC fibers. Then, with the execution of step S3, the method for forming the ceramic matrix composite 1 is completed.

[0021] For example, a filler-containing base resin that is difficult to impregnate is used as the base resin of the fiber layer 5, and the fiber 11 has a fiber diameter of 7 μm and a basis weight of 8 g / m 2 It has been confirmed that when a nonwoven fabric of carbon fibers having a thickness of 16% by weight of PVA binder resin is applied to the nonwoven fabric, the impregnation paths 8 formed are impregnated with molten silicon.

[0022] Next, another example of a method for forming a ceramic-based composite material 1 will be described with reference to FIG. 3. In the forming method of FIG. 3, in step S2 of forming impregnation paths 8 in the matrix layer 6, the fibers 11 of the matrix layer 6 of the laminate or the binder resin attached to the fibers 11 are dissolved before the laminate is carbonized. That is, in the forming method of FIG. 3, when the fibers 11 used in the matrix layer 6 are to be dissolved, fibers that dissolve in a solvent are used. Also, in the forming method of FIG. 3, when the fibers 11 used in the matrix layer 6 are not dissolved, it is preferable to attach a binder resin to the fibers 11. Note that steps S1 and S3 shown in FIG. 3 are similar to steps S1 and S3 shown in FIG. 2, and therefore description thereof will be omitted.

[0023] In step S2, the formed laminate is immersed in a liquid tank 15 containing a solvent to dissolve the fibers 11 or binder resin in the matrix layer 6 of the laminate (step S2a). For example, an acid is used as the solvent. In step S2a, the fibers 11 or binder resin in the matrix layer 6 are dissolved to form impregnation paths 8 in the matrix layer 6 across the in-plane direction of the laminate. Then, in step S2a, after the fibers 11 are dissolved, the laminate is removed from the liquid tank 15 and appropriately washed. Subsequently, in step S2, the laminate from which the fibers 11 or binder resin have been removed is carbonized to carbonize the matrix resin remaining in the matrix layer 6 (step S2b). In step S2b, since the impregnation paths 8 have been formed in step S2a, the matrix resin and the remaining fibers 11 are carbonized to form carbon in the impregnation paths 8.

[0024] 3, in step S2, the impregnation paths 8 are formed and carbon is formed within the impregnation paths 8. If the hollow regions (cavities) of the impregnation paths 8 are large, carbon is unlikely to be formed within the impregnation paths 8 in the carbonization step of step S2. However, in the subsequent impregnation step of step S3, carbon supplied from around the impregnation paths 8 combines with molten silicon that has penetrated into the impregnation paths 8 to form silicon carbide, and the impregnation paths 8 become silicon carbide.

[0025] As described above, the method for forming the ceramic-based composite material 1 and the ceramic-based composite material 1 described in the embodiment can be understood, for example, as follows.

[0026] The method for forming a ceramic matrix composite 1 according to the first aspect is a method for forming a ceramic matrix composite 1 by impregnating it with molten metal (e.g., molten silicon), and includes the steps of: step S1 of forming a laminate in which a plurality of fiber layers 5, which are layers of reinforcing fibers impregnated with a matrix resin, are stacked, and matrix layers 6 containing fibers 11 extending in the impregnation direction of the molten metal are disposed between the fiber layers 5; step S2 of carbonizing the formed laminate to form impregnation paths 8 in the matrix layers 6 in an in-plane direction perpendicular to the stacking direction of the laminate; and step S3 of impregnating the laminate in which the impregnation paths 8 have been formed with the molten metal.

[0027] According to this configuration, by including fibers 11 extending in the impregnation direction of the molten metal in the matrix layer 6, it is possible to form impregnation paths 8 in the in-plane direction of the matrix layer 6 of the laminate. Therefore, since appropriate impregnation paths 8 can be formed without dividing the impregnation paths 8, the molten silicon can be appropriately impregnated along the impregnation paths 8, suppressing the occurrence of molding defects such as the formation of voids, cracks, and unreacted Si, and enabling the ceramic matrix composite to be suitably molded.

[0028] In a second embodiment, the fibers 11 of the matrix layer 6 are nonwoven, woven, or unidirectional.

[0029] According to this configuration, the impregnation paths 8 can be appropriately formed throughout the matrix layer 6.

[0030] In a third aspect, the fiber diameter of the fibers 11 in the matrix layer 6 is 0.5 to 20 μm.

[0031] According to this configuration, it is possible to form impregnation paths 8 that are easy for the molten metal to penetrate, and therefore the reaction between carbon and the molten metal can be carried out efficiently.

[0032] In a fourth aspect, the fiber diameter of the fibers 11 in the matrix layer 6 is 1 to 7 μm.

[0033] In a fifth aspect, the fiber diameter of the fibers 11 in the matrix layer 6 is 1 to 5 μm.

