JP2006219754A - Method for manufacturing metallic material and method for manufacturing electromagnetic wave absorber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a metallic material by which the recoverability of the metallic material as a manufacture can be improved and a reaction system containing harmful CO and carbonyl compounds can be easily formed into a closed system. <P>SOLUTION: A reactant-holding section where a reactant which reacts with metal carbonyl to accelerate the decomposition of the metal carbonyl is held is disposed in a reaction space composed of a CO atmosphere under a pressure higher than atmospheric pressure. The following steps are cyclically performed in the reaction space by means of a transporting action using, as a medium, a vapor phase concerned with the reaction system for the formation and decomposition of the metal carbonyl: a metal carbonyl formation step where, in the reaction space, a metal or a metal-containing substance as a starting raw material is allowed to react with CO to form the metal carbonyl and fluidize it; a carbonyl decomposition step where the metal carbonyl is fed to the reactant-holding section and the metal carbonyl is decomposed by reaction with the reactant to form a metallic material as a decomposition product derived from the metal carbonyl and CO gas; and a CO feedback step where the CO gas resulting from the decomposition is fed back to the CO atmosphere in the reaction space. Then, the metallic material as a decomposition product is recovered as a manufacture from the reaction space. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a metal-based material, in which a useful metal-based material produced using metal carbonyl as a starting material is steadily produced without taking it out of the system using a closed production system. And a method of manufacturing a radio wave absorber using the same.

JP 2004-124199 A German Patent Publication DE483603 US Patent Publication US2710797

Metal carbonyl compounds are conventionally produced under CO pressure conditions by direct reaction of the metal with carbon monoxide by the Mondo method or the like. However, in addition to the inefficient reaction, metal carbonyls such as CO gas and Ni (CO) ₄ as raw materials are generally harmful, and production in Japan tends to decrease from the viewpoint of environmental and health damage. .

  On the other hand, metal carbonyl produces atomic or cluster metal by decomposition, and it is easy to produce thin films and fine particles of any size based on this (build-up method). In recent years, the metal carbonyl compounds have become dangerous. Despite being expensive, its applications tend to expand. Further, the metal can be purified by utilizing the formation of metal carbonyl and the thermal decomposition action. Such a method is described in Patent Document 1.

  In the method of Patent Document 1, the carbonyl compound or metal extraction side from the reaction system is open, and it is difficult to completely close the toxic CO gas or carbonyl compound recovery system. In addition, since a high pressure is generated locally using detonation, it is difficult to expect a uniform reaction, and the reaction product is easily scattered by detonation or stuck to the wall of the container, which improves the recoverability of the product metal. There are also difficulties. In Patent Documents 2 and 3, the carbonylation reaction is used for the isolation and recovery of transition metals such as iron, nickel, and cobalt. After recovering the metal as metal carbonyl, heat is generated in the same reaction line. In order to obtain metal powder by decomposition, the system configuration is substantially the same as that of Patent Document 1.

  An object of the present invention is to provide a method for producing a metal-based material that is excellent in recoverability of a metal-based material as a product and that can easily close a reaction system containing harmful CO and carbonyl compounds, and a radio wave using the method. It is in providing the manufacturing method of an absorbent material.

Means for solving the problems and effects of the invention

In order to solve the above problems, a method for producing a metal-based material of the present invention includes:
A reaction agent holding part holding a reaction agent that reacts with metal carbonyl and promotes decomposition of the metal carbonyl in a reaction space consisting of a CO atmosphere pressurized from normal pressure is disposed,
In the reaction space, a metal or metal-containing substance as a starting material is reacted with CO to generate metal carbonyl and fluidize it, and the generated metal carbonyl is supplied to the reactant holding unit, A carbonyl decomposition step in which carbonyl is reacted with a reactant and decomposed to generate a decomposition-derived metal material derived from the metal carbonyl and CO gas, and CO gas generated by the decomposition is converted into a CO atmosphere in the reaction space. A CO feedback step that feeds back to the reaction space is circulated in the reaction space by a gas phase-mediated transport action involved in the reaction system for the formation and decomposition of metal carbonyl, and the metal product of decomposition product is produced from the reaction space. It is characterized by collect | recovering as.

