Method for manufacturing metallic solid

Abstract

To provide a method for manufacturing a metallic solid, capable of easily producing the metallic solid.SOLUTION: A method for manufacturing a metallic solid from a metallic material includes: forming a solidified mold by using a mold material that includes a curable material containing calcium, the mold having a melting point higher than that of the metallic material; covering at least a part of the periphery of the metallic material with the solidified mold; and irradiating microwaves onto the metallic material, at least a part of the periphery of which is covered with the solidified mold, to heat the metallic material, thereby sintering or melting and solidifying the metallic material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a metallic solid. [Background technology]

[0002] Conventionally, solid metal parts used in daily necessities, home appliances, machine tools, and the like are manufactured by processing ingots, billets, and the like. The process of processing ingots and billets is complex and includes various steps. Furthermore, the process of processing ingots and billets may involve various processors. Therefore, the process of processing ingots and billets may involve transportation by logistics. Therefore, the process of processing ingots and billets is expensive. Furthermore, if one process in the process of processing ingots and billets is delayed, all downstream processes may be delayed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-158790 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-145151 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-035776 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-216943 [Patent Document 5] Japanese Patent Application Laid-Open No. 2017-145151 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a method for producing a metal solid, which allows for easy production of a metal solid. [Means for solving the problem]

[0005] A method for producing a metal solid according to an embodiment of the present invention is a method for producing a metal solid from a metal material, and includes: forming a solidified mold using a mold material having a melting point higher than that of the metal material and including a hardenable material containing calcium; covering at least a portion of the periphery of the metal material with the solidified mold; and irradiating microwaves to the metal material, at least a portion of the periphery of which is covered with the solidified mold, to heat the metal material and sinter or melt-solidify the metal material.

[0006] In the method for producing a metal solid according to an embodiment of the present invention, the hardenable material may include cement, lime, or gypsum.

[0007] In the method for producing a metal solid according to an embodiment of the present invention, a binder may be added to at least a portion of the mold material when forming the solidified mold.

[0008] In the method for producing a metal solid according to an embodiment of the present invention, the binder may be carbonized at a temperature equal to or lower than the sintering temperature of the metal material.

[0009] In the method for producing a metal solid according to an embodiment of the present invention, the binder may contain sugar.

[0010] In the method for producing a metal solid according to an embodiment of the present invention, the binder may contain water.

[0011] In the method for producing a metal solid according to an embodiment of the present invention, the binder may contain alcohol.

[0012] Methods for producing metal solids according to embodiments of the present invention may include removing non-bindered portions of the mold material.

[0013] In the method for producing a metal solid according to an embodiment of the present invention, the mold material may be made of particles having a size of 100 μm or less.

[0014] In the method for manufacturing a metal solid according to an embodiment of the present invention, the mold material may include a high-melting-point material having a melting point higher than that of the metal material, and the high-melting-point material may include a heat-insulating material that absorbs microwaves less than the metal material.

[0015] In the method for producing a metal solid according to an embodiment of the present invention, the heat insulating material may include an oxide.

[0016] In the method for producing a metal solid according to an embodiment of the present invention, 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.

[0017] In the method for producing a metal solid according to an embodiment of the present invention, the mold material may include a high-melting-point material having a melting point higher than the melting point of the metal material, and the high-melting-point material may include an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal material absorbs microwaves.

[0018] In the method for producing a metal solid according to an embodiment of the present invention, the absorbing material may include a carbon material.

[0019] In the method for producing a metal solid according to an embodiment of the present invention, the absorbing material may include at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

[0020] In the method for producing a metal solid according to an embodiment of the present invention, the mold material may include a high-melting-point material having a melting point higher than that of the metal material, and the high-melting-point material may include a heat insulating material that absorbs microwaves to a lesser extent than the metal material, and an absorbing material that absorbs microwaves in a temperature range that is at least partially lower than the temperature range in which the metal material absorbs microwaves.

[0021] In the method for manufacturing a metal solid according to an embodiment of the present invention, the mold material may include a high-melting-point material having a melting point higher than that of the metal material, and the high-melting-point material may combine a heat insulating material and an absorbent material. The heat insulating material may be covered with the absorbent material.

[0022] In the method for producing a metal solid according to an embodiment of the present invention, the heat insulating material may be particles.

[0023] In the method for producing a metal solid according to an embodiment of the present invention, the heat insulating material may include an oxide.

[0024] In the method for producing a metal solid according to an embodiment of the present invention, the absorbing material may include a carbon material.

