Sintered body of ceramic matrix composite material and method for manufacturing the same

Abstract

A ceramic matrix composite material sintered body (10) comprises: a matrix base material (20) which is a ceramic material that contains boron carbide, silicon carbide, and metallurgical-grade silicon or a silicon alloy and that does not contain reinforcing fibers therein; and a fiber-reinforced composite material layer (30) which covers the outer surface of the matrix base material (20) and which contains reinforcing fibers.

Description

Technical Field

[0001] The present disclosure relates to a ceramic-based composite material sintered body in which a matrix base material made of a ceramic material and a fiber reinforced composite material are combined, and a method for manufacturing the same.

Background Art

[0002] In response to the rise in fuel prices or the demand for reducing carbon dioxide (CO2) emissions, the demand for energy conservation for air conditioners, refrigeration equipment, automobiles equipped with combustion engines, aircraft, etc. has become stricter. In air conditioners and refrigeration equipment, high efficiency of compressors is required for energy conservation, and for this realization, weight reduction or high rigidity of drive parts is necessary. Also, in order to increase the efficiency of gas turbine engines and turbine generators, it is required to raise the operating temperature or reduce the weight of the turbine.

[0003] Research on materials that satisfy these requirements has been conducted. Although the high-temperature performance has improved through the development of iron-based, nickel-based, and cobalt-based alloys, weight reduction is still insufficient, and alternative materials are being considered. Also, lightweight ceramic materials have high heat resistance and low density compared to metal materials, and thus are attracting attention as heat-resistant materials. However, since ceramic materials are relatively brittle, ceramic-based composite materials (Ceramic Matrix Composites: CMC) combined with fibers or the like have been in the spotlight as materials applicable to structural parts. Generally, a ceramic-based composite material is a material in which a ceramic matrix and reinforcing fibers are combined. In Patent Document 1, SiC / SiC in which silicon carbide (SiC) is used for the matrix and SiC fibers are used for the reinforcing fibers, and SiC and SiC fibers are combined, is disclosed as a ceramic-based composite material.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] However, the highest-performing SiC fiber products currently available have a tensile modulus (Young's modulus) of approximately 380 GPa and a specific gravity of approximately 2.85 to 3.1. Furthermore, the specific modulus (Young's modulus / specific gravity), which indicates the modulus of elasticity per unit of specific gravity, is approximately 122.6 to 133.3. For materials used in the aforementioned compressors, gas turbine engines, and turbine generators, further improvements are needed to enhance both the specific modulus and the brittleness of the ceramic material.

[0006] This disclosure has been made in view of the above, and aims to provide a ceramic matrix composite sintered body that can improve the specific modulus of elasticity and reduce brittleness compared to conventional materials. [Means for solving the problem]

[0007] To solve the above-mentioned problems and achieve the objective, the ceramic matrix composite sintered body according to this disclosure contains boron carbide, silicon carbide, and metallic silicon or silicon alloy. The spaces between dispersed boron carbide particles are filled with silicon carbide and metallic silicon or silicon alloy. The device comprises a matrix base material which is a ceramic material that does not contain reinforcing fibers internally, and a fiber-reinforced composite material layer which contains reinforcing fibers and covers the surface of the matrix base material. The fiber-reinforced composite material layer is made of fiber-reinforced metal. the law of nature The matrix material of the fiber-reinforced composite layer is a light alloy with a lower specific gravity than the matrix base material. The reinforcing fibers are one or more materials selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers. [Effects of the Invention]

[0008] The ceramic matrix composite sintered body according to this disclosure has the effect of improving the specific modulus of elasticity and reducing brittleness compared to conventional materials. [Brief explanation of the drawing]

[0009] [Figure 1] A perspective view showing an example of the structure of a ceramic matrix composite sintered body according to Embodiment 1. [Figure 2] A perspective view showing an example of the structure of a ceramic matrix composite sintered body according to Embodiment 2. [Figure 3] A perspective view showing an example of the structure of a ceramic matrix composite sintered body according to Embodiment 3. [Figure 4] A magnified perspective view of a portion of region R in Figure 3. [Figure 5] A flowchart showing an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 4. [Figure 6] A flowchart showing an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 5. [Figure 7] A flowchart showing an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 6. [Figure 8] A schematic perspective view illustrating an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 6. [Figure 9] A schematic perspective view illustrating an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 6. [Figure 10] A schematic perspective view illustrating an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 6. [Figure 11] A schematic perspective view illustrating an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 6. [Modes for carrying out the invention]

[0010] The ceramic matrix composite sintered body and its manufacturing method according to embodiments of the present disclosure will be described in detail below with reference to the drawings. Here, in the following drawings, including Figure 1, components denoted by the same reference numerals are the same or equivalent components and are common to the entire text of the embodiments described below. Furthermore, the forms of the components shown in the entire specification are merely illustrative and are not limited to the forms described in the specification.

[0011] Embodiment 1. Figure 1 is a perspective view showing an example of the structure of a ceramic matrix composite sintered body according to Embodiment 1. Figure 1 also shows the internal structure of the ceramic matrix composite sintered body 10 with a portion of the surface layer removed. The structure of the ceramic matrix composite sintered body 10 will be explained using Figure 1.

[0012] As shown in Figure 1, the ceramic matrix composite sintered body 10 according to Embodiment 1 comprises a matrix base material 20 made of ceramic material and not containing reinforcing fibers internally, and a fiber-reinforced composite material layer 30 containing reinforcing fibers that covers the surface of the matrix base material 20, in this case the outer surface. The ceramic matrix composite sintered body 10 does not have any voids inside the structure and has a solid structure in which the interior is filled with the matrix base material 20.

[0013] The matrix base material 20 contains boron carbide (B4C) as the main component, and as other elements, it contains silicon carbide and silicon (Si), which is metallic silicon or a silicon alloy. Examples of commercially available boron carbide include boron carbide powder F240 manufactured by 3M. In the composition of the matrix base material 20, the volume ratio of boron carbide, which is the main component, is 50% or more. The specific gravity of boron carbide is smaller than that of silicon carbide, metallic silicon, and silicon alloys. If the matrix base material 20 contains a large amount of silicon or silicon carbide, the apparent specific elastic modulus decreases. Therefore, in order to improve the specific elastic modulus of the matrix base material 20, the volume ratio of boron carbide, which has the highest specific elastic modulus among the above-mentioned constituent materials, in the matrix base material 20 is set to 50% or more, and boron carbide is used as the main component of the matrix base material 20.

[0014] Silicon is metallic silicon or a silicon alloy. The reason silicon is included is that it is difficult to set the silicon content to zero and fill it with other components during the manufacturing process. It is possible to replace silicon with voids. However, voids correspond to defects in the material and the material properties deteriorate. Therefore, filling with silicon rather than leaving it in a void state is desirable in terms of improving the material properties and the specific elastic modulus.

