Heating accelerator, metal heating method, and metal solid manufacturing method

Abstract

A heating accelerator for accelerating the heating of a metal, the heating accelerator containing an absorption material that absorbs microwaves and not containing at least either uncarbonized organic substances or liquids.

Description

Heating accelerator, metal heating method, and method for producing metal solid

[0001] Some aspects of the present invention relate to heating promoters, methods for heating metals, and methods for producing metal solids.

[0002] When heating a metal by irradiating it with microwaves, it has been proposed to surround the metal with a material having a higher melting point than the metal (see, for example, Patent Documents 1 and 2).

[0003] International Publication No. WO 2022 / 195989 International Publication No. WO 2022 / 196681

[0004] An object of some aspects of the present invention is to provide a heating promoter capable of accelerating the heating of a metal, a method for heating a metal, and a method for producing a metal solid.

[0005] A heating promoter according to an embodiment of the present invention is a heating promoter for promoting heating of a metal, the heating promoter including an absorbing material and not including at least one of an uncarbonized organic material and a liquid. The absorbing material may absorb microwaves in a temperature range at least partly lower than the temperature range in which the metal to be heated absorbs microwaves.

[0006] In the above heating promoter, the liquid may be water or oil.

[0007] The heating accelerator may further contain an inorganic binder.

[0008] In the heating promoter, the absorbing material may include a carbon material.

[0009] In the heating accelerator, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0010] The heating promoter may further include a heat insulating material, which may have a lower microwave absorption rate than the metal to be heated.

[0011] In the heating promoter, the heat insulating material may include an oxide.

[0012] In the heating accelerator, the heat insulating material may include at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

[0013] In the heating accelerator, the metal to be heated may include at least one selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0014] In the heating accelerator, the metal to be heated may contain at least one compound selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0015] In the heating accelerator, the metal to be heated may contain an alloy component.

[0016] In the above-mentioned heating promoter, the alloy component may include at least one selected from the group consisting of silicon, manganese, chromium, nickel, carbon, boron, copper, aluminum, titanium, niobium, vanadium, zinc, and sulfur.

[0017] A method for heating a metal according to an embodiment of the present invention includes irradiating a heating promoter and the metal with microwaves to heat the metal, wherein the heating promoter includes an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal absorbs microwaves, and the heating promoter does not include at least either uncarbonized organic matter or liquid.

[0018] In the above-described method for heating a metal, the liquid may be water or oil.

[0019] In the above-described method for heating a metal, the metal may be in contact with at least a portion of the heating promoter while the metal is being irradiated with microwaves.

[0020] In the above-described method for heating a metal, the heating promoter may further contain an inorganic binder.

[0021] In the above-described method for heating a metal, the absorbing material contained in the heating promoter may contain a carbon material.

[0022] In the above-described method for heating a metal, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0023] In the above-described method for heating a metal, the heating promoter may further contain a heat insulating material that absorbs microwaves to a lesser extent than the metal to be heated.

[0024] In the above-described method for heating a metal, the heat insulating material may contain an oxide.

[0025] In the above-described method for heating a metal, the heat insulating material may contain at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

[0026] In the above-described method for heating a metal, the metal to be heated may contain at least one selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0027] In the above-described method for heating a metal, the metal to be heated may contain at least one compound selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0028] In the above-described method for heating a metal, the metal to be heated may contain an alloy component.

[0029] In the above-described method for heating a metal, the alloy component may include at least one selected from the group consisting of silicon, manganese, chromium, nickel, carbon, boron, copper, aluminum, titanium, niobium, vanadium, zinc, and sulfur.

[0030] In the above-described method for heating a metal, heating the metal may include reducing the metal.

[0031] The above-mentioned metal heating method may further include heating the heating promoter and removing at least one of uncarbonized organic matter and liquid from the heating promoter before irradiating the heating promoter and the metal with microwaves to heat the metal.

[0032] A method for producing a metal solid according to an embodiment of the present invention includes irradiating a heating promoter and a metal with microwaves to heat the metal and sinter or melt and solidify the metal, wherein the heating promoter includes an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal absorbs microwaves, and the heating promoter does not include at least either uncarbonized organic matter or liquid.

