Method for heat treating metal powder

Abstract

According to one aspect of the present invention, there is provided a method for heat treating a metal powder, comprising the steps of: preparing a metal powder-sintering inhibitor composite including metal powders dispersed and spaced apart within a sintering inhibitor; and heat treating the metal powder-sintering inhibitor composite.

Description

[Technical Field]

[0001] The technical concept of the present invention relates to a method for heat treating metal powder, and more particularly to a heat treatment method that prevents aggregation and sintering between particles during high-temperature heat treatment of metal powder and provides a uniform particle size. [Background technology]

[0002] Multilayer ceramic capacitors (MLCCs) are chip-type capacitors that temporarily charge electricity and remove noise in electronic circuits. They store current and then stably supply the required amount of electricity, ensuring the proper operation of electronic devices. Demand for multilayer ceramic capacitors is so high today that they are considered the bread and butter of the electronics industry. For example, a personal computer or smartphone requires approximately 1,000 of them, and a TV requires approximately 2,000.

[0003] Such multilayer ceramic capacitors require a reduction in size and an increase in storage capacitance. To achieve this, they have a structure in which approximately 500 ceramic layers and metal electrode layers are alternately stacked inside. Multilayer ceramic capacitors are formed through a molding process in which a ceramic sheet is formed on a release film, a printing process in which an electrode pattern is formed on the ceramic sheet, and a lamination process in which the ceramic sheet is cut, the release film is removed, and then the ceramic sheet and metal electrode layers are laminated. The key technologies for multilayer ceramic capacitors are to stack as many metal electrode layers as possible while keeping them as thin as possible and to form them without cracking even at high temperatures of over 1000°C.

[0004] In recent years, as the multilayer ceramic capacitors have become increasingly miniaturized and stacked, there has been a demand for ultra-thin internal electrodes. As the metal electrode layers continue to become finer, additional measures are required.

[0005] As part of these measures, various heat treatments have been carried out, such as adding sulfur (S) to nickel powder, which has traditionally been used as a material for the metal electrode layer, oxidizing the surface of the nickel powder, improving the crystallinity of the nickel powder, growing the crystal grains, or removing the sulfur components added during the manufacturing process.

[0006] However, because this heat treatment is typically performed at high temperatures, there is a problem in that nickel particles sinter and agglomerate during the heat treatment. When nickel particles sinter, their particle size increases and their shape becomes irregular, resulting in poor quality of the nickel powder. This problem is not limited to nickel powder, but is a general problem that can occur when ordinary metal powders are heat treated at high temperatures. Summary of the Invention [Problem to be solved by the invention]

[0007] The technical problem to be solved by the technical concept of the present invention is to provide a heat treatment method that prevents agglomeration due to sintering between metal powders during high-temperature heat treatment of various metal powders, including nickel powder. However, this problem is merely an example, and the technical concept of the present invention is not limited thereto. [Means for solving the problem]

[0008] According to one aspect of the present invention, a method for heat treating a metal powder is provided.

[0009] According to one embodiment of the present invention, the method for heat-treating a metal powder includes the steps of: preparing a metal powder-sintering inhibitor composite including metal powders dispersed and spaced apart within a sintering inhibitor; and heat-treating the metal powder-sintering inhibitor composite.

[0010] According to one embodiment of the present invention, the sintering inhibitor may include a metal salt, and the metal salt may include a metal chloride, such as NiCl, BaCl, NaCl, and KCl.

[0011] According to an embodiment of the present invention, the metal powder may include at least one of nickel powder, copper powder, silver powder, iron powder, and alloy powder thereof.

[0012] According to one embodiment of the present invention, the sintering inhibitor may further include a ceramic precursor that is converted into a ceramic by heat, along with the metal salt, and the ceramic precursor may include Al(NO3)3, Al2(SO4)3, Ba(NO3)2, TiCl4, and Mg(NO3)2.

[0013] According to an embodiment of the present invention, the heat-treating step may include converting the ceramic precursor into a ceramic.

