CN112423912B - Metal powder, method for producing same, and method for predicting sintering temperature - Google Patents
Metal powder, method for producing same, and method for predicting sintering temperature Download PDFInfo
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- CN112423912B CN112423912B CN201980043273.5A CN201980043273A CN112423912B CN 112423912 B CN112423912 B CN 112423912B CN 201980043273 A CN201980043273 A CN 201980043273A CN 112423912 B CN112423912 B CN 112423912B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/16—Making metallic powder or suspensions thereof using chemical processes
- B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
- B22F9/28—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from gaseous metal compounds
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2301/00—Metallic composition of the powder or its coating
- B22F2301/15—Nickel or cobalt
Abstract
The present invention provides a metal powder containing metal particles having a controlled concentration or distribution of sulfur, and a method for producing the same. The present invention provides a method of manufacturing a metal powder. The method comprises the following steps: the metal chloride gas is produced by chlorinating a metal with chlorine, and the metal particles are produced by reducing the metal chloride as a gas in the presence of a sulfur-containing gas. The reduction is performed such that the total concentration of sulfur in the metal particles is 0.01 to 1.0 wt%, and the local concentration of sulfur at a position 4nm from the surface of the metal particles is 2 at% or more. The total concentration and the local concentration are estimated by an inductively coupled plasma emission spectrometer and an energy dispersive X-ray spectrometer provided in a scanning transmission electron microscope, respectively.
Description
Technical Field
One embodiment of the present invention relates to a metal powder and a method for producing the same. Alternatively, one embodiment of the present invention relates to a method for quality control of metal powder, a method for estimating characteristics of metal powder, or a method for predicting sintering temperature.
Background
An aggregate containing fine metal particles (hereinafter referred to as metal powder) is applied to various fields, and a powder of a metal having high conductivity such as copper, nickel, and silver is widely used as a raw material of an electronic component such as an internal electrode of a multilayer ceramic capacitor (MLCC). The MLCC has a laminate of a ceramic layer including a dielectric material and an internal electrode including a metal as a basic structure. The laminate is formed by alternately coating a dispersion containing a dielectric material and a dispersion containing a metal powder, and then heating to sinter the dielectric material and the metal powder. For example, patent documents 1 and 2 disclose methods for controlling sintering characteristics of metal powder at the time of heating.
[ Prior Art literature ]
[ patent literature ]
JP-A-11-80816A (patent document 1)
[ patent document 2] Japanese patent application laid-open No. 2014-189820
Disclosure of Invention
Technical problem to be solved by the invention
One of the problems of the embodiments of the present invention is to provide a metal powder containing metal particles having a controlled concentration or distribution of sulfur, and a method for producing the same. Alternatively, one of the problems of the embodiments of the present invention is to provide a metal powder having a high sintering initiation temperature and a method for producing the same. Alternatively, one of the problems of the embodiments of the present invention is to provide a metal powder having a small variation in sintering initiation temperature and a method for producing the same. Alternatively, one of the problems of the embodiments of the present invention is to provide a method for quality control of metal powder, a method for estimating characteristics of metal powder, or a method for predicting sintering temperature.
Technical means for solving the technical problems
One embodiment of the present invention is a metal powder. The metal powder includes a metal and sulfur-containing metal particles. The total concentration of sulfur in the metal particles is 0.01 to 1.0 wt%, and the local concentration of sulfur at a position 4nm from the surface of the metal particles is 2 at% or more. The total concentration and the local concentration are estimated by an inductively coupled plasma emission spectrometer and an energy dispersive X-ray spectrometer provided in a scanning transmission electron microscope, respectively.
One embodiment of the present invention is a method of manufacturing a metal powder. The method includes generating a metal chloride gas by chlorinating a metal with chlorine, and generating metal particles by reducing the metal chloride as a gas in the presence of a sulfur-containing gas. The reduction is performed such that the total concentration of sulfur in the metal particles is 0.01 to 1.0 wt% and the local concentration of sulfur in the metal particles at a position 4nm from the surface is 2 at% or more. The total concentration and the local concentration are estimated by an inductively coupled plasma emission spectrometer and an energy dispersive X-ray spectrometer provided in a scanning transmission electron microscope, respectively.
