WO2024143517A1 - 焼結金属材料、焼結用金属微粒子及びそれらの製造方法 - Google Patents

焼結金属材料、焼結用金属微粒子及びそれらの製造方法 Download PDF

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WO2024143517A1
WO2024143517A1 PCT/JP2023/047165 JP2023047165W WO2024143517A1 WO 2024143517 A1 WO2024143517 A1 WO 2024143517A1 JP 2023047165 W JP2023047165 W JP 2023047165W WO 2024143517 A1 WO2024143517 A1 WO 2024143517A1
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sintered
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fine particles
carbon
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邦宏 福本
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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
    • 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
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • 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
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/102—Metallic powder coated with organic material
    • 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
    • B22F9/24—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from liquid metal compounds, e.g. solutions
    • 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
    • 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
    • C22C19/07—Alloys based on nickel or cobalt based on cobalt
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/02—Alloys based on gold
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/04—Alloys based on a platinum group metal
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C5/00—Alloys based on noble metals
    • C22C5/06—Alloys based on silver
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C9/00—Alloys based on copper

Definitions

  • the present invention relates to sintered metal materials with fine grain structures, metal particles for sintering, and methods for producing them.
  • Thermomechanical processing is the most common method for refining grains, and involves heat-treating the processed material under various conditions to refine the grains.
  • the grain size obtained by this thermomechanical processing is at least 1 ⁇ m, and is usually around 10 ⁇ m (Patent Documents 1 and 2).
  • the ultra-high processing method which goes even further, can ultra-fine grains by applying processing strain equivalent to a rolling reduction of 95% or more.
  • Representative examples of ultra-high processing methods are the ESCP method and the ARB method, which can obtain ultra-fine grains with grain sizes of around 0.1 ⁇ m (Non-Patent Documents 1 to 3).
  • Ultra-high processing methods do not show static recrystallization behavior, which is a problem with conventional thermomechanical processing methods, and only show grain growth.
  • Ultra-high processing methods can obtain high-strength materials by obtaining ultra-fine grain structures, and are attracting attention as a method of increasing strength that can replace the addition of alloying elements.
  • the bottom-up sintering method involves finely grinding metal powder produced by gas or water atomization using a mechanical device such as a ball mill, and applying a large strain to the metal powder to modify it into powder with a crystal grain size of 0.1 ⁇ m or less (hereinafter referred to as the MM method).
  • the spark plasma sintering method (hereinafter referred to as the SPS method) is used to sinter at a low temperature in a short time, suppressing the growth of crystal grains during sintering and producing a nanocrystalline metal bulk (hereinafter referred to as the MM-SPS method) (Patent Documents 3 and 4, Non-Patent Document 4).
  • Non-Patent Document 5 investigates the densification conditions, crystal grain size, density, and hardness of ultrafine copper, nickel, cobalt, and iron particles (particle size: 0.02-0.05 ⁇ m) produced by the gas evaporation method when uniaxially pressed and sintered without pressure.
  • Non-Patent Document 6 investigates the structure, density, hardness, etc. of ultrafine copper and nickel particles (particle size: 0.09 ⁇ m) produced by the thermal plasma method, producing a solidified body by uniaxially pressing and sintering without pressure under conditions that eliminate the effects of oxidation.
  • Industrially used techniques for producing bulk metal bodies from powdered metal include powder metallurgy, in which powdered metal is placed in a mold, compressed and molded, and sintered at high temperatures to produce high-precision parts, and metal injection molding (hereafter referred to as MIM), in which powdered metal and resin are mixed to produce pellets, which are then injection molded into a mold, degreased, and sintered to produce parts with even higher precision and complex shapes.
  • MIM metal injection molding
  • Metal powders used in powder metallurgy and MIM methods are produced by water atomization or gas atomization, but for smaller metal powders of less than 1 ⁇ m, special manufacturing methods are required.
  • Technological development for producing fine metal powders has been driven by metal powders for sintered metal pastes, including internal electrode materials for multilayer ceramic capacitors (hereafter referred to as MLCCs).