[0025] In the method for producing a metal solid according to an embodiment of the present invention, the high melting point material may include a heat insulating material and an absorbent material, and the high melting point material may include 1% to 95% by mass of the absorbent material. [Effects of the Invention]

[0026] According to the present invention, it is possible to provide a method for producing a metal solid, which allows for easy production of a metal solid. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic perspective view of a manufacturing apparatus for a metal solid according to an embodiment. [Figure 2] FIG. 2 is a schematic process diagram of a method for producing a metal solid according to an embodiment. [Figure 3] FIG. 3 is a schematic process diagram of a method for producing a metal solid according to an embodiment. [Figure 4] FIG. 4 is a schematic process diagram of a method for producing a metal solid according to an embodiment. [Figure 5] FIG. 5 is a schematic process diagram of a method for producing a metal solid according to an embodiment. [Figure 6] FIG. 6 is a schematic process diagram of a method for producing a metal solid according to an embodiment. [Figure 7] FIG. 7 is a schematic process diagram of a method for producing a metal solid according to an embodiment. [Figure 8] FIG. 8 is a schematic perspective view of a manufacturing apparatus for a metal solid according to an embodiment. [Figure 9] FIG. 9 is a schematic perspective view of a manufacturing apparatus for a metal solid according to an embodiment. [Figure 10] FIG. 10 is a schematic perspective view of a manufacturing apparatus for a metal solid according to an embodiment. [Figure 11] FIG. 11 is a photograph of a mold and a green compact of a metal material according to the example. [Figure 12] FIG. 12 is a photograph of a metal solid according to an example. [Figure 13] FIG. 13 is a photograph of a metal solid according to an example. [Figure 14] FIG. 14 is a photograph of the mold and the green compact of the metal material according to the example. [Figure 15] FIG. 15 is a photograph of uncoated alumina powder and carbon-coated alumina powder according to the example. [Figure 16] FIG. 16 is a schematic diagram of a mold, a high-melting-point material, and a metal material according to a reference embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, identical or similar parts are denoted by identical or similar reference numerals. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Furthermore, it goes without saying that the dimensional relationships and ratios between the drawings may differ.

[0029] A method for producing a metal solid according to an embodiment is a method for producing a metal solid from a metal material, and includes the steps of: forming a solidified mold using a mold material having a melting point higher than that of the metal material and including a hardenable material containing calcium; covering at least a portion of the periphery of the metal material with the solidified mold; and irradiating microwaves onto the metal material, at least a portion of which is covered with the solidified mold, to heat the metal material and sinter or melt-solidify the metal material. The microwaves are, for example, electromagnetic waves with a frequency of 300 MHz or more and 30 GHz or less. It is preferable that the metal material and the solidified mold are in close contact with each other in the portion of the metal material covered with the solidified mold.

[0030] The metal material may include an elemental 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). 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.

[0031] The metallic material 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 metallic material 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 metallic material preferably has better microwave absorption properties than its surrounding metals. This allows the metal material to be heated more easily by microwaves than the surrounding mold.

[0032] The shape of the metal material is not particularly limited, but may be a powder. The average particle size of the metal material is, for example, 200 μm or less, 190 μm or less, or 180 μm or less. The average particle size of the metal material is, for example, the median diameter D in the cumulative particle size distribution on a volume basis measured by a laser diffraction / scattering method. 50 Preferably, the particle size distribution of the metal material is D 10 / D 50 >0.5 and D 50 / D 90 If the average particle size of the metal material is 200 μm or less, the metal material tends to easily absorb microwaves.

[0033] The mold material may contain a high-melting-point material having a melting point higher than that of the metal material. The high-melting-point material contained in the mold material may contain an insulating material having higher microwave transparency and lower microwave absorption than the metal material. The insulating material has a melting point higher than that of the metal material. The insulating material has a low microwave absorption rate, so that it generates less heat when irradiated with microwaves and exhibits an insulating effect. Furthermore, because the insulating material has a higher melting point than the metal material, its shape is stable even when irradiated with microwaves. Therefore, the mold containing the insulating material can maintain its shape even while the metal material irradiated with microwaves is sintered or melted. The insulating material may be a powder in the mold material before solidification.

[0034] The 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 insulating material may be a compound of these.

[0035] The high-melting point material may include an absorbing material that absorbs microwaves in at least a portion of a temperature range lower than the temperature range in which the metallic material absorbs microwaves. The absorbing material has a melting point higher than the melting point of the metallic material. At least a portion of the temperature range in which the absorbing material absorbs microwaves is lower than the temperature range in which the metallic material absorbs microwaves. The temperature range in which the metallic material absorbs microwaves is, for example, 300°C to 1200°C, 450°C to 1100°C, or 600°C to 800°C. The temperature range in which the absorbing material absorbs microwaves is, for example, 100°C to 1000°C, 250°C to 900°C, or 400°C to 600°C.

[0036] Preferably, at least a portion of the temperature range in which the absorbing material absorbs microwaves overlaps with the temperature range in which the metal material 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 material absorbs microwaves, and thus generates heat faster than the metal material. Therefore, the absorbing material can heat the metal material before it reaches the temperature range in which the metal material absorbs microwaves. Therefore, when a high-melting-point material contains an absorbing material, the temperature of the metal material quickly reaches the temperature range in which the microwaves are absorbed, thereby shortening the heating time of the metal material. Furthermore, since the absorbing material absorbs microwaves in at least a portion of a temperature range lower than the temperature range in which the metal material absorbs microwaves, it is possible to prevent the high-melting-point material from being heated more than necessary. Therefore, the shape of a mold containing an absorbing material can be stable even while the metal material irradiated with microwaves is being sintered or melted. Here, the absorbing material in the mold material before solidification may be powder.

