WO2015123851A1 - Wet ball-milling method for tantalum powder and tantalum powder prepared therefrom - Google Patents

Abstract

A wet ball-milling method for a tantalum powder, which method uses a grinding aid containing a ball-milling medium and a surfactant. The method has a simple process and strong controllability, and the product obtained has a lower content of metallic impurities.

Description

 Wet ball milling method for powdered powder and tantalum powder prepared by the method

 The invention belongs to the field of rare metal smelting, and relates to a processing technology of tantalum powder, in particular to a wet ball milling method of tantalum powder and a tantalum powder prepared by the method. Background technique

 Tantalum powder is mainly used in the manufacture of high-reliability solid electrolytic capacitors and is widely used in various industries such as mobile phones and computers. When the base metal is used as the anode material of the electrolytic capacitor, the finer the powder, the larger the specific surface area and the higher the specific volume. With the miniaturization and miniaturization of electronic products, tantalum capacitors continue to demand increased capacity and reduce equivalent series resistance (ESR), in order to further increase tantalum capacitor capacity, and maintain good leakage current, small ESR and high Reliability, the basic characteristics of the powder must be improved. It is well known that the chemical composition and physical structure of tantalum powder affect the performance of the final tantalum electrolytic capacitor, including leakage current, ESR and reliability. At present, one of the challenges is to produce tantalum powder with high specific volume, high burn resistance and pressure resistance.

 It is well known that most of the tantalum powder produced in large quantities is obtained by chemically reacting potassium fluoroantimonate with sodium in a reactor. In this process, the physical properties of the tantalum powder such as the particle size and specific surface area of the tantalum powder are controlled by controlling the reducing conditions such as the ratio of the diluted salts KC1 and KF which do not participate in the reaction. Adjusting the reducing conditions makes the tantalum powder thinner and the specific surface area of the tantalum powder increases. The tantalum powder obtained by this method is a porous agglomerate having a high specific surface area composed of a combination of many fine primary particles, which has a complicated structure and a large specific surface area. In general, the above-mentioned tantalum powder has a large specific surface area and a relatively high specific volume, but the corresponding breakdown voltage is relatively low, pressure resistance and reliability are poor, and such tantalum powder is difficult to work at a high voltage. In order to obtain a high-reliability and high-resistance tantalum powder, it is necessary to obtain a simple granular powder from the structural change of the primary particles.

Flaky powder is a kind of tantalum powder in which the primary particles are flakes. From a three-dimensional perspective, the size of the sheet is smaller than the dimensions of the other two directions, that is, there is a certain degree of flatness or a so-called ratio of diameter to thickness. This type of tantalum powder-fcl is obtained by grinding other powders into flakes and then subjecting them to subsequent treatments such as oxygen reduction and heat agglomeration. The specific surface of the tantalum powder relative to the reduced powder The product is smaller, the grain shape is simpler, and the corresponding specific volume is also lower.

 At present, the well-known tableting process is to grind a granular powder (for example, sodium reduced tantalum powder or EB powder (electron bombardment powder obtained by hydrogenation of an electron bombardment ingot) in a ball mill to flatten it. In order to reduce contamination and oxidation, the cerium particles are ground in an organic solvent and subsequently purified by pickling. The unique surface area and final specificity of the flakes are determined by the thickness and size of the flakes. The thinner and smaller the film, the larger the specific surface area and the higher the specific volume.

 In order to obtain a thinner and finer piece, the most straightforward method is to extend the ball milling time. The particle size of the powder gradually decreases with time, but it does not! The limit is reduced. When grinding to a certain particle size, reverse grinding occurs, which prevents the particle size from continuing to decrease and the particle size to increase. This is because the material is continuously squeezed and broken during the ball milling process, and more and more chemical breaks, forming many unsaturated bonds on the surface of the material, resulting in many fresh free surfaces. The particles inside the material are interacted by the surrounding particles, the energy is in equilibrium, and the particles in the surface layer are strongly inward, but the outward direction is weak, so the particle surface of the material is expressed. The remaining bond energy (ie, surface free energy) exists, and the smaller the particle size, the larger the specific surface area, and the greater the surface free energy. From the thermodynamic point of view, due to the presence of unsaturated bonds on the surface of the material, it is necessary to adsorb the surrounding materials to compensate them to reduce the surface energy, so that the cohesive force is formed between the particles of the material particles, so that the chemical bonds that have been broken are re-polymerized, and the material is ground to After a certain degree, the particle size does not become smaller, but it becomes larger. In addition, due to the infinite extension of the milling time, the metal impurity content and the o and C contents are greatly increased.

