Heat generating structure and heat generating device

Abstract

A heat generating structure and a heat generating device that can improve stability and controllability of heat generation by a heat generating element are provided. A heat generating structure 2 includes a silicon substrate 13 and a heat generating element 14 that generates heat by occluding and discharging 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 made of at least one of a porous body, a hydrogen permeable film, and a proton conductor, and the multilayer film 62 includes a first layer 71 that is made of a hydrogen storage metal or a hydrogen storage alloy and has a thickness of less than 1000 nm, and a second layer 72 that is made of a hydrogen storage metal or a hydrogen storage alloy, which is different from that of the first layer 71, or ceramics and has a thickness of less than 1000 nm.

Description

Technical Field

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

[0002] In recent years, a heat generation phenomenon has been reported in which a nanostructure made of a hydrogen storage metal or the like generates heat by occluding and discharging hydrogen (see Non-Patent Literature 1). This heat generation phenomenon can obtain heat energy more than that of a chemical reaction, and thus it is expected to be used as an effective heat source or power supply.

[0003] The inventors of the present application have previously proposed a heat generating device including a heat generating element including a base made of a hydrogen storage metal, a hydrogen storage alloy, or a proton conductor, and a multilayer film formed on a surface of the base (see Patent Literature 1). The heat generating element is provided inside a container into which a hydrogen-based gas that contributes to heat generation is introduced. The multilayer film has a configuration in which a first layer that is made of a hydrogen storage metal or a hydrogen storage alloy and has a thickness of less than 1000 nm and a second layer that is made of a hydrogen storage metal or a hydrogen storage alloy different from the first layer or made of ceramics and has a thickness of less than 1000 nm are stacked, and a heterogeneous material interface is formed between the first layer and the second layer. In the heat generating device of Patent Literature 1, after hydrogen is occluded in the heat generating element, the heat generating element is heated by a heater and the inside of the container is evacuated, so that the hydrogen permeates through the heterogeneous material interface in a manner of quantum diffusion, or the hydrogen diffuses through the heterogeneous material interface in a manner of quantum diffusion, thereby generating heat in the heat generating element.Citation ListNon-Patent Literature

[0004] Non-Patent Literature 1: 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.Patent Literature

[0005] Patent Literature 1: WO2018 / 230447Summary of InventionTechnical Problem

[0006] However, when a surface of a base has microscopic irregularities, it is difficult to form a smooth heterogeneous material interface, and thus there is a problem that stability and controllability of heat generation by a heat generating element are reduced.

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

[0008] A heat generating structure according to the present invention includes a silicon substrate; and a heat generating element that generates heat by occluding and discharging hydrogen, in which the heat generating element includes a support provided on the silicon substrate and a multilayer film provided on the support, the support is made of at least one of a porous body, a hydrogen permeable film, and a proton conductor, and the multilayer film includes a first layer that is made of a hydrogen storage metal or a hydrogen storage alloy and has a thickness of less than 1000 nm, and a second layer that is made of a hydrogen storage metal or a hydrogen storage alloy, which is different from that of the first layer, or ceramics and has a thickness of less than 1000 nm.

[0009] A heat generating device according to the present invention includes the above heat generating structure; a sealed container that houses the heat generating structure; a supply unit that supplies a hydrogen-based gas containing the hydrogen into the sealed container; and a discharge unit that discharges the hydrogen-based gas inside the sealed container.Advantageous Effects of Invention

[0010] According to the present invention, a heat generating structure and a heat generating device can be provided in which a support is provided on a silicon substrate, a multilayer film is provided on the support, so that a smooth heterogeneous material interface can be formed, and stability and controllability of heat generation by a heat generating element can be improved.Brief Description of Drawings

[0011] Fig. 1 is a diagram illustrating a configuration of a heat generating device according to an embodiment. Fig. 2 is a diagram illustrating a configuration of a heat generating structure according to an embodiment. Fig. 3 is a cross-sectional view illustrating a structure of the heat generating element. Fig. 4 is a cross-sectional view illustrating a structure of a stacked body having a first layer and a second layer. Fig. 5 is a diagram illustrating generation of excess heat. Fig. 6 is a diagram illustrating a heat generating element having a first layer, a second layer, and a third layer according to a first modification. Fig. 7 is a diagram illustrating a heat generating element having a first layer, a second layer, a third layer, and a fourth layer according to a second modification. Fig. 8 is a diagram illustrating a heat generating method. Fig. 9 is a diagram illustrating a state in which crystallites of a ternary alloy are formed. Fig. 10 is a diagram illustrating alteration and reduction of a heterogeneous material interface. Fig. 11 is a diagram illustrating a configuration of a heat generating device according to another embodiment. Description of Embodiments

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description and drawings, common components are given common reference numerals. Descriptions of the configurations given common reference numerals will be omitted as appropriate.(Heat Generating Device)

[0013] Fig. 1 is a diagram illustrating a configuration of a heat generating device 1 according to the present embodiment. In Fig. 1, the heat generating device 1 includes a heat generating structure 2, a sealed container 3, a supply unit 4, a discharge unit 5, a vacuum evacuation unit 6, a control unit 7, and a supporting mechanism 8.