[0037] 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 material, metal nitride, metal oxide, metal boride, etc. that absorbs microwaves in a temperature range at least partially lower than the temperature range in which the metal material to be sintered or melted and solidified 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.

[0038] The high melting point material may include a reducing material that reduces the metallic material. The reducing material has a melting point higher than that of the metallic material. Examples of reducing materials include carbon and silicon carbide. Carbon materials used as absorbent materials may also function as reducing materials.

[0039] The high-melting-point material may consist solely of an insulating material, solely of an absorbing material, solely of a reducing material, or a combination thereof. The insulating material, absorbing material, and reducing material may have overlapping properties and functions. For example, a carbon material functions both as an absorbing material and as a reducing material. The mold material before solidification may contain a mixture of an insulating material and a curable material, a mixture of an absorbing material and a curable material, or a mixture of a reducing material and a curable material. The mold material before solidification may contain a mixture of an insulating material, an absorbing material, and a curable material, a mixture of an absorbing material, a reducing material, and a curable material, a mixture of a reducing material, an insulating material, and a curable material, or a mixture of an insulating material, an absorbing material, a reducing material, and a curable material.

[0040] In the high-melting-point material, the heat insulating material and the absorbent material may be bonded together. The heat insulating material may be covered with the absorbent material. For example, particles made of the heat insulating material may be covered with the absorbent material. For example, particles made of metal and semi-metal oxides may be covered with a carbon material. The absorbent material is lighter than the heat insulating material and therefore more likely to scatter, but by bonding the absorbent material to the heat insulating material, it is possible to prevent the absorbent material from scattering.

[0041] When the high-melting-point material includes a heat insulating material and an absorbent material, for example, the mass ratio of the absorbent material in the high-melting-point material is 1 mass% or more, 2 mass% or more, or 5 mass% or more, and 95 mass% or less, 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 absorbent material in the high-melting-point material to 95 mass% or less or 90 mass% or less, it is possible to ensure the microwave transparency of the high-melting-point material and to optimize the sintering or melt-solidification rate of the metal material.

[0042] Examples of hardenable materials containing calcium include calcium aluminate, cement, lime, gypsum, and mixtures thereof.

[0043] The calcium aluminate is, for example, amorphous calcium aluminate. Calcium aluminate is 3CaO·Al2O3, 2CaO·Al2O3, 12CaO·7A l2 O3, 5CaO·3Al2O3, CaO·Al2O3, 3CaO·5Al2O3, and CaO·2Al2O3. Calcium aluminate may be solid-solved with or substituted by a halogen. Calcium aluminate solid-solved with or substituted by a halogen may be calcium haloaluminate, including calcium fluoroaluminates such as 3CaO·3Al2O3·CaF2 and 11CaO·7Al2O3·CaF2.

[0044] The calcium aluminate may be calcium sodium aluminate such as 8CaO·Na2O·3Al2O3 and 3CaO·2Na2O·5Al2O3. The calcium aluminate may be calcium lithium aluminate. The calcium aluminate may be alumina cement. Trace elements such as Na, K, Li, Ti, Fe, Mg, Cr, P, F, and / or S and / or their oxides may be dissolved in the calcium aluminate.

[0045] The cement may be rapid hardening cement, ultra rapid hardening cement, normal Portland cement, high early strength Portland cement, moderate heat Portland cement, low heat Portland cement, white Portland cement, ecocement, blast furnace cement, fly ash cement, and cement clinker powder.

[0046] The lime may be quicklime or slaked lime. The gypsum may be anhydrite, hemihydrate, or dihydrate.

[0047] At least a portion of the calcium-containing hardenable material may also function as a high melting point material, for example, calcium aluminate may also function as an absorbent material because it contains metal oxides.

[0048] The shape of the mold material is not particularly limited, but may be a powder. The average particle diameter of the mold material is, for example, 100 μm or less, 90 μm or less, or 80 μm or less. The average particle diameter of the mold material is 50 μm or more. The average particle diameter of the mold material is, for example, the median diameter D in the cumulative particle size distribution on a volume basis measured by a laser diffraction / scattering method. 50 By keeping the average particle size of the mold material at 100 μm or less, the flowability of the mold material is easily maintained, the mold material hardens easily, the shape precision of the mold to be formed is easily improved, and the mold to be formed is less likely to collapse.

[0049] Furthermore, thick molds may be manufactured by repeatedly hardening a mold material to form a mold, hardening the mold material on top of the mold, and stacking the molds. In this case, by setting the average particle size of the mold material to 100 μm or less, the mold underneath the mold material is less likely to be damaged or destroyed when the powder mold material placed on the hardened mold is smoothed with a roller or the like. Furthermore, it is preferable that the individual powder particles of the mold material are spherical. This spherical shape helps maintain the fluidity of the mold material, making the mold material uniform before solidification and facilitating solidification into a mold with uniform strength. Furthermore, maintaining the fluidity of the mold material makes it easier to pour the mold material into the narrow parts of the frame when hardening it within the frame.