  • MLCCs internal electrode materials for multilayer ceramic capacitors
  • studies are underway to reduce the average particle size of nickel powder used to form internal electrodes to around 0.05 ⁇ m, less than 0.10 ⁇ m.
  • Dry methods include chemical vapor deposition, which is classified as a gas-phase method, in which high-temperature nickel chloride vapor is reduced with hydrogen to produce nickel powder, plasma chemical vapor deposition, which is classified as a CVD method, in which nickel coarse powder is evaporated in plasma to produce nickel powder, and physical vapor deposition (PVD) methods.
  • chemical vapor deposition which is classified as a gas-phase method, in which high-temperature nickel chloride vapor is reduced with hydrogen to produce nickel powder
  • plasma chemical vapor deposition which is classified as a CVD method, in which nickel coarse powder is evaporated in plasma to produce nickel powder
  • PVD physical vapor deposition
  • the gas phase method uses a high-temperature process at over 1000°C to produce highly crystalline metal particles, but it is difficult to control the particle size distribution.
  • it is necessary to remove not only the coarse particles that cause insulation breakdown, but also the highly active fine powder, and classification processing is essential to ensure the required particle size quality, which is a major factor in increasing costs.
  • the thinning of internal electrodes requires nickel particles as small as 0.05 ⁇ m to 0.10 ⁇ m, making more advanced classification technology necessary.
  • Patent Documents 11 and 12 Other known methods include a method of obtaining metal particles by complexing a metal formate salt with an amine compound and reducing it by thermal decomposition (Patent Documents 11 and 12), and a method of obtaining metal particles by adding an alkali to an inorganic metal salt to convert it into a metal hydroxide, complexing it with hydrazine, and reducing it by thermal decomposition (Patent Documents 10 and 13).
  • the yield strength is improved and the stress relaxation properties are improved, but the recrystallization temperature is low at around 400°C, and considering the long-term stress relaxation properties, for example, when heat resistance of 150°C or more is required, it cannot be said to be sufficient from the viewpoint of the time-temperature conversion rule of creep properties.
  • Non-patent documents 5 and 6 describe a method for grain refinement that does not use the driving energy of plastic processing, in other words, a method for producing a solidified body by sintering that utilizes the high surface free energy of ultrafine particles.
  • this method despite the relatively low molding pressure of 300 MPa, it has been shown that when heated to 600°C or higher, the grains become coarse and the hardness decreases.
  • Patent Document 7 describes that carbon is dissolved in FCC nanocrystalline metal by electrodeposition, and the carbon segregates at the grain boundaries, resulting in excellent mechanical properties.
  • the examples describe grain growth and a decrease in hardness when heated to 300°C.
  • saccharin is used as the carbon source, but it is a common additive for the sulfamate method.
  • Ceramic dispersion strengthened alloys in which nano-scale ceramic oxides are uniformly dispersed, are known as materials whose hardness does not decrease even after high-temperature annealing at 800°C.
  • the fine ceramic particles suppress grain growth and dislocation movement at high temperatures through the pinning effect, improving the mechanical properties at high temperatures.
  • their manufacture requires mechanical alloying and hot/cold working, and there is a problem that it takes time and money to obtain a homogeneous material.
  • nanocrystals are dispersed and strengthened at a relatively high concentration of 0.3 to 1.5 wt%, welding and solid diffusion bonding are difficult, and liquid phase bonding using brazing material is required (a specific example is the alumina dispersion strengthened copper alloy GLIDCOP (registered trademark) by Höganäs High Alloys, North America, USA).
  • GLIDCOP alumina dispersion strengthened copper alloy
  • the heat resistance issue here is not for high-strength, ultra-heat-resistant metal materials that require absolute hot strength at temperatures of 1000°C or higher, but rather for fields that require mechanical strength in the medium temperature range of 150°C to 400°C, such as fields that require high-temperature operation at 200°C or higher, such as next-generation power semiconductors and in-vehicle motors, fields where the thermal history added in the manufacturing process of ceramic electronic components that require simultaneous firing of ceramic and electrode materials, and heat sink components that require soldering, and fields that require high reliability to prevent fatal damage to functional parts and structural materials due to abnormal heat generation and heating that occurs transiently during use.