[0033] In the above method for producing a metal solid, the liquid may be water or oil.

[0034] In the above-described method for producing a metal solid, the metal may be in contact with at least a portion of the heating promoter while the metal is irradiated with microwaves.

[0035] In the above-mentioned method for producing a metal solid, the heating promoter may further contain an inorganic binder.

[0036] In the above-described method for producing a metal solid, the absorbing material contained in the heating promoter may contain a carbon material.

[0037] In the above-described method for producing a metal solid, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0038] In the above-described method for producing a metal solid, the heating promoter may further contain a heat insulating material that absorbs microwaves to a lesser extent than the metal to be heated.

[0039] In the above-described method for producing a metal solid, the heat insulating material may contain an oxide.

[0040] In the above-described method for producing a metal solid, the heat insulating material may contain at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

[0041] In the above-described method for producing a metal solid, the metal to be heated may contain at least one selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0042] In the above-described method for producing a metal solid, the metal to be heated may contain at least one compound selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0043] In the above-described method for producing a metal solid, the metal to be heated may contain an alloy component.

[0044] In the above-described method for producing a metal solid, the alloy component may include at least one selected from the group consisting of silicon, manganese, chromium, nickel, carbon, boron, copper, aluminum, titanium, niobium, vanadium, zinc, and sulfur.

[0045] In the above method for producing a metal solid, heating the metal may include reducing the metal.

[0046] The above-mentioned method for producing a metal solid may further include heating the heating promoter and removing at least one of uncarbonized organic matter and liquid from the heating promoter before irradiating the heating promoter and the metal with microwaves to heat the metal.

[0047] A heating promoter according to an embodiment of the present invention is a heating promoter for promoting heating of a metal, and includes an absorbing material and does not include at least one of a ferromagnetic material and water of crystallization. The absorbing material may absorb microwaves in a temperature range at least partly lower than the temperature range in which the metal to be heated absorbs microwaves.

[0048] In the heating accelerator, the ferromagnetic material may be iron or iron oxide.

[0049] In the heating promoter, the absorbing material may include a carbon material.

[0050] In the heating accelerator, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0051] The heating promoter may further include a heat insulating material, which may have a lower microwave absorption rate than the metal to be heated.

[0052] In the heating accelerator, the heat insulating material may contain an oxide other than iron oxide.

[0053] In the heating accelerator, the heat insulating material may include at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

[0054] In the heating accelerator, the metal to be heated may include at least one selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0055] In the heating accelerator, the metal to be heated may contain at least one compound selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0056] In the heating accelerator, the metal to be heated may contain an alloy component.

[0057] In the above-mentioned heating promoter, the alloy component may include at least one selected from the group consisting of silicon, manganese, chromium, nickel, carbon, boron, copper, aluminum, titanium, niobium, vanadium, zinc, and sulfur.

[0058] A method for heating a metal according to an embodiment of the present invention includes irradiating a heating promoter and the metal with microwaves to heat the metal, wherein the heating promoter includes an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal absorbs microwaves, and the heating promoter does not include at least one of a ferromagnetic material and water of crystallization.

[0059] In the above-described method for heating a metal, the ferromagnetic material may be iron or iron oxide.

[0060] In the above-described method for heating a metal, the metal may be in contact with at least a portion of the heating promoter while the metal is being irradiated with microwaves.

[0061] In the above-described method for heating a metal, the absorbing material contained in the heating promoter may contain a carbon material.

[0062] In the above-described method for heating a metal, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0063] In the above-described method for heating a metal, the heating promoter may further contain a heat insulating material that absorbs microwaves to a lesser extent than the metal to be heated.

[0064] In the above-described method for heating a metal, the heat insulating material may contain an oxide other than iron oxide.

[0065] In the above-described method for heating a metal, the heat insulating material may contain at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

[0066] In the above-described method for heating a metal, the metal to be heated may contain at least one selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0067] In the above-described method for heating a metal, the metal to be heated may contain at least one compound selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0068] In the above-described method for heating a metal, the metal to be heated may contain an alloy component.

