Composite structure, method for manufacturing composite structure, and heat storage method

Abstract

To provide a composite structure useful as a heat storage body or the like, which prevents leakage of an internal structure part to the outside, is high in quality, and high in mechanical strength, and can stably exhibit heat storage performance.SOLUTION: A composite structure 10 comprises: a ceramic seamless outer shell 4 having an internal space 8 and a hole 6 communicated with the internal space 8; and an internal structure 2 included in the internal space 8. The internal structure 2 is a solid article formed by heat-melting and then solidifying a metal material filling the internal space 8. The metal material is mainly made of copper, and contains metals other than the copper at a rate of 50 mass% relative to the entire metal material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite structure useful as a heat storage medium, a method for producing the same, and a heat storage method using the composite structure as a heat storage medium. [Background technology]

[0002] One known heat storage method is latent heat storage, which utilizes latent heat accompanying a phase change. As a heat storage material utilizing this type of latent heat storage, a capsule-shaped heat storage material containing a latent heat storage material has been proposed.

[0003] For example, Patent Document 1 proposes a latent heat storage capsule in which one or more layers of a metal coating are formed on the surface of a latent heat storage material by electrolytic plating. Patent Document 2 also proposes a heat storage microcapsule in which a water-soluble latent heat storage material that stores or releases heat by phase change is used as a core material, and this core material is covered with a composite capsule wall formed by compounding an inorganic compound and an organic polymer compound.

[0004] Furthermore, Patent Document 3 proposes a heat storage microcapsule having a core substance made of a water-soluble heat storage material such as a sugar, a first capsule wall that covers the core substance and is made of a composite material of an inorganic compound and an organic polymer compound, and a second capsule wall that covers the first capsule wall and is made of a polymer material.

[0005] However, the metal coating of the latent heat storage capsule proposed in Patent Document 1 has low heat resistance, which causes problems such as it breaking when used at high temperatures, making the heat storage material inside prone to leak. Furthermore, the capsule walls of the heat storage microcapsules proposed in Patent Documents 2 and 3 have low strength due to their low density. This makes them difficult to use under high temperature conditions or in harsh environments prone to corrosion. Furthermore, the above-mentioned conventional heat storage capsules and the like have low energy density and insufficient heat resistance in the outer shell, making it impossible to fully utilize sensible heat generated by temperature differences, resulting in a problem of low energy density.

[0006] In order to solve such problems, for example, Patent Document 4 proposes a heat storage body that contains an internal heat storage body such as metal within an outer shell formed by fitting a pair of hollow hemispheres made of ceramic together at their dividing surfaces. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-23172 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-238912 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-108167 [Patent Document 4] Japanese Patent Application Laid-Open No. 2012-111825 Summary of the Invention [Problem to be solved by the invention]

[0008] The heat storage body proposed in Patent Document 4 had a high energy density and was useful to a certain extent. However, this heat storage body was prone to leakage of the metal that constituted the internal heat storage body from the fittings in the outer shell, and its mechanical strength was somewhat insufficient. In addition, the manufacturing process was complicated, resulting in high costs, and it was difficult to consistently manufacture a heat storage body with stable performance.

[0009] The present invention has been made in view of the problems of the prior art, and an object of the present invention is to provide a composite structure that is useful as a heat storage body, etc., in which the internal structure is of high quality and is resistant to external leakage, has high mechanical strength, and can stably exhibit heat storage performance. Another object of the present invention is to provide a simple method for producing the above composite structure, and a heat storage method using the above composite structure. [Means for solving the problem]

[0010] That is, according to the present invention, there is provided the following composite structure. [1] A composite structure comprising: a seamless outer shell made of ceramic having an internal space and holes communicating with the internal space; and an internal structure contained within the internal space, wherein the internal structure is a solid formed by heating and melting a metal material filled in the internal space and then solidifying it, the metal material containing copper as its main component and containing metals other than copper in a proportion of 50 mass% or less based on the total mass of the metal material. [2] The composite structure according to [1], wherein the ceramic is at least one selected from the group consisting of alumina, silicon nitride, and silicon carbide. [3] The composite structure according to [1] or [2], wherein the other metal is at least one selected from the group consisting of aluminum, nickel, titanium, zirconium, manganese, and iron. [4] The composite structure according to any one of [1] to [3], wherein the proportion of the other metal contained in the metal material is 3 to 30 mass % based on the total mass of the metal material. [5] A composite structure according to any one of [1] to [4], wherein the internal structure comprises a large number of granular portions primarily composed of copper, and a network-like portion primarily composed of the other metal, filling the gaps between adjacent granular portions. [6] The composite structure according to any one of [1] to [5] above, which is used as a heat storage medium.