[0015] The fiber reinforced composite material layer 30 covers the surface portion of the matrix base material 20. The matrix base material 20 and the fiber reinforced composite material layer 30 form an integral structure and constitute the ceramic-based composite material sintered body 10. Since the matrix base material 20 contains 50% or more of boron carbide by volume ratio, it has a high specific elastic modulus, but since it is a ceramic, it is a brittle material. Due to this brittleness, it is difficult to apply it to structural members and the like. Therefore, by covering and integrating the surface of the matrix base material 20 with the fiber reinforced composite material layer 30, the crack propagation property due to external impact is significantly improved. Furthermore, since the fiber reinforced composite material layer 30 can realize a structure that is lighter and has a higher elastic modulus than the matrix base material 20, the specific elastic modulus of the ceramic-based composite material sintered body 10 can be further improved by compounding. Thus, the fiber reinforced composite material layer 30 is composed of a material having a specific gravity smaller than that of the matrix base material 20 and a high elastic modulus.

[0016] The fiber reinforced composite material layer 30 has a matrix material and reinforcing fibers. The fiber reinforced composite material layer 30 is a material in which reinforcing fibers are compounded in a matrix material.

[0017] As an example of the reinforcing fibers used in the fiber reinforced composite material layer 30, carbon fibers can be mentioned. Among carbon fibers, it is particularly desirable to combine them with pitch-based carbon fibers having an ultra-high elastic modulus. Some pitch-based carbon fibers have a specific gravity of 2.1 or more and 2.2 or less, an elastic modulus of 800 GPa or more, and a specific elastic modulus of 360 or more in this case. Thus, pitch-based carbon fibers have a smaller specific gravity and a higher elastic modulus than boron carbide and silicon carbide of the matrix base material 20. Therefore, by covering and compounding the surface of the matrix base material 20 with the fiber reinforced composite material layer 30 using pitch-based carbon fibers as reinforcing fibers, the specific elastic modulus can be improved and the brittleness can be improved compared to the conventional case.

[0018] Here, the reinforcing fibers of the fiber-reinforced composite material layer 30 may be carbon fibers, ceramic fibers, polyacrylonitrile (PAN)-based carbon fibers, glass fibers, or aramid fibers, or a combination of two or more of these may be used. Aramid fibers are an example of organic fibers.

[0019] The reinforcing fibers of the fiber-reinforced composite layer 30 are selected according to the desired properties of the ceramic matrix composite sintered body 10. For example, to further improve the specific modulus of the ceramic matrix composite sintered body 10 integrated with the fiber-reinforced composite layer 30, it is preferable to use pitch-based carbon fibers as reinforcing fibers. On the other hand, to improve the brittleness of the ceramic matrix composite sintered body 10 integrated with the fiber-reinforced composite layer 30 and further improve its fracture toughness, it is preferable to mainly combine aramid fibers as reinforcing fibers. Furthermore, by combining pitch-based carbon fibers and aramid fibers, it becomes possible to achieve both improvements in the specific modulus of the ceramic matrix composite sintered body 10 integrated with the fiber-reinforced composite layer 30 and improvements in its fracture toughness.

[0020] An example of a matrix material for the fiber-reinforced composite material layer 30 is a resin. In the case of fiber-reinforced plastics (FRP), epoxy resin is an example of the resin, but depending on the usage environment conditions, resins other than epoxy resin, such as resins with higher heat resistance, may be used. In addition to thermosetting resins such as phenolic resin, furan resin, polyimide resin, cyanate resin, and vinyl ester resin, thermoplastic resins such as nylon and polyester resin may be used as the resin, or resins that harden with a catalyst such as epoxy resin may be used, or a combination of these resins may be used.

[0021] Furthermore, the matrix material may be carbon, ceramics, or metal in addition to resin. When the matrix material is a resin such as plastic, there are limitations on the heat resistance temperature of the operating environment. For this reason, when used in an environment where higher heat resistance is required, it is desirable to use a ceramic matrix composite sintered body 10 in which a fiber-reinforced composite material layer 30 and a matrix base material 20 are integrated, using metal, carbon, or ceramics as the matrix material, which has superior heat resistance compared to plastic materials.

[0022] When using metal as the matrix material, it can be combined with light alloys such as aluminum alloys or magnesium alloys, which have a lower specific gravity than the matrix base material 20. If even greater heat resistance than that of metal is required, it is desirable to combine it with carbon or ceramics. When using carbon, it is susceptible to oxidation in air, so it is desirable to use it in a non-oxidizing atmosphere. Alternatively, the ceramic matrix composite sintered body 10 may further have an oxidation-preventive coating layer provided on the surface of the fiber-reinforced composite material layer 30. In other words, the carbon matrix material may be combined with an oxidation-preventive coating layer provided on the surface of the fiber-reinforced composite material layer 30.

[0023] Here, a material in which the matrix material is ceramic and the reinforcing fibers are selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers is a ceramic matrix composite. A material in which the matrix material is metal and the reinforcing fibers are selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers is a fiber-reinforced metal (FRM). A material in which the matrix material is carbon and the reinforcing fibers are carbon fibers is a carbon fiber-reinforced carbon matrix composite (C / C composite). A material in which the matrix material is resin and the reinforcing fibers are selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers is an FRP (fiber-reinforced plastic).

[0024] In other words, the fiber-reinforced composite material layer 30 is one or more materials selected from the group consisting of ceramic matrix composites, FRM, C / C composites, and FRP. Specifically, the fiber-reinforced composite material layer 30 is one or more materials selected from the group consisting of ceramics, metals, carbon, and resins for the matrix material, and one or more materials selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers for the reinforcing fibers.

[0025] As described above, the combination of reinforcing fiber types and matrix material types for the fiber-reinforced composite material layer 30 can be appropriately selected and combined according to the usage environment conditions.

[0026] The ceramic matrix composite sintered body 10 according to Embodiment 1 comprises a matrix base material 20 which is a ceramic material containing boron carbide, silicon carbide, metallic silicon or silicon alloy, and does not contain reinforcing fibers internally, and a fiber-reinforced composite material layer 30 which contains reinforcing fibers and covers the surface of the matrix base material 20. By combining the above material compositions of the matrix base material 20 of the ceramic matrix composite sintered body 10, the specific gravity can be reduced and the elastic modulus can be increased, thus increasing the specific modulus of elasticity. Furthermore, by compounding and integrating the fiber-reinforced composite material layer 30, which has a higher elastic modulus and lower density than the matrix base material 20, the elastic modulus can be further increased and the specific gravity can be reduced. Therefore, the specific modulus of elasticity of the ceramic matrix composite sintered body 10 can be made even higher than that of the matrix base material 20. Moreover, by integrating with the fiber-reinforced composite material layer 30, the brittleness of the ceramic matrix base material 20 can be improved, that is, the fracture toughness can be significantly improved.