[0014] The sealed container 3 is a hollow container having an upper portion 3a, a bottom portion 3b, and a side portion 3c. At least one of the upper portion 3a and the bottom portion 3b of the sealed container 3 is detachable from the side portion 3c, and the sealed container 3 is sealed by attaching the upper portion 3a and the bottom portion 3b to the side portion 3c. In the sealed container 3, a pressure sensor (not illustrated) that detects a pressure inside the sealed container 3 is provided. The sealed container 3 is made of a material having heat resistance and pressure resistance, such as carbon steel, austenitic stainless steel, and heat-resistant non-ferrous alloy steel, or a material that reflects radiant heat, such as Ni, Cu, or Mo. A shape of the sealed container 3 is not particularly limited, and may be a cylindrical shape, an elliptical cylindrical shape, a rectangular cylindrical shape, or the like.

[0015] A hydrogen-based gas is introduced into the sealed container 3. The hydrogen-based gas refers to a gas that contains isotopes of hydrogen. As the hydrogen-based gas, a deuterium gas, a protium gas, or a mixed gas of a deuterium gas or a protium gas and an inert gas is used. The protium gas includes a mixture of naturally occurring protium and deuterium, that is, a mixture in which an abundance ratio of protium is 99.985% and an abundance ratio of deuterium is 0.015%. In the following description, when there is no need to distinguish between protium and deuterium, a description of "hydrogen" or "H 2 " is made. As the inert gas, for example, Ar gas, N 2 gas, He gas, or Ne gas is used.

[0016] The supply unit 4 includes a pipe 4a connected to the sealed container 3, and an on-off valve 4b provided on the pipe 4a. Although not illustrated, the supply unit 4 also includes a tank that stores the hydrogen-based gas, a pump that delivers the hydrogen-based gas in the tank to the sealed container 3, a pressure sensor that detects a pressure inside the pipe 4a, and the like. The on-off valve 4b is a pressure adjustment valve configured to open and close in accordance with the pressure inside the pipe 4a.

[0017] The discharge unit 5 includes a pipe 5a connected to the sealed container 3, and an on-off valve 5b provided on the pipe 5a. The discharge unit 5 functions as a safety mechanism for preventing the sealed container 3 from breaking down when excessive heat is generated and the pressure inside the sealed container 3 is excessively increased. Although not illustrated, the discharge unit 5 also includes a pump that discharges the hydrogen-based gas inside the sealed container 3, a pressure sensor that detects a pressure inside the pipe 5a, and the like. The on-off valve 5b is a pressure adjustment valve configured to open and close in accordance with the pressure inside the pipe 5a.

[0018] The vacuum evacuation unit 6 includes a pipe 6a connected to the sealed container 3, and an on-off valve 6b provided on the pipe 6a. Although not illustrated, the vacuum evacuation unit 6 also includes a pump that evacuates the hydrogen-based gas inside the sealed container 3, a pressure sensor that detects a pressure inside the pipe 6a, and the like. The on-off valve 6b is a pressure adjustment valve configured to open and close in accordance with the pressure inside the pipe 6a.

[0019] The control unit 7 mainly includes, for example, an arithmetic device (a central processing unit), and a storage unit such as a read only memory and a random access memory. The arithmetic device executes various kinds of arithmetic processing using a program, data, and the like stored in the storage unit.

[0020] The control unit 7 controls operations of the supply unit 4, the discharge unit 5, and the vacuum evacuation unit 6 of the heat generating device 1. The control unit 7 is electrically connected to the pressure sensor and the on-off valve 4b provided on the pipe 4a of the supply unit 4, and controls 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 the pressure sensor and the on-off valve 5b provided on the pipe 5a of the discharge unit 5, and controls 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 the pressure sensor and the on-off valve 6b provided on the pipe 6a of the vacuum evacuation unit 6, and controls 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 a heater 15 and a temperature sensor 16 to be described later, and controls an output of the heater 15 based on a temperature detected by the temperature sensor 16. The control unit 7 controls the output of the heater 15 to adjust a temperature of a heat generating element 14, and maintains the heat generating element 14 at an optimum temperature (for example, 300°C to 1000°C) for heat generation.

[0022] The supporting mechanism 8 is provided inside the sealed container 3, and supports the heat generating structure 2. The supporting mechanism 8 includes an installation portion 8a on which the heat generating structure 2 is installed, and supporting column portions 8b that fix the installation portion 8a to the sealed container 3. The supporting mechanism 8 includes, for example, four supporting column portions 8b protruding from a bottom portion of the installation portion 8a, and the four supporting column portions 8b are fixed to the bottom portion 3b of the sealed container 3.(Heat Generating Structure)

[0023] Fig. 2 is a diagram illustrating a configuration of the heat generating structure 2 according to the present embodiment. As illustrated in Fig. 2, the heat generating structure 2 includes a silicon substrate 13, the heat generating element 14, the heater 15, and the temperature sensor 16. In the present 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 unitized. The heat generating structure 2 is configured to be detachably attached to the installation portion 8a of the supporting mechanism 8.