  • grain refinement technology that can provide high-strength metal materials with a secondary recrystallization temperature of 800°C or higher and excellent annealing softening characteristics.
  • Non-Patent Document 8 reports that the sintering behavior of powders of normal particle size (several tens to several hundreds of ⁇ m) used in conventional powder metallurgy methods is different from the sintering behavior of fine metal particles with a small particle size (0.05 ⁇ m). Furthermore, Non-Patent Document 8 describes that when copper powder of normal particle size is used, if the green density is 90-95% or more by volume and sintered, the sintered body expands due to the trapped gas pressure, and that if the green density is 90-95% by volume, a sintered body that does not expand or shrink can be obtained.
  • the MIM method is used as a method of forming metal powder with a particle size of 10 ⁇ m or less to obtain a sintered body, and recently the ⁇ -MIM method using sub- ⁇ m metal powder has also been implemented.
  • the MIM method is widely used as a manufacturing method that can manufacture metal parts with complex shapes with high precision by filling a polymer with excellent thermal decomposition properties at high density, injection molding it into a molding die, and degreasing and sintering it.
  • Non-Patent Document 8 copper powder with particle sizes of 10 ⁇ m and 0.7 ⁇ m is produced by the MIM method, and its sintering characteristics are reported.
  • the sintered density was 93% by volume and 95% by volume at a sintering temperature of 700°C or higher.
  • the carbon content of the sintered body was 0.013% by weight and 0.025% by weight, respectively. It has been reported that when the aforementioned spark plasma sintering method (SPS method) is performed with 0.7 ⁇ m copper powder, the sintered density increases to 99.8% by volume, and when hot isostatic pressing (HIP method) is used, it increases to 98.9% by volume.
  • SPS method spark plasma sintering method
  • HIP method hot isostatic pressing
  • sub- ⁇ m copper powder with a small particle size has a high density of 95% by volume, but the residual carbon concentration is twice that of micro copper powder, and it has been pointed out that the carbon content is higher than that of ingot materials.
  • the metal is a pure metal with a carbon content of 0.001-0.1% by weight, a nitrogen content of 0.001% by weight or less, a sulfur content of 0.01% by weight or less, and no other metallic or inorganic elements except for unavoidable impurities.
  • the sintered metal material is made of a pure metal that is substantially free of carbon, nitrogen, sulfur, and other unavoidable impurities, yet has a fine grain structure even after sintering, and is heat resistant, providing an unprecedented microstructure structure.
  • the metal is one metal selected from the group consisting of Co, Ni, Ag, Au, Pt, Pd, Rh and Cu. All of these metals have stacking fault energy of 150 mJ/ m2 or less, do not form stable compounds with carbon, and are capable of dissolving carbon in the metal. Therefore, according to the present invention, the above-mentioned precipitated carbon can act as a pinning effect, and high strength and high heat resistance can be achieved.
  • Patent Document 6 describes that it is difficult to introduce deformation twins by processing unless the stacking fault energy is 50 mJ/m 2 or less.
  • the stacking fault energies of various metals are described as silver (2 mJ/m 2 ), copper (78 mJ/m 2 ), cobalt (15 mJ/m 2 ), nickel (128 mJ/m 2 ), brass (about 20 mJ/m 2 ), etc. It describes that when the stacking fault energy is 50 mJ/m 2 or more, it is possible to introduce deformation twins by lowering it by adding impurity elements, as in the case of brass, etc.
  • annealing twins with a twin spacing of 250 nm or less by simply sintering metal particles at 700°C or higher and cooling them, without adding impurity elements or using any processing. It is believed that annealing twins, like deformation twins, have the role of constraining crystal grains and suppressing the growth of crystal grains.
  • fine metal particles with an average particle size of 20 to 200 nm are uniaxially molded, sintered at normal pressure, and then cooled to obtain a high-strength sintered metal material with fine grains.
