Heat generating structure and heat generating device

Abstract

Provided are a heat generating structure and a heat generating device with which it is possible to achieve improved stability and controllability of heat generation by a heat generating element. A heat generating structure 2 comprises a silicon substrate 13 and a heat generating element 14 for generating heat by storage and release of hydrogen. The heat generating element 14 includes a support 61 provided on the silicon substrate 13, and a multilayer film 62 provided on the support 61. The support 61 is formed of at least one of a porous body, a hydrogen permeable membrane, and a proton conductor. The multilayer film 62 has a first layer 71 formed of a hydrogen storage metal or a hydrogen storage alloy and having a thickness of less than 1000 nm, and a second layer 72 formed of a hydrogen storage metal, a hydrogen storage alloy, or ceramics different from the first layer 71 and having a thickness of less than 1000 nm.

Description

Heat-generating structure and heat-generating device

[0001] The present invention relates to a heat generating structure and a heat generating device.

[0002] In recent years, a heat generation phenomenon has been reported in which nanostructures formed from hydrogen storage metals or the like generate heat by absorbing and releasing hydrogen (see Non-Patent Document 1). This heat generation phenomenon can produce more thermal energy than chemical reactions, and is therefore expected to be used as an effective heat source or power source.

[0003] The present inventors previously proposed a heating device including a heating element having a base made of a hydrogen storage metal, a hydrogen storage alloy, or a proton conductor and a multilayer film formed on the surface of the base (see Patent Document 1). The heating element is provided inside a container into which a hydrogen-based gas that contributes to heat generation is introduced. The multilayer film includes a first layer made of a hydrogen storage metal or a hydrogen storage alloy and having a thickness of less than 1000 nm, and a second layer made of a different hydrogen storage metal, alloy, or ceramic and having a thickness of less than 1000 nm, stacked together, with a dissimilar material interface formed between the first and second layers. In the heating device disclosed in Patent Document 1, after hydrogen is absorbed into the heating element, the heating element is heated by a heater and the container is evacuated. This causes hydrogen to permeate or diffuse through the dissimilar material interface by quantum diffusion, generating heat in the heating element.

[0004] A. Kitamura, A. Takahashi, K. Takahashi, R. Seto, T. Hatano, Y. Iwamura, T. Itoh, J. Kasagi, M. Nakamura, M. Uchimura, H. Takahashi, S. Sumitomo, T. Hioki, T. Motohiro, Y. Furuyama, M. Kishida, H. Matsune, “Excess heat evolution from nanocomposite samples under exposure to “hydrogen isotope gases”, International Journal of Hydrogen Energy 43 (2018) 16187-16200.

[0005] International Publication No. 2018 / 230447

[0006] However, when the surface of the base has minute irregularities, it is difficult to form a smooth interface between different materials, which poses a problem of reduced stability and controllability of heat generation by the heating element.

[0007] An object of the present invention is to provide a heat-generating structure and a heat-generating device that can improve the stability and controllability of heat generation by a heat-generating element.

[0008] The heat-generating structure according to the present invention comprises a silicon substrate and a heat-generating element that generates heat by absorbing and releasing hydrogen, the heat-generating element having a support provided on the silicon substrate and a multilayer film provided on the support, the support being formed of at least one of a porous body, a hydrogen-permeable film, and a proton conductor, the multilayer film having a first layer less than 1000 nm thick and made of a hydrogen-absorbing metal or a hydrogen-absorbing alloy, and a second layer less than 1000 nm thick and made of a hydrogen-absorbing metal, hydrogen-absorbing alloy, or ceramic different from the first layer.

[0009] The heat generating device according to the present invention comprises the above-mentioned heat generating structure, a sealed container that houses the heat generating structure, a supply unit that supplies a hydrogen-based gas containing hydrogen into the sealed container, and an exhaust unit that exhausts the hydrogen-based gas from the sealed container.

[0010] According to the present invention, a support is provided on a silicon substrate, and a multilayer film is provided on the support, thereby forming a smooth interface between different materials and providing a heating structure and a heating device that can improve the stability and controllability of heat generation by the heating element.

[0011] FIG. 1 is an explanatory diagram illustrating the configuration of a heat generating device according to the present embodiment; FIG. 2 is an explanatory diagram illustrating the configuration of a heat generating structure according to the present embodiment; FIG. 3 is a cross-sectional view showing the structure of a heat generating element; FIG. 4 is a cross-sectional view showing the structure of a laminate having a first layer and a second layer; FIG. 5 is an explanatory diagram illustrating the generation of excess heat; FIG. 6 is an explanatory diagram illustrating a heat generating element of a first modified example having a first layer, a second layer, and a third layer; FIG. 7 is an explanatory diagram illustrating a heat generating method; FIG. 8 is an explanatory diagram illustrating the state in which crystallites of a ternary alloy are formed; and FIG. 9 is an explanatory diagram illustrating the alteration and reduction of the interface between different materials. FIG. 10 is an explanatory diagram illustrating the configuration of a heat generating device according to another embodiment.

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description and drawings, common components are designated by common reference numerals. Descriptions of components designated by common reference numerals will be omitted as appropriate.

[0013] 1 is an explanatory diagram illustrating the configuration of a heating device 1 according to this embodiment. In FIG. 1, the heating device 1 includes a heating structure 2, a sealed container 3, a supply unit 4, a discharge unit 5, a vacuum exhaust unit 6, a control unit 7, and a support mechanism 8.