[0024] The silicon substrate 13 is used as a base of the heat generating element 14. The silicon substrate 13 has a smooth surface, and the heat generating element 14 is provided on the smooth surface. A 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 an arithmetic mean roughness Ra specified in Japanese Industrial Standard JIS B 0601:2013. A thickness of the silicon substrate 13 is not particularly limited, and 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, a disc-shaped commercially available product is used, for example. The thickness of the silicon substrate 13 is not particularly limited, but is, for example, 1 mm or less. A thickness of the silicon oxide film 13a is not particularly limited, and is, for example, 3 nm to 100 nm. The silicon substrate 13 is not limited to the single-crystal silicon wafer having the silicon oxide film 13a, and for example, may be a single-crystal silicon wafer without a silicon oxide film.

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

[0027] The heat generating element 14 generates heat by occluding and discharging 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. A detailed configuration of the heat generating element 14 will be described later with reference to another drawing.

[0028] The heater 15 heats the heat generating element 14. The heater 15 increases a temperature in accordance with supplied electric power. A power supply that supplies electric power to the heater 15 is provided in, for example, the control unit 7. In the present embodiment, the heater 15 is a plate-shaped ceramic heater having a configuration in which a conductor is provided inside a base made of ceramics.

[0029] The temperature sensor 16 detects the temperature of the heat generating element 14. In the present embodiment, the temperature sensor 16 is a thermocouple built in the heater 15 and is configured to detect the temperature of the heat generating element 14 thorough the heater 15.(Heat Generating Element)

[0030] Next, a detailed structure of the heat generating element 14 will be described with reference to Figs. 3 and 4. As illustrated in Fig. 3, the heat generating element 14 has a stacked body 14a including the support 61 and the multilayer film 62.

[0031] The support 61 may have any configuration that allows the hydrogen-based gas to be occluded in the heat generating element 14 and discharged from the heat generating element 14, and is made of at least one of a porous body, a hydrogen permeable film, and a proton conductor. In this example, the support 61 is formed in a plate shape having a front surface and a back surface. The porous body has, for example, pores having a size that allows the hydrogen-based gas to pass therethrough. The porous body is made of, for example, a metal, a non-metal, or ceramics. The porous body is preferably made of a material that does not hinder a reaction (hereinafter, referred to as a heat generating reaction) between the hydrogen-based gas and the multilayer film 62. The hydrogen permeable film is made of, for example, a hydrogen storage metal or a hydrogen storage alloy. Examples of the hydrogen storage metal include Ni, Pd, V, Nb, Ta, and Ti. Examples of the hydrogen storage alloy include LaNi 5 , Ca 5 Cu, Mg 2 Zn, ZrNi 2 , ZrCr 2 , TiFe, TiCo, Mg 2 Ni, and Mg 2 Cu. The hydrogen permeable film includes a film having a mesh-like sheet. Examples of the proton conductor include a BaCeO 3 -based conductor (for example, Ba(Ce 0.95 Y 0.05 )O 3-δ ), a SrCeO 3 -based conductor (for example, Sr(Ce 0.95 Y 0.05 )O 3-δ ), a CaZrO 3 -based conductor (for example, CaZr 0.95 Y 0.05 O 3-α ), a SrZrO 3 -based conductor (for example, SrZr 0.9 Y 0.1 O 3-α ), β Al 2 O 3 , and β Ga 2 O 3 .

[0032] As illustrated in Fig. 4, the multilayer film 62 is provided on the support 61. The multilayer film 62 has 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 or a hydrogen storage alloy different from that of the first layer 71, or ceramics. A heterogeneous material interface 73 to be 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 surface (for example, the front surface) of the support 61. The first layer 71 and the second layer 72 each have five layers. The number of layers of each of the first layer 71 and the second layer 72 may be changed as appropriate. The multilayer film 62 may be formed by alternately stacking the second layer 72 and the first layer 71 in this order on the front 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 heterogeneous material interfaces 73. As illustrated in Fig. 2, when the first layer 71 and the second layer 72 are alternately stacked in this order on the front surface of the support 61, the heterogeneous material interface 73 is also formed between the first layer 71 and the support 61. Although not illustrated, when the second layer 72 and the first layer 71 are alternately stacked in this order on the front surface of the support 61, the heterogeneous material interface 73 is also formed between the second layer 72 and the support 61.

[0033] The first layer 71 is made of, for example, any one of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, and an alloy thereof. An alloy for forming the first layer 71 is preferably an alloy made of two or more of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy for 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, and Ta.

[0034] The second layer 72 is made of, for example, any one of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, an alloy thereof, and SiC. An alloy for forming the second layer 72 is preferably an alloy made of two or more of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy for 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, and Ta.