  According to the present invention, the metal carbonyl reacts with the metal carbonyl even under an appropriate temperature condition of CO pressurization to form a metal carbonyl. Alternatively, the metal component is continuously carbonylated from the metal-containing substance and combined with the reactant to efficiently and constantly produce a metal-based material. According to the method for producing a metal-based material of the present invention, based on the technique conceived above, a carbonyl compound containing the metal as a component is formed using a metal and a metal-containing substance as a raw material, and further reacted with a reactant. By decomposing and capturing as a metal alloy or compound, the CO component is re-released into the gas phase, and the carbonylation reaction can be efficiently circulated even with a limited CO gas introduction amount.

  Then, once formed metal carbonyl is decomposed by thermal decomposition or reaction with a reactant, the CO component returns to the gas phase again, and the CO pressure can be maintained at a high pressure even after long-time reaction. Thus, steady carbonylation, which is impossible with a conventional sealed system, can be performed even with a limited amount of CO. Almost all of the produced metal carbonyl is decomposed in a sealed container and converted into a harmless metal-based material. Therefore, it is possible to effectively avoid health damage and environmental pollution due to harmful metal carbonyl. In addition, since the reaction between pressurized CO and the metal component in the starting material proceeds in a relatively static environment within a closed reaction space, scattering of reactants due to detonation as in Patent Document 1 also occurs. In addition, the product can be easily recovered. In addition, it is not necessary to supply fuel or combustion-supporting gas for generating detonation.

  Metal carbonyls are produced according to the equilibrium of the metal and CO gas under conditions of set CO pressure and temperature. That is, generally, the higher the CO pressure is, the more the reaction proceeds in the direction in which metal carbonyl is generated. On the other hand, metal carbonyl becomes unstable as the temperature rises and decomposes into metal and CO. However, this decomposition temperature depends on the CO pressure, and generally this temperature increases with the CO pressure. By utilizing this property, metal carbonyl can be used as a raw material, and it can be decomposed at low pressure (generally normal pressure) and high temperature (up to 1000 ° C.) to produce a thin film or fine particles of metal or alloy, intermetallic compound.

  FIG. 1A shows an example of an apparatus for realizing the method for producing a metal-based material of the present invention. In this apparatus 1, a starting material is placed in a container forming a reaction space, pressurized CO gas is sealed in the container, and the starting material is reacted with CO gas by a first heater in the container. Thus, metal carbonyl is produced by local heating to a temperature at which metal carbonyl is produced. Since CO is pressurized to a pressure higher than normal pressure, carbonylation can be promoted even at a relatively low temperature by local heating. Considering the weight reduction of the reaction vessel and the ease of handling, it is appropriate that the CO pressure in the reaction space is higher than atmospheric pressure and 500 atmospheres or lower, and the reaction temperature for the formation of metal carbonyl is from room temperature to 500 atmospheres. It is good to set it as below ℃.

  In the apparatus 1 of FIG. 1A, a carbonylation space and a decomposition space are provided separately, and are heated independently by the first heater 3 and the second heater 8, respectively. Specifically, the carbonylation space forming container 2 and the decomposition space forming container 7 have a structure connected by a connecting portion 5 that connects them, and surround each container 2, 7 from the outside of the wall portion. The first heater 3 and the second heater 8 are provided. In the carbonylation space forming container 2, a starting material holding part 4 for storing the starting material SM in a state in which contact with the internal CO is allowed is arranged. On the other hand, a reactant holding part 10 containing a reactant 9 is disposed in the decomposition space forming container 7. Further, in order to prevent solids such as residue from leaking out to the decomposition space forming container 7 side, the connecting part 5 is allowed to pass through gas and not allowed to pass through solids having a predetermined particle diameter or more. As the filter portion, a porous partition plate 6 made of ceramic or the like is provided.

In apparatus of FIG. 1A, the heating temperature T _A of the first heater 3 by the carbonylation space formation vessel 2 is higher than the carbonyl product temperature of the metal components in the starting material SM, and aggressive formed metal carbonyl The temperature is set to 500 ° C. or lower so as not to cause proper decomposition. On the other hand, the heating temperature T _B in the decomposition space formed container 7 according to the second heater 8, as aggressive decomposition of the metal carbonyl is generated at the reaction agent 9, the hot (and than the temperature T _A, the reaction Devised so that the gas in the container (especially, between the carbonylation space forming container 2 and the decomposition space forming container 7) easily circulates by convection. ing. As a result, the metal component in the starting material SM is, as described above, between two containers that are locally heated by individual heaters at different temperatures, that is, from the carbonylation space formation container 2 to the decomposition space formation container 7. It is refined as a decomposition product metal material PM in a form that is vapor-phase transported.