[0014] According to one embodiment of the present invention, a method for manufacturing the metal powder-sintering inhibitor composite may include the steps of: preparing a sintering inhibitor solution in which a sintering inhibitor is dissolved in a solvent; adding metal powder to the sintering inhibitor solution and dispersing the metal powder in the sintering inhibitor solution to prepare a metal powder dispersion; and spray-drying the dispersed particle dispersion.

[0015] According to an embodiment of the present invention, the method may further include removing the sintering inhibitor after the heat treatment.

[0016] According to an embodiment of the present invention, the heat treatment may be performed in an atmosphere including any one of a hydrogen atmosphere, an oxidizing atmosphere, a carbonizing atmosphere, a decarbonizing atmosphere, a reducing atmosphere, an inert atmosphere, an air atmosphere, a sulfurizing atmosphere, a desulfurizing atmosphere, and a vacuum atmosphere.

[0017] According to one embodiment of the present invention, the method may further include removing the sintering inhibitor and recovering the metal powder after the heat treatment is completed, and in the step of removing the sintering inhibitor, the ceramic converted from the ceramic precursor may remain on at least a portion of the surface of the recovered metal powder. [Effects of the Invention]

[0018] According to the technical concept of the present invention, the sintering inhibitor prevents sintering between metal powder particles during heat treatment of the metal powder at high temperatures, eliminating the problem of agglomeration of the metal powder. Furthermore, the ceramic precursor contained in the sintering inhibitor remains on the surface of the metal powder after being converted to ceramic during the heat treatment and then removed, thereby improving resistance to sintering shrinkage when the metal powder is subsequently used to manufacture metal electrode layers of MLCCs.

[0019] The above-mentioned effects of the present invention are merely examples, and the scope of the present invention is not limited to these effects. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a flow chart illustrating a method for heat treating metal powder according to the technical concept of the present invention. [Figure 2] The nickel powder and nickel powder-sintering inhibitor composite used in the experiment were observed using an SEM. [Figure 3] 1 shows the results of SEM observation of the states of Control Groups 1 to 4 after heat treatment. [Figure 4] The photographs show the state of experimental groups 3 and 4 after heat treatment (upper photograph), and the state of the nickel powder recovered after removing the sintering inhibitor (lower photograph), observed with an SEM. [Figure 5] This shows the results of observing the state of the nickel powder recovered after removing all of the sintering inhibitor from the nickel powder-sintering inhibitor composite that had undergone heat treatment using an SEM and conducting component analysis using EDS. [Figure 6]The graph shows the results of TGA analysis using nickel powder that has not undergone post-treatment and nickel powder that has undergone post-treatment. [Figure 7] 1 is a diagram showing the structure of the metal powder-sintering inhibitor composite obtained by the spray drying process. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Each embodiment of the present invention is provided to more completely explain the technical concept of the present invention to those skilled in the art. The following embodiments may be modified into various other forms, and the scope of the technical concept of the present invention is not limited to the following embodiments. Rather, these embodiments are provided to make the present disclosure more complete and complete and to fully convey the technical concept of the present invention to those skilled in the art. The same reference numerals refer to the same elements throughout this specification. Furthermore, various elements and regions in the drawings are illustrated schematically. Therefore, the technical concept of the present invention is not limited by the relative sizes and spacings shown in the accompanying drawings.

[0022] FIG. 1 shows a method for heat-treating a metal powder using a metal powder-sintering inhibitor composite prepared according to an embodiment of the present invention.

[0023] Referring to step S1 of FIG. 1, a sintering inhibitor is added to a solvent and then dissolved to form a sintering inhibitor solution. The sintering inhibitor is a substance that is dissolved in a solvent and then re-precipitated in the spray-drying step described below. The solvent may be water or an organic solvent.

[0024] The sintering inhibitor includes a metal salt, such as a metal chloride, such as NiCl2, BaCl2, NaCl, or KCl.