 No. 6,706,240 B2, WO 00/56,486 discloses a process for the manufacture of bismuth and other metal powders by wet grinding in the presence of a liquid solution of at least one fluoride or perfluoride. Get a sheet metal. The advantage of using a liquid solvent of fluoride or pervaporate is that the final sheet produced has a lower content of 0, Fe and C than the conventional alcohol solvent, but the final waste liquid after ball milling contains a large amount of Fluorine will bring certain difficulties to the disposal of waste liquid.

U.S. Patent No. 5,580,367 discloses an improved sheet-like and method for producing flaky powder which is produced by the above conventional method, After the large piece is subjected to hydrogenation treatment, the size of the sheet is reduced by mechanical crushing. Its purpose is mainly to improve the fluidity, briquetting strength and formability of tantalum powder, but it does not contribute much to increasing the CV value (specific capacitance, referred to as specific volume). In addition, due to the high hardness of the hydrogenated material, a large amount of metal impurities are introduced in the subsequent crushing process, resulting in a higher impurity content of the final product. Since the treatment process requires hydrogenation treatment, and hydrogen is a dangerous chemical, there is a safety hazard of hydrogen ignition and explosion in the production process.

 In summary, the preparation of flaky powder, the prior art has the following disadvantages: First, with the increasing requirements of the comparative volume, the use of the traditional flaky powder production process, in achieving a higher ratio The production of Rongfu powder has been limited. At the same time, considering the impact of ball-milling waste liquid on the environment, the choice of medium is also crucial. Secondly, the hydrogenation and crushing process after the first production is adopted, the process is complicated, the process route is long, and the cost is high. Moreover, the hydrogen content in the hydrogenation process is not easy to control, the selection of the later crushing mode is high, and the metal impurity content is high, and there is a safety hazard of hydrogen ignition and explosion in the production process, and there are certain limitations in practical application. Summary of the invention

 SUMMARY OF THE INVENTION An object of the present invention is to provide a process for preparing a medium-high pressure tantalum powder having a finer and more uniform particle size distribution and a lower impurity content. The method is simple in process and controllable, and the safety risk in the production process is low. The method can obtain a flaky powder having a higher specific surface area, and the electrolytic capacitor obtained after further processing has a lower impurity content, a higher specific volume, and a lower leakage current at a higher voltage. And a higher breakdown voltage.

 A first aspect of the invention provides a method of wet ball milling of tantalum powder, characterized in that the grinding aid used in the method contains a ball milling medium and a surfactant.

 In a preferred embodiment, in the wet ball milling method of the first aspect of the invention, the surfactant is used in an amount of 0.001-50% by weight of the tantalum powder, preferably 1 to 50% by weight of the tantalum powder, 1.5 to 50. % or 10~50%, (eg 1%, 1.5%, 2%, 3%, 5%, 8%, 9%, 10%, 15%, 20%, 30%, 40% or 50%).

In a preferred embodiment, in the wet ball milling method of the first aspect of the invention, the surfactant is selected from the group consisting of oleic acid, benzoic acid, methyl ethyl ketone, polyethylene glycol, isopropanol, and cyclohexane. Alcohol, sodium hexametaphosphate, sodium tripolyphosphate or a combination thereof. Preferably, the surfactant is selected from the group consisting of oleic acid, cyclohexanol, polyethylene glycol, isopropanol, methyl ethyl ketone, benzoic acid or a combination thereof.

 In a preferred embodiment, in the wet ball milling method of the first aspect of the invention, the ball milling medium is water or an organic solvent (e.g., anhydrous ethanol).