[0027] In the matrix base material 20, the volume ratio of boron carbide is 50% or more. This is due to the presence of silicon carbide and silicon in the matrix base material 20. ratio This can suppress the decrease in elastic modulus.

[0028] Furthermore, the fiber-reinforced composite layer 30 is one or more materials selected from the group consisting of ceramic matrix composites, FRM, C / C composites, and FRP, and the reinforcing fibers are one or more materials selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers. By arranging the combination of reinforcing fibers and matrix material of the fiber-reinforced composite layer 30 to match the operating environment conditions of the ceramic matrix composite sintered body 10, an optimal configuration for specific modulus of elasticity and fracture toughness can be achieved.

[0029] Embodiment 2. Figure 2 is a perspective view showing an example of the structure of a ceramic matrix composite sintered body according to Embodiment 2. Figure 2 shows the internal structure of the ceramic matrix composite sintered body 10A with a portion of the surface layer removed, and the internal structure of the ceramic matrix composite sintered body 10A. The structure of the ceramic matrix composite sintered body 10A will be explained using Figure 2.

[0030] The ceramic matrix composite sintered body 10A according to Embodiment 2 further comprises a reinforcing structural member 40 inside the matrix base material 20, in addition to the configuration of Embodiment 1. The reinforcing structural member 40 is made of a fiber-reinforced composite material. Here, "inside the matrix base material 20" means the inside of the structure formed by the ceramic matrix composite sintered body 10A. An example of the reinforcing structural member 40 is a plate 41, a rod 42, etc. In this example, the inside of the ceramic matrix composite sintered body 10A is a solid structure with a solid interior rather than a hollow structure, and the matrix base material 20 is arranged around the reinforcing structural member 40, so that the reinforcing structural member 40 and the matrix base material 20 are integrated into one structure.

[0031] The ceramic matrix composite sintered body 10A in Figure 2 has a base portion 11 and a fin-shaped main body portion 12 provided on the base portion 11. Inside the base portion 11 is a plate 41, which is an example of a reinforcing structural member 40, and inside the main body portion 12 are a plurality of rods 42, which are an example of a reinforcing structural member 40. The plurality of rods 42 are integrally formed with the plate 41. In the ceramic matrix composite sintered body 10 of Embodiment 1, only the surface of the matrix base material 20 was covered with a fiber-reinforced composite material layer 30, forming an integrated structure. However, in the ceramic matrix composite sintered body 10A of Embodiment 2, a reinforcing structural member 40 made of fiber-reinforced composite material is further enclosed inside the matrix base material 20, forming an integrated structure with the matrix base material 20.

[0032] The ceramic matrix composite sintered body 10A can achieve weight reduction, improved specific modulus of elasticity, and reduced brittleness of the matrix base material 20 by encapsulating reinforcing structural members 40 made of fiber-reinforced composite material inside the matrix base material 20. By encapsulating reinforcing structural members 40 such as plates 41 and rods 42 made of fiber-reinforced composite material inside the matrix base material 20, it is possible to suppress the propagation of cracks, etc., throughout the matrix base material 20 and the resulting separation if cracks occur in the matrix base material 20. The fiber-reinforced composite material constituting the reinforcing structural members 40 has a lower specific gravity and a higher elastic modulus than the matrix base material 20, so the apparent specific gravity of the matrix base material 20 with the reinforcing structural members 40 is reduced and the elastic modulus is improved.

[0033] Furthermore, the reinforcing fibers and matrix material used in the fiber-reinforced composite material layer 30 and the reinforcing structural member 40 are not limited to a single combination, as in Embodiment 1, but can be configured in any combination to suit the operating environment conditions.

[0034] The ceramic matrix composite sintered body 10A according to Embodiment 2 further comprises a reinforcing structural member 40 made of fiber-reinforced composite material within the matrix base material 20, and the reinforcing structural member 40 is integrated with the matrix base material 20. This allows for further improvement of the strength and rigidity of the matrix base material 20 compared to Embodiment 1. Furthermore, since the reinforcing structural member 40, which is made of fiber-reinforced composite material, has a lower density than the matrix base material 20, it is possible to achieve an even lower overall density of the ceramic matrix composite sintered body 10A compared to Embodiment 1.

[0035] Embodiment 3. Figure 3 is a perspective view showing an example of the structure of a ceramic matrix composite sintered body according to Embodiment 3. Figure 4 is a perspective view showing an enlarged view of a portion of region R in Figure 3. Figures 3 and 4 also show the internal structure of the ceramic matrix composite sintered body 10B with a portion of the surface layer removed. The structure of the ceramic matrix composite sintered body 10B will be explained using Figures 3 and 4.

[0036] While the ceramic matrix composite sintered bodies 10 and 10A in Embodiments 1 and 2 had a solid structure, the ceramic matrix composite sintered body 10B in Embodiment 3 is intended to have a hollow structure. In the example shown in Figures 3 and 4, the ceramic matrix composite sintered body 10B has a hollow, elliptical cylindrical structure. The ceramic matrix composite sintered body 10B according to Embodiment 3 comprises a matrix base material 20, a fiber-reinforced composite material layer 30 formed on the outer surface of the matrix base material 20, and a fiber-reinforced composite material layer 31 formed on the inner surface of the matrix base material 20. In other words, not only is the fiber-reinforced composite material layer 30 provided on the outer surface of the hollow, elliptical cylindrical matrix base material 20, but the fiber-reinforced composite material layer 31 is also provided on the inner surface of the elliptical cylindrical matrix base material 20. Furthermore, the matrix base material 20 and the fiber-reinforced composite material layer 30 on the outer surface and the matrix base material 20 and the fiber-reinforced composite material layer 31 on the inner surface form an integrated structure. The term "inner surface" refers to the matrix base material 20 or the surface of the ceramic matrix composite sintered body 10B that faces the hollow structure of the ceramic matrix composite sintered body 10B.

[0037] By making the inside of the matrix base material 20 hollow and thinning its walls, a lightweight structure can be realized. However, the matrix base material 20 is a ceramic material, and since ceramic materials are brittle, they are prone to cracking when subjected to localized impact. Therefore, by compounding the outer and inner surfaces of the matrix base material 20 with fiber-reinforced composite material layers 30 and 31, which have high fracture toughness and are resistant to cracking, it becomes possible to mitigate and diffuse localized impacts on the ceramic material. As a result, the strength and fracture toughness of the structure can be further improved.