One embodiment of the present invention is a method of predicting the sintering temperature of a metal powder. The method comprises measuring the local concentration of sulfur at a location 4nm from the surface of metal particles selected from the metal powder. The local concentration of sulfur was measured with a scanning transmission electron microscope provided with an energy dispersive X-ray spectrometry.
Drawings
Fig. 1 is a schematic cross-sectional view of a reduction furnace of a metal powder manufacturing apparatus according to an embodiment of the present invention.
Fig. 2 is a graph showing the sulfur concentration distribution of metal particles in the metal powders containing examples and comparative examples.
Fig. 3 is a graph showing the relationship between the sintering initiation temperature and the total concentration of sulfur of the metal powders of examples and comparative examples.
Detailed Description
Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention may be embodied in various forms within a scope not departing from the gist thereof and is not limited to the description of the embodiments shown below for explanation.
Although the drawings may schematically represent the width, thickness, shape, etc. of each component compared to the actual embodiment for the sake of clarity of description, the drawings are merely examples, and do not limit the explanation of the present invention. In the present specification and each drawing, elements having the same functions as those of elements described in the already-mentioned drawings may be denoted by the same reference numerals, and duplicate descriptions may be omitted.
< embodiment 1 >
In this embodiment, the structure and characteristics of the metal powder 100 as one of the embodiments of the present invention are described.
1. Structure of the device
The metal powder 100 is an aggregate of a plurality of metal particles 102, the metal particles 102 containing a metal and sulfur. The metal is selected from nickel, copper, silver, etc., typically nickel. The number average particle diameter of the metal powder 100 may be 50nm to 400nm, 100nm to 300nm, or 100nm to 250 nm. In other words, the average particle diameter of the plurality (e.g., 600) of metal particles 102 selected from the metal powder 100 may fall within the above range as the number average particle diameter of the metal powder 100. As the number average particle diameter, for example, the metal particles 102 contained in the metal powder 100 are observed by a scanning electron microscope, the particle diameters of a plurality of particles (for example, 600 particles) are measured, and the average value thereof is adopted. The particle diameter is the diameter of the smallest circle inscribing the particle.
The metal powder 100 contains sulfur. Specifically, the total sulfur concentration of the metal powder 100 is 0.01 wt% or more and 1.0 wt% or less, or more than 0.01 wt% and 0.6 wt% or less, or 0.15 wt% or more and 0.6 wt% or less, or 0.16 wt% or more and 0.6 wt% or less. In other words, the average value of the particle concentration of sulfur in the plurality of metal particles 102 selected from the metal powder 100 (for example, the number corresponding to 0.5 g) falls within the above range. The overall concentration of sulfur is the ratio of the weight of sulfur to the weight of metal particles 102. The overall concentration of sulfur of one metal particle 102 or the average value of the overall concentration of sulfur of a plurality of metal particles 102 selected from the metal powder 100 is calculated as the overall concentration of the metal powder 100.
The overall concentration of sulfur can be measured by inductively coupled plasma emission spectroscopy. For example, measurement can be performed using an inductively coupled plasma emission spectrometer (SPS 3100) manufactured by SII nanotechnology corporation. The specific measurement method is that after dissolving the metal powder 100 with acid, ICP emission spectrum analysis is performed at the measurement wavelength of 182.036nm, and the total concentration of sulfur can be obtained.