[0025] The sintering inhibitor may further include a ceramic precursor in addition to the metal salt. The ceramic precursor is a material that is transformed into a ceramic by thermal decomposition during a subsequent heat treatment. The ceramic may include metal oxides, metal nitrides, metal carbides, and composites thereof (e.g., metal oxynitrides). For example, metal oxides include aluminum oxide (Al2O3) and barium titanium oxide (BaTiO3). For example, aluminum oxide precursors may include aluminum nitrate (Al(NO3)3) and aluminum sulfate (Al2(SO4)3), barium titanium oxide precursors may include barium nitrate (Ba(NO3)2) and titanium chloride (TiCl4), and magnesium oxide precursor may include magnesium nitrate (Mg(NO3)2).

[0026] The sintering inhibitor dissolved in the solvent may be a metal salt. Alternatively, the metal salt and the ceramic precursor may be dissolved together. When the metal salt and the ceramic precursor are dissolved together in the solvent, the sintering inhibitor precipitated during the spray-drying step is precipitated as a mixture of the metal salt and the ceramic precursor.

[0027] Referring to step S2 of FIG. 1, metal powder is added to a solution in which a sintering inhibitor is dissolved, and dispersed in the solution to prepare a metal powder dispersion.

[0028] The metal powder may include, but is not limited to, nickel powder, copper powder, silver powder, nickel-copper alloy powder, iron powder, and alloy powders thereof (e.g., nickel-copper alloy powder, iron-cobalt alloy powder, etc.).

[0029] Referring to step S3 of Figure 1, a metal powder-sintering inhibitor composite is produced by spray-drying the metal powder dispersion. During the spray-drying process, the metal powder dispersion is atomized by spraying, and then dried using hot air to instantly evaporate the liquid phase, thereby obtaining a powder phase containing the metal powder and the sintering inhibitor (hereinafter referred to as a metal powder-sintering inhibitor composite).

[0030] The structure of a metal powder-sintering inhibitor composite obtained by spray drying is shown in Figure 7. Referring to Figure 7, the metal powder-sintering inhibitor composite may have a structure in which multiple metal powders (metal particles) are dispersed and spaced apart from one another within the sintering inhibitor.

[0031] The sintering inhibitor is formed by precipitating a metal salt dissolved in a solution or a mixture of a metal salt and a ceramic precursor as a solid during the spray-drying process. During the precipitation process, the sintering inhibitor is formed while covering the metal powder.

[0032] In some cases, the sintering inhibitor may contain ceramic formed as a result of transformation of some of the ceramic precursors during the spray drying process.

[0033] 7, in the metal powder-sintering inhibitor composite manufactured according to an embodiment of the present invention, the sintering inhibitor surrounds the metal powder, so the metal powder is physically separated. Therefore, even when the metal powder-sintering inhibitor composite is heat-treated at high temperatures, the sintering inhibitor prevents the metal powder from coming into contact with each other and then sintering and agglomerating during the heat treatment process.

[0034] Referring to step S4 of FIG. 1, after forming the metal powder-sintering inhibitor composite through the spray drying process, the metal powder-sintering inhibitor composite may be heat-treated.

[0035] The heat treatment is performed to improve or modify the properties of the metal powder. For example, in the case of nickel powder, heat treatment may be performed to add sulfur to the surface or oxidize the surface to suppress sintering and shrinkage of the nickel powder during the MLCC manufacturing process. As another example, heat treatment may be performed in a vacuum or inert atmosphere to improve the crystallinity of the nickel powder. As yet another example, heat treatment may be performed in a desulfurization atmosphere to re-de-sulfurize the sulfur components added to the nickel powder during the manufacturing process of nickel powder by a chemical vapor deposition method.

[0036] In addition, various atmospheres such as a reducing atmosphere, an oxidizing atmosphere, a vacuum atmosphere, an inert atmosphere, etc. may be used to modify metal powders other than nickel powder.

[0037] During such heat treatment, the sintering inhibitor prevents sintering between the nickel powder particles.

[0038] Meanwhile, the sintering inhibitor formed by spray drying contains minute spaces within which gas can move. Therefore, when heat-treated in an oxygen or sulfur atmosphere, reactive gases such as oxygen gas or sulfur gas can reach the metal powder inside the sintering inhibitor through the sintering inhibitor.