[0014] The sealed container 3 is a hollow container composed of a top 3a, a bottom 3b, and a side 3c. At least one of the top 3a and the bottom 3b is detachably attached to the side 3c, and the sealed container 3 is sealed by attaching the top 3a and the bottom 3b to the side 3c. The sealed container 3 is provided with a pressure sensor (not shown) that detects the pressure inside the sealed container 3. The sealed container 3 is made of a heat-resistant and pressure-resistant material such as carbon steel, austenitic stainless steel, or a heat-resistant non-ferrous alloy steel, or a material that reflects radiant heat such as Ni, Cu, or Mo. The shape of the sealed container 3 is not particularly limited and may be a cylindrical, elliptical, or rectangular cylinder, etc.

[0015] A hydrogen-based gas is introduced into the sealed container 3. The hydrogen-based gas is a gas containing hydrogen isotopes. As the hydrogen-based gas, deuterium gas, proton gas, heavy hydrogen gas, or a mixture of proton gas and an inert gas is used. Proton gas includes a mixture of naturally occurring protons and deuterium, that is, a mixture in which the abundance ratio of protons is 99.985% and the abundance ratio of deuterium is 0.015%. In the following description, when there is no need to distinguish between protons and deuterium, the term "hydrogen" or "H ２ Examples of inert gases include Ar gas, N ２ Gas, He gas, Ne gas, etc. are used.

[0016] The supply unit 4 has a pipe 4a connected to the sealed container 3 and an on-off valve 4b provided on the pipe 4a. Although not shown, the supply unit 4 further has a tank for storing the hydrogen-based gas, a pump for sending the hydrogen-based gas from the tank to the sealed container 3, a pressure sensor for detecting the pressure inside the pipe 4a, etc. The on-off valve 4b is a pressure regulating valve configured to open and close in accordance with the pressure inside the pipe 4a.

[0017] The exhaust unit 5 has a pipe 5a connected to the sealed container 3 and an on-off valve 5b provided on the pipe 5a. The exhaust unit 5 functions as a safety mechanism to prevent the sealed container 3 from breaking down in the event that excessive heat is generated and the pressure inside the sealed container 3 rises excessively. Although not shown, the exhaust unit 5 further has a pump that exhausts the hydrogen-based gas from inside the sealed container 3, a pressure sensor that detects the pressure inside the pipe 5a, and the like. The on-off valve 5b is a pressure regulating valve configured to open and close according to the pressure inside the pipe 5a.

[0018] The vacuum exhaust unit 6 has a pipe 6a connected to the sealed container 3 and an on-off valve 6b provided on the pipe 6a. Although not shown, the vacuum exhaust unit 6 further has a pump that evacuates the inside of the sealed container 3, a pressure sensor that detects the pressure inside the pipe 6a, and the like. The on-off valve 6b is a pressure adjustment valve configured to open and close according to the pressure inside the pipe 6a.

[0019] The control unit 7 mainly includes, for example, a central processing unit, a storage unit such as a read-only memory or a random access memory, etc. The processing unit executes various types of arithmetic processing using, for example, programs and data stored in the storage unit.

[0020] The control unit 7 controls the operations of the supply unit 4, exhaust unit 5, and vacuum exhaust unit 6 of the heat generating device 1. The control unit 7 is electrically connected to a pressure sensor and on-off valve 4b provided in the pipe 4a of the supply unit 4, and controls the opening and closing of the on-off valve 4b based on the pressure detected by the pressure sensor. The control unit 7 is electrically connected to a pressure sensor and on-off valve 5b provided in the pipe 5a of the exhaust unit 5, and controls the opening and closing of the on-off valve 5b based on the pressure detected by the pressure sensor. The control unit 7 is electrically connected to a pressure sensor and on-off valve 6b provided in the pipe 6a of the vacuum exhaust unit 6, and controls the opening and closing of the on-off valve 6b based on the pressure detected by the pressure sensor.

[0021] The control unit 7 is electrically connected to the heater 15 and temperature sensor 16, which will be described later, and controls the output of the heater 15 based on the temperature detected by the temperature sensor 16. By controlling the output of the heater 15, the control unit 7 adjusts the temperature of the heating element 14 and maintains the heating element 14 at an optimum temperature for heat generation (for example, 300°C to 1000°C).

[0022] The support mechanism 8 is provided inside the sealed container 3 and supports the heat generating structure 2. The support mechanism 8 has an installation portion 8a on which the heat generating structure 2 is installed and support portions 8b that fix the installation portion 8a to the sealed container 3. For example, the support mechanism 8 has four support portions 8b protruding from the bottom of the installation portion 8a, and these four support portions 8b are fixed to the bottom 3b of the sealed container 3.

[0023] (Heat generating structure) Fig. 2 is an explanatory diagram illustrating the configuration of the heat generating structure 2 according to this embodiment. As shown in Fig. 2, the heat generating structure 2 includes a silicon substrate 13, a heat generating element 14, a heater 15, and a temperature sensor 16. In this embodiment, the heat generating structure 2 has a configuration in which the silicon substrate 13, the heat generating element 14, the heater 15, and the temperature sensor 16 are integrated into a unit. The heat generating structure 2 is configured to be detachably attached to the installation portion 8a of the support mechanism 8.