The metal particles 102 contain sulfur not only near the surface but also in the interior relatively far from the surface toward the interior of the particle. Specifically, although the concentration of sulfur decreases as approaching from the surface of the metal particle 102 toward the inside, the concentration of sulfur at a position 4nm from the surface (hereinafter, the concentration of sulfur at a specific position of the metal particle 102 is referred to as a local concentration) is 2 at% or more. The sulfur concentration at a position 4nm from the surface may be 4 at% or less. The average value of the local concentration of sulfur at the above-described positions of the plurality (e.g., 10) of metal particles 102 selected from the metal powder 100 falls within the above-described range.
In addition, a position having a local concentration of 1-2 of the local concentration of sulfur on the surface of the metal particles 102 (hereinafter referred to as a half-decay depth) may exist in a range of 2nm to 4 nm. That is, the average value of the half-decay depths of the plurality (e.g., 10) of metal particles 102 selected from the metal powder 100 may fall within the above range.
The local concentration of sulfur can be estimated, for example, by an energy dispersive X-ray spectroscopy (STEM-EDS: scanning Transmission Electron Microscope-Energy Dispersive X-ray spectroscopy) provided in a scanning transmission electron microscope. In a specific measurement method, first, the metal powder 100 is dispersed in a resin, and the resin is cured. Then, the cross section was exposed using a cross section polisher (CP), and a thin film sample was prepared by planar sampling using a Focused Ion Beam (FIB). By setting the thickness of the sample to about 100nm, the metal particles 102 are formed as a thin film having the thickness. Then, by performing EDS measurement on the obtained thin film on a straight line passing through the center of the metal particle 102, a local concentration can be obtained. As the conditions for EDS measurement, for example, conditions of an acceleration voltage of 200kV, a probe diameter of 1nm, a pitch width of 3nm and a measurement time of 15 seconds per spot can be selected.
2. Characteristics of
Since the metal powder 100 containing the metal particles 102 has a high overall concentration and sulfur is widely distributed in the surface layer portion of the metal particles 102, it has a high sintering initiation temperature, for example, in the range of 600 ℃ or more. The sintering initiation temperature may be 700 ℃ or less. Based on the above characteristics, the local concentration of sulfur in the surface layer portion of the metal particles is measured, and when the local concentration satisfies the above conditions, it can be determined that the metal powder, which is an aggregate of the metal particles, has a high sintering initiation temperature. Accordingly, the present embodiment provides an effective method for predicting the characteristics of metal powders.
As shown in the present embodiment, it is suggested that the broad distribution and high overall concentration of sulfur is related to the high sintering initiation temperature of the metal powder 100. If the total concentration of sulfur is the same, the distribution of sulfur is broad (sulfur exists in the surface layer up to deep), which is advantageous from the standpoint of increasing the sintering initiation temperature. By taking advantage of this fact, the sintering initiation temperature of the metal powder can be estimated or estimated by measuring the distribution and the overall concentration of sulfur in the surface layer. For example, when metal particles are arbitrarily selected from metal powders by STEM-EDS analysis and the condition that the local concentration of sulfur is 2 at% or more at a position of 4nm from the surface of the metal particles is satisfied, it can be estimated that the sintering temperature of the metal powder containing the metal particles is 600 ℃ or more. In other words, according to the present embodiment, even if the metal powder is not sintered, the sintering behavior of the metal powder can be estimated by measuring the sulfur concentration in the surface layer, and thus an effective method of managing the quality of the metal powder is provided by the embodiment of the present invention.
For example, when metal powder is used as a raw material of an internal electrode of an MLCC, a dispersion containing a dielectric and a dispersion containing metal powder are alternately coated and then fired. The dispersion containing a dielectric substance contains Ba or Ti-based oxide powder, a polymer material used as a binder, a solvent, a dispersant, and the like, and the dispersion containing a metal powder contains not only a metal powder but also a binder, a solvent, a dispersant, and the like. During firing, the binder, solvent and dispersant evaporate or decompose, and the oxide powder and the metal powder sinter, providing dielectric films and internal electrodes, respectively. Since the sintering initiation temperature of the dielectric is generally higher than that of the metal powder, sintering of the metal powder is started first at the time of sintering. Therefore, a gap is generated between the dielectric and the internal electrode during baking, and sometimes peeling is generated between the internal electrode and the dielectric film due to the gap, thereby reducing the characteristics and yield of the MLCC.