[0011] Furthermore, according to the present invention, there is provided a method for producing a composite structure as follows. [7] A method for producing a composite structure according to any one of [1] to [6] above, comprising the steps of: preparing a seamless outer shell made of ceramic having an internal space and having pores communicating with the internal space; filling a metal material containing copper as a main component and 50 mass % or less of metals other than copper into the internal space through the pores to obtain a heat-treated body; and heat-treating the heat-treated body at 900 to 1,300°C with the pores facing upward to obtain a primary heat-treated body. [8] The method for manufacturing a composite structure according to [7], further comprising a step of heat treating the primary heat-treated body at 900 to 1,300°C with the hole facing downward. [9] A method for manufacturing a composite structure according to [7] or [8], wherein the metal material comprises a particulate first filler mainly composed of copper and a powdered second filler having a smaller particle size than the first filler, and after the first filler is filled into the internal space, the second filler is filled so as to fill the gaps between adjacent first fillers, thereby obtaining the object to be heat-treated.

[0012] Furthermore, according to the present invention, there is provided the following heat storage method.

[10] A heat storage method comprising the step of heating the composite structure according to [6] above to a temperature equal to or higher than the melting point of the internal structure, thereby storing heat in the composite structure. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a composite structure that is useful as a heat storage medium, etc., in which the internal structure is of high quality and is resistant to external leakage, has high mechanical strength, and can stably exhibit heat storage performance. Furthermore, according to the present invention, it is possible to provide a simple method for producing the above composite structure, and a heat storage method using the above composite structure. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view schematically showing one embodiment of a composite structure of the present invention. [Figure 2] 1A to 1C are schematic diagrams illustrating an embodiment of a method for producing a composite structure according to the present invention. [Figure 3] 10A and 10B are schematic diagrams showing an example of a method for filling the internal space of the outer shell with a metal material. [Figure 4] 1 is an electron microscope photograph showing the microstructure of the interface between the outer shell portion and the internal structure portion of the composite structure produced in Example 1. [Figure 5] 1 is an electron microscope photograph showing the microstructure of the interface between the outer shell portion and the internal structure portion of the composite structure produced in Example 2. [Figure 6] 1 is an electron microscope photograph showing the microstructure of the interface between the outer shell portion and the internal structure portion of the composite structure produced in Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0015] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments. The composite structure of the present invention includes a seamless outer shell made of ceramic and having an internal space, and an internal structure contained in the internal space of the outer shell. The outer shell has holes that communicate with the internal space. The internal structure is a solid formed by heating and melting a metal material filled in the internal space of the outer shell and then solidifying it. The metal material filled in the internal space of the outer shell is primarily composed of copper, and contains metals other than copper in a proportion of 50 mass% or less based on the total metal material. The composite structure of the present invention is described in detail below.

[0016] Fig. 1 is a cross-sectional view schematically illustrating one embodiment of a composite structure of the present invention. As shown in Fig. 1, the composite structure 10 of this embodiment includes a seamless outer shell 4 having an internal space 8 and holes 6 communicating with the internal space 8, and an internal structure 2 contained in the internal space 8 of the outer shell 4.

[0017] (Outer shell) The outer shell 4 constituting the composite structure 10 is formed of ceramics. The composite structure 10 of this embodiment contains the internal structure 2 in the internal space 8 of the outer shell 10 formed of such ceramics, and therefore has good temperature rise characteristics and excellent mechanical strength. As the ceramic, for example, at least one selected from the group consisting of alumina, silicon nitride, and silicon carbide can be used. Of these, alumina and silicon nitride are preferred, and alumina is more preferred.

[0018] The outer shell 4 is a seamless part (member) that can be manufactured by integral molding, with essentially no so-called "seams" such as fittings or joints. Therefore, the internal structure 2 does not leak from fittings, joints, or other joints, and can be used stably and continuously for a long period of time. Furthermore, the absence of fittings or joints makes it easier to improve mechanical strength, and eliminates the need for fitting, joining, or other operations during manufacturing, making it easier to manufacture.