[0024] The silicon substrate 13 is used as a base for the heating element 14. The silicon substrate 13 has a smooth surface on which the heating element 14 is provided. The surface roughness of the smooth surface of the silicon substrate 13 is preferably 10 nm or less, and more preferably 1 nm or less. The surface roughness can be calculated, for example, based on the arithmetic mean roughness Ra defined in Japanese Industrial Standards JIS B 0601:2013. The thickness of the silicon substrate 13 is not particularly limited, but is, for example, 1 mm or less.

[0025] The silicon substrate 13 is a single crystal silicon wafer having a silicon oxide film 13a. As the single crystal silicon wafer having the silicon oxide film 13a, for example, a disc-shaped commercially available product is used. The thickness of the silicon substrate 13 is not particularly limited, but is, for example, 1 mm or less. The thickness of the silicon oxide film 13a is not particularly limited, but is, for example, 3 nm to 100 nm. Note that the silicon substrate 13 is not limited to a single crystal silicon wafer having the silicon oxide film 13a, and may be, for example, a single crystal silicon wafer without a silicon oxide film.

[0026] The purity of the silicon substrate 13 is preferably 99.99999% or more, and more preferably 99.999999999% or more.

[0027] The heating element 14 generates heat by absorbing and releasing hydrogen. The heating element 14 has a support 61 provided on the silicon substrate 13 and a multilayer film 62 provided on the support 61. The detailed configuration of the heating element 14 will be described later using another drawing.

[0028] The heater 15 heats the heating element 14. The heater 15 increases in temperature in response to the power supplied thereto. A power supply that supplies power to the heater 15 is provided in, for example, the control unit 7. In this embodiment, the heater 15 is a plate-shaped ceramic heater having a configuration in which a conductor is provided inside a base body made of ceramic.

[0029] The temperature sensor 16 detects the temperature of the heating element 14. In this embodiment, the temperature sensor 16 is a thermocouple built into the heater 15, and is configured to detect the temperature of the heating element 14 via the heater 15.

[0030] (Heater) Next, the detailed structure of the heater 14 will be described with reference to Figures 3 and 4. As shown in Figure 3, the heater 14 has a laminate 14a having a support 61 and a multilayer film 62.

[0031] The support 61 may be formed of at least one of a porous material, a hydrogen-permeable membrane, and a proton conductor, as long as it allows hydrogen-based gas to be absorbed into and released from the heating element 14. In this example, the support 61 is formed in a plate shape with a front and back surface. The porous material has pores of a size that allows hydrogen-based gas to pass through. The porous material may be formed of, for example, a metal, a non-metal, or a ceramic. Preferably, the porous material is formed of a material that does not inhibit the reaction between the hydrogen-based gas and the multilayer film 62 (hereinafter referred to as the exothermic reaction). The hydrogen-permeable membrane may be formed of, for example, a hydrogen storage metal or a hydrogen storage alloy. Examples of hydrogen storage metals include Ni, Pd, V, Nb, Ta, and Ti. Examples of hydrogen storage alloys include LaNi5, Ca5Cu, Mg2Zn, ZrNi2, ZrCr2, TiFe, TiCo, Mg2Ni, and Mg2Cu. The hydrogen-permeable membrane may be formed of a mesh sheet. As proton conductors, BaCeO3-based (e.g., Ba(Ce 0.95 Y 0.05 )O 3-δ ), SrCeO3 system (e.g., Sr(Ce 0.95 Y 0.05 )O 3-δ ), CaZrO3 system (e.g., CaZr 0.95 Y 0.05 O 3-α ), SrZrO3-based (e.g., SrZr 0.9 Y 0.1 O 3-α ), β Al2O3, β Ga2O3, etc. are used.

[0032] As shown in FIG. 4 , the multilayer film 62 is provided on a support 61. The multilayer film 62 is formed of a first layer 71 made of a hydrogen storage metal or a hydrogen storage alloy, and a second layer 72 made of a hydrogen storage metal, a hydrogen storage alloy, or a ceramic different from the first layer 71. A dissimilar material interface 73 (described later) is formed between the first layer 71 and the second layer 72. In FIG. 4 , the multilayer film 62 is formed by alternately stacking the first layer 71 and the second layer 72 in this order on one side (e.g., the front surface) of the support 61. The first layer 71 and the second layer 72 each have five layers. Note that the number of layers in the first layer 71 and the second layer 72 may be changed as appropriate. The multilayer film 62 may also be formed by alternately stacking the second layer 72 and the first layer 71 in this order on the surface of the support 61. The multilayer film 62 may have one or more first layers 71 and one or more second layers 72, and may have one or more dissimilar material interfaces 73. When the first layers 71 and the second layers 72 are alternately stacked in this order on the surface of the support 61, as shown in Fig. 2, the dissimilar material interfaces 73 are also formed between the first layers 71 and the support 61. Although not shown, when the second layers 72 and the first layers 71 are alternately stacked in this order on the surface of the support 61, the dissimilar material interfaces 73 are also formed between the second layers 72 and the support 61.

[0033] The first layer 71 is formed of, for example, Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, or an alloy thereof. The alloy forming the first layer 71 is preferably an alloy consisting of two or more of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy forming the first layer 71 may be an alloy obtained by adding an additive element to Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, or Ta.

[0034] The second layer 72 is formed of, for example, any of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, alloys thereof, or SiC. The alloy forming the second layer 72 is preferably an alloy consisting of two or more of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy forming the second layer 72 may be an alloy obtained by adding an additive element to Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, or Ta.