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

[0036] As illustrated in Fig. 5, hydrogen atoms permeate through the heterogeneous material interface 73. Fig. 5 is a schematic diagram illustrating a state in which hydrogen atoms in a metal lattice of the first layer 71 permeate through the heterogeneous material interface 73 and move to a metal lattice of the second layer 72 in the first layer 71 and the second layer 72 each made of a hydrogen storage metal having a face-centered cubic structure. It is known that hydrogen is light and performs quantum diffusion while hopping in hydrogen-occupied sites (octahedral sites or tetrahedral sites) of substance A and substance B. Therefore, hydrogen occluded in the heat generating element 14 performs quantum diffusion while hopping in the multilayer film 62. In the heat generating element 14, hydrogen permeates through the first layer 71, the heterogeneous material interface 73, and the second layer 72 in a manner of quantum diffusion.

[0037] A thickness of each of the first layer 71 and the second layer 72 is preferably less than 1000 nm. When the thickness of each of the first layer 71 and the second layer 72 is 1000 nm or more, hydrogen is less likely to permeate through the multilayer film 62. When the thickness of each of the first layer 71 and the second layer 72 is less than 1000 nm, a nano-structure that does not exhibit a bulk property can be maintained. The thickness of each of the first layer 71 and the second layer 72 is more preferably less than 500 nm. When the thickness of each of the first layer 71 and the second layer 72 is less than 500 nm, a nano-structure that does not exhibit a bulk property at all can be maintained.

[0038] An example of a method for manufacturing the heat generating element 14 will be described. In this case, the plate-shaped support 61 is prepared, an evaporation device is used to make a hydrogen storage metal or a hydrogen storage alloy for forming the first layer 71 or the second layer 72 into a gas phase state, and then the first layer 71 and the second layer 72 are alternately formed on the front surface of the support 61 by aggregation or adsorption. Accordingly, the stacked body 14a having the multilayer film 62 on the front surface of the support 61 is formed. The first layer 71 and the second layer 72 are preferably formed continuously in a vacuum state. Accordingly, between the first layer 71 and the second layer 72, no natural oxide film is formed and only the heterogeneous material interface 73 is formed. The evaporation device may use a physical evaporation device in which the hydrogen storage metal or the hydrogen storage alloy is evaporated by a physical method. The physical evaporation device is preferably a sputtering device, a vacuum evaporation device, and a chemical vapor deposition (CVD) device. The hydrogen storage metal or the hydrogen storage alloy may be deposited on the front surface of the support 61 by an electroplating method, and the first layer 71 and the second layer 72 may be alternately formed.

[0039] The heat generating element 14 is provided on the smooth surface of the silicon substrate 13 that serves as the base as described above. Therefore, the support 61 is formed on the smooth surface of the silicon substrate 13, and the multilayer film 62 is formed on the support 61, so that the smooth heterogeneous material interface 73 can be formed.

[0040] The support 61 functions as a hydrogen storage layer that stores hydrogen. A thickness of the support 61 is set in advance 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 the present embodiment, the support 61 is made of Pd. The thickness of the support 61 is 20 nm. The multilayer film 62 includes the first layer 71 made of Cu and the second layer 72 made of Ni. The first layer 71 and the second layer 72 each have six layers. The thickness of the first layer 71 is 2 nm. The thickness of the second layer 72 is 14 nm.

[0042] In the present embodiment, the heat generating device 1 includes the heat generating element 14, and may include a heat generating element having a configuration different from that of the heat generating element 14. A first modification will be described with reference to Fig. 6, and a second modification will be described with reference to Fig. 7.[First Modification]

[0043] The heat generating device 1 includes a heat generating element 75 illustrated in Fig. 6 instead of the heat generating element 14. In the heat generating element 75 as illustrated in Fig. 6, the multilayer film 62 of the stacked body further has a third layer 77 in addition to the first layer 71 and the second layer 72. The third layer 77 is made of a hydrogen storage metal, a hydrogen storage alloy, or ceramics different from the first layer 71 and the second layer 72. A 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 front surface of the support 61 in order of the first layer 71, the second layer 72, the first layer 71, and the third layer 77. The first layer 71, the second layer 72, and the third layer 77 may be stacked on the front surface of the support 61 in order of the first layer 71, the third layer 77, the first layer 71, and the second layer 72. That is, the multilayer film 62 has a stacking structure in which the first layer 71 is provided between the second layer 72 and the third layer 77. The multilayer film 62 preferably has one or more third layers 77. Similar to the heterogeneous material interface 73, the hydrogen atoms permeate through a heterogeneous material interface 78 formed between the first layer 71 and the third layer 77.

[0044] The third layer 77 is made of, for example, any one of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, an alloy thereof, SiC, CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO. The alloy for forming the third layer 77 is preferably an alloy made of two or more of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy for forming the third layer 77 may be an alloy obtained by adding an additive element to Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta.