[0069] In the above-described method for heating a metal, the alloy component may include at least one selected from the group consisting of silicon, manganese, chromium, nickel, carbon, boron, copper, aluminum, titanium, niobium, vanadium, zinc, and sulfur.

[0070] In the above-described method for heating a metal, heating the metal may include reducing the metal.

[0071] The above-mentioned metal heating method may further include heating the heating promoter and removing water of crystallization from the heating promoter before irradiating the heating promoter and the metal with microwaves to heat the metal.

[0072] A method for producing a metal solid according to an embodiment of the present invention includes irradiating a heating promoter and a metal with microwaves to heat the metal and sinter or melt and solidify the metal, wherein the heating promoter includes an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal absorbs microwaves, and the heating promoter does not include at least either a ferromagnetic material or water of crystallization.

[0073] In the above method for producing a metal solid, the ferromagnetic material may be iron or iron oxide.

[0074] In the above-described method for producing a metal solid, the metal may be in contact with at least a portion of the heating promoter while the metal is irradiated with microwaves.

[0075] In the above-described method for producing a metal solid, the absorbing material contained in the heating promoter may contain a carbon material.

[0076] In the above-described method for producing a metal solid, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0077] In the above-described method for producing a metal solid, the heating promoter may further contain a heat insulating material that absorbs microwaves to a lesser extent than the metal to be heated.

[0078] In the above-described method for producing a metal solid, the heat insulating material may contain an oxide other than iron oxide.

[0079] In the above-described method for producing a metal solid, the heat insulating material may contain at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

[0080] In the above-described method for producing a metal solid, the metal to be heated may contain at least one selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0081] In the above-described method for producing a metal solid, the metal to be heated may contain at least one compound selected from the group consisting of iron, nickel, copper, gold, silver, aluminum, and cobalt.

[0082] In the above-described method for producing a metal solid, the metal to be heated may contain an alloy component.

[0083] In the above-described method for producing a metal solid, the alloy component may include at least one selected from the group consisting of silicon, manganese, chromium, nickel, carbon, boron, copper, aluminum, titanium, niobium, vanadium, zinc, and sulfur.

[0084] In the above method for producing a metal solid, heating the metal may include reducing the metal.

[0085] The method for producing the metal solid may further include heating the heating promoter and removing water of crystallization from the heating promoter before irradiating the heating promoter and the metal with microwaves to heat the metal.

[0086] According to some aspects of the present invention, it is possible to provide a heating promoter capable of accelerating the heating of a metal, a method for heating a metal, and a method for producing a metal solid.

[0087] [Heat Accelerator Free of Uncarbonized Organic Matter and / or Liquid] The heat accelerator for accelerating the heating of metal according to the embodiment includes an absorbing material that absorbs microwaves in a temperature range at least partially lower than the temperature range in which the metal to be heated absorbs microwaves, and does not include uncarbonized organic matter and / or liquid. The microwaves are, for example, electromagnetic waves with a frequency of 300 MHz or higher and 30 GHz or lower. The liquid is not particularly limited, but may be, for example, water or oil. The heat accelerator may further include an insulating material that absorbs microwaves to a lesser extent than the metal to be heated. The heat accelerator may further include a reducing material that reduces the metal to be heated.

[0088] The heating promoter may be a powder or a molded body. A molded heating promoter may be obtained by solidifying a powdered absorbing material with a binder. A molded heating promoter may be obtained by solidifying a mixture of a powdered absorbing material and a heat insulating material with a binder. A molded heating promoter may be obtained by solidifying a mixture of a powdered absorbing material, a heat insulating material, and a reducing material with a binder. The heating promoter may be included in a heating promotion member having a structure. The structure of the heating promotion member containing the heating promoter according to this embodiment is not particularly limited.

[0089] The shape of the metal to be heated is not particularly limited. The metal may be a metal powder or an aggregate of metal pieces. The metal material to be heated may include a single metal or a metal compound such as an alloy. Examples of metals include iron (Fe), nickel (Ni), copper (Cu), gold (Au), silver (Ag), aluminum (Al), cobalt (Co), tungsten (W), titanium (Ti), chromium (Cr), molybdenum (Mo), beryllium (Be), magnesium (Mg), tin (Sn), cerium (Ce), lead (Pb), mercury (Hg), sodium (Na), bismuth (Bi), and gallium (Ga).