[0039] If the sintering inhibitor contains a ceramic precursor, the ceramic precursor may be converted to a ceramic during the heat treatment. When the heat treatment is completed, the sintering inhibitor in the metal powder-sintering inhibitor composite may contain the ceramic converted from the ceramic precursor along with the metal salt.

[0040] The ceramic formed by the transformation from the ceramic precursor further improves the sintering prevention properties of the sintering inhibitor, and in some cases, the ceramic may remain on the surface of the metal powder even after the sintering inhibitor removal step described below, thereby affecting the properties of the metal powder.

[0041] For example, when the metal powder is nickel powder, aluminum oxide, magnesium oxide, barium titanium oxide, or a precursor of barium titanium oxide may remain on the surface of the nickel powder as a ceramic. If the ceramic remains on the surface of the nickel powder, when the nickel powder is used as an electrode for an MLCC, the abnormal growth of the nickel powder due to sintering at high temperatures can be suppressed.

[0042] The heat treatment may have a section in which a predetermined temperature is maintained for a predetermined time depending on the purpose. When a ceramic precursor is contained in the sintering inhibitor, the heat treatment temperature may be increased to a temperature higher than the thermal decomposition temperature of the ceramic precursor.

[0043] Alternatively, the heat treatment may be performed during a continuous temperature increase process, in which case the ceramic precursor may transition to a ceramic during the process of increasing the temperature to the heat treatment temperature, rather than maintaining the temperature at a specific temperature for a predetermined time.

[0044] Referring to step S5 of FIG. 1, the metal powder-sintering inhibitor composite that has undergone the heat treatment step is washed to selectively remove the sintering inhibitor and recover the metal powder.

[0045] The sintering inhibitor can be removed by washing with a cleaning solution that can dissolve the sintering inhibitor. For example, if the sintering inhibitor contains water-soluble metal chlorides such as NiCl2 or BaCl2, it can be completely dissolved and removed by washing with water. Alternatively, an organic solvent or an acid / alkali solution can be used as the cleaning solution.

[0046] Experimental results will be presented below to facilitate understanding of the present invention. These experimental results are merely examples to facilitate understanding of the present invention, and it should be understood that the present invention is not limited thereto.

[0047] First experiment

[0048] The metal powder used was nickel powder (average diameter 200 nm) produced by chemical vapor synthesis using NiCl2 and H2 as raw materials. Figure 2(a) shows the results of SEM observation of the produced nickel powder.

[0049] Metal salts, NiCl2 and BaCl2, were used as sintering inhibitors. 207.6 g each of NiCl2 and BaCl2 were dissolved in 450 ml of water to prepare sintering inhibitor solutions. Nickel powder was added to each of the prepared sintering inhibitor solutions to prepare metal powder dispersions. The metal powder dispersions were spray-dried at 180°C to prepare metal powder-sintering inhibitor composites.

[0050] Figures 2(b) and 2(c) show SEM observations of nickel particle-sintering inhibitor composites using NiCl2 and BaCl2 as sintering inhibitors, respectively. From these images, it can be seen that the nickel particles are well dispersed in the sintering inhibitors, NiCl2 and BaCl2. Analysis of the sintering inhibitor components using EDS (energy dispersive spectroscopy) revealed that Ni and Cl were detected in the specimen shown in Figure 2(b), and Ba and Cl in the specimen shown in Figure 2(c), confirming that the sintering inhibitors were successfully manufactured.

[0051] The manufactured metal powder-sintering inhibitor composite was heat-treated in a hydrogen (H2) or oxygen (O2) atmosphere, and then the sintering of the metal powder, the grain size, and the nickel oxide (NiO) content were measured. Table 1 shows the types of test specimens used in the first experiment and the post-treatment experimental conditions.