On the other hand, since the metal powder 100 exhibits a high sintering initiation temperature, sintering starts at a temperature closer to the sintering initiation temperature of oxide powder or the like. As a result, high adhesion between the internal electrode and the dielectric can be ensured at the time of baking, and peeling can be suppressed. Accordingly, the metal powder 100 can be used as a raw material for providing various electronic components having excellent characteristics.
As described above, since the sintering behavior of the metal powder can be estimated without sintering, a quality control method for manufacturing the metal powder having high reliability as an electrode material of an MLCC can be provided by the present embodiment.
< embodiment 2 >
In the present embodiment, an example of a manufacturing method of the metal powder 100 is described.
The metal powder 100 is manufactured by a gas phase method. That is, metal chlorides are produced by reducing a vapor of a metal chloride (hereinafter simply referred to as chloride) obtained by chlorinating a metal or a vapor obtained by heating a metal chloride in the presence of a sulfur-containing gas. However, since high purity chloride vapor can be obtained and the supply amount of the chloride vapor can be stabilized, it is more preferable to generate the chloride vapor by chlorinating the metal. Since a known apparatus for chlorinating a metal (chlorination furnace) can be used, a description thereof will be omitted.
A schematic cross-sectional view of a reduction device 110 as a device for reducing chloride is shown in fig. 1. The reduction device 110 has a function of generating the metal powder 100 by reducing the chloride and simultaneously introducing sulfur into the metal particles 102. The reduction device 110 includes a reduction furnace 112 and a heater 114 for heating the reduction furnace 112 as basic structures. The 1 st transfer pipe 116 is connected to the reduction furnace 112, and the metal chloride gas is introduced into the reduction furnace 112 through this. The reduction furnace 112 is further provided with a 1 st gas introduction pipe 118 for supplying reducing gas such as hydrazine, ammonia, methane, and the like. A reducing gas supply source, not shown, is connected to the 1 st gas introduction pipe 118. The valve 120 is attached to the 1 st gas introduction pipe 118, whereby the supply amount of the reducing gas can be controlled.
The 1 st transfer pipe 116 is provided with a 2 nd gas introduction pipe 122 for supplying sulfur-containing gas. The 2 nd gas introduction pipe 122 is connected to a sulfur-containing gas source, not shown, through a valve 124, and the supply amount thereof can be adjusted by the valve 124. With this structure, the reducing gas can be brought into contact with the mixed gas of the chloride gas and the sulfur-containing gas. The 1 st gas introduction pipe 118 and the 2 nd gas introduction pipe 122 may also be connected to an inert gas supply source, whereby an inert gas as a carrier gas can be mixed with a reducing gas or a sulfur-containing gas and supplied into the reduction furnace 112. With this structure, a mixed gas of the chloride gas and the sulfur-containing gas is supplied into the reduction furnace 112. Although not shown in the drawing, the 2 nd gas introduction pipe 122 may be connected to the reduction furnace 112 instead of being connected to the 1 st transfer pipe 116, or the chloride gas and the sulfur-containing gas may be supplied to the reduction furnace 112, respectively.
The chloride is reduced by the reducing gas in the reducing furnace 112 heated by the heater 114, thereby producing the metal particles 102, and sulfur derived from the sulfur-containing gas is introduced into the metal particles 102. Note that, preferably, not the separated chloride gas but the chloride gas generated in a chlorination furnace not shown in the drawing is introduced. By adopting such a form, chlorination and reduction can be continuously performed, and metal powder can be efficiently produced.