[0090] The sintering temperature of iron (Fe) is, for example, 1200°C. The melting point of iron (Fe) is 1538°C. The sintering temperature of nickel (Ni) is, for example, 1200°C. The melting point of nickel (Ni) is 1495°C. The sintering temperature of copper (Cu) is, for example, 800°C. The melting point of copper (Cu) is 1085°C. The sintering temperature of gold (Au) is, for example, 800°C. The melting point of gold (Au) is 1064°C. The sintering temperature of silver (Ag) is, for example, 750°C. The melting point of silver (Ag) is 962°C. The sintering temperature of aluminum (Al) is, for example, 500°C. The melting point of aluminum (Al) is 660°C. The sintering temperature of cobalt (Co) is, for example, 1100°C. The melting point of cobalt (Co) is 1455°C.

[0091] The metal material to be heated may contain one type of metal or multiple types of metals. Examples of metal compounds include, but are not limited to, alloys of multiple metal elements, alloys of metal elements and non-metal elements, metal oxides, metal hydroxides, metal chlorides, metal carbides, metal borides, and metal sulfides. The metal may contain, as alloy components, for example, silicon (Si), manganese (Mn), chromium (Cr), nickel (Ni), carbon (C), boron (B), copper (Cu), aluminum (Al), titanium (Ti), niobium (Nb), vanadium (V), zinc (Zn), antimony (Sb), palladium (Pd), lanthanum (La), gold (Au), potassium (K), cadmium (Cd), indium (In), molybdenum (Mo), and sulfur (S). The metal material preferably has better microwave absorption characteristics than the heating promoter. This makes the metal more easily heated by microwaves than the heating promoter.

[0092] The metal to be heated may be a molded body of multiple metal pieces. The metal pieces may be, for example, metal slices, metal fragments, metal chips, metal swarf, or metal powder. For example, a molded metal body may be produced by filling multiple metal pieces into a mold and applying pressure to the multiple metal pieces. The molded body may be a briquette. The molded body may be disk-shaped, but is not limited to this. The pressure applied to the multiple metal pieces is not limited, but is, for example, 1 MPa or more, 100 MPa or more, or 200 MPa or more, and 2000 MPa or less, 1900 MPa or less, or 1800 MPa or less. By applying pressure, the metal solid produced by sintering or melt-solidifying with microwave irradiation tends to become dense. Pressurizing methods include uniaxial molding, cold isostatic pressing (CIP) molding, hot isostatic pressing (HIP) molding, and roller pressing.

[0093] The absorbing material contained in the heating promoter absorbs microwaves in, for example, a temperature range at least partially lower than the temperature range in which the metal to be heated absorbs microwaves. The absorbing material has a melting point higher than the melting point of the metal to be heated. At least a portion of the temperature range in which the absorbing material absorbs microwaves is lower than the temperature range in which the metal to be heated absorbs microwaves. The temperature range in which the metal to be heated absorbs microwaves is, for example, 300°C or higher and 1200°C or lower, 450°C or higher and 1100°C or lower, or 600°C or higher and 800°C or lower. The temperature range in which the absorbing material absorbs microwaves is, for example, 100°C or higher and 1000°C or lower, 250°C or higher and 900°C or lower, or 400°C or higher and 600°C or lower.

[0094] It is preferable that at least a portion of the temperature range in which the absorbing material absorbs microwaves overlaps with the temperature range in which the metal to be heated absorbs microwaves. The absorbing material absorbs microwaves in at least a portion of a temperature range lower than the temperature range in which the metal to be heated absorbs microwaves, and thus generates heat faster than the metal to be heated. Therefore, the absorbing material can heat the metal to be heated before the temperature range in which the metal to be heated absorbs microwaves is reached. Therefore, when the heating promoter contains an absorbing material, the temperature of the metal to be heated reaches the temperature range in which microwaves are absorbed more quickly, and the heating time of the metal to be heated can be shortened. Furthermore, because the absorbing material absorbs microwaves in at least a portion of a temperature range lower than the temperature range in which the metal to be heated absorbs microwaves, it is possible to prevent the heating promoter from being heated more than necessary. Therefore, when the heating promoter has a fixed shape, the shape of the heating promoter can be stable even while the metal to be heated is being heated by microwave irradiation.