  • the present invention is a new method of increasing strength that replaces the addition of alloying elements, and is advantageous in terms of resource conservation and ease of recycling.
  • the present invention starts with fine metal particles with a relatively uniform grain size, it is expected to have the same effect as the ultra-strong processing method described above, and there is no static recrystallization at the time of production of the sintered metal material, and fine grains are achieved through normal grain growth.
  • the present invention makes it possible to separate recrystallization and grain growth, which has the great advantage of simplifying the manufacturing process and condition management.
  • the present inventor believes that the "metal that does not form a stable compound with carbon and can be solid-soluble with carbon" constituting the present invention is an important technical component for expressing the unique high strength and heat resistance of the present invention.
  • the average particle size of metal particles means the number-average particle size obtained from a scanning electron microscope image of the metal particles. In the case of an ellipse, the average value of the major axis and the minor axis is adopted as the particle size of the particle.
  • the average particle size of metal particles is in the range of 20 nm to 200 nm, and is appropriately selected according to the type of metal and the desired mechanical properties.
  • metal fine particles are obtained by a wet method, and uniform ultrafine metal oxide particles of 10 nm or less obtained during the reaction are used as a reservoir for metal nuclei. Therefore, it is possible to obtain metal fine particles with a narrow particle size distribution.
  • an index of particle size distribution it can be expressed by a coefficient of variation, which is the value (%) obtained by dividing the standard deviation of the particle size by the average particle size.
  • the coefficient of variation of the present invention is preferably 30% or less, and more preferably 20% or less. If the coefficient of variation exceeds 30%, the particle size distribution is wide, which causes variation in the particle surface energy at the start of sintering, which affects the variation in the grown crystal grain size after sintering, and is therefore undesirable.
  • Carbon and nitrogen indicate the amount of organic coating agent on the metal fine particles resulting from the chemicals in the reaction solution, and the sulfur content indicates the content resulting from impurities or contamination derived from the raw material of the metal salt.
  • the organic coating agent in the metal fine particles is thermally decomposed during the firing process, carbonized at 600°C or higher, and a part of it remains at the grain boundary. When heated to a high temperature, carbon is dissolved in the metal. The amount of solid solution is thought to depend on the metal-carbon binary alloy phase diagram, and it is estimated that the part that is not solid-dissolved remains at the grain boundary.
  • the value obtained by dividing the carbon content Cw (wt%) by the specific surface area (m 2 /g) calculated from the crystallite diameter is preferably 50 to 500 ( ⁇ g/m 2 ), and the value obtained by dividing the nitrogen content Nw (wt%) by the specific surface area (m 2 /g) calculated from the crystallite diameter is preferably 5 to 100 ( ⁇ g/m 2 ).
  • Sulfur is also known to deteriorate electrical characteristics by dissolving in metal or forming sulfides, and therefore the content is preferably 0.01% by weight or less, and more preferably 0.001% by weight or less.
  • Patent Documents 9 and 10 abnormal thermal shrinkage behavior is reported due to impurities trapped in metal fine particles. Specifically, when a pellet made by pressing nickel powder is heated from 25°C to 1200°C (1000°C in the case of copper) in an inert atmosphere or reducing atmosphere, the behavior of expansion after reaching the maximum shrinkage amount is described as a defect.
  • the expansion behavior during sintering of metal powder occurs when open pores are blocked with grain growth, and water vapor generated by reduction of metal oxide is trapped, and the powder expands due to internal pressure. Therefore, as in the Patent Documents, measures are taken to add sulfur to nickel powder to reduce catalytic activity and suppress the generation of decomposition gas and grain growth at low temperatures. In other words, grain growth is suppressed until the release of internally generated gas is completed to prevent blockage.