The reduction furnace 112 is also equipped with a 3 rd gas introduction pipe 126 for supplying cooling gas to the reduction furnace 112. The 3 rd gas introduction pipe 126 is preferably disposed at a position distant from the 1 st delivery pipe 116. For example, in the case where the 1 st transfer pipe 116 is provided at the upper portion of the reduction furnace 112, the 3 rd gas introduction pipe 126 is provided at the lower portion of the reduction furnace 112. As the cooling gas, inert gases such as nitrogen and argon may be used, and a supply source (not shown) of these gases is connected to the 3 rd gas introduction pipe 126. The flow of cooling gas is controlled by valve 128. By supplying the cooling gas, the growth of the metal particles 102 formed in the reduction furnace 112 can be controlled. The metal powder 100 is fed to the separator and the recovery device through the 2 nd feed pipe 130 by the cooling gas, and separated and purified.
In the reduction, the reduction furnace 112 is heated by the heater 114, and the metal chloride gas and the sulfur-containing gas are introduced into the reduction furnace 112 through the 1 st transfer pipe 116 and the 2 nd gas introduction pipe 122, while the reducing gas is supplied into the reduction furnace 112 through the 1 st gas introduction pipe 118. The heating temperature of the reduction furnace 112 is preferably lower than the melting point of the metal, and is selected from the range of 800 to 1100 ℃, for example. Thus, the metal generated in the reduction furnace 112 can be taken out as solid metal particles 102. The amount of reducing gas supplied into the reduction furnace 112 is regulated by using a valve 120 so as to be stoichiometrically equal to or slightly excessive of the supplied metal chloride.
As the sulfur-containing gas, a gas containing a component selected from the group consisting of hydrogen sulfide, sulfur dioxide, and sulfur halide is used. As the sulfur halide, snCl may be mentioned 2 (n is an integer of 2 or more), SF 6 ，SF 5 Cl，SF 5 Br, etc. Among them, sulfur dioxide which is easy to handle is preferable. The flow rate of the sulfur-containing gas is adjusted to be 0.01 to 1.0 wt% with respect to the metal powder produced per unit time of the chloride supplied from the reduction furnace 112 by using the valve 124.
By adopting the above-described method, the total concentration and the local concentration of sulfur can be controlled within the ranges described in embodiment 1, and the metal particles 102 containing sulfur at a high concentration and the metal powder 100 containing the metal particles 102 can be produced not only near the surface but also in the interior away from the surface.
Examples (example)
1. Example 1
In this example, an example of manufacturing the metal powder 100 by applying the manufacturing method described in embodiment 2 is shown.
The chlorine gas was reacted with nickel in the chlorination furnace to produce nickel chloride gas, the reduction furnace 112 was heated to 1100 ℃, and a mixed gas of nickel chloride, sulfur dioxide gas as a sulfur-containing gas, and nitrogen gas was introduced into the reduction furnace 112 from the 1 st transfer pipe 116 connected to the chlorination furnace at a flow rate of 2.8 m/sec (in terms of 1100 ℃). At the same time, hydrogen gas was introduced into the reduction furnace 112 from the 1 st gas introduction pipe 118 at a flow rate of 2.2 m/sec (in terms of 1100 ℃). As the cooling gas, nitrogen gas is used, and supplied from the 3 rd gas introduction pipe 126. The obtained nickel powder (number average particle diameter of 190 nm) was purified by using a production apparatus or the like not shown. The total sulfur concentration of the resulting nickel powder was 0.15 wt.%.
As comparative example 1 of example 1, a nickel powder prepared by sulfur treatment of a nickel powder obtained by reducing nickel chloride in the absence of sulfur-containing gas was used, and the sulfur concentration thereof was measured. The nickel powder in comparative example 1 was prepared by preparing a nickel powder without introducing sulfur-containing gas into the reduction furnace 112 in the above-described examples, and then performing the post-treatment described below.
That is, an aqueous thiourea solution having a sulfur content of 0.15% by weight relative to the nickel powder was added to the slurry obtained in the process of purifying the nickel powder (number average particle diameter 190 nm) produced in the absence of sulfur-containing gas, and stirred for 30 minutes. Then, the slurry was dried with a pneumatic dryer to obtain the nickel powder of comparative example 1.