[0095] The absorbing material includes, for example, a carbon material. Examples of carbon materials include, but are not limited to, carbon black, amorphous carbon, graphite, silicon carbide, carbon resin, and metal carbide. The absorbing material may include a metal, metal nitride, metal oxide, metal boride, or the like that absorbs microwaves in a temperature range at least partially lower than the temperature range in which the metal to be heated absorbs microwaves. The absorbing material may also be a compound of these. It is preferable that the absorbing material does not contain volatile components. By not containing volatile components in the absorbing material, it is possible to prevent microwaves from being absorbed by the volatile components.

[0096] The heating promoter may further include an insulating material that absorbs microwaves to a lesser extent than the metal to be heated. The insulating material, for example, has higher microwave transparency than the metal to be heated and absorbs microwaves to a lesser extent than the metal to be heated. The insulating material has a melting point higher than the melting point of the metal. Because the insulating material has a low microwave absorption rate, it generates less heat even when irradiated with microwaves, thereby exhibiting an insulating effect. Furthermore, because the insulating material has a higher melting point than the metal, its shape remains stable even when irradiated with microwaves. Therefore, when the heating promoter has a fixed shape, the shape of the heating promoter including the insulating material can remain stable even while the metal irradiated with microwaves is being heated.

[0097] The thermal insulating material may include a metal oxide or a metalloid oxide. Examples of metal and metalloid oxides include, but are not limited to, aluminum oxide (Al2O3), silicon oxide (SiO2), magnesium oxide (MgO), zirconium oxide (ZrO2), and titanium oxide (TiO2). For example, the melting point of aluminum oxide (Al2O3) is 2072°C. The melting point of silicon oxide (SiO2) is 1710°C. The melting point of magnesium oxide (MgO) is 2852°C. The thermal insulating material may be a compound of these.

[0098] The mixture containing the insulating material and the absorbent material may further contain a reducing material that reduces the metal to be heated. The reducing material has a melting point higher than the melting point of the metal to be heated. Examples of reducing materials include carbon and silicon carbide. A carbon material used as an absorbent material may also function as a reducing material.

[0099] The insulating material, the absorbing material, and the reducing material may have overlapping properties and functions. For example, a carbon material functions both as an absorbing material and as a reducing material. When the heating promoter contains an insulating material and an absorbing material, it is preferable that the insulating material and the absorbing material are uniformly distributed in the heating promoter. The heating promoter may contain a mixture of an insulating material and an absorbing material. Furthermore, when the heating promoter contains an insulating material, an absorbing material, and a reducing material, it is preferable that the insulating material, the absorbing material, and the reducing material are uniformly distributed in the heating promoter. The heating promoter may contain a mixture of an insulating material, an absorbing material, and a reducing material.

[0100] In the heating promoter, the mass ratio of the insulating material to the absorbing material is preferably 1:1, or the mass ratio of the insulating material is greater than the mass ratio of the absorbing material. For example, the mass ratio of the absorbing material in the heating promoter is 1 mass% or more, 2 mass% or more, or 5 mass% or more, and 90 mass% or less, 80 mass% or less, 70 mass% or less, 50 mass% or less, 40 mass% or less, 30 mass% or less, 20 mass% or less, or 10 mass% or less. By setting the mass ratio of the absorbing material in the heating promoter to 90 mass% or less, it is possible to ensure the microwave transparency of the heating promoter and to appropriately heat the metal to be heated.

[0101] Heating the metal may be carried out in an inert gas atmosphere. Examples of inert gases include argon (Ar) and helium (He). Heating the metal may also be carried out in a neutral gas atmosphere. Examples of neutral gases include nitrogen (N), dry hydrogen (H), and ammonia (NH). Heating the metal may also be carried out in a reducing atmosphere. Examples of reducing gases that provide a reducing atmosphere include hydrogen (H), carbon monoxide (CO), and hydrocarbon gases (CH, CH, CH). 10 etc.)