[0038] In Embodiment 3, the fiber-reinforced composite material used in the inner surface fiber-reinforced composite layer 31 can be composed of various combinations, similar to the fiber-reinforced composite layer 30 described in Embodiments 1 and 2. Furthermore, when the outer and inner surface fiber-reinforced composite layers 30 and 31 of the matrix base material 20 are composed of the same material combination, it is desirable to lower the elastic modulus of the inner surface fiber-reinforced composite layer 31 and increase its flexibility compared to the outer surface fiber-reinforced composite layer 30. This allows the elastic modulus to be changed by adjusting the content ratio of matrix material to reinforcing fibers in the fiber-reinforced composite layers 30 and 31. For example, in the case of the outer surface fiber-reinforced composite layer 30, the volume content of reinforcing fibers can be set to 55%, and in the case of the inner surface fiber-reinforced composite layer 31, the volume content of reinforcing fibers can be set to 45%, thereby controlling the elastic modulus of the inner and outer fiber-reinforced composite layers 30 and 31. Alternatively, instead of controlling the elastic modulus by changing the volume content, different fibers can be combined to change the elastic modulus. For example, the reinforcing fibers of the outer surface fiber-reinforced composite material layer 30 can be made of highly elastic pitch-based carbon fibers, while the reinforcing fibers of the inner surface fiber-reinforced composite material layer 31 can be made of PAN-based carbon fibers. However, the reinforcing fibers are not limited to carbon fibers, and one or more materials selected from the group consisting of ceramic fibers, inorganic fibers, glass fibers, and organic fibers may be used. Organic fibers include aramid fibers, etc. In addition, the matrix material can be made of resin, or one or more materials selected from the group consisting of carbon, metal, and ceramics.

[0039] In this way, by making the elastic modulus of the inner surface fiber-reinforced composite material layer 31 lower than that of the outer surface fiber-reinforced composite material layer 30, the brittleness, or tendency to crack, of the ceramic material of the matrix base material 20 can be improved. In other words, by covering the surface with the fiber-reinforced composite material layer 30, the toughness is improved, and the ceramic matrix composite sintered body 10B becomes less prone to cracking. However, if the properties of the fiber-reinforced composite material layer 30, specifically its elastic modulus, are low, it will reduce the properties of the matrix base material 20, specifically its elastic modulus. Therefore, it is ideal to cover the matrix base material 20 with a fiber-reinforced composite material that has a higher elastic modulus and superior toughness, i.e., is less prone to cracking. In the case of fiber-reinforced composite materials, the higher the elastic modulus, the lower the toughness tends to be, but it is still sufficiently high compared to ceramic materials. Therefore, for the outer surface, which has a high degree of influence on structural rigidity, a fiber-reinforced composite material layer 30 with a high modulus of elasticity is used to prioritize rigidity, while for the inner surface, which has a smaller degree of influence on structural rigidity, a fiber-reinforced composite material layer 31 with higher toughness and a lower modulus of elasticity is used. This makes it possible to efficiently improve both the modulus of elasticity and fracture toughness.

[0040] Furthermore, if improving rigidity is not the top priority, a fiber-reinforced composite material layer 30 with a low modulus of elasticity, i.e., high fracture toughness, may be set on the surface. In other words, the following three patterns are possible for the combination of the fiber-reinforced composite material layer 30 on the outer surface and the fiber-reinforced composite material layer 31 on the inner surface. (1) When prioritizing the improvement of rigidity of the ceramic matrix composite sintered body 10B and not requiring significant improvement of toughness: The outer surface fiber-reinforced composite layer 30 and the inner surface fiber-reinforced composite layer 31 are composed of highly elastic fiber-reinforced composite layers. For example, if the fiber-reinforced composite layers 30 and 31 are fiber-reinforced composite materials whose elastic modulus can be controlled by changing the volume content of reinforcing fibers, the reinforcing fiber content in this fiber-reinforced composite material should be relatively higher, for example, compared to the case in (2) below. (2) When prioritizing the improvement of toughness of the ceramic matrix composite sintered body 10B and not requiring significant improvement of rigidity: The outer surface fiber-reinforced composite layer 30 and the inner surface fiber-reinforced composite layer 31 are composed of low-elasticity fiber-reinforced composite layers. For example, if the fiber-reinforced composite layers 30 and 31 are fiber-reinforced composite materials whose elastic modulus can be controlled by changing the volume content of reinforcing fibers, the content of reinforcing fibers in this fiber-reinforced composite material can be made relatively small, for example, smaller than in the case of (1) above. (3) When a balance between rigidity and toughness is required: The outer surface fiber-reinforced composite material layer 30 is composed of a highly elastic fiber-reinforced composite material layer, and the inner surface fiber-reinforced composite material layer 31 is composed of a low-elasticity fiber-reinforced composite material layer. For example, if the fiber-reinforced composite material layers 30 and 31 are fiber-reinforced composite materials whose elastic modulus can be controlled by changing the volume content of reinforcing fibers, then, as described above, the reinforcing fiber content in the inner surface fiber-reinforced composite material layer 31 should be relatively less than that in the outer surface fiber-reinforced composite material layer 30.

[0041] In the example shown in Figure 3, a hollow ceramic matrix composite sintered body 10B having two bottom portions 61 and 62 and an elliptical cylindrical side portion 63 connecting the two bottom portions 61 and 62 is given as an example. However, the ceramic matrix composite sintered body 10B may also have a structure in which at least one of the two bottom portions 61 and 62 is absent. Furthermore, it may be cylindrical or polygonal cylindrical instead of elliptical.

[0042] The ceramic matrix composite sintered body 10B according to Embodiment 3 comprises fiber-reinforced composite material layers 30 and 31 on the outer and inner surfaces, respectively, of a matrix base material 20 having a hollow internal structure. By making the matrix base material 20 hollow, further weight reduction can be achieved compared to a solid matrix base material 20 having the same external shape. Furthermore, by covering not only the outer surface but also the inner surface of the matrix base material 20 with the fiber-reinforced composite material layer 31, crack resistance is further improved, enabling the realization of a lightweight and highly rigid ceramic matrix composite sintered body 10B.

[0043] Furthermore, the elastic modulus of the fiber-reinforced composite material layer 31 on the inner surface and the fiber-reinforced composite material layer 30 on the outer surface of the hollow ceramic matrix composite sintered body 10B was varied. This makes it possible to obtain a molded body with properties suited to the operating environment conditions.

[0044] Embodiment 4. Embodiment 4 describes a method for manufacturing the ceramic matrix composite sintered body 10 described in Embodiment 1. Figure 5 is a flowchart showing an example of the procedure for manufacturing the ceramic matrix composite sintered body according to Embodiment 4. As shown in Figure 5, the method for manufacturing the ceramic matrix composite sintered body 10 includes a raw material mixing step (step S1), a molding step (step S2), a heat treatment step (step S3), a shaping step (step S4), a silicon immersion and silicon carbide reaction sintering step (step S5), a composite integration step (step S6), and a finishing step (step S7). Each step will be described below.