  • the method for producing metal fine particles according to the present invention uses a wet method, and can be produced by the following basic steps: That is, the method for producing metal fine particles having an average particle size of 20 to 200 nm by reducing a transition metal having a standard oxidation-reduction potential of -0.30 V to +0.60 V comprises the steps of (first step) heating and stirring a basic low-molecular-weight organic acid metal salt of a metal ion, a long-chain aliphatic carboxylic acid in an amount of at least 1 mol % relative to the metal salt, and a non-polar solvent capable of forming an azeotrope with water and/or alkanolamines to add the long-chain aliphatic carboxylic acid to the metal salt; and (second step) adding 4.0 ⁇ 1.0 molar equivalents of a long-chain aliphatic carboxylic acid in an amount of at least 1 mol % relative to the metal salt to the metal salt.
  • the method includes, in the order of step 2, adding an agent selected from alkanolamines as a complexing agent, heating and stirring to completely dissolve the metal salt and complex it into a metal complex; step 3, heating and stirring while distilling off the water in the reaction solution, including the coordinated water of the metal, and the complexing agent liberated by decomposition by azeotropic distillation to decompose the metal complex to produce a metal hydroxide sol, which is then converted into metal oxide fine particles by dehydration; and step 4, heating to a temperature at which the metal oxide is reduced to the metal to produce metal fine particles.
  • an agent selected from alkanolamines as a complexing agent
  • the average particle size is 20 nm to 200 nm, with a crystallite size of 4 nm to 40 nm, which is smaller than the average particle size, and with low crystallinity.
  • thermal decomposition reduction method a method in which a metal salt complex is thermally decomposed to directly obtain metal powder and reduced in one step
  • an oxide reduction method a method using a hydrazine metal complex salt as disclosed in Patent Documents 9 and 10
  • a method using a metal formate complex as disclosed in Patent Document 11 a method using a copper alkanolamine complex as disclosed in Patent Document 12 are known.
  • Patent Document 13 a reference is included in Patent Document 13.
  • the temperature is raised to the decomposition temperature as quickly as possible to generate metal nuclei in a short time, which is characterized by the fact that uniform metal microparticles with a narrow particle size distribution can be obtained.
  • the metal nuclei are generated rapidly, impurities are easily incorporated when the primary particles aggregate to form secondary particles (Patent Documents 9 and 10). Suppressing the reaction by slowing down the rate at which the temperature is increased, for example, can lead to a broadening of the particle size distribution, so a countermeasure is taken by adding noble metals as metal nuclei.
  • the metal oxide functions as a reservoir for metal nuclei, making it relatively easy to control the frequency of metal nuclei generation and the growth of the nuclei, and because the particle size of the metal oxide is highly correlated with the particle size of the metal powder after reduction, particle size control is easy.
  • metal salts are converted to metal hydroxides using alkali metals, which means that inorganic impurities are incorporated and a water-based reaction solvent is used, which means that oxides and hydroxides are likely to be generated along with the generation of metal fine particles.
  • the inventors have diligently studied a manufacturing method that solves the problems of the conventional methods and at the same time solves the problems of the present invention, and have obtained new findings. They have discovered that by using alkanolamine as a complexing agent to complex a low molecular weight organic acid metal salt (hydrate) into a metal complex and dissolving it, and by continuing to heat under reduced pressure, the low molecular weight organic acid of the metal salt forms an amine salt with the alkanolamine, which triggers a decrease in the basicity of the reaction system, promoting the decomposition of the metal complex and producing a metal hydroxide. They have also discovered that this is further converted into a metal oxide by a dehydration reaction.
  • the low molecular weight organic acid is a reducing organic acid such as formic acid
  • it exhibits a reducing action under a certain basic environment.
  • they have discovered and completed a new method for reducing the oxide of metal powder by appropriately controlling the amount of low molecular weight organic acid added to the system and the basicity, amount, and content of alkanolamines added as complexing agents.
  • Alkanolamines are known reducing agents, as described in Patent Document 14, that act as reducing agents for precious metals and copper ions.
  • these alkanolamines have a long history of use as carbon dioxide gas absorbents, and aqueous solutions that have absorbed carbon dioxide gas can cause problems with corrosion of metals such as stainless steel.
  • the cause of this corrosion is carbamate ions, which are known to have the ability to dissolve metal oxides. It is therefore considered preferable to set the corrosive action so that it does not degrade the quality of the metal microparticles.