[0034] These configurations allow the formation of impregnation paths 8 that are more easily impregnated with the molten metal, thereby enabling the reaction between carbon and the molten metal to occur more efficiently.

[0035] In a sixth embodiment, the fibers 11 of the matrix layer 6 have a basis weight of 20 g / m 2 The following is the result.

[0036] According to this configuration, the fibers 11 can be arranged uniformly in the matrix layer 6 at a basis weight, and therefore the impregnation paths 8 can be formed uniformly in the matrix layer 6.

[0037] In a seventh aspect, the fiber of the matrix layer has a basis weight of 8 g / m 2 The following is the result.

[0038] According to this configuration, the fiber 11 can be arranged more uniformly in the matrix layer 6 at a basis weight, and therefore the impregnation paths 8 can be formed more uniformly in the matrix layer 6.

[0039] In an eighth embodiment, the fibers 11 of the matrix layer 6 are carbon fibers to which a binder resin is attached, inorganic fibers to which a binder resin is attached, or organic fibers.

[0040] This configuration allows for an increased number of options for the fibers 11 while allowing for the appropriate formation of carbon within the impregnation paths 8.

[0041] In a ninth aspect, the binder resin and the organic fibers are made of a resin having a lower decomposition temperature than the matrix resin.

[0042] According to this configuration, when the laminate is carbonized, the volatile components of the binder resin and organic fiber can be volatilized before the matrix resin, and the impregnation path 8 can be used as a flow path for the volatilization of the volatile components of the matrix resin, thereby suppressing the occurrence of cracks.

[0043] In a tenth aspect, in the step of forming the impregnation paths 8 in the matrix layer 6, the fibers 11 in the matrix layer 6 of the laminate are dissolved before the laminate is carbonized.

[0044] According to this configuration, the impregnation paths 8 can be formed by dissolving the fibers 11.

[0045] The ceramic-based composite material 1 according to the eleventh aspect includes a fiber layer 5 that is a layer containing ceramic-based reinforcing fibers, and a matrix layer 6 that is provided between a plurality of the fiber layers 5 stacked in the stacking direction and that is formed by impregnating molten metal into impregnation paths 8 that are formed across the in-plane direction perpendicular to the stacking direction of the fiber layers 5, and causing a reaction.

[0046] According to this configuration, ceramic carbide can be formed along the impregnation paths 8, and therefore the strength can be increased. [Explanation of symbols]

[0047] 1. Ceramic matrix composites 5 fiber layers 6 matrix layer 8 Impregnation Path 11. Fiber 15 Liquid tank

Claims

1. A method for forming a ceramic matrix composite material by impregnating a ceramic matrix composite material with molten metal, comprising: A prepreg is used in which a fiber layer, which is a layer of reinforcing fibers impregnated with a base resin, and a matrix layer that does not include first fibers are integrated, the first fibers are fibers that form impregnation paths in the matrix layer when carbonized; forming a laminate in which a plurality of the prepregs are laminated and the first fibers extending in the impregnation direction of the molten metal are arranged between the layers of the prepregs; heating the laminate to melt the matrix layer and integrate the matrix layer with the first fibers; forming impregnation paths in the matrix layer in an in-plane direction perpendicular to the stacking direction of the laminate by carbonizing the laminate in which the matrix layer and the first fibers are integrated; and impregnating the laminate in which the impregnation paths are formed with the molten metal.

2. 2. The method for forming a ceramic matrix composite material according to claim 1, wherein the first fibers integrated with the matrix layer are nonwoven fabric, woven fabric, or unidirectional material.

3. 3. The method for forming a ceramic matrix composite material according to claim 1, wherein the first fibers integrated with the matrix layer have a fiber diameter of 0.5 to 20 μm.

4. 4. The method for forming a ceramic composite material according to claim 3, wherein the first fibers integrated with the matrix layer have a fiber diameter of 1 to 7 μm.

5. 5. The method for forming a ceramic composite material according to claim 4, wherein the first fibers integrated with the matrix layer have a fiber diameter of 1 to 5 μm.

6. 6. The method for molding a ceramic composite material according to claim 1, wherein the first fibers integrated with the matrix layer have a basis weight of 20 g / m<2 > or less.

7. 7. The method for molding a ceramic composite material according to claim 6, wherein the first fibers integrated with the matrix layer have a basis weight of 8 g / m<2 > or less.

8. 8. The method for molding a ceramic matrix composite material according to claim 1, wherein the first fibers integrated with the matrix layer are carbon fibers having a binder resin attached thereto, inorganic fibers having a binder resin attached thereto, or organic fibers.

9. 9. The method for molding a ceramic matrix composite material according to claim 8, wherein the binder resin and the organic fibers are resins having a lower decomposition temperature than the matrix resin.

10. 10. The method for molding a ceramic matrix composite material according to claim 1, wherein in the step of forming impregnation paths in the matrix layer, the first fibers integrated with the matrix layer of the laminate are dissolved before the laminate is carbonized.

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