[0050] In forming the solidified mold, a binder is added to at least a portion of the mold material. The binder hardens the curable material. The binder may be a material that carbonizes at or below the sintering temperature of the metal material. This allows the binder to be used as an absorbing material that absorbs microwaves at a temperature range at least partially lower than the temperature range at which the metal material absorbs microwaves. Examples of binders include water, alcohol, sugar, and mixtures thereof. The binder may be mixed with the mold material, or the binder may be added to any portion of the mold material to harden any portion of the mold material. The mold material is solidified by drying after adding the binder. The drying temperature is, for example, 20°C or higher, 40°C or higher, 60°C or higher, 80°C or higher, or 100°C or higher. The higher the temperature, the shorter the drying and solidification time. The hardness of the solidified mold may be confirmed using a hardness tester such as a durometer. Examples of mold hardness include, but are not limited to, 40A or higher, 50A or higher, or 60A or higher. The portion of the mold material to which no binder has been added does not solidify, and the unsolidified portion of the mold material to which no binder has been added is removed, thereby enabling the molding of a mold of the desired shape.

[0051] Examples of alcohols contained in the binder include isopropyl alcohol and ethyl alcohol. The alcohol also functions to adjust the viscosity of the binder. Examples of sugars contained in the binder include sugar. The melting point of sugar is 170°C to 190°C, and the carbonization temperature is 215°C. The binder may contain a lubricant such as a surfactant, a heat inhibitor such as glycerin, and a colorant such as anhydrous ink and dye. The binder may also contain a fluidizing agent and a surface tension reducing agent.

[0052] Unlike photocurable resins, calcium-containing curable materials do not cure upon exposure to light, so they do not need to be stored in a dark place and are easy to manage. Furthermore, photocurable resins volatilize upon heating, and unevenly volatilized photocurable resins may absorb microwaves and prevent the metal material from uniformly absorbing microwaves. Because calcium-containing curable materials are less likely to volatilize, such problems are less likely to occur. Furthermore, calcium-containing curable materials are less likely to crumble even at high temperatures.

[0053] A metal material is placed in a mold corresponding to the desired three-dimensional shape, at least a portion of the metal material is covered with the mold, and then microwaves are irradiated onto the metal material covered with the mold, thereby sintering the metal material and producing a metal solid of the desired shape. Alternatively, microwaves are irradiated onto the metal material covered with the mold, and then the metal material is melted and solidified by cooling, thereby producing a metal solid of the desired shape. The entire periphery of the metal material may be covered with the mold. The thickness, volume, etc. of the mold can be appropriately set based on microwave transparency. The composition of the metal material placed in the mold may vary depending on the position. For example, the type of metal constituting the metal powder or the alloy components of the metal powder may be changed depending on the position.

[0054] After placing the metal material in the mold, and before irradiating it with microwaves, the metal material may be subjected to a pressure of, 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 produced metal solid tends to become dense. Examples of pressure application methods include uniaxial molding, cold isostatic pressing (CIP) molding, hot isostatic pressing (HIP) molding, and roller pressing.

[0055] The metal material to be irradiated with microwaves may be a powder compact. After forming the metal material into a powder compact into a desired three-dimensional shape, at least a portion of the powder compact is covered with a mold containing a high-melting point material, and then microwaves are irradiated onto the powder compact, causing the powder compact to sinter and producing a metal solid of the desired shape through metallurgy. Alternatively, microwaves are irradiated onto the powder compact covered with the mold containing the high-melting point material, and then the powder compact is melted and solidified by cooling, producing a metal solid of the desired shape. The entire periphery of the powder compact may be covered with a mold containing a high-melting point material. The thickness, volume, etc. of the mold containing the high-melting point material that covers the powder compact can be appropriately set based on microwave transmittance.

[0056] When forming a metal material into a powder compact, the metal material may be subjected to a pressure of, 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. Applying pressure tends to make the produced metal solid dense. Examples of pressing methods include uniaxial molding, cold isostatic pressing (CIP), hot isostatic pressing (HIP), and roller pressing. The entire metal material may be a powder, or a portion of the metal material may be a powder compact.

[0057] After sintering or melt-solidifying a metal material, pressure may be applied to the resulting metal solid. In this case, pressure is preferably applied when the metal solid has heat and is at a temperature higher than the ambient temperature before it is cooled to the ambient temperature. The applied pressure 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 produced metal solid tends to become dense. Examples of pressurizing methods include uniaxial molding, cold isostatic pressing (CIP) molding, hot isostatic pressing (HIP) molding, and roller pressing.