[0102] Furthermore, if the metal to be heated is mixed with a non-metal, the non-metal is vaporized or liquefied and removed by irradiating microwaves. Examples of non-metals include, but are not limited to, release agents, coolant liquids, oils, organic substances, and water. In this disclosure, "mixing" includes adhesion due to mixing and adjacency without adhesion due to mixing. In this disclosure, "mixing" also includes a state in which a different material is contained within a certain material. Non-metals may be silicon, oxygen, and fluorine.

[0103] While the metal to be heated and the heating promoter are irradiated with microwaves, at least a portion of the metal to be heated may be in contact with the heating promoter. Alternatively, the metal to be heated may be disposed adjacent to the heating promoter. A metal heated by irradiating microwaves together with a heating promoter may be reduced. Furthermore, a metal irradiated with microwaves together with a heating promoter may be sintered or melted and solidified. When a metal is heated to a temperature above the sintering temperature and close to the melting point, a dense sintered body is likely to be obtained. Therefore, the metal may be heated by microwaves to 1400°C or higher, or 1500°C or higher. To melt and solidify the metal, the metal should be heated to a temperature above the melting point.

[0104] The uncarbonized organic material is, for example, a resin. Examples of the resin include polyamide, polyacetal, polycarbonate, polyester, cyclic polyolefin, phenol resin, melamine resin, urea resin, alkyd resin, epoxy resin, unsaturated polyester resin, polyurethane, polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyurethane, polylactic acid, acrylic resin, and polyvinyl chloride.

[0105] Here, "carbonized" refers to the process in which organic matter is thermally decomposed by heating, and elements other than carbon are removed, leaving carbon behind. "Uncarbonized" refers to the process in which organic matter has not been carbonized, and therefore uncarbonized organic matter contains hydrogen, nitrogen, oxygen, sulfur, phosphorus, halogens, and metal elements in addition to carbon. However, carbon monoxide, carbon dioxide, carbonyl complexes, and carbonates are not included in organic matter.

[0106] If the heating promoter contains uncarbonized organic matter, when microwaves are irradiated onto the heating promoter, the moisture absorbed by the uncarbonized organic matter may evaporate. The evaporated water may affect the heating of the metal to be heated. Furthermore, when microwaves are irradiated onto the heating promoter, the uncarbonized organic matter may vaporize and emit a foul odor. Furthermore, when microwaves are irradiated onto the heating promoter, the uncarbonized organic matter may carbonize, and the carbonized organic matter may locally absorb the microwaves and generate heat. Therefore, the heating promoter according to the embodiment does not contain at least one of uncarbonized organic matter and liquid.

[0107] Before irradiating the heating promoter and the metal to be heated with microwaves to heat the metal, the heating promoter may be heated to liquefy or vaporize at least one of the uncarbonized organic matter and water contained in the heating promoter, thereby removing at least one of the uncarbonized organic matter and water from the heating promoter. Alternatively, before irradiating the heating promoter and the metal to be heated with microwaves to heat the metal, the heating promoter may be heated to vaporize the liquid contained in the heating promoter, thereby removing the liquid from the heating promoter.

[0108] The heating accelerator may further contain an inorganic binder. Examples of inorganic binders include Portland cement such as calcium silicate hydrate, alumina cement such as calcium aluminate, magnesia cement such as a mixture of magnesia and magnesium chloride, gypsum such as calcium sulfate, phosphate, sodium silicate such as an aqueous solution of sodium silicate, silica sol such as a colloidal solution of colloidal silica, and alumina sol such as a colloidal solution of alumina. The inorganic binder may be a solid such as a powder, or may be a liquid. Since inorganic binders do not carbonize as easily as organic binders, they are less likely to evaporate moisture or produce unpleasant odors even when irradiated with microwaves.

[0109] (Reference Example 1) When a plate made of cement, glass fiber, and organic matter was irradiated with 5000 W microwaves, water evaporated from the plate, emitting an unpleasant odor. Furthermore, the steam caused condensation on the thermometer, making the measured temperature unstable. Furthermore, the organic matter carbonized, and the temperature of the carbonized organic matter became higher than that of other parts of the plate, resulting in thermal runaway, in which microwaves were locally absorbed by the carbonized organic matter.