[0019] The outer shell 4 has holes 6 formed therein that communicate with the internal space 8. When manufacturing the composite structure 10 by the manufacturing method described below, the metal material that is the raw material of the internal structure 2 is filled into the internal space 8 through the holes 6.

[0020] (internal structure) The internal structure 2 constituting the composite structure 10 is a portion that mainly functions as an internal heat storage body. This internal structure 2 is a solid material that is solid at room temperature (25°C) and is formed by heating and melting a metal material filled in the internal space 8 of the outer shell 4, followed by solidification. Considering that the composite structure 10 may be used as a heat storage body that recovers and reuses waste heat in the temperature range of 1,000 to 1,500°C, the melting point of the internal structure 2 is preferably 1,500°C or lower, and more preferably 1,000 to 1,400°C.

[0021] The metal material that constitutes the internal structure 2 is a material that contains copper as a main component and contains metals other than copper in a proportion of 50 mass % or less, preferably 3 to 30 mass %, and more preferably 4 to 25 mass %, based on the total mass of the metal material. Surprisingly, even when the outer shell (body to be fired) 4, in which the internal space 8 is filled with a metal material of this composition, is heated to a temperature at which the filled metal material melts, the molten metal material does not substantially leak from the holes 6. Furthermore, even when the composite structure 10 obtained in this manner is heated to a temperature above the melting point of the internal structure 2 and repeatedly heat-storage is performed in the composite structure 10, the internal structure 2 does not substantially leak from the holes 6.

[0022] The internal structure is a solid formed by heating and melting a copper-based metal material, which contains a predetermined proportion of metals other than copper, inside (inside) the ceramic outer shell (internal space) while the material is filled, and then solidifying. The composition of the solid internal structure formed in this manner is practically difficult to identify through analysis, etc., because complex reactions may occur between the ceramic and metal materials that make up the outer shell. The internal structure may be configured, for example, with numerous granular portions primarily composed of copper and a network-like portion primarily composed of another metal that fills the gaps between adjacent granular portions.

[0023] The proportion of copper contained in the metal material is 50% by mass or more based on the total mass of the metal material. If the proportion of other metals contained in the metal material exceeds 50% by mass, the heat storage capacity of the formed solid (internal structure) decreases. In addition, gaps (spaces) are likely to occur between the outer shell 4 and the internal structure 2, reducing the thermal conductivity and mechanical strength.

[0024] The other metal is preferably at least one selected from the group consisting of aluminum, nickel, titanium, zirconium, manganese, and iron, and aluminum is particularly preferred.

[0025] The composite structure of the present invention comprises two structural components that are significantly different both physically and chemically: (i) a robust, seamless outer shell, and (ii) an internal structural component enclosed within the outer shell. Therefore, by taking advantage of its properties, the composite structure of the present invention is useful, for example, as a heat storage body for recovering waste heat in a harsh, corrosive environment at temperatures above 1,000°C, such as in a steel converter, or as a heat generating body that utilizes radiation. Furthermore, by taking advantage of the excellent corrosion resistance and high thermal conductivity of the composite structure of the present invention, it is expected to be applied to catalyst substrates, heat dissipation substrates, and heat exchangers.

[0026] <Method of manufacturing a composite structure> Next, a method for manufacturing a composite structure of the present invention will be described. The method for manufacturing a composite structure of the present invention is a method for manufacturing the above-mentioned composite structure, and includes the steps of: preparing a seamless outer shell made of ceramic having an internal space and formed with pores communicating with the internal space (step (1)); filling the internal space with a metal material containing copper as a main component and 50 mass % or less of metals other than copper through the pores to obtain an object to be heat-treated (step (2)); and heat-treating the object to be heat-treated at 900 to 1,300°C with the pores facing upward to obtain a primary heat-treated object (step (3)). The method for manufacturing a composite structure of the present invention will be described in detail below.

[0027] (Process (1)) Figure 2 is a schematic diagram showing one embodiment of the method for producing a composite structure of the present invention. In step (1), a seamless outer shell 4 made of ceramic having an internal space 8 and having pores 6 communicating with the internal space 8 is prepared (Figure 2(A)). The outer shell 4 having such a structure can be produced by a conventionally known method, such as an integral molding method for producing a ceramic molded body.

[0028] The opening diameter of the hole 6 may be set to a size that allows the introduction of a powdered or granular metal material into the internal space 8, and is preferably about 3 to 15 mm, and more preferably about 4 to 10 mm.