[0045] Step S1, the raw material mixing step, is a process to obtain a mixed raw material containing boron carbide powder, a binder resin as a carbon precursor, and a matrix filler as a silicon carbide precursor. An example of the matrix filler is carbon or graphite powder. In the raw material mixing step, the boron carbide powder, binder resin, and matrix filler are uniformly mixed in a predetermined mixing ratio to produce the mixed raw material. It is desirable that the average particle size of the powder raw materials in the mixed raw material has two or more different distributions.

[0046] Table 1 shows an example of the relationship between the average particle size distribution of boron carbide and silicon carbide precursors, which are the powder raw materials used, and the carbon used as the matrix filler. In one example, in Case 1, where the average particle size distribution of the boron carbide raw material powder used is one level, two or more levels of carbon raw material are used as the matrix filler. In this case, if the average particle size distributions of the two levels of carbon raw material in the matrix filler are PD1(C) and PD2(C), and PD1(C) > PD2(C), then as shown in Table 1, it is desirable that the average particle size distribution PD(B4C) of boron carbide be between the average particle size distributions PD1(C) and PD2(C) of the two levels of carbon raw material in the matrix filler. Carbon raw material in the matrix filler with a larger average particle size distribution has the effect of widening the dispersion interval of boron carbide particles and suppressing clustering. Carbon raw material in the matrix filler with a smaller average particle size distribution than boron carbide fills some of the gaps between boron carbide particles. The molded body is formed in the next step, S2, through a molding process, using a structure in which these raw materials are fixed with a binder resin.

[0047] [Table 1]

[0048] Furthermore, as shown in Case 2 of Table 1, the average particle size distribution of boron carbide is not limited to one level, but may be two or more levels. If the average particle size distributions of the two levels of boron carbide are PD1(B4C) and PD2(B4C), and PD1(B4C) > PD2(B4C), then it is desirable that the average particle size distributions of the two levels of boron carbide, PD1(B4C) and PD2(B4C), be between the average particle size distributions of the two levels of carbon raw materials, PD1(C) and PD2(C).

[0049] Here, graphite powder is given as an example of a carbon raw material for the matrix filler, but in addition to graphite powder, milled carbon fibers may also be used.

[0050] Step S2, the molding process, involves filling a mold with the mixed raw materials prepared in Step S1, heating and pressurizing the mixed raw materials to cure the binder resin and obtain a molded body.

[0051] Step S3, the heat treatment step, involves heat-treating the molded body formed in Step S2 in an inert atmosphere to carbonize the binder resin within the molded body by thermal decomposition and obtain a fired body. Since the amount of binder resin component in the molded body is small, the generation of decomposition gases and thermal shrinkage due to the heat treatment are minimal. For this reason, special operations such as pressurizing during heat treatment or fixing the shape with a jig are not necessary. However, it is also possible to intentionally perform the heat treatment under load using a jig or the like to force deformation.

[0052] Step S4, the shaping process, is a process of machining the sintered body obtained in the heat treatment process of Step S3 into the desired shape. The sintered body is a porous material consisting of a matrix material in which the binder resin has been carbonized, and which contains voids in which boron carbide powder and carbon matrix filler are fixed. For this reason, the sintered body can be easily shaped using conventional machining tools. The shaped sintered body will be referred to as the substrate below.

[0053] Step S5, the silicon immersion and silicon carbide reaction sintering step, involves heating the substrate obtained in the shaping step S4 together with metallic silicon or a silicon alloy to immerse the metallic silicon or silicon alloy into the substrate, react it with the carbon to form silicon carbide, and simultaneously sinter the substrate, i.e., the boron carbide powder, to obtain a sintered body. Specifically, the substrate is heated together with metallic silicon or a silicon alloy in a vacuum or inert atmosphere. This causes the molten metallic silicon or molten silicon alloy to immerse into the substrate, react it with the carbon inside the substrate to form silicon carbide, and sinter the boron carbide powder to obtain a sintered body. This sintered body becomes the matrix base material 20. The metallic silicon or silicon alloy necessary for the silicon carbide reaction can be continuously supplied from the outside, and the carbon contained inside the substrate reacts with the metallic silicon or silicon alloy to form silicon carbide, causing volume expansion. As a result, the voids in the substrate are filled with the silicon carbide produced by the reaction and the immersed metallic silicon or silicon alloy. As a result, the sintered body becomes a dense sintered body with virtually no voids. Furthermore, the shrinkage that occurs during sintering, which is common in conventional ceramic materials, is almost nonexistent before and after sintering. In other words, cracking and deformation during sintering are less likely to occur. Therefore, it becomes possible to easily manufacture structures with varying thickness, hollow structures, or large structures.

[0054] The composite integration process in step S6 involves compounding a fiber-reinforced composite material layer 30 onto the surface of the sintered body obtained in the silicon fusion and silicon carbide reaction sintering process in step S5, thereby integrating the sintered body and the fiber-reinforced composite material layer 30. In other words, the composite integration process involves laminating the fiber-reinforced composite material layer 30 onto the outer surface of the sintered body and integrating the fiber-reinforced composite material layer 30 with the sintered body. By integrally installing the fiber-reinforced composite material layer 30 on the surface of the sintered body, the crack propagation and crack susceptibility of the sintered body made of ceramic material, i.e., the matrix base material 20, against external impacts are significantly improved. In other words, the crack propagation of the ceramic matrix composite material sintered body 10, which has a matrix base material 20 and a fiber-reinforced composite material layer 30 integrally formed on the surface of the matrix base material 20, can be suppressed, and its crack resistance can be improved.

[0055] In the composite integration process, a prepreg, which is made by pre-impregnating reinforcing fibers with resin, is placed on the surface of the sintered body, and a fiber-reinforced composite material layer 30 is formed on the surface of the sintered body by performing a composite integration process. If the resin is a thermosetting resin, the resin hardens when the prepreg is heated as part of the composite integration process, and an integrated fiber-reinforced composite material layer 30 is formed on the surface of the sintered body. If the resin is a reactive resin, the resin is hardened at a low temperature by treating it with a catalyst or the like as part of the composite integration process. This forms an integrated fiber-reinforced composite material layer 30 on the surface of the sintered body. If the resin is a thermoplastic resin, the resin is melted as part of the composite integration process, and the molten resin is brought into close contact with the surface of the sintered body, thereby forming an integrated fiber-reinforced composite material layer 30 on the surface of the sintered body.

[0056] The composite integration process for fiber-reinforced composite materials involves changing the materials used and processing conditions to match the required properties of the matrix material of the fiber-reinforced composite layer 30, according to the operating environment conditions of the ceramic matrix composite sintered body 10.