  Use of a metal halide or an organometallic compound as the reactant 9 facilitates the decomposition of the metal carbonyl and is suitable for the present invention. In FIG. 8A, the liquid reactant is held as a reactant 9 in a container that forms the reactant holding unit 10, carbonyl is brought into contact with the liquid reactant, and the decomposition product metal material PM is contained in the liquid reactant 9. The precipitate is collected. Since the reaction is via a liquid phase, it is more efficient than a solid reactant, and the decomposition-generated metal material is precipitated, so that it can be easily recovered. Further, since the metal element in the organometallic compound is alloyed with the carbonyl-derived metal element by the decomposition reaction, it is particularly advantageous when it is desired to recover the organometallic compound in the form of an alloy.

  As the metal halide, a halide of a noble metal (especially a Pt group metal) is used, which is an element more noble than the metal element. Therefore, it becomes a metal carbonyl reducing agent, and the noble metal element is reduced. The alloy or the intermetallic compound may be formed. Further, as the organometallic compound, use of any alkyl compound of boron, aluminum, silicon, gallium, indium, germanium, tin, palladium and platinum causes the decomposition of the metal carbonyl, so that MB, M -Al, M-Si (M is a metal element constituting carbonyl, which means an alloy or a compound of the metal and B, Al, or Si) is preferable in that it produces a substance. In particular, a dispersion obtained by dispersing or dissolving a metal halide or an organometallic compound in a hydrocarbon-based or silicone-based solvent such as dodecane is preferable. By making the reactant into a solution in which the reactant is dissolved in an organic solvent having a high boiling point as described above, the metal material produced by the reaction between the metal carbonyl and the reactant is produced as fine particles having a uniform particle size. It becomes possible to do. Specifically, the decomposition-generated metal material can be recovered in the form of a powder having a particle size of 10 nm to 200 μm.

  In addition, in the metal carbonyl production step, it is effective to add an appropriate amount of sulfur to the starting material in order to promote the metal carbonyl production reaction. For this purpose, the amount of sulfur added to the starting material is preferably 4 to 7% by weight.

  It is particularly advantageous in the present invention that the metal (metal to be recovered) contained in the starting material is a transition metal that can be easily carbonylated. In this case, the decomposition-generated metal material has a higher transition metal content than the starting material. In the present invention, since a metal material is manufactured through formation of a metal carbonyl compound, a material made of a high-purity metal can be manufactured even when the metal and the substance containing the metal contain impurities. it can.

  In particular, the transition metal is one of iron, nickel, and cobalt, which has a high carbonylation reaction, and high production efficiency can be expected. In this case, the decomposition-generated metal-based material can be recovered in the form of a metal, alloy, or intermetallic compound containing iron, nickel, or cobalt as a main component.

  More specific forms of application include, as a starting material, solid or powder waste generated from a rare earth magnet manufacturing process, the rare earth magnet waste recovered from used electronic equipment, and a recycling process of used batteries. The aspect which uses either the iron, nickel, and cobalt containing wastes collect | recovered can be illustrated. By applying the present invention, it becomes possible to recycle rare earth-transition metal scrap generated with the production or disposal of rare earth magnets and hydrogen storage alloys at lower cost and more effectively.

  In particular, when the starting material contains a rare earth element, the rare earth element hardly undergoes carbonylation as compared with the transition metal, so that the residue of the starting material after the transition metal component and the like have jumped away by the progress of carbonylation. The rare earth material contained in the starting material is concentrated. Therefore, if this residue is utilized, a high concentration rare earth element can be efficiently recovered.

  FIG. 1B is a flowchart schematically showing the entire processing flow according to the method for producing a metal-based material of the present invention. The starting material (M metal-containing substance) is carbonylated to produce M metal carbonyl M (CO) n, which is decomposed to obtain a purified metal material (decomposition product metal material). When carbonyl decomposition is performed by reaction with a metal-based reactant, it can be recovered as an alloy-based material of a metal component derived from the reactant and a starting metal component. The CO generated by the decomposition is circulated in the vessel and again used for carbonylation of the starting material. Since useful components (for example, rare earth elements) in the starting material that do not contribute to carbonylation are concentrated in the residue, they can be recovered in a form that can be easily transported and worked up.