[0029] (Process (2)) In step (2), the aforementioned metal material 12, which is mainly composed of copper, is filled into the internal space 8 through the holes 6 to obtain the heat treatment object 15 (FIG. 2(B)). As the metal material 12, for example, a mixture of copper powder or particles and powder or particles of another metal can be used. Alternatively, as the metal material 12, powder or particles of an alloy of copper and another metal can also be used.

[0030] When powdered or particulate metal material is filled into the internal space, the maximum packing density is around 70%. Even when uniformly sized spheres are closest packed, the geometric limit is 74%. In contrast, the packing density of the metal material filled into the internal space can be further increased by adjusting the particle size of the metal material used. FIG. 3 is a schematic diagram showing an example of a method for filling the internal space of the outer shell with metal material. As shown in FIG. 3, a metal material 14 is used, which includes particulate first fillers 14a containing copper as the main component and powdered second fillers 14b having a smaller particle size than the first fillers 14a. The first fillers 14a are then filled into the internal space 8 of the outer shell 4. Next, the second fillers 14b are filled so as to fill the gaps between adjacent first fillers 14a, thereby obtaining a heat-treated body 25. This results in a heat-treated body having a packing density of the metal material in the internal space of preferably 75% or more, more preferably 80% or more. It is preferable to vibrate after filling the second filler 14b, as this can further increase the filling density of the metal material 14. Then, by heat treating an object to be heat-treated that has a high filling density of metal material and solidifying the metal material after heating and melting it, it is possible to obtain a composite structure with a small gap (space) between the outer shell and the internal structure, which has excellent temperature rise characteristics and high mechanical strength.

[0031] The first filler may be, for example, spherical copper beads, rod-shaped or angular copper pieces obtained by cutting wire, or a distorted billet. In this specification, for convenience, the term "particulate" includes not only the spherical beads but also rod-shaped, angular, and distorted billet shapes. The first filler is a particulate material whose main component is copper, and may be copper alone or a copper alloy. The particle diameter of the first filler is preferably 0.5 to 4 mm, and more preferably 1 to 3 mm. Furthermore, it is preferable that the first filler be a mixture of two or more types of particulate material with different particle diameters, as this can further increase the packing density of the metal material.

[0032] The second filler may be, for example, a mixture of copper powder and powder of another metal, or a powder of an alloy of copper and another metal. The particle size of the second filler is smaller than that of the first filler. Specifically, the particle size of the second filler is preferably 1 to 200 μm, and more preferably 50 to 150 μm. The particle sizes of the first and second fillers may be the particle size of the raw materials or the particle size of the granules.

[0033] (Step (3)) In step (3), the heat-treated body obtained in step (2) is heat-treated at 900 to 1,300°C, preferably 1,000 to 1,200°C, with the holes 6 facing upward. When the metal material filled in the internal space is heat-treated, heated and melted, and then solidified, an internal structure 2 that is solid at room temperature (25°C) is formed, and a primary heat-treated body 21 is obtained (FIG. 2(C)). The resulting primary heat-treated body 21 may be used as the composite structure 20, or a secondary heat-treated body obtained through further heat treatment in step (4) described below may be used as the composite structure.

[0034] As mentioned above, even if the heat-treated body 15 is heated to a temperature at which the filled metal material melts, the molten metal material 12 will not leak from the holes 6, and even if it does leak, it will be an extremely small amount that will have no practical effect (FIG. 2(B)). Furthermore, even if the obtained primary heat-treated body 21 (composite structure 20) is heated to a temperature above the melting point of the internal structure 2 and repeatedly stored heat, the internal structure 2 will not leak from the holes 6, and even if it does leak, it will be an extremely small amount that will have no practical effect (FIG. 2(C)).

[0035] (Step (4)) The method for producing a composite structure of this embodiment may further include a step of turning the primary heat-treated body obtained in step (3) upside down and heat-treating it at 900 to 1,300°C, preferably 1,000 to 1,200°C, with the holes 6 facing downward. By turning the primary heat-treated body upside down and further heat-treating it, it is possible to obtain a composite structure 30, which is a secondary heat-treated body 22, while confirming that no leakage of the internal structure 2 occurs through the holes 6. Note that even when firing is performed with the holes 6 facing downward, the internal structure 2 does not substantially leak through the holes 6.