[0035] As a combination of the first layer 71 and the second layer 72, when the types of elements are expressed as "first layer 71-second layer 72 (second layer 72-first layer 71)", the following are preferred: Pd-Ni, Ni-Cu, Ni-Cr, Ni-Fe, Ni-Mg, Ni-Co, and Ni-Ca. When the second layer 72 is made of ceramics, the "first layer 71-second layer 72" is preferably Ni-SiC.

[0036] As shown in Figure 5, the dissimilar material interface 73 allows hydrogen atoms to pass through. Figure 5 is a schematic diagram showing how hydrogen atoms in the metal lattice of the first layer 71 and the second layer 72, both of which are formed from a face-centered cubic hydrogen-storing metal, pass through the dissimilar material interface 73 and move into the metal lattice of the second layer 72. Hydrogen is light and is known to undergo quantum diffusion by hopping between sites (octohedral or tetrahedral sites) occupied by hydrogen in materials A and B. Therefore, hydrogen absorbed in the heating element 14 undergoes quantum diffusion while hopping within the multilayer film 62. In the heating element 14, hydrogen passes through the first layer 71, the dissimilar material interface 73, and the second layer 72 by quantum diffusion.

[0037] The thickness of the first layer 71 and the thickness of the second layer 72 are preferably each less than 1000 nm. If the thickness of each of the first layer 71 and the second layer 72 is 1000 nm or more, hydrogen becomes less likely to permeate through the multilayer film 62. Furthermore, by having the thickness of each of the first layer 71 and the second layer 72 less than 1000 nm, a nanostructure that does not exhibit bulk characteristics can be maintained. It is more preferable that the thickness of each of the first layer 71 and the second layer 72 be less than 500 nm. By having the thickness of each of the first layer 71 and the second layer 72 less than 500 nm, a nanostructure that does not exhibit bulk characteristics can be maintained.

[0038] Next, an example of a manufacturing method of the heating element 14 will be described. In this case, a plate-shaped support 61 is prepared, and a vapor deposition apparatus is used to convert a hydrogen-storing metal or alloy that will become the first layer 71 and the second layer 72 into a gaseous state. The first layer 71 and the second layer 72 are then alternately deposited on the surface of the support 61 by aggregation and adsorption. This results in a laminate 14a having a multilayer film 62 on the surface of the support 61. The first layer 71 and the second layer 72 are preferably deposited successively in a vacuum. This results in only a heterogeneous material interface 73 being formed between the first layer 71 and the second layer 72, without any native oxide film being formed. A physical vapor deposition apparatus that physically deposits the hydrogen-storing metal or the hydrogen-storing alloy is used as the vapor deposition apparatus. Examples of the physical vapor deposition apparatus include a sputtering apparatus, a vacuum deposition apparatus, and a CVD (Chemical Vapor Deposition) apparatus. Alternatively, the first layer 71 and the second layer 72 may be alternately deposited on the surface of the support 61 by electroplating.

[0039] As described above, the heating element 14 is provided on the smooth surface of the silicon substrate 13 serving as a base. Therefore, by forming the support 61 on the smooth surface of the silicon substrate 13 and then forming the multilayer film 62 on the support 61, a smooth interface 73 between different materials can be formed.

[0040] The support 61 functions as a hydrogen storage layer that stores hydrogen. The thickness of the support 61 is predetermined according to the thickness of the multilayer film 62. The thickness of the support 61 is approximately the same as or slightly larger than the thickness of the multilayer film 62. Specifically, when the thickness of the support 61 is T1 and the thickness of the multilayer film 62 is T2, T1 / T2 is preferably 0.1 or more and 2.0 or less, and more preferably 0.2 or more and 1.0 or less.

[0041] In this embodiment, the support 61 is made of Pd. The support 61 has a thickness of 20 nm. The multilayer film 62 is composed of a first layer 71 made of Cu and a second layer 72 made of Ni. The first layer 71 and the second layer 72 each have six layers. The first layer 71 has a thickness of 2 nm. The second layer 72 has a thickness of 14 nm.

[0042] Although the heat generating device 1 includes the heat generating element 14 in this embodiment, it may include a heat generating element having a different configuration from the heat generating element 14. A first modified example will be described with reference to Fig. 6, and a second modified example will be described with reference to Fig. 7.

[0043] [First Modification] The heating device 1 includes a heating element 75 shown in FIG. 6 instead of the heating element 14. In the heating element 75 shown in FIG. 6, the multilayer film 62 of the laminate further includes a third layer 77 in addition to the first layer 71 and the second layer 72. The third layer 77 is formed of a hydrogen storage metal, a hydrogen storage alloy, or a ceramic different from the first layer 71 and the second layer 72. The thickness of the third layer 77 is preferably less than 1000 nm. In FIG. 6, the first layer 71, the second layer 72, and the third layer 77 are stacked on the surface of the support 61 in the following order: first layer 71, second layer 72, first layer 71, third layer 77. Alternatively, the first layer 71, the second layer 72, and the third layer 77 may be stacked on the surface of the support 61 in the following order: first layer 71, third layer 77, first layer 71, second layer 72. That is, the multilayer film 62 has a stacked structure in which the first layer 71 is provided between the second layer 72 and the third layer 77. The multilayer film 62 may include one or more third layers 77. The dissimilar material interface 78 formed between the first layer 71 and the third layer 77 allows hydrogen atoms to pass through, similar to the dissimilar material interface 73.