[0045] In particular, the third layer 77 is preferably made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO. In the heat generating element 75 having the third layer 77 made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO, an occluding amount of hydrogen is increased, an amount of hydrogen permeating through the heterogeneous material interface 73 and the heterogeneous material interface 78 is increased, and a high output of excess heat can be achieved. The thickness of the third layer 77 made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO is preferably 10 nm or less. Accordingly, the hydrogen atoms easily permeate through the multilayer film 62. The third layer 77 made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO may not be formed into a complete film shape and may be formed into an island shape. The first layer 71 and the third layer 77 are preferably formed continuously in a vacuum state. Accordingly, between the first layer 71 and the third layer 77, no natural oxide film is formed and only the heterogeneous material interface 78 is formed.

[0046] A combination of the first layer 71, the second layer 72, and the third layer 77 is preferably Pd-CaO-Ni, Pd-Y 2 O 3 -Ni, Pd-TiC-Ni, Pd-LaB 6 -Ni, Ni-CaO-Cu, Ni-Y 2 O 3 -Cu, Ni-TiC-Cu, Ni-LaB 6 -Cu, Ni-Co-Cu, Ni-CaO-Cr, Ni-Y 2 O 3 -Cr, Ni-TiC-Cr, Ni-LaB 6 -Cr, Ni-CaO-Fe, Ni-Y 2 O 3 -Fe, Ni-TiC-Fe, Ni-LaB 6 -Fe, Ni-Cr-Fe, Ni-CaO-Mg, Ni-Y 2 O 3 -Mg, Ni-TiC-Mg, Ni-LaB 6 -Mg, Ni-CaO-Co, Ni-Y 2 O 3 -Co, Ni-TiC-Co, Ni-LaB 6 -Co, Ni-CaO-SiC, Ni-Y 2 O 3 -SiC, Ni-TiC-SiC, and Ni-LaB 6 -SiC when types of elements are expressed as "first layer 71-third layer 77-second layer 72".

[0047] Similar to the heat generating element 14, the heat generating element 75 is provided on the smooth surface of the silicon substrate 13 that serves as the base. Therefore, the support 61 is formed on the smooth surface of the silicon substrate 13, and the multilayer film 62 is formed on the support 61, so that the smooth heterogeneous material interface 73 and the smooth heterogeneous material interface 78 can be formed.[Second Modification]

[0048] The heat generating device 1 includes a heat generating element 80 illustrated in Fig. 7 instead of the heat generating element 14. In the heat generating element 80 as illustrated in Fig. 7, the multilayer film 62 of the stacked body further has 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 made of a hydrogen storage metal, a hydrogen storage alloy, or ceramics different from the first layer 71, the second layer 72, and the third layer 77. A 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 front surface of the support 61 in order of the first layer 71, the second layer 72, the first layer 71, the third layer 77, the first layer 71, and the fourth layer 82. The first layer 71, the second layer 72, the third layer 77, and the fourth layer 82 may be stacked on the front surface of the support 61 in order of the first layer 71, the fourth layer 82, the first layer 71, the third layer 77, the first layer 71, and the second layer 72. That is, the multilayer film 62 has a stacking structure in which the second layer 72, the third layer 77, and the fourth layer 82 are stacked in any order and the first layer 71 is provided between the second layer 72 and the third layer 77, between the third layer 77 and the fourth layer 82, and between the second layer 72 and the fourth layer 82. The multilayer film 62 preferably has one or more fourth layers 82. Similar to the heterogeneous material interface 73 and the heterogeneous material interface 78, the hydrogen atoms permeate through a heterogeneous material interface 83 formed between the first layer 71 and the fourth layer 82.

[0049] The fourth layer 82 is made of, for example, any one of Ti, V, Ni, Pd, Cu, Mn, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, Ta, an alloy thereof, SiC, CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO. The alloy for forming the fourth layer 82 is preferably an alloy made of two or more of Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta. The alloy for forming the fourth layer 82 may be an alloy obtained by adding an additive element to Ti, V, Ni, Pd, Cu, Cr, Fe, Mg, Co, Ca, Zr, Nb, Mo, and Ta.

[0050] In particular, the fourth layer 82 is preferably made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO. In the heat generating element 80 having the fourth layer 82 made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO, an occluding amount of hydrogen is increased, an amount of hydrogen permeating through the heterogeneous material interface 73, the heterogeneous material interface 78, and the heterogeneous material interface 83 is increased, and a high output of excess heat can be achieved. A thickness of the fourth layer 82 made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO is preferably 10 nm or less. Accordingly, the hydrogen atoms easily permeate through the multilayer film 62. The fourth layer 82 made of any one of CaO, Y 2 O 3 , TiC, LaB 6 , SrO, and BaO may not be formed into a complete film shape and may be formed into an island shape. The first layer 71 and the fourth layer 82 are preferably formed continuously in a vacuum state. Accordingly, between the first layer 71 and the fourth layer 82, no natural oxide film is formed and only the heterogeneous material interface 83 is formed.

[0051] A combination of the first layer 71, the second layer 72, the third layer 77, and the fourth layer 82 is preferably Ni-CaO-Cr-Fe, Ni-Y 2 O 3 -Cr-Fe, Ni-TiC-Cr-Fe, and Ni-LaB 6 -Cr-Fe when types of elements are expressed as "first layer 71-fourth layer 82-third layer 77-second layer 72".