[0036] <Heat storage method> Next, the heat storage method of the present invention will be described. The heat storage method of the present invention is a method in which the above-mentioned composite structure is used as a heat storage body. That is, the heat storage method of the present invention includes a step of heating the above-mentioned composite structure (heat storage body) to a temperature equal to or higher than the melting point of the internal structure, and storing heat in the composite structure (heat storage step).

[0037] In the heat storage step, it is preferable to heat the composite structure so that the sensible heat stored in the outer shell portion accounts for 20% or more of the total heat (total heat amount of the heat storage body) of the sensible heat of the internal structure before melting, the latent heat of the internal structure before melting, the sensible heat of the internal structure in the molten state, and the sensible heat of the outer shell portion. This heat storage method makes it possible to utilize all of the sensible heat of the internal structure before melting, the latent heat of the internal structure before melting, the sensible heat of the internal structure in the molten state, and the sensible heat of the outer shell portion, thereby achieving heat storage with high energy density. These sensible and latent heats can be calculated using the following formula (1). The temperature to which the composite structure is heated can then be determined based on the calculated sensible and latent heats.

[0038] TIFF0007730115000001.tif10128

[0039] In the above formula (1), T i is the initial temperature, T e is the final temperature, m is the mass, C ps is the specific heat at fixed state, C pl indicates the specific heat in the liquid state, and L indicates the latent heat. [Example]

[0040] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are by mass unless otherwise specified.

[0041] <Manufacturing the outer shell> (Production Example 1) Alumina powder (product name "SA34", manufactured by Nippon Light Metal Co., Ltd.) and distilled water were mixed at a volume ratio of 45:55. An appropriate amount of dispersant (product name "Cerna D-305", manufactured by Chukyo Yushi Co., Ltd.) was added, and the mixture was mixed for 24 hours using a ball mill. After adding appropriate amounts of water-soluble binder and antifoaming agent, the mixture was further stirred using a stirrer to obtain a slurry. A plaster mold (25 mm in diameter) with an injection hole on its top surface was prepared. The slurry was poured into the cavity of the plaster mold through the injection hole. The mixture was left to stand, allowing the dispersion medium (water) in the slurry to be absorbed by the plaster mold, and the alumina powder was deposited on the outer surface of the cavity (the inner surface of the plaster mold) with a nearly uniform thickness. After holding for approximately 5 minutes, the unsolidified slurry was discharged from the plaster mold, and a molded outer shell with a hollow portion inside was obtained. The molded body had a wall thickness of approximately 4 mm and an outer diameter of 25 mm. The molded body released from the plaster mold was dried and then fired at 1,600°C to obtain an alumina shell having a wall thickness of 3.5 mm and an outer diameter of 21 mm.

[0042] (Production Example 2) Silicon nitride powder (trade name "SN-7", manufactured by Denka Co., Ltd.), yttrium oxide, and alumina were mixed in a mass ratio of 92:5:3 to obtain a mixed powder. The obtained mixed powder was mixed with distilled water in a volume ratio of 4:6. An appropriate amount of dispersant (trade name "Cerna D-305", manufactured by Chukyo Yushi Co., Ltd.) was added, and the mixture was mixed for 24 hours using a ball mill. An appropriate amount of water-soluble binder and antifoaming agent were added, and the mixture was further stirred using a mixer to obtain a slurry. Thereafter, a molded body having an outer shell with a hollow portion therein was obtained in the same manner as in the above-mentioned Production Example 1. The molded body had a wall thickness of approximately 4 mm and an outer diameter of 25 mm. The molded body was released from the plaster mold, dried, and then heated to 1,850°C in nitrogen gas at 9 atmospheres and fired to obtain a silicon nitride outer shell with a wall thickness of 3.5 mm and an outer diameter of 21 mm.

[0043] <Manufacturing of composite structures (1)> Example 1 Copper powder (150 μm) and aluminum powder (150 μm) were mixed to prepare a mixed powder (metal material) containing 5% aluminum. The mixed powder was placed through the holes in the alumina shell obtained in Production Example 1, filling the internal space of the shell with the mixed powder to obtain a heat-treated body. The obtained heat-treated body was placed with the holes facing upward and heat-treated in air at 1,200°C for 2 hours to obtain a composite structure.

[0044] Observation of the shell of the resulting composite structure revealed that it had reacted slightly with the contents that had leaked out of the holes, but this was at a level that would not pose a problem for practical use. Furthermore, the mass change calculated from the mass before and after heat treatment was +0.3%.