[0058] When a metal material contains a metal oxide, the metal oxide can be reduced by irradiating microwaves onto the metal material covered with a mold containing a reducing material. Heating the metal material to a temperature above the sintering temperature and close to the melting point tends to produce a dense sintered body. Therefore, the metal material may be heated to 1400°C or higher, or even 1500°C or higher, using microwaves. To melt and solidify the metal material, the metal material may be heated to a temperature above the melting point. The oxide of the metal may be reduced before irradiating the metal material with microwaves. For example, the metal oxide powder can be reduced by mixing the metal oxide powder with carbon powder and heating the mixture. The reduced metal powder can be separated from the carbon powder, for example, using a magnet.

[0059] Heating the metal material may be performed in an inert gas atmosphere. Examples of inert gases include argon (Ar) and helium (He). Heating the metal material may also be performed in a neutral gas atmosphere. Examples of neutral gases include nitrogen (N2), dry hydrogen (H2), and ammonia (NH3). Heating the metal material may also be performed in a reducing atmosphere. Examples of reducing gases that provide a reducing atmosphere include hydrogen (H2), carbon monoxide (CO), and hydrocarbon gases (CH4, C3H8, C4H). 10 In addition, an inert gas, a neutral gas, or a reducing gas may be supplied to the inside of the mold.

[0060] A laminated metal solid may be formed by repeatedly covering at least a portion of the periphery of the metal material with a mold and sintering or melt-solidifying the metal material. The metal solid obtained by the above method may also be polished. Alternatively, the metal solid obtained by the above method may be used as a core, a metal material may be placed around it, and a mold may be placed around the metal material, followed by repeated microwave irradiation. This allows the scale-up of the metal solid. The compositions of the metal material and the mold may also be changed each time microwave irradiation is performed. For example, the alloy components of the metal material may be changed each time microwave irradiation is performed.

[0061] 1, the metal solid manufacturing apparatus according to the embodiment includes a stage 10 on which a metal material and a mold that covers at least a portion of the periphery of the metal material are placed, and a microwave irradiation unit 20 that irradiates microwaves onto the metal material, at least a portion of which is covered by the mold, to heat the metal material and sinter or melt and solidify the metal material. The metal solid manufacturing apparatus according to the embodiment can, for example, carry out the metal solid manufacturing method according to the embodiment described above.

[0062] The stage 10 is not particularly limited as long as it can accommodate a metal material and a high-melting-point material. The stage 10 may be movable in three mutually perpendicular axial directions. For example, the stage 10 may be movable in the gravity direction and horizontally.

[0063] The metal solid manufacturing apparatus according to the embodiment may further include a mold material placement unit 31 that places a mold material on the stage 10. The mold material placement unit 31 may apply a high-melting point material to the stage 10. The mold material placement unit 31 may form a layer of mold material on the stage 10. The mold material placement unit 31 may be movable in three mutually perpendicular axial directions. For example, the mold material placement unit 31 may be movable in the direction of gravity and the horizontal direction. For example, as shown in FIGS. 2(a) to 2(c), the mold material placement unit 31 may apply powder mold material to the stage 10 while moving over the stage 10, thereby forming a layer 101 of mold material on the stage 10.

[0064] As shown in FIG. 1 , the metal solid manufacturing apparatus according to the embodiment may further include a binder adding unit 32 that adds a binder to at least a portion of the mold material. The binder adding unit 32 adds the binder to the portion of the mold material to be cured and does not add the binder to the portion of the mold material to be uncured. The binder may be, for example, a liquid, and the binder adding unit 32 may impregnate the portion of the mold material to be cured with the binder. The binder adding unit 32 may be movable in three mutually perpendicular axial directions. For example, the binder adding unit 32 may be movable in the direction of gravity and horizontally. For example, as shown in FIGS. 3( a) and 3(b), the binder adding unit 32 may move over a layer 101 of mold material on the stage 10, patterning and applying the binder to the layer 101 of mold material, and adding the binder to the portion 102 of the layer 101 of mold material to be cured without adding the binder to the portion 102 of the layer 101 of mold material to be cured. The binder adding unit 32 may be equipped with, for example, an inkjet nozzle, and may add the binder to the mold material by a binder jetting method.

[0065] The mold material placement section 31 and the binder addition section 32 may be integrated.

[0066] As shown in FIG. 1, the manufacturing apparatus for a metal solid according to the embodiment may further include a drying device 40 that dries the mold material to which the binder has been added. The drying device 40 may be a heat source. The drying device 40 may be movable in three mutually perpendicular axial directions. For example, the drying device 40 may be movable in the gravity direction and horizontally.

[0067] 1, the metal solid manufacturing apparatus according to the embodiment may further include an unhardened material removal unit 50 that removes unhardened high-melting point material. For example, as shown in FIGS. 4(a) and 4(b), the unhardened material removal unit 50 may apply air pressure to an unhardened, powder portion 102 of a mold material layer 101 to remove the unhardened, powder portion 102 from the mold material layer 101, thereby forming a mold 101.