  If the decomposition-generated metal material obtained by the method of the present invention is used as a raw material, a high-performance radio wave absorbing material can be produced.

Hereinafter, the present invention will be described in detail according to examples.
Example 1
After putting 1.38 g of Nd-Fe-B sintered magnet polishing scraps into a 50 ml autoclave container, carbon monoxide is filled with 156 atmospheres and treated at a reaction temperature of 200 ° C. for 24 hours to carry out a carbonylation reaction. It was. For comparison, the same operation was performed on 1 g of iron powder. Further, the same polishing waste was disproportionated and decomposed by treating it at 600 ° C. for 3 hours in a hydrogen stream, and a carbonylation reaction was also attempted. About the residue after reaction, the production amount of metal carbonyl was estimated from the weight change and the composition analysis by EDX.

  Table 1 below shows the results of the reaction rate estimated from the weight change and EDX elemental analysis of the sample after the carbonylation reaction.

  In the direct reaction of iron, boron boride, polishing scraps, and carbon monoxide for all samples, the target metal carbonyl was hardly obtained. Therefore, sulfur was added to iron as a catalyst at a weight ratio of iron / sulfur = 93/7, and the reaction was performed under the same conditions. As a result, it was confirmed that about 90% of iron reacted with metal carbonyl as estimated from the change in weight.

  Next, when a reaction was performed on untreated polishing scraps under the same conditions, the carbonylation reaction was also promoted by the addition of sulfur here, but the rate of formation was slower than that of iron alone. A carbonylation reaction was also performed on a sample in which iron was deposited by the hydrogenation disproportionation treatment of scrap. At that time, carbonylation was carried out by changing the weight ratio of iron / sulfur = 96/4, 93/7, 87/13, and 81/19. The results are also shown in FIG. When sulfur was added to the hydrocracked abrasive scraps at a ratio of iron / sulfur = 93/7, it was confirmed that the reaction proceeded at almost the same rate as in the case of iron alone. In addition, when sulfur was added at a ratio of iron / sulfur = 96/4, the highest reaction rate was obtained.

As shown in the XRD measurement results in FIG. 3, the difference in reaction rate between the hydrotreated and untreated samples is that the hydrocracked sample is composed of a phase of iron and neodymium hydride. It appears that the carbonylation reaction proceeded easily due to the precipitation of. From this result, it was found that the reactivity with carbon monoxide was higher for iron than untreated polishing scraps (mainly Nd ₂ Fe ₁₄ B phase).

  As a result of the reaction of increasing the amount of sulfur added to the hydrogenated polishing scrap, the reaction rate decreased with the increase of the amount added. From the XRD measurement result of the sample after the reaction shown in FIG. 3, an iron sulfide phase that was not observed when iron / sulfur = 93/7 appeared, and the reaction rate decreased as the peak intensity increased. From the above, it is considered that the production of iron sulfide inhibits the carbonylation reaction.

FIG. 4 shows the results obtained by analyzing the iron carbonyl complex obtained above by FT-IR. As a comparison, when compared with commercially available Fe (CO) ₅ , both samples showed a peak attributed to C = O stretching motion in the vicinity of 2000 cm ⁻¹ . As a result, it was confirmed that Fe (CO) ₅ was produced.

  The above carbonyl complex and diphenylsilane were dissolved in decane, and this was heat-treated at 200 ° C. for 5 hours to produce an iron-silicon fine powder. The obtained iron fine powder was evaluated by XRD and SEM. From the SEM photograph shown in FIG. 5, the obtained powder is spherical particles having a diameter of about 10 μm. From the results of EDX measurement performed simultaneously, the generated metal fine particles have a composition ratio of iron and silicon of 80:20. It was confirmed that the alloy phase was formed and impurities such as sulfur subjected to the reaction were not included.

  Moreover, when XRD measurement of this iron-silicon alloy fine powder was performed, it was recognized that it had an amorphous form since a clear diffraction peak was not obtained only by a broad peak. This sample was heat-treated at 600 ° C. for 1 hour in an argon atmosphere, but no change was observed in the XRD pattern, and it was revealed that the amorphous state was maintained.