[0045] (Examples 2 to 6, Comparative Example 1) A composite structure was obtained in the same manner as in Example 1, except that a metal material containing aluminum was used in the proportions shown in Table 1. The observation results of the shell state of the obtained composite structure and the mass change rate are shown in Table 1.

[0046] TIFF0007730115000002.tif77170

[0047] Electron microscope photographs showing the microstructure of the interface between the outer shell portion and the internal structure portion of the composite structures obtained in Examples 1 to 3 are shown in Figures 4 to 6. In Figures 4 to 6, the internal structure portion is shown in the upper right, and the outer shell portion is shown in the lower left. As shown in Figure 4, in the composite structure of Example 1, in which the proportion of aluminum in the metal material used was 5%, there was no gap between the outer shell portion and the internal structure portion, and it was found that they were in close contact. It was also found that as the proportion of aluminum in the metal material used increased, gaps appeared between the outer shell portion and the internal structure portion, and the resulting gaps gradually expanded.

[0048] <Manufacturing of composite structures (2)> Example 7 Powder of a metal material (Cu-20%Al) was placed through the holes in the alumina shell obtained in Production Example 1, and the metal material was filled into the internal space of the shell to obtain a heat-treated body. The obtained heat-treated body was placed with the holes facing upward and heat-treated in air at 1,200°C for 2 hours. Next, with the holes facing downward, it was heat-treated in air at 1,200°C for 2 hours to obtain a composite structure.

[0049] Observation of the shell of the resulting composite structure confirmed that the contents had not leaked and that no reaction had occurred in the shell. In addition, there was almost no change in mass (only a slight increase) before and after heat treatment.

[0050] <Manufacturing of composite structures (3)> Example 8 Powder of a metal material (Cu-20%Al) was placed through the holes in the silicon nitride shell obtained in Production Example 2, filling the internal space of the shell with the metal material to obtain a heat-treated body. The obtained heat-treated body was placed with the holes facing upward and heat-treated in air at 1,200°C for 2 hours. Next, with the holes facing downward, it was heat-treated in air at 1,200°C for 2 hours to obtain a composite structure.

[0051] Observation of the shell of the resulting composite structure confirmed that the contents had not leaked and that no reaction had occurred in the shell. Furthermore, the mass change calculated from the mass before and after heat treatment was +0.5%.

[0052] (Examples 9 to 15, Comparative Example 2) A composite structure was obtained in the same manner as in Example 8, except that the shell and metal materials used were those shown in Table 2. Table 2 shows the observation results of the state of the shell of the obtained composite structure and the mass change rate.

[0053] TIFF0007730115000003.tif91170

[0054] <Evaluation> (Temperature rise characteristics) A hole with a diameter of 0.5 mm was drilled in the center of the manufactured composite structure. A thermocouple was inserted through the drilled hole so that its tip was positioned at the center of the internal structure. The composite structure with the thermocouple inserted was placed in a furnace heated to approximately 1,150°C. The time until the temperature at the center became almost constant (time to stabilization) was measured and used as an index of the temperature rise characteristics. The measurement results for the time to stabilization are shown in Table 3.

[0055] (mechanical strength) A compressive load was applied to the manufactured composite structure using a strength testing machine. The load at which the composite structure broke (breaking load) was measured and used as an index of mechanical strength. The measurement results of the breaking load are shown in Table 3.

[0056] TIFF0007730115000004.tif64170

[0057] Example 16 An alumina shell with a wall thickness of 2 mm, an outer diameter of 25 mm, and a hole opening diameter of 5 mm was prepared. Copper spherical beads (3 mm) were inserted as the first filler through the holes of the prepared shell and filled the internal space of the shell. Next, atomized Cu-40Al alloy powder (manufactured by Hikari Materials Co., Ltd., particle size approximately 150 μm) was filled as the second filler while vibrating, resulting in a heat-treated body. The filling density of the metal material filled inside the obtained heat-treated body was 88% (void ratio 12%). The aluminum content of the filled metal material was 19%. The obtained heat-treated body was placed with the holes facing upward and heat-treated in air at 1,200°C for 2 hours to obtain a composite structure.