[0068] As shown in FIG. 1 , the manufacturing apparatus for a metal solid according to the embodiment may further include a metal material placement unit 33 that places a metal material on the stage 10. A recoater can be used as the metal material placement unit 33. The metal material placement unit 33 may apply a metal material onto the stage 10. The metal material placement unit 33 may be movable in three mutually perpendicular axial directions. For example, the metal material placement unit 33 may be movable in the direction of gravity and in the horizontal direction. For example, as shown in FIGS. 5( a) and 5(b), the metal material placement unit 33 may place a metal material 200 in a recess 103 of a mold 101 on the stage 10. The metal material placed on the surface of the mold 101 on the stage 10 in a portion where the recess 103 is not formed may be removed using a roller, brush, or the like.

[0069] The mold material disposing section 31 and the metallic material disposing section 33 may be integrated. The binder adding section 32 and the metallic material disposing section 33 may be integrated. The mold material disposing section 31, the binder adding section 32, and the metallic material disposing section 33 may be integrated.

[0070] As shown in FIG. 1, the manufacturing apparatus for a metal solid according to the embodiment may further include a pressurizing unit 60 that applies pressure to a metal material placed on a stage 10. As shown in FIG. 5(c), the pressurizing unit 60 applies pressure to a metal material 200 before it is irradiated with microwaves. Examples of pressurizing methods include uniaxial molding, cold isostatic pressing (CIP) molding, hot isostatic pressing (HIP) molding, and roller pressurizing. In the case of roller pressurizing, a pressurizing technique may be selected in which the pressurizing tip of the pressurizing unit 60 is a roller type, and the stage 10 is slid while the roller is pressed against the stage 10.

[0071] For example, as shown in FIG. 6 , the microwave irradiation unit 20 irradiates microwaves onto a metal material 200 placed in a recess 103 of a mold 101 on a stage 10. The microwave irradiation unit 20 may irradiate the entire surface of the metal material 200 with microwaves all at once, or may irradiate the metal material 200 while scanning the metal material 200. The metal solid manufacturing apparatus according to the embodiment may further include an inert gas supply unit that supplies an inert gas to the metal material. The inert gas supply unit supplies an inert gas to the periphery of the metal material 200 at least while the metal material 200 is being irradiated with microwaves. The metal solid manufacturing apparatus according to the embodiment may further include a reducing gas supply unit that supplies a reducing gas to the metal material. The reducing gas supply unit supplies a reducing gas to the periphery of the metal material 200 at least while the metal material 200 is being irradiated with microwaves. The metal solid manufacturing apparatus according to the embodiment may further include a neutral gas supply unit that supplies a reducing gas to the metal material. The neutral gas supply unit supplies a neutral gas to the periphery of the metal material 200 at least while the metal material 200 is being irradiated with microwaves. The inert gas supply unit and the reducing gas supply unit may be integrated. The inert gas supply unit and the neutral gas supply unit may be integrated. The reducing gas supply unit and the neutral gas supply unit may be integrated.

[0072] As shown in FIG. 1 , the manufacturing apparatus for a metal solid according to the embodiment may include a thermometer 71 that measures the temperature of the metal material placed on the stage 10. A radiation thermometer can be used as the thermometer 71. The radiation thermometer measures the temperature of the metal material based on the emissivity of the metal material. The thermometer 71 may also measure the temperature of the mold. The microwaves irradiated by the microwave irradiator 20 may be controlled based on the temperature of the metal material measured by the thermometer 71. The manufacturing apparatus for a metal solid according to the embodiment may also include a microwave detector 72 that detects the microwaves irradiated by the microwave irradiator 20. The microwaves irradiated by the microwave irradiator 20 may be controlled based on the characteristics of the microwaves detected by the microwave detector 72.

[0073] 1 may apply pressure to the metal material 200 after the metal material 200 has been irradiated with microwaves. Examples of pressurizing methods include uniaxial molding, cold isostatic pressing (CIP) molding, hot isostatic pressing (HIP) molding, and roller pressurizing. In the case of roller pressurizing, a pressurizing technique may be selected in which the pressurizing tip of the pressurizing unit 60 is a roller type, and the stage 10 is slid while the roller is pressed against the stage 10.

[0074] The metal material 200 placed in the recess 103 of the mold 101 on the stage 10 shown in Fig. 6 and irradiated with microwaves is then cooled and sintered or melted and solidified into a metal solid. Note that the metal material 200 near the edge of the recess 103 of the mold 101 tends to be easily heated. Therefore, the mass ratio of the absorbing material in the mold near the edge of the recess 103 may be lower than in other parts.

[0075] The stage 10, microwave irradiation unit 20, and the like of the metal solid manufacturing apparatus according to the embodiment may be housed in a housing.

[0076] The metal solid manufacturing apparatus according to the embodiment may repeatedly form a mold 101 surrounding a metal material on a sintered or melt-solidified metal solid and a mold 101 surrounding the metal solid, and sinter or melt-solidify the metal material. This allows for the metal solid to be stacked, even if the thickness of the metal solid formed by a single microwave irradiation is thin, and a thick metal solid can be manufactured. By changing the shape of the recess formed in the mold 101 each time a mold 101 surrounding a metal material is formed, it is possible to manufacture a metal solid having a complex three-dimensional shape.