[0057] For example, if heat resistance is not required, the fiber-reinforced composite material layer 30 can be constructed from FRP by using resin as the matrix material of the fiber-reinforced composite material layer 30.

[0058] As another example, when greater heat resistance is required, carbon is used instead of resin as the matrix material for the fiber-reinforced composite layer 30. When the matrix material is composed of carbon, phenolic resin can be used as the matrix raw material for the fiber-reinforced composite layer 30 used in the composite integration process. Subsequently, heat treatment can be performed in an inert atmosphere to carbonize the phenolic resin and convert it into carbon. If necessary, resin impregnation and heat treatment may be repeated to fill the matrix material with additional carbon. Alternatively, carbon may be filled by thermal decomposition methods such as chemical vapor deposition (CVD) or chemical vapor infiltration (CVI). By making the matrix material of the fiber-reinforced composite layer 30 carbon, the heat resistance in an inert atmosphere can be improved compared to when the matrix material is resin.

[0059] As another example, if heat resistance in an oxidizing atmosphere is required, the matrix material can be made of metal and the fiber-reinforced composite material layer 30 can be made of FRM, or the matrix material can be made of ceramics and the fiber-reinforced composite material layer 30 can be made of ceramic matrix composite material.

[0060] When the fiber-reinforced composite material layer 30 is constructed using FRM, in one example, a preformed yarn or sheet in which reinforcing fibers are coated with an aluminum alloy is formed on the surface, and the preform material is pressed down and heated to near the melting point of the aluminum alloy to form and integrate the preform material. Here, the metal used in the preform material can be any combination of fibers and metals that can be used as FRM, such as magnesium alloy in addition to aluminum alloy.

[0061] When the fiber-reinforced composite material layer 30 is made of a ceramic matrix composite material, taking the case where the matrix material is made of silicon carbide as an example, the matrix material of the fiber-reinforced composite material layer 30 can be converted to silicon carbide by first converting the matrix material to carbon through heat treatment, and then reacting it with metallic silicon or a silicon alloy in a vacuum or inert atmosphere to convert it to silicon carbide.

[0062] In the case of harsh operating conditions, or when improved long-term reliability is required, a coating layer for reaction suppression, such as oxidation prevention, can be formed on the surface of the fiber-reinforced composite material layer 30. The material and method of the coating layer can be selected according to the operating conditions. Examples of coating methods include CVD, plasma spraying, and ion sputtering.

[0063] Thus, the fiber-reinforced composite material layer 30 used in the composite integration process is one or more materials selected from the group consisting of ceramic matrix composites, FRM, C / C composites, and FRP. Furthermore, the reinforcing fibers of the fiber-reinforced composite material layer 30 are one or more materials selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers.

[0064] The finishing process in step S7 is a process of finishing the sintered body, which was formed by integrating the sintered body and the fiber-reinforced composite material layer 30 in the composite integration process in step S6, into the shape of an article. By performing the finishing process on the sintered body to the final shape, an article made of the ceramic matrix composite material sintered body 10 is obtained. Since the sintered body before the final finishing process is close to the shape of the final article, it can be finished with only a small amount of processing, and productivity is greatly improved.

[0065] According to Embodiment 4, a ceramic matrix composite sintered body 10 is manufactured by compounding and integrating a fiber-reinforced composite material layer 30 onto the surface of a matrix base material 20. As a result, the elastic modulus of the ceramic matrix composite sintered body 10 becomes even higher and the specific gravity becomes even lower compared to the matrix base material 20. In other words, it is possible to manufacture a ceramic matrix composite sintered body 10 with an even higher specific modulus of elasticity compared to the matrix base material 20. Furthermore, by integrating the matrix base material 20, which is made of ceramic material, with the fiber-reinforced composite material layer 30, the brittleness of the matrix base material 20 can be improved, that is, its fracture toughness can be significantly enhanced.

[0066] Embodiment 5. Embodiment 5 describes a method for manufacturing the ceramic matrix composite sintered body 10A described in Embodiment 2. Figure 6 is a flowchart showing an example of the procedure for manufacturing the ceramic matrix composite sintered body according to Embodiment 5. Steps identical to those in Figure 5 of Embodiment 4 are given the same step numbers, and their explanations are omitted.

[0067] The method for manufacturing the ceramic matrix composite sintered body 10A described in Embodiment 2 is basically the same as the method for manufacturing the ceramic matrix composite sintered body 10 described in Embodiment 4. However, in the shaping process of step S4, in addition to shaping the outer form, a new process is added to embed reinforcing structural members 40 inside. An example of the internal reinforcing structural members 40 is a plate 41, a rod 42, etc., made of fiber-reinforced composite material. Processing necessary to embed these reinforcing structural members 40 is performed on the fired body.

[0068] In this case, in the silicon immersion and silicon carbide reaction sintering step S5, the embedded reinforcing structural member 40 may also be reacted together with the other materials, and silicon carbide reaction sintering may be performed to siliconize the matrix material of the reinforcing structural member 40 in the same way as the fired body. Alternatively, in the silicon immersion and silicon carbide reaction sintering step S5, the embedded reinforcing structural member 40 may be integrated with the fired body, but without siliconization. In other words, the reinforcing structural member 40 may be made of FRP, which is a plastic resin, as its matrix material.

[0069] Furthermore, since the fiber-reinforced composite material layer 30 integrated in the composite integration process of step S6 has not undergone heat treatment such as the silicon immersion and silicon carbide reaction sintering process of step S5, the matrix material remains resin. In one example, if the resin is a thermosetting resin, the fiber-reinforced composite material layer 30 is only heated to about 100-something degrees Celsius, which is the temperature required to cure the resin. Therefore, the matrix material of the fiber-reinforced composite material layer 30 may be carbon instead of resin, resulting in a C / C composite.

[0070] In this case, the manufacturing method for the ceramic matrix composite sintered body 10A further includes a heat treatment step (step S11) after the composite integration step in step S6, as shown in Figure 6. In the heat treatment step of step S11, the resin component of the fiber-reinforced composite material layer 30 is carbonized. As a result, the fiber-reinforced composite material layer 30 becomes a C / C composite. Thus, the heat treatment step of step S11 is performed to control the material properties of the matrix material of the fiber-reinforced composite material layer 30 as needed. After this, the finishing process in step S7 is carried out.

[0071] The heat treatment step S11 may be performed after the composite integration step S6 of Embodiment 4. Furthermore, if necessary, a coating layer may be formed on the surface of the obtained ceramic matrix composite sintered body 10A.