  A powder obtained by thermal decomposition of iron carbonyl and diphenylsilane is mixed with 20% by weight of an epoxy resin and heat-cured at 150 ° C. for 30 minutes to form a molded product. Method) was evaluated in the region of 0.05 to 18 GHz. The radio wave absorption characteristics of the produced molded body are shown in FIG. The obtained molded product showed good radio wave absorption characteristics of −20 dB or less in the region of 1.6 to 4.3 GHz. That is, it can be seen that the radio wave absorbing material is manufactured.

  As mentioned above, the alloy fine powder produced in the present invention has an amorphous form, and in the case of iron, it is known that the amorphous electrical resistivity is 1 to 2 orders of magnitude higher than that of the crystal. Yes. From this, since the electrical resistivity of amorphous powder is high, it is considered that the eddy current loss induced by the electromagnetic field is effectively suppressed, and thus the above-mentioned good radio wave absorption characteristics are obtained.

(Example 2)
Based on the carbonylation reaction conditions found in Example 1, the reaction vessel was improved as shown in FIG. 7, and the Nd—Fe—B sintered magnet polishing scraps were subjected to CO pressurization at a predetermined temperature. The process of forming metal carbonyl by heating under (low temperature) conditions and recovering it as a metal in the high temperature part by vapor transport of the generated metal carbonyl was examined. First, the reaction part of carbonylation was set to 200 ° C. as in Example 1, and the reaction was carried out at a decomposition temperature (high temperature part) of 300 ° C. for 10 hours. From the result of XRD measurement of this precipitate shown in FIG. 8, it was confirmed that the precipitate was iron. Moreover, as shown in Table 2, it was found from the EDX measurement on this powder that high-purity iron was obtained.

  On the other hand, when the temperature is high (400 ° C.), the reaction proceeds rapidly, but the equilibrium reaction shifts to the product side. Therefore, the reaction efficiency is lower than that in the low temperature (300 ° C.) region. To do.

(Example 3)
The produced metal carbonyl vapor is diffused and transferred to a solvent having low CO gas solubility, and Al (C ₂ H ₅ ) ₃ (b.p194 ° C.), Si (C ₂ H ₅ ) ₄ (b. p.154 ° C.) or the like is added as a reaction agent, and a metal carbonyl vapor is supplemented to cause a decomposition reaction between the metal carbonyl and the organometallic compound. An alloy or an intermetallic compound produced by the reaction between the metal component therein and the reactant was obtained (reaction temperature was 200 ° C., pressure was 300 atmospheres). The outline of the reactor is shown in FIG. 9 (similar to the apparatus of FIG. 1, but the constricted connecting portion is not formed in the container). FIG. 10 shows an SEM image of the alloy fine powder obtained by the reaction between iron carbonyl and diphenylsilane.

  As the solvent to be used, for example, a solvent having low solubility of carbon monoxide such as decane, preventing recarbonylation of iron and the like which has been decomposed and precipitated, and having high solubility of the organometallic compound is preferable.

  The merit here is that the metal carbonyl complex formed by the reaction between the gas phase (carbonyl compound) and the liquid phase (solvent) is captured in the solution, and the alloy or compound of the metal component by the reaction of the metal carbonyl and the reactant. The CO gas decomposed into CO gas and released again out of the solution can be circulated and used for the production of metal carbonyl. The reaction rate is higher than that of Example 1 because the metal carbonyl produced in the same manner as in Example 2 decomposes as a sequential alloy or an intermetallic compound, and CO gas can be circulated, and the alloy obtained in this reaction is As Fe-Si (silicon steel), Fe-Al-Si (Sendust), etc., it can be used as an excellent magnetic powder for radio wave absorption materials. Since silicon steel has been demonstrated in Example 1, it becomes amorphous.

On the other hand, it is possible to form intermetallic compound fine particles such as PtFe and PtFe ₃ by dissolving noble metal chloride such as platinum in a silicone solvent as a vapor reactant and similarly generating metal carbonyl under CO pressure. Become. The obtained PtFe ₃ fine particles are applied as a high-density magnetic recording material.

Schematic of the metal-based material production reactor in the present invention. FIG. 3 is a flowchart illustrating the operation of the present invention. The figure which shows the reaction rate dependence of iron with respect to the addition amount of sulfur. The figure which shows the XRD pattern of the grinding | polishing waste, the hydrogenation-process grinding | polishing waste, and the sample which processed this carbonylation. The figure which shows the FT-IR data of the obtained carbonyl complex. The image which shows the SEM image of the fine powder produced by thermal decomposition. The figure which shows the electromagnetic wave absorption characteristic of the produced resin molding. The schematic of the reactor which provided the temperature gradient. The figure which shows the XRD pattern of the powder which precipitated in the high temperature part. Schematic of reactor using gas-liquid reaction. The SEM image of the obtained fine powder.