[0058] The shell of the resulting composite structure was observed, and it was confirmed that the contents had not leaked. Furthermore, the formed internal structure and the outer shell were in close contact, with no gaps. The resulting composite structure was cut, and the distribution of aluminum in the internal structure was analyzed using energy dispersive X-ray analysis (EDX). The results confirmed the formation of a structure containing numerous granular portions, primarily copper, in which aluminum was dissolved, and a network-like portion containing aluminum oxide (alumina) that filled the gaps between adjacent granular portions.

[0059] Furthermore, when the temperature rise characteristics of the obtained composite structure were evaluated, it took 16 seconds for the temperature at the center to become almost constant (time until stabilization), and the breaking load was 22 kN.

[0060] Example 17 A composite structure was obtained in the same manner as in Example 16, except that a mixture containing 3 mm diameter copper spherical beads and 1 mm diameter copper spherical beads in a mass ratio of 3:1 was used as the first filler. A heat-treated body was obtained. The packing density of the metal material filled inside the obtained heat-treated body was 90% (void ratio 10%). The aluminum content of the filled metal material was 13%.

[0061] The obtained heat-treated body was placed with the holes facing upward and heat-treated in air at 1,200°C for 2 hours to obtain a composite structure. The shell of the obtained composite structure was observed to confirm that the contents had not leaked. In addition, the formed internal structure and outer shell were in close contact, with no gaps. The obtained composite structure was cut and the distribution of aluminum in the internal structure was analyzed using energy dispersive X-ray analysis (EDX). The results confirmed the formation of a structure containing numerous granular portions, primarily copper, in which aluminum was dissolved, and a network-like portion containing aluminum oxide (alumina) that filled the gaps between adjacent granular portions.

[0062] Furthermore, when the temperature rise characteristics of the obtained composite structure were evaluated, it took 14 seconds for the temperature at the center to become almost constant (time until stabilization), and the breaking load was 25 kN. [Industrial Applicability]

[0063] The composite structure of the present invention is useful, for example, as a heat storage body for recovering waste heat in a harsh, corrosive environment at temperatures of 1,000°C or higher, such as in a steel converter. [Explanation of symbols]

[0064] 2: Internal structure 4: Outer shell 6: Hole 8: Interior space 10,20,30: Composite structure 12,14: Metal materials 14a: First filling 14b:Second filling 15, 25: Heat treatment object 21: Primary heat treatment body 22: Secondary heat-treated body

Claims

1. a seamless outer shell portion made of ceramic having an internal space and having holes communicating with the internal space; an internal structure contained in the internal space, the internal structure is a solid formed by heating and melting a metal material filled in the internal space and then solidifying it, The metal material contains copper as a main component and contains metals other than copper in an amount of 50 mass% or less based on the entire metal material, A composite structure, wherein the internal structure includes a large number of granular portions mainly composed of copper, and a network-like portion mainly composed of the other metal that fills the gaps between adjacent granular portions.

2. 2. The composite structure according to claim 1, wherein the ceramic is at least one selected from the group consisting of alumina, silicon nitride, and silicon carbide.

3. 3. The composite structure according to claim 1, wherein the other metal is at least one selected from the group consisting of aluminum, nickel, titanium, zirconium, manganese, and iron.

4. 4. The composite structure according to claim 1, wherein the ratio of the other metal contained in the metal material is 3 to 30 mass % based on the total mass of the metal material.

5. The composite structure according to any one of claims 1 to 4, which is used as a heat storage medium.

6. A method for producing a composite structure according to any one of claims 1 to 5, comprising: a step of preparing a seamless outer shell portion made of ceramic having an internal space and having holes formed therein communicating with the internal space; a step of filling the internal space through the hole with a metal material containing copper as a main component and 50 mass % or less of metals other than copper to obtain an object to be heat-treated; a step of heat-treating the object to be heat-treated at 900 to 1,300°C with the hole facing upward to obtain a primary heat-treated object; A method for manufacturing a composite structure comprising:

7. The method for manufacturing a composite structure according to claim 6, further comprising the step of heat treating the primary heat-treated body at 900 to 1,300° C. with the holes facing downward.

8. the metal material includes a particulate first filler mainly composed of copper and a powdery second filler having a smaller particle size than the first filler, 8. The method for manufacturing a composite structure according to claim 6 or 7, wherein the first filler is filled into the internal space, and then the second filler is filled so as to fill gaps between adjacent first fillers, thereby obtaining the body to be heat-treated.

9. A heat storage method comprising the step of heating the composite structure according to claim 5 to a temperature equal to or higher than the melting point of the internal structure, and storing heat in the composite structure.

Images