[0077] That is, as shown in FIG. 7, a first-layer mold 101A is formed on a stage 10, and a metal material 200A is placed in the recess of the mold 101A. Next, microwaves are irradiated onto the metal material 200A, causing the metal material 200A to become a first-layer metal solid 201A. Next, a second-layer mold 101B is formed on the first-layer mold 101A, and the metal material 200B is placed in the recess of the mold 101B. Here, the first-layer metal solid 201A is exposed from the recess of the mold 101B, and the metal material 200B comes into contact with the surface of the first-layer metal solid 201A. Next, microwaves are irradiated onto the metal material 200B, causing the metal material 200B to become a second-layer metal solid 201B. At this time, the second-layer metal solid 201B is fixed to the first-layer metal solid 201A. Thereafter, by repeating the same process, metal solids are stacked.

[0078] While the present invention has been described above by way of exemplary embodiments, the descriptions and drawings that form part of this disclosure should not be construed as limiting the present invention. Various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art from this disclosure. For example, the pressure unit 60 shown in FIG. 1 may apply pressure to the entire surface of the placed metal material 200. Alternatively, as shown in FIG. 8, the pressure unit 60, having a contact area smaller than the surface area of ​​the placed metal material 200, may continuously press the metal material 200 while moving. Examples of pressing methods include uniaxial molding, cold isostatic pressing (CIP) molding, hot isostatic pressing (HIP) molding, and roller pressing. In the case of roller pressing, as shown in FIG. 9, the pressure unit 60 may include a roller, and the roller may be moved over the stage 10 while pressing the roller against the stage 10, or the stage 10 may be slid. Furthermore, for example, as shown in FIG. 10, the metal solid manufacturing apparatus according to the embodiment may include a reduction device 80 that reduces the metal material before the metal material is irradiated with microwaves. The reduction device 80 is, for example, a heating device that heats the metal material to reduce it. As such, it should be understood that the present invention encompasses various embodiments not described herein. [Example]

[0079] Example 1 A mold material was prepared containing alumina (99.9% Al2O3, particle size 50 to 100 μm) as the insulating material, calcium aluminate cement (CaO·Al2O3, CaO·2Al2O3, composition: CaO 36%, Al2O3 55%, SiO2 4%, Fe2O3 1%) as the hardening material, and carbon (95% C, activated carbon) as the absorbent material. The weight ratio of alumina to cement in the mold material was alumina:cement = 100:10 to 100:20. The weight ratio of alumina to carbon in the mold material was alumina:carbon = 14:1.

[0080] Isopropyl alcohol diluted 50% with water was prepared as a binder. A circular layer of mold material was formed and the surface was flattened. Using a printer, the binder was sprayed onto the area of ​​the mold material layer to solidify it. A layer of mold material was formed on top of the partially solidified mold material, and this process was repeated to solidify the mold material layer with the binder, thereby stacking the mold material layers. The unsolidified portions of the stacked mold material were removed by suction to form a mold with an opening. The mold was then dried at 20°C to 30°C for 6 hours. As shown in Figure 11, this resulted in the preparation of a cover mold without an opening, a first mold with a square opening, a second mold with two opposing L-shaped openings, and a first mold with a square opening. In the photograph shown in Figure 11, the metal material described below has already been filled into the mold openings.

[0081] Die steel (SKD61) powder was prepared as the metal material. The metal material was filled into each of the first, second, and third molds, and pressure was applied to the metal material to compact it. The first mold, which was covered on the top and bottom with cover molds and filled with the metal compact, was heated and sintered in an air atmosphere by irradiating it with 500W microwaves for 30 minutes while applying pressure. A second mold was placed on top of the first mold, and the bottom of the first mold and the top of the second mold were covered with cover molds. The metal material in the second mold was sintered under the same conditions. During this process, the metal in the first mold and the metal in the second mold bonded. A third mold was placed on top of the second mold, and the bottom of the first mold and the top of the third mold were covered with cover molds. The metal material in the third mold was sintered under the same conditions. During this process, the metal in the second mold and the metal in the third mold bonded. Furthermore, the mold became brittle when heated and easily turned into powder when pressure was applied.

[0082] Figure 12 shows a photograph of the metal solid obtained after removing the brittle mold with an air duster. Figures 13A and 13B show photographs of the metal solid after the surface was polished. A metal solid was produced with through-holes that were bent internally like cranks.

[0083] Example 2 A mold material containing gypsum (98% CaSO4) as a hardening material and carbon (95% C, activated carbon) as an absorbent material was prepared. In the mold material, the mass ratio of gypsum to carbon was gypsum:carbon = 14:1. Water was prepared as a binder. A mold was formed in the same manner as in Example 1. The mold formed in Example 2 is shown in Figure 14. Note that in the photograph shown in Figure 14, the metal material has already been filled into the opening of the mold. Thereafter, the metal material was sintered using the mold of Example 2 in the same manner as in Example 1, to obtain a metal solid.