[0072] In Embodiment 5, a reinforcing structural member 40 made of fiber-reinforced composite material is embedded inside the fired body during the shaping process, and the reinforcing structural member 40 is integrated with the fired body during the silicon fusion and silicon carbide reaction sintering process. This makes it possible to manufacture a ceramic matrix composite material sintered body 10A having a reinforcing structural member 40 inside, as described in Embodiment 2.

[0073] Embodiment 6. Embodiment 6 describes a method for manufacturing the ceramic matrix composite sintered body 10B described in Embodiment 3. Figure 7 is a flowchart showing an example of the procedure for manufacturing the ceramic matrix composite sintered body according to Embodiment 6. Steps identical to those in Figure 5 of Embodiment 4 and Figure 6 of Embodiment 5 are given the same step numbers, and their descriptions are omitted.

[0074] The method for manufacturing the ceramic matrix composite sintered body 10B described in Embodiment 3 is basically the same as the method for manufacturing the ceramic matrix composite sintered body 10 described in Embodiment 4. However, in the shaping process of step S4, in addition to shaping the outer form, a process to create a hollow structure inside is added.

[0075] In cases where the hollow structure is complex, the ceramic matrix composite sintered body 10B can also be manufactured by dividing the substrate into multiple parts and then joining the divided parts together.

[0076] Figures 8 to 11 are schematic perspective views showing an example of the procedure for manufacturing a ceramic matrix composite sintered body according to Embodiment 6. As shown in Figure 8, the substrate 50 corresponding to the shape of the finished product is appropriately divided into multiple parts. In other words, the substrate 50 is divided into a simple shell structure. In the example in Figure 8, the elliptical cylindrical substrate 50 is divided into two bottom parts 51 and 52 and two side parts 53 and 54. In this case, after carrying out the silicon immersion and silicon carbide reaction sintering process of step S5 for each divided part, fiber-reinforced composite material layers 30 and 31 are placed on the outer and inner surfaces in the composite integration process, and after assembling the divided parts, the parts can be joined by performing the composite integration process on the fiber-reinforced composite material layers 30 and 31.

[0077] Furthermore, when covering the inner and outer surfaces with fiber-reinforced composite material layers 30 and 31, if the sintered body is integrated and the hollow interior cannot be accessed, after the silicon fusion and silicon carbide reaction sintering process, fiber-reinforced composite material is placed in the hollow inner surface portion of each part of the divided sintered body, and a composite integration process is performed to form the fiber-reinforced composite material layer 31 in the inner surface portion. Subsequently, as shown in Figures 9 to 11, after assembling the parts 51a, 52a, 53a, and 54a of the sintered body with the fiber-reinforced composite material layer 31 formed on the inner surface, the fiber-reinforced composite material is placed on the outer surface, and the parts 51a, 52a, 53a, and 54a can be joined by performing a composite integration process on the fiber-reinforced composite material. The fiber-reinforced composite material on the outer surface can cover the joint of the matrix base material 20 made of the inner ceramic material, and can reinforce the joint.

[0078] Alternatively, after performing a shaping process on each divided part, the parts may be combined and rejoined using a mixed raw material and a binder to create a single, integrated structure. Furthermore, integration can be achieved through a silicon immersion and silicon carbide reaction sintering process, where the parts are fused together by a silicon carbide reaction. In this case, the divided joint surfaces are integrated in the same way as the other parts. Since the joints between the divided parts are sintered in the same way as the other parts, the same strength characteristics as the other parts can be achieved. The choice of which of the above methods to adopt will be determined by the final shape.

[0079] Furthermore, the manufacturing method of the ceramic matrix composite material sintered body 10B shown in Figure 7 further includes a silicon immersion and silicon carbide reaction sintering step (step S21) after the heat treatment step in step S11. In the silicon immersion and silicon carbide reaction sintering step in step S21, the matrix material of the fiber-reinforced composite material layer 30 on the outer surface, which was carbonized in the heat treatment step in step S11, is converted to silicon carbide. As a result, the matrix material of the fiber-reinforced composite material layer 30 becomes a silicon carbide ceramic material, and its heat resistance is improved compared to the case of plastic resin. After this, the finishing process in step S7 is carried out.

[0080] The composition of the reinforcing fibers and matrix material in the fiber-reinforced composite material layers 30 and 31 can be any combination depending on the operating environment conditions. Furthermore, the combination of reinforcing fibers and matrix material in the outer and inner surface fiber-reinforced composite material layers 30 and 31 does not need to be the same. Preferably, the inner surface fiber-reinforced composite material layer 31 has a lower elastic modulus and higher flexibility than the outer surface fiber-reinforced composite material layer 30.

[0081] Furthermore, the silicon immersion and silicon carbide reaction sintering process in step S21 may be performed after the heat treatment process in step S11 of Embodiment 5. Also, the heat treatment process in step S11 and the silicon immersion and silicon carbide reaction sintering process in step S21 may be performed after the composite integration process in step S6 of Embodiment 4. In addition, if necessary, a coating layer may be formed on the surface of the obtained ceramic matrix composite material sintered body 10B.

[0082] In Embodiment 6, a substrate having a hollow structure is formed in the shaping process, and fiber-reinforced composite material layers 30 and 31 are integrated onto the outer and inner surfaces. This makes it possible to manufacture the ceramic matrix composite material sintered body 10B having the hollow structure described in Embodiment 3. [Examples]

[0083] Next, an example of the ceramic matrix composite sintered body 10 according to Embodiment 1 is shown. The ceramic matrix composite sintered body 10 is manufactured by the manufacturing method shown in Embodiment 4. First, in the raw material mixing step S1, 3M boron carbide F150 is used for the boron carbide powder of the mixed raw materials, Gun-ei Chemical Industry Co., Ltd. powder phenol resin PG-9400 is used for the binder resin, and Fujifilm Wako Pure Chemical Industries Ltd. graphite powder is used for the carbon filler. The mixing ratios of the various raw materials are adjusted so that the volume content of boron carbide after sintering is 50% or more, and the volume content of voids in the molded body is 15% or more when molded at a maximum molding pressure of less than 40 MPa in the molding step S2, and the mixed raw materials are prepared.

[0084] Next, in the molding process of step S2, the mixed raw materials are filled into a mold, and the binder resin is cured and molded to obtain a molded body by heating the mixture to 150°C and holding the temperature for 90 minutes, within a range of a maximum molding pressure of less than 40 MPa. The bulk density and void content of the molded body were checked, and the bulk density was found to be 1.8, and the volume content of voids was approximately 17%.

[0085] Subsequently, in the heat treatment process of step S3, the molded body is heat-treated in an inert atmosphere to carbonize the binder resin and obtain a fired body. During the heat treatment, heating is performed while the atmosphere inside the furnace is evacuated using a rotary pump. At this time, the molded body is heated to approximately 800°C in a free state without pressurization, and then the temperature is maintained for 30 minutes before being slowly cooled to obtain a fired body. Compared to the molded body before firing, the weight of the fired body after firing decreases by approximately 5%, and the dimensions remain almost unchanged, changing by less than 1%. In addition, the volume content of voids in the fired body after firing is approximately 27%. No cracks occur in the fired body.