  • the reaction is completed at each step. For example, it is preferable that (1) the raw metal salt is completely dissolved, (2) the particle size of the intermediate metal hydroxide or metal oxide is small and uniform, and (3) no metal hydroxide remains in the metal oxide at the start of reduction.
  • the above conditions can be satisfied by controlling the following (A) to (C).
  • A) Appropriately select the counter anion of the metal salt (carbonate, low molecular weight organic acid, etc.) and add 1.0 ⁇ 0.2 molar equivalents of the metal ion and 4.0 ⁇ 1.0 molar equivalents of alkanolamine.
  • B) The alkanolamine liberated by the hydrolysis of the metal complex salt is removed by azeotropic distillation to control the basicity, thereby reducing the particle size of the precipitated metal hydroxide, resulting in uniformly dispersed ultrafine metal oxide.
  • C) Since reduced water is distilled off during the reduction reaction, the end point of the reaction can be determined.
  • the basic low molecular weight organic acid metal salt is a double salt of a metal carbonate such as basic copper carbonate or basic nickel carbonate and a metal hydroxide, and usually has water of crystallization.
  • the reason for selecting a basic metal salt is that when a metal formate or metal acetate is used, it has 2 molar equivalents of low molecular weight carboxylic acid per 1 metal ion, which forms a salt with an alkanolamine, but the basicity is rapidly reduced, so that a coarse metal hydroxide with poor dispersibility is generated, and there is a risk that the reaction solution cannot be stirred.
  • the alkanolamine is temporarily consumed in excess, it is necessary to add extra alkanolamine to ensure the basicity, which is economically undesirable.
  • the basic low molecular weight organic metal salt may be prepared by adding a low molecular weight organic acid such as formic acid or acetic acid to a basic metal carbonate.
  • the basic metal salt may be used as a raw material as is, but a basic low molecular weight organic acid such as formic acid may be added in an amount of 1 molar equivalent to the metal ion to produce a basic low molecular weight organic acid salt (basic formate), or the basic metal formate may be dissolved in pure water and left to stand to produce a basic metal formate.
  • Ordinary industrial grade basic carbonate may be used as the raw material. It is more preferable that the raw material be electronic material grade.
  • the amount of low molecular weight organic acid added to the basic metal carbonate is preferably 1.0 ⁇ 0.2 molar equivalents per metal ion. If the amount is less than this range, the poorly soluble basic metal carbonate will remain undissolved and may become mixed into the reduced metal particles, which is not preferred. If the amount exceeds this range, the above-mentioned problems (production of coarse metal hydroxides with poor dispersibility, economics) will occur, which is not preferred.
  • Basic low molecular weight organic acid metal salts are preferably used because they can reduce impurities such as nitrogen, sulfur, and halogen in metal fine particles, such as nitrate ions, halogen ions, and sulfate ions.
  • impurities such as nitrogen, sulfur, and halogen in metal fine particles, such as nitrate ions, halogen ions, and sulfate ions.
  • solubilization becomes difficult unless water is used in the reaction system, and the presence of water is undesirable because it tends to create an oxidizing atmosphere in the environment for producing reduced metals.
  • Basic low molecular weight organic acid metal salts are preferably used because they can proceed with the reaction in a non-polar solvent from which water is excluded as much as possible.
  • alkanolamines The amount of alkanolamine added is preferably 4.0 ⁇ 1.0 molar equivalents per 1 metal ion. This amount is an appropriate amount required to quickly dissolve the basic low-molecular organic acid metal salt and maintain the basicity that does not cause the corresponding metal hydroxide to precipitate. If the amount is less than this range, the dissolution rate decreases, and the metal hydroxide precipitates in an unstable state or in an environment of low basicity, making it impossible to form uniform and small particles. If the amount exceeds this range, the amount of excess alkanolamine to be removed becomes unnecessarily large, which is not preferable.
  • alkanolamines that have a primary amino group and/or a secondary amino group and a primary alcohol group, and that have a pH of 10 to 12.5 and an SP value of 11 to 15.