Regarding the nickel powders of example 1 and comparative example 1, the local concentration of sulfur in the depth direction from the surface was measured using STEM-EDS. The measurement was performed using a scanning transmission electron microscope (JEM-2100F manufactured by Japanese electric Co., ltd.) equipped with an energy dispersive X-ray spectrometer (JED-2300T manufactured by Japanese electric Co., ltd.). The results obtained are shown in Table 1 and FIG. 2.
TABLE 1 local concentration of Sulfur in Nickel powder
As shown in table 1 and fig. 2, the local concentration of sulfur on the surface of the nickel powder in comparative example 1 was higher than that in example 1, but decreased rapidly with increasing depth from the surface, i.e., with approaching the inside. On the other hand, in the nickel powder in example 1, although the local concentration of sulfur on the surface was low, the reduction rate in the depth direction was small, and sulfur was also distributed in the nickel powder. In this example 1, the half-life depth was 3.2nm.
The results show that by using the manufacturing method according to the embodiment of the present invention, a metal powder in which sulfur is distributed to deeper positions can be obtained.
2. Example 2
In example 2, the effect of the overall concentration of sulfur on the sintering initiation temperature was investigated. The same method as in example 1 was applied, and nickel powders having various total sulfur concentrations were prepared by varying the flow rate of sulfur-containing gas in the range from 1.7 m/sec to 2.2 m/sec (in terms of 1100 ℃). Similarly, using the same method as comparative example 1 described in example 1, the concentration and the addition amount of the thiourea aqueous solution were changed to prepare nickel powders having various sulfur total concentrations as comparative example 2. The total concentration of sulfur was measured by the same method as in example 1.
The sintering initiation temperature was measured by a scanning electron microscope (SU-5000 manufactured by hitachi high-tech co., ltd.) equipped with a heating stage (Murano 525heating stage manufactured by Gatan corporation). To give a specific method, first, 100 metal powders were molded into particles having a diameter of 5mn×1mm, adhered to a heating stage, and then introduced into a scanning electron microscope. The heating table was observed with a scanning electron microscope while the temperature of the heating table was gradually increased from room temperature to 800 ℃. Although the metal particles 102 start sintering with an increase in temperature, the temperature at which the nickel powder in half or more of the visual field is sintered is set as the sintering initiation temperature. The results are shown in FIG. 3.
In comparative example 2, it can be seen that the sintering initiation temperature increases with an increase in the total concentration of sulfur. However, as described in example 1, in the metal powder of comparative example 2, sulfur is not distributed to the inside of the metal particles at a high concentration, and thus the total concentration of sulfur has an upper limit. The total concentration of sulfur, which may be caused thereby, is at most about 0.2 wt.%, with a sintering initiation temperature of from about 500 ℃ to about 600 ℃.
In contrast, the sintering initiation temperature of the nickel powder of example 2 was higher than that of comparative example 2. In example 2, since sulfur is distributed inside the nickel particles, a higher total concentration of sulfur can be achieved as compared to the nickel powder in comparative example 2. For example, in this example 2, the total concentration of sulfur exceeds 0.2 wt%, and even a metal powder having a total concentration of sulfur of 0.3 wt% or more is obtained. As a result, the sintering initiation temperature of the nickel powder in example 2 can reach 600 ℃ or higher, even about 700 ℃. When the total concentration of sulfur is the same, by applying the manufacturing method of the present embodiment, nickel powder having a higher sintering initiation temperature can be manufactured.