 In a specific embodiment, in the wet ball milling method according to the first aspect of the present invention, the surfactant is oleic acid, and the amount thereof is 10 to 50% by weight of the tantalum powder (for example, 10%, 20%, 50%).

 In another specific embodiment, in the wet ball milling method of the first aspect of the invention, the surfactant is selected from the group consisting of isopropanol, methyl ethyl ketone, benzoic acid, cyclohexanol, polyethylene glycol or The combination is used in an amount of 0.5 to 15% by weight of the tantalum powder (for example, 1%, 1.5%, 5%, 10%, 15%).

 In the wet ball milling method of the tantalum powder according to the first aspect of the present invention, the tantalum powder obtained by the sodium reduction or the electron bombardment of the tantalum ingot may be selected as the raw material, and the ball mill equipment may be a stirring ball mill or a vibrating ball mill. The stainless steel ball is used as the grinding ball, and the diameter of the stainless steel ball is generally selected from 10 to 10 mm, preferably 3 to 6 mm.

 In the above wet ball milling method, the tantalum powder may be continuously ball milled for 1 to 50 hours, preferably by ball milling for 18 to 30 hours, for example, 20 hours and 25 hours.

 A second aspect of the present invention provides a grinding aid for wet powder ball milling, comprising a ball milling medium and a surfactant, wherein the ball milling medium is water or an organic solvent (for example, anhydrous ethanol), The surfactant is selected from the group consisting of oleic acid, benzoic acid, butanone, polyethylene glycol, isopropanol, cyclohexanol, sodium hexametaphosphate, sodium tripolyphosphate or a combination thereof; preferably, wherein the surfactant is Selected from oleic acid, cyclohexanol, polyethylene glycol, isopropanol, butanone, benzoic acid or a combination thereof.

 In a preferred embodiment, the grinding aid according to the second aspect of the invention, wherein the surfactant is used in an amount of 0.001-50% by weight of the tantalum powder (for example, 1%, 1.5%, 5%, 10%, 15%) %, 20%, 50%), preferably 1 to 50%, 1.5 to 50% or 10 to 50% by weight.

In another preferred embodiment, the grinding aid according to the second aspect of the invention, wherein the surfactant is oleic acid, the amount of which is 10 to 50% by weight of the tantalum powder (for example, 10%, 20%, 50%) Or wherein the surfactant is selected from the group consisting of isopropanol, butanone, benzoic acid, cyclohexanol, Polyethylene glycol or a combination thereof is used in an amount of 0.5 to 15% by weight of the tantalum powder (for example, 1%, 1.5%, 5%, 10%, 15%).

 A third aspect of the invention provides a sheet form S prepared by the wet ball milling method of any one of the first aspects of the invention. Preferably, the flaky powder has a metal impurity content of ∑Fe+Ni+Cr<50 ppm and a C content of <50 ppm. The flaky enamel powder can be obtained by a combination of pelletization granulation, high-temperature high-vacuum heat treatment, doping treatment, or a combination of a plurality of treatments, thereby obtaining a high-reliability high-capacity electrolytic capacitor for tantalum powder. .

 A fourth aspect of the present invention provides a tantalum powder for a highly reliable high-capacity electrolytic capacitor, which is subjected to pelletizing granulation, high-temperature high-vacuum heat treatment, and 1⁄4 3⁄4 oxygen treatment according to the third aspect of the present invention. A treatment or a combination of multiple treatments is obtained.

 According to a fifth aspect of the invention, there is provided an electrolytic capacitor anode which is produced from the tantalum powder of the fourth aspect of the invention. Preferably, the electrolytic capacitor anode has a specific capacitance of 5000-6000 (^FV/g, and an energizing voltage of 50-270V.