[0052] Similar to the heat generating element 14, the heat generating element 80 is provided on the smooth surface of the silicon substrate 13 that serves as the base. Therefore, the support 61 is formed on the smooth surface of the silicon substrate 13, and the multilayer film 62 is formed on the support 61, so that the smooth heterogeneous material interface 73, the smooth heterogeneous material interface 78, and the smooth heterogeneous material interface 83 can be formed.

[0053] As the heat generating element including a plurality of layers, two or more of the heat generating element 14 illustrated in Fig. 4, the heat generating element 75 illustrated in Fig. 6, and the heat generating element 80 illustrated in Fig. 7 may be mixed and used. The heat generating elements having a plurality of layer configurations may be arranged in any order. A configuration of the multilayer film 62 such as a ratio of layer thicknesses, the number of layers of each layer, and a material may be appropriately changed according to a temperature to be used.(Operation and Effect)

[0054] In the heat generating device 1 configured as described above, the sealed container 3 is opened, and the heat generating structure 2 is installed on the installation portion 8a of the supporting mechanism 8 provided inside the sealed container 3. The sealed container 3 is sealed, and the pump of the vacuum evacuation 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 heater 15 increases the temperature of the heat generating element 14 to approximately 200°C, thereby removing moisture from the heat generating element 14.

[0055] An output of the heater 15 is increased, and the heat generating element 14 is further heated. For example, the heater 15 increases the temperature of the heat generating element 14 to approximately 300°C. The pump of the supply unit 4 is driven, and the hydrogen-based gas stored in the tank (not illustrated) flows through the pipe 4a and is introduced into the sealed container 3. Accordingly, hydrogen is occluded into the support 61 and the multilayer film 62 of the heat generating element 14. The hydrogen-based gas may use, for example, a mixed gas containing H 2 and Ar (3% H 2 / Ar gas). After hydrogen is occluded into the heat generating element 14, the driving of the supply unit 4 is stopped. The output of the heater 15 is controlled to set the temperature of the heat generating element 14 to any temperature within an optimum temperature range for heat generation (for example, approximately 700°C), and the heat generating element 14 is heated. As the heat generating element 14 is heated, the pump of the vacuum evacuation unit 6 is driven, and the hydrogen-based gas inside the sealed container 3 flows through the pipe 6a and is discharged. Accordingly, the heat generating element 14 enters a state of generating heat (hereinafter, referred to as the "heat generating state"). That is, hydrogen occluded in the support 61 and the multilayer film 62 of the heat generating element 14 penetrates through the heterogeneous material interface 73 in a manner of quantum diffusion, or hydrogen diffuses through the heterogeneous material interface 73 in a manner of quantum diffusion, thereby generating excess heat in the heat generating element 14.

[0056] In a state in which the vacuum evacuation unit 6 continues to perform vacuum exhaust, hydrogen occluded in the heat generating element 14 is gradually released (discharged). Therefore, if the heat generating element 14 continues the heat generating state for a long period of time, the driving of the vacuum evacuation unit 6 is stopped, and the supply unit 4 is driven to introduce the hydrogen-based gas into the sealed container 3, thereby causing the heat generating 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. In this case, the output of the heater 15 is controlled to maintain the temperature of the heat generating element 14 within the optimum temperature range for heat generation. After the heat generating element 14 occludes hydrogen, the driving of the supply unit 4 is stopped and the vacuum evacuation unit 6 is driven, so that the heat generating element 14 can continue the heat generating state.

[0057] Fig. 8 is a diagram illustrating a heat generating method. In Fig. 8, the heater 15 and the temperature sensor 16 of the heat generating structure 2 are omitted. The hydrogen-based gas is introduced into the sealed container 3, so that hydrogen molecules are adsorbed onto a surface (a surface opposite to the support 61) of the multilayer film 62 of the heat generating element 14, and each of the hydrogen molecules is dissociated into two hydrogen atoms. The hydrogen atoms obtained by dissociation penetrate (are occluded) into the multilayer film 62 and the support 61. In this case, the hydrogen atoms penetrating into the multilayer film 62 and the support 61 do not penetrate into the silicon substrate 13. When the hydrogen-based gas inside the sealed container 3 is discharged, the hydrogen atoms penetrating the multilayer film 62 and the support 61 return to the surface of the multilayer film 62, and are recombined to be released as the hydrogen molecules. As a result, the hydrogen atoms penetrate the heterogeneous material interface 73 (see Fig. 5) in a manner of quantum diffusion, or alternatively, the hydrogen atoms diffuse through the heterogeneous material interface 73 in a manner of quantum diffusion, the temperature in the heat generating element 14 is increased to a temperature equal to or higher than a heating temperature of the heater 15, and excess heat can be generated.