Claims (18)

A reaction agent holding part holding a reaction agent that reacts with metal carbonyl and promotes decomposition of the metal carbonyl in a reaction space consisting of a CO atmosphere pressurized from normal pressure is disposed,
In the reaction space, a metal carbonyl generating step of reacting a metal or a metal-containing material as a starting material with CO to generate metal carbonyl and fluidizing it, and supplying the generated metal carbonyl to the reactant holding unit, A carbonyl decomposition step in which a metal product derived from the metal carbonyl and CO gas are decomposed by reacting the metal carbonyl with the reactant to decompose, and the CO gas generated by the decomposition is reacted. A CO feedback step for feeding back to the CO atmosphere in the space is circulated in the reaction space by a gas phase-mediated transport action involved in the reaction system for the production and decomposition of the metal carbonyl, A method for producing a metal-based material, wherein the system material is recovered as a product from the reaction space. The starting material is placed in a container forming the reaction space, pressurized CO gas is sealed in the container, and the starting material is reacted with the CO gas by a first heater in the container. The method for producing a metal-based material according to claim 1, wherein the metal carbonyl is generated by locally heating to a temperature at which the metal carbonyl is generated. A liquid reactant as the reactant is held in a container forming the reactant holding portion, the carbonyl is brought into contact with the liquid reactant, and the decomposition-generated metal material is precipitated and recovered in the liquid reactant. The manufacturing method of the metal type material of Claim 1 or Claim 2. The method for producing a metal-based material according to claim 2 or 3, wherein a metal halide or an organometallic compound is used as the reactant. The method for producing a metal-based material according to claim 4, wherein a noble metal halide is used as the metal halide. The method for producing a metal-based material according to claim 4, wherein an alkyl compound of any one of boron, aluminum, silicon, gallium, indium, germanium, tin, palladium, and platinum is used as the organometallic compound. 7. The liquid reactant according to claim 5, wherein the metal halide or the organometallic compound is dispersed or dissolved in a hydrocarbon or silicone solvent to form the liquid reactant according to claim 5. A method for producing a metallic material. The method for producing a metal-based material according to any one of claims 1 to 7, wherein a metal contained in the starting material is a transition metal. The method for producing a metal-based material according to claim 8, wherein the decomposition-generated metal-based material has a content of the transition metal higher than that of the starting material. The method for producing a metal-based material according to claim 8 or 9, wherein the transition metal is any one of iron, nickel, and cobalt. The method for producing a metal-based material according to claim 10, wherein the decomposition-generated metal-based material is recovered in the form of a metal, an alloy, or an intermetallic compound containing iron, nickel, or cobalt as a main component. As the starting material, solid or powder waste generated from the rare earth magnet manufacturing process, the rare earth magnet waste recovered from used electronic equipment, iron, nickel and cobalt recovered in the recycling process of used batteries The method for producing a metal-based material according to claim 10 or 11, wherein any one of wastes is used. The method for producing a metal-based material according to claim 12, wherein the rare earth material contained in the starting material is concentrated in the residue after the metal carbonyl formation of the starting material in the reaction space and recovered. The CO pressure in the reaction space is higher than atmospheric pressure and 500 atmospheric pressure or lower, and the reaction temperature related to the formation of the metal carbonyl is room temperature or higher and 500 ° C. or lower. A method for producing a metal-based material. The method for producing a metal-based material according to any one of claims 1 to 14, wherein, in the metal carbonyl production step, sulfur is added to the starting material in order to promote a production reaction of the metal carbonyl. The metal according to any one of claims 1 to 14, wherein in the metal carbonyl production step, the starting material is subjected to a disproportionation treatment by hydrogenation treatment in order to promote a production reaction of the metal carbonyl. A method for manufacturing a system material. The method for producing a metal-based material according to any one of claims 1 to 15, wherein the decomposition-generated metal-based material is recovered in a powder form having a particle size of 10 nm or more and 200 µm or less. A method for producing a radio wave absorbing material, characterized in that a radio wave absorbing material is produced using the decomposition-generated metal material obtained by the method according to any one of claims 1 to 17 as a raw material. .