[0086] Next, in step S5, the silicon immersion and silicon carbide reaction sintering process, a high-temperature vacuum furnace is used to melt metallic silicon and immerse it into the fired body that has been shaped in step S3. The carbon in the fired body reacts with the immersed metallic silicon to form silicon carbide, and further reaction sintering is performed to obtain a sintered body. The bulk density of the sintered body after sintering is approximately 2.7, and the dimensions of the sintered body after sintering change by about 1% compared to the fired body before sintering. Furthermore, no distortion or cracks occur in the sintered body after sintering.

[0087] Test specimens were cut from the sintered body obtained after the silicon fusion and silicon carbide reaction sintering process in Step S5, and the main material properties were confirmed. Here, the bending strength, fracture toughness, and elastic modulus were confirmed using the Japanese Industrial Standards (JIS) 4-point bending test. The bending strength was 280 MPa and the fracture toughness was 4.1 MPa·m. 1 / 2 The elastic modulus is 390 GPa.

[0088] Meanwhile, in the composite integration process of step S6, preparations are made to form a ceramic matrix composite sintered body 10 by covering the surface of the sintered body obtained in step S5 with a fiber-reinforced composite material layer 30. A prepreg sheet using pitch-based carbon fiber, DiaLead (registered trademark) K63712 manufactured by Mitsubishi Chemical Corporation, and epoxy resin is laminated on the surface of the sintered body as a fiber-reinforced composite material, and integrated molding is performed by heat curing. At this time, the thickness of the matrix base material 20 is set to 2.4 mm, and the thickness of the upper and lower surfaces of the fiber-reinforced composite material layer 30 on the surface is set to 0.3 mm each for composite formation. The bulk density of the ceramic matrix composite sintered body 10 obtained in this way is 2.45.

[0089] Furthermore, test specimens were cut from the ceramic matrix composite sintered body 10 obtained in this manner, and the main material properties were confirmed in the same manner as described above. The elastic modulus of the ceramic matrix composite sintered body 10 was 388 GPa, which was almost unchanged from the elastic modulus of the sintered body before composite formation. However, the bulk density changed from 2.7 to 2.45, so the specific modulus improved from 144.4 GPa to 158.4 GPa. The bending strength was confirmed to have increased from 280 MPa before composite formation to 300 MPa. At this time, the fracture mode showed brittle fracture before composite formation, but after composite formation, even if a crack occurred, it did not fracture all at once, but instead became a tough fracture mode, the fracture strain was approximately doubled, and the fracture energy was confirmed to have improved to more than three times.

[0090] The configurations shown in the above embodiments are merely examples, and it is possible to combine them with other known technologies, combine different embodiments, and omit or modify parts of the configuration without departing from the gist of the invention. [Explanation of symbols]

[0091] 10, 10A, 10B Ceramic matrix composite sintered body, 11 Base part, 12 Main body part, 20 Matrix base material, 30, 31 Fiber reinforced composite material layer, 40 Reinforcement structural member, 41 Plate, 42 Rod, 50 Substrate, 51, 52, 61, 62 Bottom surface part, 53, 54, 63 Side surface part.

Claims

1. A matrix material is a ceramic material containing boron carbide, silicon carbide, and metallic silicon or silicon alloy, wherein the spaces between dispersed particulate boron carbide particles are filled with silicon carbide and metallic silicon or silicon alloy, and the matrix material does not contain reinforcing fibers internally. A fiber-reinforced composite material layer containing reinforcing fibers covers the surface of the matrix base material, Equipped with, The fiber-reinforced composite material layer is a fiber-reinforced metal, and the matrix material of the fiber-reinforced composite material layer is a light alloy with a lower specific gravity than the matrix base material. The ceramic matrix composite sintered body is characterized in that the reinforcing fibers are one or more materials selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers.

2. The matrix base material further comprises reinforcing structural members made of fiber-reinforced composite material, The ceramic matrix composite sintered body according to claim 1, characterized in that the reinforcing structural member is integrated with the matrix base material.

3. The matrix base material has a hollow structure, The ceramic matrix composite sintered body according to claim 1, characterized in that the fiber-reinforced composite material layer covers the outer surface of the matrix base material and the inner surface facing the hollow structure.

4. The ceramic matrix composite sintered body according to claim 1, characterized in that the matrix base material contains 50% or more of the boron carbide by volume.

5. A ceramic matrix composite sintered body according to any one of 1 to 4, further comprising a coating layer on the surface of the fiber-reinforced composite material layer.

6. A method for manufacturing a ceramic matrix composite sintered body, A raw material mixing step to obtain a mixed raw material containing boron carbide powder, a binder resin as a carbon precursor, and a matrix filler as a silicon carbide precursor, A molding step in which the mixed raw materials are filled into a mold, heated and pressurized to obtain a molded body, A heat treatment step of heat-treating the molded body in an inert atmosphere to carbonize the binder resin and obtain a fired body, A shaping step to obtain a substrate obtained by shaping the aforementioned fired body by machining, A silicon fusion and silicon carbide reaction sintering step is performed to impregnate the substrate with metallic silicon or a silicon alloy, convert the carbon inside the substrate into silicon carbide, and sinter the substrate to obtain a sintered body that will serve as the matrix base material. A composite integration step is performed to composite a fiber-reinforced composite material layer containing reinforcing fibers onto the surface of the sintered body, and to integrate the sintered body and the fiber-reinforced composite material layer. Includes, The fiber-reinforced composite material layer is a fiber-reinforced metal, and the matrix material of the fiber-reinforced composite material layer is a light alloy with a lower specific gravity than the matrix base material. A method for producing a ceramic matrix composite sintered body, characterized in that the reinforcing fiber is one or more materials selected from the group consisting of inorganic fibers, carbon fibers, and organic fibers.

7. In the shaping process, a reinforcing structural member made of fiber-reinforced composite material is embedded inside the fired body, and the external shape of the fired body is processed to form the substrate. The method for manufacturing a ceramic matrix composite sintered body according to claim 6, characterized in that the reinforcing structural member is integrated with the fired body in the silicon immersion and silicon carbide reaction sintering step.

8. In the shaping process described above, the substrate having a hollow structure inside is formed. The method for manufacturing a ceramic matrix composite sintered body according to claim 6, characterized in that, in the composite integration step, the fiber-reinforced composite material layer is integrated onto the inner surface of the sintered body facing the hollow structure, and then the fiber-reinforced composite material layer is integrated onto the outer surface of the sintered body.

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