[0058] According to the heat generating structure 2 of the present embodiment, the heat generating element 14 is provided on the silicon substrate 13 that serves as the base, so that the smooth heterogeneous material interface 73 is formed, and stability and controllability of heat generation by the heat generating element 14 can be improved.

[0059] The heat generating structure 2 can be easily produced at a low cost because the silicon substrate 13 may use a commercially available single-crystal silicon wafer having the silicon oxide film 13a. By using a single-crystal silicon wafer with a large diameter as the silicon substrate 13 and providing the heat generating element 14 with a large diameter on the surface thereof, higher output can be achieved.

[0060] In the heat generating structure 2, the purity of the silicon substrate 13 is 99.99999% or higher, so that contamination and alteration of the heterogeneous material interface 73 caused by impurities contained in the silicon substrate 13 are prevented, and the stability and the controllability of heat generation by the heat generating element 14 can be further improved.

[0061] The heat generating structure 2 has the configuration in which the silicon substrate 13, the heat generating element 14, the heater 15, and the temperature sensor 16 are unitized. Therefore, the number of heat generating structures 2 installed in the heat generating device 1 can be easily increased or decreased, and a degree of design flexibility of the heat generating device 1 can be improved.

[0062] According to the heat generating device 1 of the present embodiment, the heat generating structure 2 described above is included, so that the stability and the controllability of the heat generation by the heat generating element 14 can be improved.

[0063] In the heat generating device 1, when a temperature T of the heat generating element 14 reaches a critical temperature Tc, a chemical reaction or alloying reaction occurs between the metal constituting the first layer 71, the metal constituting the second layer 72, and the metal constituting the support 61, and crystallites of a ternary alloy with different alloy concentrations (alloy compositions) are formed. The critical temperature Tc is a temperature at which the metal constituting the support 61, the metal constituting the first layer 71, and the metal constituting the second layer 72 are alloyed, and is also referred to as an alloying reaction start 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 heat generating element 14 reaches the critical temperature Tc (500°C), crystallites of a ternary alloy (Pd-Ni-Cu alloy) are formed.

[0064] Fig. 9 is a diagram illustrating a state in which crystallites of a ternary alloy are formed. As illustrated in Fig. 9, if a condition of T = Tc is satisfied, the metal constituting the first layer 71, the metal constituting the second layer 72, and the metal constituting the support 61 in the heat generating element 14 are alloyed, and crystallites 90 of a ternary alloy with different alloy concentrations are formed. In Fig. 9, differences in the alloy concentrations of the crystallites 90 are represented by different types of hatching. A heterogeneous material interface 91 different from the heterogeneous material interface 73 is formed between the crystallites 90 of the ternary alloy with different alloy concentrations. Here, for convenience, the formation of the heterogeneous material interface 91 different from the heterogeneous material interface 73 is referred to as "alteration of the heterogeneous material interface". The silicon atoms constituting the silicon substrate 13 do not diffuse or penetrate into the support 61 or the multilayer film 62 (first layer 71 and second layer 72). Since the silicon substrate 13 has a high purity, impurity elements in the silicon substrate 13 do not segregate in the support 61 or the multilayer film 62.

[0065] When the thickness of the support 61 is approximately the same as or slightly larger than the thickness of the multilayer film 62, after the crystallites 90 of the ternary alloy are formed, the metal constituting the support 61 does not further diffuse into the crystallites 90 of the ternary alloy. Although the alloying reaction causes the alteration of the heterogeneous material interface, the reduction (also known as dilution) of the heterogeneous material interface is prevented. In the heat generating device 1, although the heterogeneous material interface is altered, the heterogeneous material interface 91 is formed, and thus hydrogen atoms can penetrate through the heterogeneous material interface 91 in a manner of quantum diffusion, or hydrogen atoms can diffuse through the heterogeneous material interface 91 in a manner of quantum diffusion, and excess heat at a temperature equal to or higher than the heating temperature can be generated in the heat generating element 14.

[0066] In the present embodiment, the thickness of the support 61 is approximately the same as or slightly larger than the thickness of the multilayer film 62, but if the thickness of the support is, for example, three or more orders of magnitude with respect to the thickness of the multilayer film, the heterogeneous material interface may be further altered and reduced when the temperature T of the heat generating element exceeds the critical temperature Tc. Hereinafter, as a comparative example of a heat generating element, a case where a thickness of a support is, for example, three orders or more of magnitude with respect to the thickness of the multilayer film will be described.

[0067] The alteration and reduction of the heterogeneous material interface will be described with reference to Fig. 10. (a) of Fig. 10 illustrates a state in which the temperature T of the heat generating element is below the critical temperature Tc. (b) of Fig. 10 illustrates a state in which the temperature T of the heat generating element reaches the critical temperature Tc. (c) of Fig. 10 illustrates a state in which the temperature T of the heat generating element exceeds the critical temperature Tc.

[0068] As illustrated in (a) of Fig. 10, a heat generating element 214 includes 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 heterogeneous material interface 273 is formed between the first layer 271 and the second layer 272. A thickness of the support 261 is, for example, three orders or more of magnitude with respect to a thickness of the multilayer film 262. In the state shown in (a) of Fig. 10, the heterogeneous material interface 273 does not alter. Therefore, the heat generating element 214 can generate heat as designed.