  • alkanolamines that have a primary amino group and/or a secondary amino group and a primary alcohol group, and that have a pH of 10 to 12.5 and an SP value of 11 to 15.
  • Specific examples include 2-aminoethanol, 3-amino-1-propanol, 4-amino-1-butanol, 5-amino-1-pentanol, 6-amino-1-hexanol, 2-(methylamino)ethanol, 2-(ethylamino)ethanol, diethanolamine, 2-(2-aminoethoxy)ethanol, 2-(2-aminoethylamino)ethanol, and 2-(3-aminopropylamino)ethanol.
  • the azeotropic solvent is a non-polar organic solvent that forms an azeotropic mixture with alkanolamine and/or water and can be selected from those with a boiling point of 80°C to 250°C.
  • the term "and/or” is used to mean the case where the azeotropic solvent forms an azeotropic mixture with alkanolamine, the case where the azeotropic solvent forms an azeotropic mixture with water, and the case where the azeotropic solvent forms an azeotropic mixture with alkanolamine and water.
  • the azeotropic solvent is more preferably an aprotic solvent.
  • dilute reaction solvent examples include those having hydrophobic alkyl groups and hydrophilic ether and hydroxyl groups in the molecule. Such dilute reaction solvents may be partially added with glycol ethers or aminoglycols that show suitable solubility for both non-polar and polar compounds. Glycol ethers are often used as cleaning agents by adding them to water together with surfactants. It is known that adding several percent to 10% to water has the effect of lowering the surface tension of water.
  • glycol ethers In the liquid discharged by azeotropy, it is necessary that the organic solvent, alkanolamine, and water are easily separable, but in the reaction liquid, if the SP values of the water or alkanolamine and the azeotropic solvent are too different, the miscibility becomes poor, which is undesirable. In such a case, adding glycol ethers can avoid such problems. In order to prevent the fine particles of metal hydroxide or metal oxide from being mixed into the azeotropic liquid, it is preferable that the boiling point is higher than that of the azeotropic solvent, and more preferably 50° C. or higher. Examples of glycol ethers include EO-based glycol ethers and PO-based glycol ethers.
  • heptanaphthenic acid monohydroxyheptanaphthenic acid, cyclohexanecarboxylic acid, cyclohexanepropionic acid, methylcyclopentanecarboxylic acid, and 3-(3-ethylcyclopentyl)propionic acid can be mentioned.
  • a basic low molecular weight organic metal salt is dispersed in an azeotropic solvent, and 1 to 10 mol % of a long-chain aliphatic carboxylic acid relative to the metal ion is weighed and added.
  • a dilute reaction solvent it is preferable to add it at this stage.
  • a portion of the solvent may be added and then further added before the fourth step.
  • stirring the mixture is continuously heated at a temperature at which the basic low molecular weight organic metal salt does not decompose, and the long-chain aliphatic carboxylic acid is added.
  • the conditions vary depending on the type of metal salt, but it is preferable to heat the mixture at 90°C to 140°C for 1 to 3 hours.
  • the reaction is further continued, and the water and alkanolamine in the system are continuously distilled off, whereby the metal hydroxide is converted into a metal oxide by a dehydration reaction.
  • alkanolamine corrodes metals in a certain pH range
  • by distilling off excess alkanolamine out of the system together with water reversible corrosion and dissolution can be prevented, and efficient conversion to a metal oxide is possible.
  • an azeotropic solvent that forms an azeotropic mixture with water and alkanolamine it can be efficiently distilled off at a low temperature, and the degree of vacuum can be easily adjusted to the set temperature required for the reaction.
  • the conversion of metal hydroxide to metal oxide can be confirmed by a change in color, but if any metal hydroxide remains at this stage, it will be mixed into the metal fine particles, which is not preferable.
  • a long-chain aliphatic amine may be added at the start of crystallization in the reduction reaction.
  • the amount added should preferably not exceed the same mol % or 10 times the mol % of the long-chain aliphatic carboxylic acid added in the first step.
  • the reduction temperature is low, so the ability of the amine as a reducing agent is low, but it acts as a dispersing agent and weakens the cohesiveness of the metal particles, so it is preferable to add it appropriately.