In order to obtain a medium-high pressure tantalum powder having a finer and more uniform particle size distribution and a lower impurity content, the inventors have found that in the pre-ball milling process, the active agent is added to the organic solvent for ball-milling treatment. When the ball milling time is reduced, the obtained niobium powder has a more uniform particle size, and the metal impurities and content are lower, the breakdown resistance of the final product is improved, and the leakage current is improved. The process idea proposed by the invention is as follows: the tantalum powder obtained by the sodium reduction or the electron bombardment of the tantalum ingot after the crushing treatment is used as the raw material, and the stirring ball mill or the vibrating ball mill is selected, the steel ball is not used as the grinding ball, and the diameter of the steel ball is used. Generally, l-10mm, preferably 3-6 mm, water or organic solvent is used as the ball milling medium. Usually, anhydrous ethanol is used, and 0.001-50% of the weight of the tantalum powder can be added to improve the surface of the powder in the dispersion medium. The active agent is used to improve the tableting efficiency, improve the morphology of the flaky powder, and reduce the content of medium carbon and metal impurities. Surfactants are often selected from the group consisting of oleic acid, benzoic acid, methyl ethyl ketone, polyethylene glycol, isopropanol and ring. Hexanol, sodium hexametaphosphate, sodium tripolyphosphate, etc., but are not limited thereto. Continuous ball milling for 1-50 hours. After washing, pickling and sieving, we finally get the flake original powder with the required particle size and morphology. The flaky raw powder obtained above is subjected to pelletization granulation, high-temperature high-vacuum heat treatment, and magnesium The combination of one of the treatments or the plurality of treatments in the original oxygen reduction treatment results in a medium high pressure a for the electrolytic capacitor.

 The flake original powder is subjected to a combination of one treatment or a plurality of treatments in a pelletized granulation, a high-temperature high-vacuum heat treatment, a magnesium-doped deoxidation treatment, and a high-reliability high-capacity electrolytic capacitor powder is obtained. Any chemical substance in the desired ratio which is advantageous for suppressing shrinkage and reducing loss of specific surface area at the time of high-temperature sintering may be added as a gas-blocking agent in the treatment. For example, one or more of phosphorus, nitrogen, and boron. The high temperature and high vacuum heat treatment temperature is generally controlled at 1300-1600. C, keep warm for 15-200 minutes. After the completion of the sintering, the temperature was lowered and the passivation treatment was carried out to obtain agglomerated crumbs, which were then broken. The specific heat treatment method can be carried out by the method described in Chinese Patent No. CN 102120258A. The deoxidation treatment is usually carried out in a reducing atmosphere in a deoxidizing treatment. In general, a small amount of a reducing agent having a higher affinity for oxygen than argon and oxygen, such as an alkaline earth metal, a rare earth metal and a hydride thereof, is mixed in the tantalum powder, and the most commonly used is a mixed weight of 0.2-6.0%. The metal magnesium powder is loaded by the method described in Chinese Patent No. CN 102120258A. Then heat under inert gas protection at 800-1000. C is kept for 2-4 hours, then vacuumed again, and then incubated for 2-4 hours under vacuum. Then cool down and passivate. The deoxidized powder must be pickled, washed, dried, and sieved.

 The above method can obtain a sheet-like tantalum powder having a metal impurity content of ∑Fe+M+Cr<50 ppmm and a C content of <50 ppm, and an electrolytic capacitor anode made thereof has a specific capacitance of 5000-6000 (^FV/g. The enabling voltage is 50-270V.

In the present invention, the physical quantity for describing the thickness of the metal particles is a specific surface area (m ² /g) of a low-temperature nitrogen adsorption BET measurement, and a Fisher's average particle diameter (FSSS/μπι) measured by a Fischer sub-screener. The Fischer's average particle size is obtained by measuring the flow rate of the powder filled in the metal tube by a gas transmission method using a Fischer sub-screener, which is related to the particle size on the one hand and to the cohesive strength of the powder; The original powder, the smaller the average particle size of the Fischer's average particle size, the larger the specific surface area; and for the agglomerated metal powder, the powders of different specific surface areas may have similar average particle diameters; for the same grade of powder, the agglomerated powder The average particle size of the Fischer is large. Advantageous effects of the invention The wet ball milling method of the tantalum powder provided by the invention has the advantages of simple process and strong controllability; and the obtained product has low metal impurity content. The flaky powder obtained by the method has a high specific surface area, has good fluidity and formability after agglomeration, has a high specific volume, and has a low leakage current and a high voltage at a higher voltage. Breakdown voltage.