[0069] As illustrated in (b) of Fig. 10, when a temperature T of the heat generating element 214 reaches the critical temperature Tc, a metal constituting the support 261, a metal constituting the first layer 271, and a metal constituting the second layer 272 are alloyed, and crystallites 290 of a ternary alloy with different alloy concentrations are formed. A heterogeneous material interface 291 different from the heterogeneous material interface 273 is formed between the crystallites 290 of the ternary alloy with different alloy concentrations. That is, the heterogeneous material interface is altered. In the state illustrated in (b) of Fig. 10, the heterogeneous material interface 291 is ultimately formed, and thus the heat generating element 214 can generate heat as designed.

[0070] As illustrated in (c) of Fig. 10, in the state in which the temperature T of the heat generating element 214 exceeds the critical temperature Tc, diffusion and penetration of the metal constituting the support 261 into the crystallites 290 of the ternary alloy progresses. As a result, the number of crystallites in which a ratio of the metal constituting the support 261 is close to 100% increases, and the heterogeneous material interface 291 is reduced. In the state illustrated in (c) of Fig. 10, the heterogeneous material interface 291 is reduced, thereby heat generated in the heat generating element 214 is decreased.(Another Embodiment)

[0071] In the above embodiments, the heat generating device 1 including one heat generating structure 2 has been described, but the present invention is not limited thereto.

[0072] Fig. 11 is a diagram illustrating a configuration of a heat generating device 100 according to another embodiment. The same or equivalent components and members as those of the above embodiments are denoted by the same reference numerals. Descriptions overlapping with the above embodiments will be omitted as appropriate, and configurations different from the above embodiments will be mainly described.

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

[0074] The supporting mechanism 108 is provided inside the sealed container 3, and supports the heat generating structures 2. The supporting mechanism 108 includes three installation portions 108a on which the three heat generating structures 2 are respectively installed, and supporting column portions 108b that fix the three installation portions 108a to the sealed container 3. The three installation portions 108a are located at different heights and are fixed to supporting column portions 108b. The supporting column portions 108b are fixed to the upper portion 3a and the bottom portion 3b of the sealed container 3.

[0075] Similar to the embodiment described above, the heat generating device 100 includes the heat generating structure 2, so that the stability and the controllability of the heat generation by the heat generating element 14 can be improved. The heat generating device 100 includes a plurality of heat generating structures 2, so that higher output can be achieved.

[0076] The present invention is not limited to the above embodiment, and can be modified as appropriate without departing from the scope of the present 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 unitized, but the present invention is not limited thereto. The heat generating structure 2 may include 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 supporting mechanism 8, and the heat generating structure 2 including the silicon substrate 13 and the heat generating element 14 may be detachably attached to the heater 15. In this case, for example, when replacing the heat generating structure 2 with another heat generating structure, the heater 15 and the temperature sensor 16 can be left on the installation portion 8a of the supporting mechanism 8, and only the heat generating structure 2 can be replaced.

[0078] In Fig. 5, the crystal structure of the hydrogen storage metal is described as the face-centered cubic structure, but the crystal structure is not limited to the face-centered cubic structure, and may be 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.Reference Sign List

[0080] 1heat generating device 2heat generating structure 3sealed container 4supply unit 4apipe 4bon-off valve 5discharge unit 5apipe 5bon-off valve 6vacuum evacuation unit 6apipe 6bon-off valve 7control unit 8supporting mechanism 8ainstallation portion 8bsupporting column portion 13silicon substrate 13asilicon oxide film 14heat generating element 14astacked body 15heater 16temperature sensor 61support 62multilayer film 71first layer 72second layer 73heterogeneous material interface 75heat generating element 77third layer 78heterogeneous material interface 80heat generating element 82fourth layer 83heterogeneous material interface 100heat generating device 108supporting mechanism 108ainstallation portion 108bsupporting column portion

Claims

1. A heat generating structure comprising: a silicon substrate; and a heat generating element that generates heat by occluding and discharging hydrogen, wherein the heat generating element includes a support provided on the silicon substrate, and a multilayer film provided on the support, the support is made of at least one of a porous body, a hydrogen permeable film, and a proton conductor, and the multilayer film includes a first layer that is made of a hydrogen storage metal or a hydrogen storage alloy and has a thickness of less than 1000 nm, and a second layer that is made of a hydrogen storage metal or a hydrogen storage alloy, which is different from that of the first layer, or ceramics and has a thickness of less than 1000 nm.

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 a purity of the silicon substrate is 99.99999% or higher.

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

5. A heat generating device comprising: the heat generating structure according to any one of claims 1 to 4; a sealed container that houses the heat generating structure; a supply unit that supplies a hydrogen-based gas containing the hydrogen into the sealed container; and a discharge unit that discharges the hydrogen-based gas inside the sealed container.

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