[0044] The third layer 77 is formed of, for example, any one of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, alloys thereof, SiC, CaO, Y2O3, TiC, LaB6, SrO, and BaO. The alloy forming the third layer 77 is preferably an alloy consisting of two or more of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy forming the third layer 77 may also be an alloy containing an additive element added to Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, or Ta.

[0045] In particular, the third layer 77 is preferably formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO. A heating element 75 having a third layer 77 formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO exhibits increased hydrogen storage capacity, increasing the amount of hydrogen permeating through the dissimilar material interfaces 73 and 78, thereby achieving high excess heat output. The third layer 77 formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO preferably has a thickness of 10 nm or less. This allows hydrogen atoms to easily permeate the multilayer film 62. The third layer 77 formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO may be formed in an island shape rather than as a complete film. Furthermore, the first layer 71 and the third layer 77 are preferably formed successively in a vacuum. As a result, no native oxide film is formed between the first layer 71 and the third layer 77, and only a different material interface 78 is formed.

[0046] Combinations of the first layer 71, the second layer 72, and the third layer 77, when the types of elements are expressed as "first layer 71-third layer 77-second layer 72", are as follows: Pd-CaO-Ni, Pd-Y2O3-Ni, Pd-TiC-Ni, Pd-LaB6-Ni, Ni-CaO-Cu, Ni-Y2O3-Cu, Ni-TiC-Cu, Ni-LaB6-Cu, Ni-Co-Cu, Ni-CaO-Cr, Ni-Y2O3-Cr, Ni-TiC-Cr, Ni-LaB6- Cr, Ni-CaO-Fe, Ni-Y2O3-Fe, Ni-TiC-Fe, Ni-LaB6-Fe, Ni-Cr-Fe, Ni-CaO-Mg, Ni-Y2O3-Mg, Ni-TiC-Mg, Ni-LaB6-Mg, N Preferred are i-CaO-Co, Ni-Y2O3-Co, Ni-TiC-Co, Ni-LaB6-Co, Ni-CaO-SiC, Ni-Y2O3-SiC, Ni-TiC-SiC, and Ni-LaB6-SiC.

[0047] Similar to the heating element 14, the heating element 75 is provided on the smooth surface of the silicon substrate 13 serving as a base. Therefore, by forming the support 61 on the smooth surface of the silicon substrate 13 and then forming the multilayer film 62 on the support 61, it is possible to form smooth dissimilar material interfaces 73 and 78.

[0048] [Second Modification] The heating device 1 includes a heating element 80 shown in FIG. 7 instead of the heating element 14. In the heating element 80 shown in FIG. 7, the multilayer film 62 of the laminate further includes a fourth layer 82 in addition to the first layer 71, the second layer 72, and the third layer 77. The fourth layer 82 is formed of a hydrogen storage metal, a hydrogen storage alloy, or a ceramic different from the first layer 71, the second layer 72, and the third layer 77. The thickness of the fourth layer 82 is preferably less than 1000 nm. In FIG. 7, the first layer 71, the second layer 72, the third layer 77, and the fourth layer 82 are stacked on the surface of the support 61 in the following order: first layer 71, second layer 72, first layer 71, third layer 77, first layer 71, and fourth layer 82. The first layer 71, the second layer 72, the third layer 77, and the fourth layer 82 may be laminated on the surface of the support 61 in the following order: first layer 71, fourth layer 82, first layer 71, third layer 77, first layer 71, second layer 72. That is, the multilayer film 62 has a laminated structure in which the second layer 72, the third layer 77, and the fourth layer 82 are laminated in any order, and the first layer 71 is provided between each of the second layer 72, the third layer 77, and the fourth layer 82. The multilayer film 62 may have one or more fourth layers 82. The dissimilar material interface 83 formed between the first layer 71 and the fourth layer 82 allows hydrogen atoms to pass through, similar to the dissimilar material interface 73 and the dissimilar material interface 78.

[0049] The fourth layer 82 is formed of, for example, any one of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, alloys thereof, SiC, CaO, Y2O3, TiC, LaB6, SrO, and BaO. The alloy forming the fourth layer 82 is preferably an alloy consisting of two or more of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy forming the fourth layer 82 may also be an alloy containing an additive element added to Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, or Ta.

[0050] In particular, the fourth layer 82 is preferably formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO. A heating element 80 having a fourth layer 82 formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO exhibits increased hydrogen storage capacity, increasing the amount of hydrogen permeating through the dissimilar material interface 73, the dissimilar material interface 78, and the dissimilar material interface 83, thereby achieving high excess heat output. The fourth layer 82 formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO preferably has a thickness of 10 nm or less. This allows hydrogen atoms to easily permeate the multilayer film 62. The fourth layer 82 formed of any one of CaO, Y2O3, TiC, LaB6, SrO, and BaO may be formed in an island shape rather than as a complete film. Furthermore, the first layer 71 and the fourth layer 82 are preferably formed successively in a vacuum. As a result, no native oxide film is formed between the first layer 71 and the fourth layer 82, and only a different material interface 83 is formed.

[0051] As a combination of the first layer 71, the second layer 72, the third layer 77, and the fourth layer 82, when the types of elements are expressed as "first layer 71-fourth layer 82-third layer 77-second layer 72", the following are preferable: Ni-CaO-Cr-Fe, Ni-Y2O3-Cr-Fe, Ni-TiC-Cr-Fe, and Ni-LaB6-Cr-Fe.