It is noted here that in example 2, when the total concentration of sulfur is 0.15 wt% or more, a sintering initiation temperature of 600 ℃ or more can be achieved, and even a sintering initiation temperature exceeding 600 ℃ or more can be achieved with a high probability. Therefore, by setting the total concentration of sulfur in the metal powder 100 to 0.15 wt% or more, even if the total concentration of sulfur is greatly changed, the sintering initiation temperature is not affected, and the fluctuation of the sintering initiation temperature can be effectively suppressed. In other words, by the manufacturing method of the present embodiment, a metal powder with small variations in sintering initiation temperature can be provided.
Those skilled in the art can appropriately add or delete structural elements, make design changes of structural elements, or make addition, omission or condition changes of processes according to the embodiments of the present invention, and are included in the scope of the present invention as long as they include the gist of the present invention.
Even other operational effects than those brought about by the aspects of the embodiments described above, which are obvious from the description of the present specification or can be easily predicted by those skilled in the art, are of course understood as effects of the present invention.
Description of the reference numerals
100:metal powder
102 Metal particles
110 reduction device
112 reduction furnace
114 heater
116 st conveying pipe
118 1 st gas inlet pipe
120 valve
122, 2 nd gas inlet pipe
124 valve
126, 3 rd gas inlet pipe
128 valve
130 the 2 nd delivery tube.
Claims (9)
1. A metal powder comprising a metal and metal particles containing sulfur having an overall concentration of 0.01 wt% or more and 1.0 wt% or less; wherein, the liquid crystal display device comprises a liquid crystal display device,
the local concentration of sulfur at a position 4nm away from the surface of the metal particles is 2 at% or more;
the metal particles have a number average particle diameter of 50nm to 400 nm;
a position where the local concentration of sulfur is 1-2 of the local concentration of sulfur on the surface of the metal particle is present in a range of 2nm to 4nm inclusive from the surface; and
the total concentration and the local concentration are estimated by an inductively coupled plasma emission spectrometry analyzer and an energy dispersive X-ray spectrometry analyzer provided in a scanning transmission electron microscope, respectively.
2. The metal powder of claim 1, wherein the local concentration of sulfur decreases as one approaches inward from the surface of the metal particles.
3. The metal powder according to claim 1, wherein the metal powder has a sintering initiation temperature of 600 ℃ or higher.
4. The metal powder of claim 1, wherein the metal is nickel, copper or silver.
5. A method of making a metal powder comprising:
generating a metal chloride gas by chlorinating a metal with chlorine; and
generating metal particles by reducing the metal chloride as a gas in the presence of a sulfur-containing gas; wherein the method comprises the steps of
The reduction is performed such that the total concentration of sulfur in the metal particles is 0.01 to 1.0 wt%, the local concentration of sulfur at a position 4nm from the surface of the metal particles is 2 at% or more, the number average particle diameter of the metal particles is 50 to 400nm, and the local concentration of sulfur is 1-2 of the local concentration of sulfur at the surface of the metal particles is present in a range of 2 to 4nm from the surface;
the total concentration and the local concentration are estimated by an inductively coupled plasma emission spectrometry analyzer and an energy dispersive X-ray spectrometry analyzer provided in a scanning transmission electron microscope, respectively.
6. The method of claim 5, wherein the reducing is performed without isolating the metal chloride.
7. The method of claim 5, wherein the sulfur-containing gas is a sulfur dioxide-containing gas.
8. The method of claim 5, wherein the reducing is performed in such a manner that the local concentration of sulfur decreases as approaching from the surface of the metal particles toward the inside.
9. The method according to claim 5, wherein the reduction is performed by treating a mixed gas of the metal chloride gas and the sulfur-containing gas with a reducing gas.
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| KR20210019547A (en) | 2021-02-22 |
| CN112423912A (en) | 2021-02-26 |
| KR102484793B1 (en) | 2023-01-05 |
| TWI720523B (en) | 2021-03-01 |
| JPWO2020004105A1 (en) | 2021-08-05 |
| TW202000344A (en) | 2020-01-01 |
| WO2020004105A1 (en) | 2020-01-02 |
| JP7193534B2 (en) | 2022-12-20 |
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