[0110] Example 1: A liquid-containing heating accelerator was prepared, and microwaves were applied to the heating accelerator to evaporate the volatile components contained in the heating accelerator. Metal was then brought into contact with the heating accelerator, and microwaves were applied to the heating accelerator and multiple metal pieces to melt and solidify the multiple metal pieces. No vapor was generated from the heating accelerator from which the volatile components had been evaporated in advance.

[0111] [Heat Promoter Not Containing Ferromagnetic Material and / or Crystal Water] A heat promoter that promotes the heating of a metal according to an embodiment includes an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal to be heated absorbs microwaves, and does not contain at least one of a ferromagnetic material and crystal water. In the present disclosure, crystal water includes hydration water. The heat promoter may further include an insulating material that absorbs microwaves to a lesser extent than the metal to be heated. The heat promoter may further include a reducing material that reduces the metal to be heated. Examples of ferromagnetic materials include iron, iron oxide, cobalt, cobalt oxide, nickel, nickel oxide, gadolinium, and gadolinium oxide.

[0112] The heating promoter may be a powder or a molded body. A molded heating promoter may be obtained by solidifying a powdered absorbing material with a binder. A molded heating promoter may be obtained by solidifying a mixture of a powdered absorbing material and a heat insulating material with a binder. A molded heating promoter may be obtained by solidifying a mixture of a powdered absorbing material, a heat insulating material, and a reducing material with a binder. The heating promoter may be included in a heating promotion member having a structure. The structure of the heating promotion member containing the heating promoter according to this embodiment is not particularly limited.

[0113] The metal to be heated, the absorbing material, the insulating material, and the reducing material are as described above. However, it is preferable that the insulating material contains an oxide other than iron oxide. Examples of iron oxides include iron (II) oxide (FeO) and iron (III) oxide (Fe2O3). While the metal to be heated and the heating promoter are irradiated with microwaves, at least a portion of the metal to be heated may be in contact with the heating promoter. Alternatively, the metal to be heated may be disposed adjacent to the heating promoter. The metal heated by irradiating microwaves together with the heating promoter may be reduced. Furthermore, the metal heated by irradiating microwaves together with the heating promoter may be sintered or melted and solidified.

[0114] If the heating promoter contains water of crystallization, the water of crystallization may evaporate when the heating promoter is irradiated with microwaves. The evaporated water may affect the heating of the metal to be heated. Furthermore, iron and iron oxide form hydrates with water of crystallization as hydration water. Furthermore, iron and iron oxide have low melting points, so they may melt locally when irradiated with microwaves. Molten iron has a high microwave absorption capacity, so heating of the molten iron is locally promoted. Therefore, the heating promoter according to the embodiment does not contain at least any of iron, iron oxide, and water of crystallization. Furthermore, ferromagnetic materials have a high microwave absorption capacity, so they are easily heated locally. Therefore, the heating promoter according to the embodiment does not contain a ferromagnetic material.

[0115] Before irradiating the heating promoter and the metal to be heated with microwaves to heat the metal, the heating promoter may be heated to vaporize the water of crystallization contained in the heating promoter and remove the water of crystallization from the heating promoter.

[0116] (Reference Example 2) When a plate containing 25.3 wt% Al2O3, 47.5% SiO2, 20.6% KO2, and 5.3% Fe2O3 was irradiated with 7000W microwaves, when the plate reached 750 ° C, the crystal water was desorbed and condensation occurred in the microwave irradiator. Furthermore, when the plate was kept at 785 ° C for 15 minutes, the temperature of the iron oxide portion became higher than that of the other portions of the plate, resulting in thermal runaway in which the microwaves were locally absorbed by the molten iron. After cooling the plate, the plate was again irradiated with 7000W microwaves, but no condensation occurred in the microwave irradiator. This indicates that the crystal water in the plate was completely desorbed by the first microwave irradiation.