[0052] Similar to the heating element 14, the heating element 80 is provided on the smooth surface of the silicon substrate 13 serving as a base. Therefore, by forming the support 61 on the smooth surface of the silicon substrate 13 and then forming the multilayer film 62 on the support 61, it is possible to form smooth dissimilar material interfaces 73, 78, and 83.

[0053] The heating element having multiple layers may be a mixture of two or more of the heating element 14 shown in FIG. 4, the heating element 75 shown in FIG. 6, and the heating element 80 shown in FIG. 7. Heating elements having multiple layer configurations may be arranged in any order. The configuration of the multilayer film 62, such as the thickness ratio of each layer, the number of layers, and the materials, may be changed as appropriate depending on the temperature used.

[0054] (Operation and Effect) In the heat generating device 1 configured as described above, the sealed container 3 is opened, and the heat generating structure 2 is placed on the installation portion 8a of the support mechanism 8 provided inside the sealed container 3. The sealed container 3 is sealed, and the pump of the vacuum exhaust unit 6 is driven to evacuate the inside of the sealed container 3. The heater 15 is driven, and the heat generating element 14 is heated. For example, the temperature of the heat generating element 14 is raised to about 200°C by the heater 15, thereby removing moisture from the heat generating element 14.

[0055] The output of the heater 15 is increased, and the heating element 14 is further heated. For example, the temperature of the heating element 14 is set to about 300° C. by the heater 15. The pump of the supply unit 4 is driven, and hydrogen-based gas stored in a tank (not shown) flows through the pipe 4a and is introduced into the sealed container 3. As a result, hydrogen is absorbed into the support 61 and the multilayer film 62 of the heating element 14. The hydrogen-based gas may be, for example, H ２ and a mixed gas containing Ar (3% H ２ / Ar gas) is used. After hydrogen is absorbed into the heating element 14, the supply unit 4 is stopped. The output of the heater 15 is controlled to set the temperature of the heating element 14 to an arbitrary temperature (e.g., about 700°C) within the optimum temperature range for heat generation, and the heating element 14 is heated. As the heating element 14 is heated, the pump of the vacuum exhaust unit 6 is driven, and the hydrogen-based gas inside the sealed container 3 is discharged through the pipe 6a. This puts the heating element 14 into a heat-generating state (hereinafter referred to as a "heat-generating state"). That is, hydrogen absorbed in the support 61 and the multilayer film 62 of the heating element 14 permeates the dissimilar material interface 73 by quantum diffusion, or hydrogen diffuses through the dissimilar material interface 73 by quantum diffusion, generating excess heat in the heating element 14.

[0056] While the evacuation by the evacuation unit 6 continues, the hydrogen stored in the heating element 14 is gradually released (discharged). Therefore, if the heating element 14 is to continue generating heat for a long period of time, the operation of the evacuation unit 6 is stopped and the supply unit 4 is driven to introduce a hydrogen-based gas into the sealed container 3, causing the heating element 14 to occlude (supply) hydrogen. For example, the hydrogen-based gas is gradually introduced until the pressure inside the sealed container 3 reaches 1 atmosphere. At this time, the output of the heater 15 is controlled to maintain the temperature of the heating element 14 within a temperature range optimal for heat generation. After the heating element 14 has occluded hydrogen, the operation of the supply unit 4 is stopped and the evacuation unit 6 is driven, allowing the heating element 14 to continue generating heat.

[0057] FIG. 8 is an explanatory diagram illustrating a heat generation method. The heater 15 and temperature sensor 16 of the heat generation structure 2 are omitted in FIG. 8 . When a hydrogen-based gas is introduced into the sealed container 3, a hydrogen molecule is adsorbed onto the surface of the multilayer film 62 of the heat generation element 14 (the surface opposite the support 61), and the hydrogen molecule dissociates into two hydrogen atoms. The dissociated hydrogen atoms then penetrate (occlude) into the multilayer film 62 and the support 61. At this time, the hydrogen atoms that penetrated into the multilayer film 62 and the support 61 do not penetrate into the silicon substrate 13. When the hydrogen-based gas is exhausted from the sealed container 3, the hydrogen atoms that penetrated into the multilayer film 62 and the support 61 return to the surface of the multilayer film 62, recombine, and are released as hydrogen molecules. As a result, hydrogen atoms pass through the dissimilar material interface 73 (see FIG. 5) by quantum diffusion, or hydrogen atoms diffuse through the dissimilar material interface 73 by quantum diffusion, causing the temperature of the heating element 14 to rise to a temperature equal to or higher than the heating temperature of the heater 15, thereby generating excess heat.

[0058] According to the heating structure 2 of this embodiment, the heating element 14 is provided on the silicon substrate 13 serving as a base, thereby forming a smooth interface 73 between different materials, thereby improving the stability and controllability of heat generation by the heating element 14.

[0059] The heating structure 2 can be easily and inexpensively manufactured because a commercially available single crystal silicon wafer having a silicon oxide film 13a can be used as the silicon substrate 13. Furthermore, by using a large-diameter single crystal silicon wafer as the silicon substrate 13 and providing a large-diameter heating element 14 on its surface, high output can be achieved.