  • the end point of the reduction reaction can be determined by the presence or absence of reduced water distillation.
  • the metal fine particles that have been aggregated, filtered, and dried, or the aggregated powder of the metal fine particles that have been heat-treated at high temperatures can be used as is, but may be crushed to an appropriate particle size.
  • dry crushing methods such as spiral jet crushing process and counter jet mill crushing process, wet crushing methods such as high-pressure fluid collision crushing process, and other general-purpose crushing methods can be applied.
  • the impurity (carbon (C), nitrogen (N), sulfur (S)) content, other impurity content, crystallite size, average particle size, and sintered density during isochronal sintering were measured.
  • the sintered metal materials the Vickers hardness, Vickers hardness after high-temperature annealing, impurity (carbon (C), nitrogen (N), sulfur (S)) content, other impurity content, crystallite size, and volume resistivity were measured.
  • Metal particles were powder molded at a molding pressure of 200 MPa to produce a sample with a diameter of 15 mm ⁇ and a thickness of about 2.5 mm.
  • the sample was sintered under a predetermined sintering condition in a mixed gas atmosphere of N 2 -H 2 (5%) to produce a sintered body with a diameter of about 12 mm ⁇ and a thickness of about 2.0 mm.
  • the sintered body was embedded in epoxy resin and polished to a mirror finish with a final 3 ⁇ m diamond slurry and colloidal silica.
  • the Vickers hardness of the polished sample was measured using a micro Vickers hardness tester (Mitutoyo Corporation: HM-2200, load: 100 g).
  • Example 4 Synthesis Example 2 of Nickel Microparticles
  • 200 g of 3-amino-1-propanol (molecular weight: 75.11) and 18.5 g of laurylamine (molecular weight: 185.35) for reduction were used, and the reduction reaction was carried out by adjusting the degree of vacuum and the heat source so that the temperature of the reaction liquid after adding them was maintained at 134°C to 136°C.
  • the reaction was carried out in the same manner as in Example 3, and a dry powder was obtained.
  • the yield was 119.5 g.
  • the nickel component contained in the dry powder was 113.8 g, and the yield was 96.95%.
  • the temperature of the reaction solution was then raised to 161°C to 165°C, and the degree of decompression and the heat source were adjusted to maintain a state in which Teklean, water, and 2-aminoethanol were distilled as an azeotrope.
  • the 2-aminoethanol and water separated in the lower layer of the distilled Teklean were separated out of the system, and Teklean was returned to the system.
  • the complexation solution was a cloudy reddish purple, and changed to a clear reddish purple as the water of hydration was removed.
  • Cobalt fine particles were obtained by the same procedure as in Example 6. The yield was 122.0 g. The amount of cobalt component contained in the dry powder was 113.8 g, and the yield was 96.54%.
  • the magnetite fine particles were placed in an alumina boat, and reduced in an electric furnace under a hydrogen atmosphere at 575°C for 6 hours, then cooled to room temperature and subjected to a slow oxidation treatment. The resulting fine iron particles were then taken out into the air. The yield of the obtained fine iron particles was 99.14g. The iron component contained in the dried powder was 97.76g, and the final yield was 87.5%.

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CN120960875A (zh) * 2025-08-31 2025-11-18 杭州科百特半导体分离膜有限公司 烧结金属过滤介质及其制备方法、滤芯以及超临界二氧化碳的过滤方法

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WO2012173187A1 (ja) * 2011-06-16 2012-12-20 新日鉄住金化学株式会社 電子部品の接合材、接合用組成物、接合方法、及び電子部品
WO2016052275A1 (ja) * 2014-10-01 2016-04-07 協立化学産業株式会社 被覆銅粒子及びその製造方法

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WO2012173187A1 (ja) * 2011-06-16 2012-12-20 新日鉄住金化学株式会社 電子部品の接合材、接合用組成物、接合方法、及び電子部品
WO2016052275A1 (ja) * 2014-10-01 2016-04-07 協立化学産業株式会社 被覆銅粒子及びその製造方法

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