[0084] Example 3 The particle size distribution of the alumina particles used in Example 1 was measured using a particle size analyzer (Horiba, Laser Scattering Particle Size Distribution Analyzer LA-960), and the average particle size was found to be 61.6 μm. The alumina powder was coated with carbon (C) using a polygonal barrel sputtering method. The alumina powder before coating is shown on the left side of the photograph in Figure 15, and the alumina powder after coating is shown on the right side of the photograph in Figure 15. When the particle size distribution of the carbon-coated alumina particles was measured, the average particle size increased by approximately 1.5 μm. This was due to the carbon coating.

[0085] (Reference embodiment) A high-melting-point material 301 shown in FIG. 16 is prepared, which does not contain a hardenable material. A mold 302 is also prepared, which will not bond with the metal material when the metal material is sintered or melted. The mold 302 is made of, for example, alumina. The inside of the mold 302 is hollow, and the high-melting-point material 301 is filled into the inside of the mold 302. The opening of the mold 302 is filled with a metal material 303, and microwaves are irradiated onto the metal material 303, at least a portion of which is covered with the mold 302 filled with the high-melting-point material 301, to sinter or melt and solidify the metal material 303. The high-melting-point material 301 inside the mold 302 is reusable. [Explanation of symbols]

[0086] 10... Stage, 20... Microwave irradiation section, 31... Mold material placement section, 32... Binder addition section, 33... Metal material placement section, 40... Drying device, 50... Unhardened material removal section, 60... Pressurizing section, 71... Thermometer, 72... Microwave detector, 80... Reduction device, 101... Mold material layer or mold, 102... Part, 103... Recess, 200... Metal material, 201... Metal solid, 301... High melting point material, 302... Mold frame, 303... Metal material

Claims

1. 1. A method for producing a metal solid from a metal material, comprising: forming a solidified mold using a mold material having a melting point higher than that of the metal material, the mold material including a hardenable material containing calcium; covering at least a portion of the periphery of the metal material with the solidified mold; irradiating the metal material, at least a portion of the periphery of which is covered with the solidified mold, with microwaves to heat the metal material and sinter or melt and solidify the metal material; A method for producing a metal solid, comprising:

2. The method for producing a metal solid according to claim 1 , wherein the hardenable material comprises calcium aluminate, cement, lime, or gypsum.

3. The method for producing a metal solid according to claim 1 , wherein a binder is added to at least a portion of the mold material in forming the solidified mold.

4. The method for producing a metallic solid according to claim 3 , wherein the binder carbonizes at a temperature equal to or lower than the sintering temperature of the metallic material.

5. The method for producing a metal solid according to claim 4, wherein the binder comprises a sugar.

6. The method for producing a metal solid according to claim 3, wherein the binder comprises water.

7. The method for producing a metal solid according to claim 3 , wherein the binder comprises an alcohol.

8. 4. The method of claim 3, further comprising removing the portion of the mold material that was not doped with the binder.

9. 2. The method for producing a metallic solid according to claim 1, wherein the mold material is made of particles having a size of 100 μm or less.

10. 2. The method for producing a metal solid according to claim 1, wherein the mold material includes a high-melting-point material having a melting point higher than that of the metal material, and the high-melting-point material includes a heat insulating material that absorbs the microwaves to a lesser extent than the metal material.

11. The method of claim 10 , wherein the insulating material comprises an oxide.

12. The method for producing a metal solid according to claim 10, wherein the heat insulating material comprises at least one selected from the group consisting of aluminum oxide, silicon oxide, magnesium oxide, zirconium oxide, and titanium oxide.

13. 2. The method for producing a metal solid according to claim 1, wherein the mold material includes a high-melting-point material having a melting point higher than the melting point of the metal material, and the high-melting-point material includes an absorbing material that absorbs the microwaves in at least a part of a temperature range that is lower than a temperature range in which the metal material absorbs the microwaves.

14. The method of claim 13 , wherein the absorbing material comprises a carbon material.

15. 14. The method for producing a metal solid according to claim 13, wherein the absorbing material comprises at least one selected from the group consisting of carbon, graphite, silicon carbide, carbon resin, and metal carbide.

16. the mold material includes a high-melting-point material having a melting point higher than the melting point of the metal material; The high melting point material is a heat insulating material that absorbs the microwaves to a lesser extent than the metal material; an absorbing material that absorbs the microwaves in a temperature range at least part of which is lower than the temperature range in which the metal material absorbs the microwaves; The method for producing the metallic solid of claim 1, comprising:

17. 17. The method of claim 16, wherein the insulating material and the absorbing material are combined.

18. 17. The method for producing a metallic solid according to claim 16, wherein the insulating material is a particle.

19. The method of claim 16, wherein the insulating material comprises an oxide.

20. The method of claim 16, wherein the absorbing material comprises a carbon material.

21. 17. The method of claim 16, wherein the high melting point material comprises 1% to 95% by weight of the absorbing material.

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