[0060] In the heating structure 2, since the purity of the silicon substrate 13 is 99.99999% or more, contamination and alteration of the interface 73 of different materials caused by impurities contained in the silicon substrate 13 is suppressed, and the stability and controllability of heat generation by the heating element 14 can be further improved.

[0061] The heat generating structure 2 has a unitary configuration of the silicon substrate 13, the heat generating element 14, the heater 15, and the temperature sensor 16. This makes it easy to increase or decrease the number of heat generating structures 2 installed in the heat generating device 1, thereby improving the degree of freedom in designing the heat generating device 1.

[0062] According to the heat generating device 1 of this embodiment, by including the heat generating structure 2 described above, it is possible to improve the stability and controllability of heat generation by the heat generating element 14 .

[0063] Furthermore, in the heating device 1, when the temperature T of the heating element 14 reaches a critical temperature Tc, a chemical reaction or alloying reaction occurs between the metals constituting the first layer 71, the metals constituting the second layer 72, and the metals constituting the support 61, forming crystallites of a ternary alloy with different alloy concentrations (alloy compositions). The critical temperature Tc is the temperature at which the metals constituting the support 61, the metals constituting the first layer 71, and the metals constituting the second layer 72 alloy, and is also referred to as the alloying reaction initiation temperature. For example, if the first layer 71 is made of Cu, the second layer 72 is made of Ni, and the support 61 is made of Pd, the critical temperature Tc is 500°C, and when the temperature T of the heating element 14 reaches the critical temperature Tc (500°C), crystallites of a ternary alloy (Pd—Ni—Cu alloy) are formed.

[0064] FIG. 9 is an explanatory diagram illustrating the state in which ternary alloy crystallites are formed. As shown in FIG. 9, when the condition T = Tc is satisfied, in the heating element 14, the metal constituting the first layer 71, the metal constituting the second layer 72, and the metal constituting the support 61 are alloyed, forming ternary alloy crystallites 90 with different alloy concentrations. In FIG. 9, the difference in alloy concentration of the crystallites 90 is represented by different types of hatching. Between the ternary alloy crystallites 90 with different alloy concentrations, a dissimilar material interface 91 different from the dissimilar material interface 73 is formed. Here, for convenience, the formation of a dissimilar material interface 91 different from the dissimilar material interface 73 is referred to as "alteration of the dissimilar material interface." Note that silicon atoms constituting the silicon substrate 13 do not diffuse or penetrate into the support 61 or the multilayer film 62 (the first layer 71 and the second layer 72). Furthermore, because the silicon substrate 13 is highly pure, impurity elements in the silicon substrate 13 do not segregate into the support 61 or the multilayer film 62.

[0065] When the thickness of the support 61 is approximately the same as or slightly greater than the thickness of the multilayer film 62, after the ternary alloy crystallites 90 are formed, the metals constituting the support 61 do not further diffuse and penetrate into the ternary alloy crystallites 90. Although the alloying reaction causes alteration of the interface between dissimilar materials, the decrease (also referred to as dilution) of the interface between dissimilar materials is suppressed. In the heating device 1, although alteration of the interface between dissimilar materials occurs, the interface between dissimilar materials 91 is formed, and hydrogen atoms can pass through the interface between dissimilar materials 91 by quantum diffusion, or hydrogen atoms can diffuse through the interface between dissimilar materials 91 by quantum diffusion, thereby generating excess heat in the heating element 14 above the heating temperature.

[0066] In this embodiment, the thickness of the support 61 is approximately the same as or slightly greater than the thickness of the multilayer film 62, but if the thickness of the support is, for example, three orders of magnitude or more thicker than the thickness of the multilayer film, when the temperature T of the heating element exceeds the critical temperature Tc, the interface between the different materials may be altered and reduced in quality. Below, as a comparative example of a heating element, a case will be described in which the thickness of the support is, for example, three orders of magnitude or more thicker than the thickness of the multilayer film.

[0067] The alteration and reduction of the interface between different materials will be explained using Figure 10. Figure 10(a) shows a state where the temperature T of the heating element is below the critical temperature Tc. Figure 10(b) shows a state where the temperature T of the heating element has reached the critical temperature Tc. Figure 10(c) shows a state where the temperature T of the heating element has exceeded the critical temperature Tc.

[0068] As shown in FIG. 10A , the heating element 214 has a support 261 and a multilayer film 262 provided on the support 261. The multilayer film 262 has a first layer 271 and a second layer 272. A dissimilar material interface 273 is formed between the first layer 271 and the second layer 272. The thickness of the support 261 is, for example, three orders of magnitude thicker than the thickness of the multilayer film 262. In the state shown in FIG. 10A , the dissimilar material interface 273 does not deteriorate. Therefore, the heating element 214 can generate heat as designed.

[0069] As shown in FIG. 10( b), when the temperature T of the heating element 214 reaches the critical temperature Tc, the metal constituting the support 261, the metal constituting the first layer 271, and the metal constituting the second layer 272 are alloyed, forming ternary alloy crystallites 290 with different alloy concentrations. A dissimilar material interface 291, different from the dissimilar material interface 273, is formed between the ternary alloy crystallites 290 with different alloy concentrations. In other words, the dissimilar material interface is altered. In the state shown in FIG. 10( b), the dissimilar material interface 291 is formed, allowing the heating element 214 to generate heat generally as designed.