[0117] (Reference Example 3) A plate containing 41% by weight of Al2O3, 53% SiO2, and 1.3% Fe2O3 was irradiated with microwaves of 700 to 1200 W and the plate was kept at 520°C for 24 minutes. As a result, the temperature of the iron oxide portion became higher than that of the other portions of the plate, and thermal runaway occurred in which the microwaves were locally absorbed by the molten iron.

[0118] (Example 2) A heating accelerator containing no ferromagnetic material was prepared, and multiple metal fragments were brought into contact with the heating accelerator. Microwaves were irradiated onto the heating accelerator and the multiple metal fragments, causing the multiple metal fragments to melt and solidify. Thermal runaway did not occur with the heating accelerator containing no ferromagnetic material.

Claims

1. A heating accelerator for accelerating the heating of metal, comprising an absorbing material for absorbing microwaves, and not containing at least one of uncarbonized organic matter and liquid.

2. The heating promoter of claim 1, wherein the liquid is water or oil.

3. The heating accelerator of claim 1, further comprising an inorganic binder.

4. The heating promoter of claim 1, wherein the absorbent material comprises a carbon material.

5. The heat enhancer of claim 1 further comprising an insulating material.

6. The heat enhancer of claim 5, wherein the insulating material comprises an oxide.

7. A method for heating a metal, comprising irradiating a heating promoter and a metal with microwaves to heat the metal, wherein the heating promoter comprises an absorbing material that absorbs the microwaves in a temperature range that is at least partially lower than a temperature range in which the metal absorbs the microwaves, and the heating promoter does not contain at least either an uncarbonized organic matter or a liquid.

8. The method for heating metals according to claim 7, wherein the liquid is water or oil.

9. The method for heating a metal according to claim 7, wherein the metal is in contact with at least a portion of the heating promoter while the metal is being irradiated with microwaves.

10. The method for heating metals according to claim 7, wherein the heating promoter further comprises an inorganic binder.

11. The method of claim 7, wherein the absorbent material comprises a carbon material.

12. The method of heating metals as set forth in claim 7, wherein the heating promoter further comprises an insulating material that absorbs microwaves to a lesser extent than the metal to be heated.

13. The method of claim 12, wherein the insulating material comprises an oxide.

14. The method of claim 7, wherein heating the metal comprises reducing the metal.

15. The method for heating a metal according to claim 7, further comprising heating the heating promoter and removing at least one of uncarbonized organic matter and liquid from the heating promoter before irradiating the heating promoter and the metal with microwaves to heat the metal.

16. A heating promoter for accelerating the heating of metals, comprising an absorbent material and not comprising at least one of a ferromagnetic material and water of crystallization.

17. The heating promoter of claim 16, wherein the ferromagnetic material is iron or iron oxide.

18. The heating enhancer of claim 16, wherein the absorbent material comprises a carbon material.

19. The heating enhancer of claim 16, further comprising an insulating material.

20. The heating enhancer of claim 19, wherein the insulating material comprises an oxide other than iron oxide.

21. A method for heating a metal, comprising irradiating a heating promoter and a metal with microwaves to heat the metal, wherein the heating promoter comprises an absorbing material that absorbs the microwaves in a temperature range that is at least partially lower than a temperature range in which the metal absorbs the microwaves, and the heating promoter does not contain at least either a ferromagnetic material or water of crystallization.

22. The method for heating metals according to claim 21, wherein the ferromagnetic material is iron or iron oxide.

23. The method for heating a metal according to claim 21, wherein the metal is in contact with at least a portion of the heating promoter while the metal is being irradiated with microwaves.

24. The method of heating metals according to claim 21, wherein the absorbent material comprises a carbon material.

25. The method of heating metals of claim 21, wherein the heating promoter further comprises an insulating material that absorbs microwaves less than the metal to be heated.

26. The method of heating metals according to claim 25, wherein the insulating material comprises an oxide other than iron oxide.

27. The method of heating a metal according to claim 21, wherein heating the metal comprises reducing the metal.

28. The method for heating a metal according to claim 21, further comprising heating the heating promoter and removing water of crystallization from the heating promoter before irradiating the heating promoter and the metal with microwaves to heat the metal.