[0052] [Table 1]

[0053] In Table 1, control groups 1 to 4 are nickel powders (hereinafter referred to as CVS nickel powders) that do not contain a sintering inhibitor and are heat-treated at different temperatures in a hydrogen atmosphere.The above treatments were carried out to confirm that the nickel powder is sintered depending on the temperature.

[0054] In experimental groups 1 to 4, nickel particle-sintering inhibitor composites in which the sintering inhibitor was BaCl2 were heat-treated at different temperatures in a hydrogen atmosphere. The above treatments were carried out to increase the crystal grain size of the nickel powder while preventing agglomeration.

[0055] In experimental groups 5 and 6, nickel particle-sintering inhibitor composites in which the sintering inhibitor was NiCl2 were heat-treated at different temperatures in an oxygen atmosphere. The above treatments were carried out to oxidize and heat-treat the nickel powder while preventing agglomeration.

[0056] The heat treatment was carried out by raising the temperature from room temperature to the heat treatment temperature over 40 minutes, maintaining the heat treatment temperature for 5 minutes, and then cooling in the furnace.

[0057] After the heat treatment, the nickel particles-sintering inhibitor of the control group and the experimental group were washed with water to remove all of the sintering inhibitor, and then the nickel powder was recovered.

[0058] Referring to Table 1, in the case of the control group, sintering between the nickel powder particles did not occur at 300° C. because the temperature was too low, but sintering occurred at all temperatures higher than that.

[0059] Figure 3 shows the results of SEM observation of the heat-treated state of Control Groups 1 to 4. Referring to Figure 3, it can be seen that sintering of the nickel powder begins actively above 400°C, and that sintering causes aggregation between particles, which can lead to drastic changes in shape.

[0060] Referring to Table 1, it can be seen that no sintering occurred at any of the temperatures in Experimental Groups 1 to 4, and that the grain size increased as the heat treatment temperature increased. The grain size was measured using X-ray diffraction.

[0061] Figure 4 shows the results of SEM observations of the nickel powders (top photo) before removal of the sintering inhibitor after heat treatment in Experimental Groups 3 and 4, and the nickel powders (bottom photo) recovered after removal of the sintering inhibitor. It can be seen from Figure 4 that in both Experimental Groups 3 and 4, the sintering inhibitor BaCl2 prevented the nickel powders from coming into contact with each other and sintering.

[0062] Referring to Table 1, it can be seen that in Experimental Groups 5 and 6, no sintering occurred at any temperature, and the crystal grain size of the nickel powder increased as the heat treatment temperature increased. Furthermore, X-ray diffraction analysis confirmed that nickel oxide (NiO) was formed. This confirms that, according to the technical concept of the present invention, highly crystalline nickel oxide can be formed on the surface of nickel particles at high temperatures while preventing sintering between metal powder particles.

[0063] Second experiment

[0064] Table 2 shows the type of test piece and the corresponding experimental conditions used in the second experiment. 5 g of CVS nickel powder, which was used in the first experiment, was dispersed in a sintering inhibitor solution prepared by dissolving 207.6 g of metal salt BaCl2 and 0.19 g of aluminum oxide precursor Al(NO3)3 in 450 ml of water. The metal powder dispersion was spray-dried at 180°C to prepare a nickel particle-sintering inhibitor composite. EDS analysis of the sintering inhibitor detected Ba, Al, and Cl components, indicating that the sintering inhibitor is a mixture of BaCl2 and Al(NO3)3.

[0065] [Table 2]

[0066] Next, this was placed in a heat treatment furnace and heat treated in a hydrogen atmosphere at temperatures of 300° C., 400° C., and 500° C. The heat treatment conditions from heating to furnace cooling were the same as in the first experiment.

[0067] EDS analysis of the heat-treated nickel particle-sintering inhibitor composite specimens from Experimental Groups 7-9 revealed the presence of Ba, Al, and Cl in all specimens. X-ray diffraction analysis also revealed the presence of aluminum oxide (Al2O3) in all specimens. This indicates that Al(NO3)3, which has a thermal decomposition temperature of approximately 200°C in the sintering inhibitor, was thermally decomposed at temperatures above 300°C and converted to aluminum oxide. Therefore, the sintering inhibitor in the heat-treated nickel particle-sintering inhibitor composites is a mixture of BaCl2 and Al2O3. Based on the amount of Al(NO3)3 added during the preparation of the sintering inhibitor solution, the sintering inhibitor contains approximately 10 wt% Al2O3.