[0070] 10(c), when the temperature T of the heating element 214 exceeds the critical temperature Tc, the metal constituting the support 261 diffuses and penetrates into the ternary alloy crystallites 290. As a result, the number of crystallites in which the ratio of the metal constituting the support 261 is close to 100% increases, and the number of dissimilar material interfaces 291 decreases. In the state shown in FIG. 10(c), the reduction in the number of dissimilar material interfaces 291 suppresses heat generation in the heating element 214.

[0071] Other Embodiments In the above-described embodiment, the heat generating device 1 including one heat generating structure 2 has been described, but the present invention is not limited to this.

[0072] 11 is an explanatory diagram illustrating the configuration of a heat generating device 100 according to another embodiment. The same reference numerals are used to designate components and members that are the same as or equivalent to those in the above embodiment. Explanations that overlap with the above embodiment will be omitted as appropriate, and the following description will focus on the configuration that differs from the above embodiment.

[0073] 11 , the heat generating device 100 includes three heat generating structures 2, a sealed container 3, a supply unit 4, a discharge unit 5, a vacuum exhaust unit 6, a control unit 7, and a support mechanism 108. The heater 15 and temperature sensor 16 of each heat generating structure 2 are electrically connected to the control unit 7. The control unit 7 controls the output of the heater 15 for each heat generating structure 2 based on the temperature detected by the temperature sensor 16. In this embodiment, the heat generating device 100 includes three heat generating structures 2, but is not limited to this and may include two or four or more heat generating structures 2.

[0074] The support mechanism 108 is provided inside the sealed container 3 and supports each of the heat generating structures 2. The support mechanism 108 has three mounting portions 108a on which the three heat generating structures 2 are respectively mounted, and support portions 108b that fix the three mounting portions 108a to the sealed container 3. The three mounting portions 108a are arranged at different heights and fixed to the support portions 108b. The support portions 108b are fixed to the top 3a and bottom 3b of the sealed container 3.

[0075] As in the above-described embodiment, the heat generating device 100 is provided with the heat generating structure 2, thereby improving the stability and controllability of heat generation by the heat generating element 14. Furthermore, the heat generating device 100 is provided with a plurality of heat generating structures 2, thereby achieving higher output.

[0076] The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the invention.

[0077] In the above embodiment, the heat generating structure 2 has a configuration in which the silicon substrate 13, the heat generating element 14, the heater 15, and the temperature sensor 16 are integrated into a unit, but the present invention is not limited to this. The heat generating structure 2 may be any structure that includes the silicon substrate 13 and the heat generating element 14. For example, in the heat generating device 1, the heater 15 and the temperature sensor 16 may be provided on the installation portion 8a of the support mechanism 8, and the heat generating structure 2 including the silicon substrate 13 and the heat generating element 14 may be configured to be detachably attached to the heater 15. In this case, for example, when replacing the heat generating structure 2 with another heat generating structure, it is possible to replace only the heat generating structure 2 while leaving the heater 15 and the temperature sensor 16 provided on the installation portion 8a of the support mechanism 8.

[0078] Although the hydrogen storage metal has a face-centered cubic crystal structure in FIG. 5, the crystal structure is not limited to a face-centered cubic structure, and may have a body-centered cubic structure or the like.

[0079] When the thickness of the support 61 is T1 and the thickness of the multilayer film 62 is T2, T1 / T2 is preferably 0.1 or more and 5.0 or less, and more preferably 0.2 or more and 3.0 or less.

[0080] REFERENCE SIGNS LIST 1 Heat generating device 2 Heat generating structure 3 Sealed container 4 Supply section 4a Pipe 4b On-off valve 5 Discharge section 5a Pipe 5b On-off valve 6 Vacuum exhaust section 6a Pipe 6b On-off valve 7 Control section 8 Support mechanism 8a Installation section 8b Support section 13 Silicon substrate 13a Silicon oxide film 14 Heat generating element 14a Laminated body 15 Heater 16 Temperature sensor 61 Support 62 Multilayer film 71 First layer 72 Second layer 73 Interface between different materials 75 Heat generating element 77 Third layer 78 Interface between different materials 80 Heat generating element 82 Fourth layer 83 Interface between different materials 100 Heat generating device 108 Support mechanism 108a Installation section 108b Support section

Claims

1. A heat generating structure comprising: a silicon substrate; and a heat generating element that generates heat by absorbing and releasing hydrogen, said heat generating element having a support provided on said silicon substrate and a multilayer film provided on said support, said support being formed from at least one of a porous body, a hydrogen permeable film, and a proton conductor, said multilayer film having a first layer less than 1000 nm in thickness formed from a hydrogen storage metal or a hydrogen storage alloy, and a second layer less than 1000 nm in thickness formed from a hydrogen storage metal, hydrogen storage alloy or ceramic different from the first layer.

2. The heat generating structure according to claim 1, wherein the silicon substrate is a single crystal silicon wafer having a silicon oxide film.

3. The heat generating structure according to claim 1, wherein the purity of the silicon substrate is 99.99999% or more.

4. The heating structure according to claim 1, comprising: a heater for heating the heating element; and a temperature sensor for detecting the temperature of the heating element.

5. A heat generating device comprising: a heat generating structure according to any one of claims 1 to 4; a sealed container housing said heat generating structure; a supply section for supplying a hydrogen-based gas containing hydrogen to the inside of said sealed container; and a discharge section for discharging said hydrogen-based gas from the inside of said sealed container.

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