[0068] After the heat treatment, the nickel particle-sintering inhibitor composites of experimental groups 7 to 9 were washed with water to remove the sintering inhibitor, and the nickel powder was then recovered. The recovered nickel powder was observed with an SEM, and it was confirmed that no sintering occurred in any of the nickel powders, regardless of the heat treatment temperature.

[0069] Figure 5 shows the nickel powder recovered after the post-treatment corresponding to Experimental Group 9, i.e., the nickel particle-sintering inhibitor composite that had been heat-treated at 500°C was washed with water to remove all of the sintering inhibitor. The nickel powder was observed with an SEM and analyzed for its components with an EDS.

[0070] 5, it can be seen that aluminum components were also detected in the recovered nickel powder, suggesting that aluminum oxide formed from the precursor during the heat treatment process was also formed on the surface of the nickel particles and remained on the surface of the nickel particles even after the sintering inhibitor was removed.

[0071] When high-melting-point aluminum oxide is formed on the nickel surface, the nickel powder has high resistance to sintering shrinkage during the MLCC manufacturing process, which means that the occurrence of problems due to sintering shrinkage is reduced.

[0072] Figure 6(a) shows the results of measuring the final oxidation end temperature by TGA, using the weight increase due to oxidation of CVS nickel powder that had not undergone any post-treatment in air. Figure 6(b) shows the results of TGA analysis of nickel powder recovered after post-treatment corresponding to Experimental Group 9.

[0073] 6(a) and 6(b), the oxidation end temperature for the CVS nickel powder that was not post-treated was 670°C, while the oxidation end temperature for the nickel powder recovered after post-treatment corresponding to Experimental Group 9 was 770°C, which was about 100°C higher. A higher oxidation end temperature can be considered to indicate a higher sintering temperature in the firing process during the MLCC manufacturing process, which means higher resistance to sintering shrinkage.

[0074] It will be apparent to those skilled in the art to which the technical idea of ​​the present invention pertains that the technical idea of ​​the present invention described above is not limited to the above-described embodiments and accompanying drawings, and that various substitutions, modifications and changes are possible within the scope of the technical idea of ​​the present invention. [Note] The present disclosure relates to the following aspects: <1> ~ <14> Also includes. <1> As a method for heat treating metal powder, Preparing a metal powder-sintering inhibitor composite including metal powders dispersed and spaced apart within a sintering inhibitor; and heat-treating the metal powder-sintering inhibitor composite. <2> the sintering inhibitor comprises a metal salt; <1> A method for heat treating a metal powder according to claim 1. <3> The sintering inhibitor further comprises a ceramic precursor that is converted to a ceramic by heat. <2> A method for heat treating a metal powder according to claim 1. <4> The heat treatment step includes: converting the ceramic precursor to a ceramic; <3> A method for heat treating a metal powder according to claim 1. <5> The method for producing the metal powder-sintering inhibitor composite includes: preparing a sintering inhibitor solution in which a sintering inhibitor is dissolved in a solvent; Adding metal powder to the sintering inhibitor solution and dispersing the metal powder to prepare a metal powder dispersion; and spray drying the dispersed particle dispersion; <1> A method for heat treating a metal powder according to claim 1. <6> The method further includes removing the sintering inhibitor after the heat treatment. <1> A method for heat treating a metal powder according to claim 1. <7> the sintering inhibitor comprises a metal salt; <5> A method for heat treating a metal powder according to claim 1. <8> The sintering inhibitor further comprises a ceramic precursor that is converted to a ceramic by heat. <7> A method for heat treating a metal powder according to claim 1. <9> The metal powder includes at least one of nickel powder, copper powder, silver powder, iron powder, and alloy powder thereof; <1> and <5> A method for heat treating a metal powder according to claim 1. <10> The metal salt comprises a metal chloride. <1> or <7> A method for heat treating a metal powder according to claim 1. <11> The metal chloride is NiCl 2 , BaCl 2 , including NaCl and KCl, <10> A method for heat treating a metal powder according to claim 1. <12> The ceramic precursor is Al(NO 3 ) 3 、Al 2 (SO 4 ) 3 , (Ba(NO 3 ) 2 ), TiCl 4 and (Mg(NO 3 ) 2 ), including <3> or <8> A method for heat treating a metal powder according to claim 1. <13> The heat treatment step includes: The treatment is carried out in an atmosphere including any one of a hydrogen atmosphere, an oxidizing atmosphere, a carbonizing atmosphere, a decarbonizing atmosphere, a reducing atmosphere, an inert atmosphere, an air atmosphere, a sulfurizing atmosphere, a desulfurizing atmosphere, and a vacuum atmosphere. <1> A method for heat treating a metal powder according to claim 1. <14> After the heat treatment step is completed, the method further includes removing the sintering inhibitor and recovering the metal powder, In the step of removing the sintering inhibitor, the ceramic converted from the ceramic precursor remains on at least a portion of the surface of the recovered metal powder. <3> A method for heat treating a metal powder according to claim 1.

Claims

1. preparing a metal powder-sintering inhibitor composite including metal powders dispersed and spaced apart within a sintering inhibitor; heat treating the metal powder-sintering inhibitor composite; and removing the sintering inhibitor from the metal powder-sintering inhibitor composite and recovering the metal powder, The step of preparing the metal powder-sintering inhibitor composite includes: preparing a sintering inhibitor solution in which a sintering inhibitor is dissolved in a solvent; Adding metal powder to the sintering inhibitor solution and dispersing the metal powder to prepare a metal powder dispersion; and spray-drying the metal powder dispersion to form the metal powder-sintering inhibitor composite; The sintering inhibitor comprises a ceramic precursor that is converted to a ceramic by heat; In the heat treatment step, the ceramic precursor is transformed into a ceramic, After the heat treatment step, the ceramic converted from the ceramic precursor remains on at least a portion of the surface of the metal powder recovered by removing the sintering inhibitor. Methods for heat treating metal powders.

2. 2. The method for heat treating a metal powder according to claim 1, wherein the sintering inhibitor is removed by washing the metal powder-sintering inhibitor composite with a washing liquid capable of dissolving the sintering inhibitor.

3. The heat treatment step includes:

2. The method for heat treating metal powder according to claim 1, wherein the heat treatment is performed in an atmosphere including any one of a hydrogen atmosphere, an oxidizing atmosphere, a carbonizing atmosphere, a decarburizing atmosphere, a reducing atmosphere, an inert atmosphere, an air atmosphere, a sulfurizing atmosphere, a desulfurizing atmosphere, and a vacuum atmosphere.

4. 2. The method of heat treating metal powder according to claim 1, wherein the ceramic precursor comprises at least one of a metal oxide, a metal nitride, a metal oxynitride, a metal sulfide, a metal chloride, and a composite thereof.

5. The ceramic precursor is Al(NO ３ ) ３ , Al ２ (SO ４ ) ３ , (Ba(NO ３ ) ２ ), TiCl ４ and (Mg(NO ３ ) ２ 2. The method for heat treating a metal powder according to claim 1, further comprising the steps of:

6. The method of heat treating a metal powder according to claim 1 , wherein the sintering inhibitor comprises a metal salt.

7. 10. The method of heat treating metal powder of claim 1, wherein the sintering inhibitor comprises a metal chloride.

8. The sintering inhibitor is NiCl ２ , BaCl ２ 2. The method for heat treating metal powder according to claim 1, wherein the metal powder contains at least one of NaCl, NaCl, and KCl.

9. 2. The method of claim 1, wherein the metal powder comprises at least one of nickel powder, copper powder, silver powder, iron powder, cobalt powder, and alloy powders thereof.

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