 The sheet prepared by the wet ball milling method provided by the present invention has a more uniform particle size distribution and a lower impurity content. The invention performs ball milling by adding a surfactant pair to the ball milling medium to obtain a sheet a, which reduces the ball milling time, and the obtained sheet has a more uniform particle size, and the metal impurities and content of the powder are lower, and the final product The breakdown resistance is improved and the leakage current is improved. The method has the advantages that a certain amount of surfactant is added during the ball milling process, the powder is improved in the ball milling medium, the secondary agglomeration of the fine powder is prevented, and the particle size distribution of the powder is more uniform and Controllable. At the same time, under the action of the force, a lot of cracks will form on the surface. After the active agent is added to the grinding medium, the surfactant molecules will enter and adsorb along these cracks, preventing the chemical bonds that have been broken from re-polymerizing. Improved ball milling efficiency and reduced grinding time. Moreover, the metal impurities and the c element which are caused by the repolymerization of the chemical bond are also encapsulated inside the tantalum powder particles (usually such mechanical inclusions are difficult to be removed in the subsequent treatment), and the powder is greatly reduced. Impurity content. In addition, due to the addition of surfactants, the surfactant adsorbs on the surface of the particles to form a protective layer, which enables the surface particles to be passivated while grinding, which can effectively inhibit the oxidation during the ball milling process and effectively control the oxygen. ^ *. In the capacitor, low iron, carbon content and oxygen content are necessary. The lower the carbon and iron contents, the lower the leakage current of the capacitor made of the flake powder and the higher the breakdown voltage. detailed description

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, however, In the examples, specific techniques or conditions are not indicated, and are carried out according to the techniques or conditions described in the literature in the art or in accordance with the product specifications. If the instrument used does not indicate the manufacturer, it is a conventional product that can be obtained by the market. The analysis equipment and model of each parameter involved in the present invention are as follows:

实施例 1:

Example 1:

The content of impurities in the raw material is determined by the reduction of sodium as a raw material: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, and oleic acid was added as a surfactant. The amount of oleic acid added was 50% by weight of the tantalum powder, and 150 kg of a steel ball of (|) 4 mm was selected. Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. The weighed powder 10K _{g was} added to a ball mill barrel of a ball mill for ball milling, the ball mill speed was 130 rpm, and the ball milling time was 20 hours to form a sheet. The ball milled powder is prepared by mixing a mixed acid of HN0 ₃ and HF (from a concentration of 69% HN0 ₃ solution and a 40% HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1. : 20 ) Pickling to remove metal impurities, drying and sieving to obtain flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment. The specific conditions are as follows: vacuum treatment under 1300 for 60 minutes, then breaking into - 50 mesh, then 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HNO ₃ acid, dry, sieve the powder to completely pass through a 50 mesh sieve to obtain sample A. The main properties and chemical impurity content of sample A are shown in Table 2. Example 2:

The content of impurities in the raw materials is as follows: O < 2000ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, and oleic acid was added as a surfactant. The amount of oleic acid added was 20% by weight of the tantalum powder. Use (|) 5mm steel ball 150Kg. Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. The weighed powder 10K _{g was} added to a ball mill barrel of a ball mill for ball milling, the ball mill speed was 130 rpm, and the ball milling time was 20 hours to form a sheet. The powder after ball milling is prepared by mixing mixed acid of HN03 and HF (from a mixture of 69% HN0 ₃ solution and 40% HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1: 20) Pickling to remove metal impurities, drying and sieving to obtain a flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 Then, it will be 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HN03 acid, dry, sieve the powder to completely pass the 50 mesh sieve to obtain sample B. The main properties and chemical impurity content of sample B are shown in Table 2. Example 3:

The content of impurities in the raw material is determined by the reduction of sodium as a raw material: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, and oleic acid was added as a surfactant. The amount of oleic acid added was 10% by weight of the tantalum powder, and 150 kg of a steel ball of (|) 3 mm was selected. Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. The weighed powder 10K _{g was} added to a ball mill barrel of a ball mill for ball milling, the ball mill speed was 130 rpm, and the ball milling time was 20 hours to form a sheet. The powder after ball milling is prepared by mixing mixed acid of HN03 and HF (from a mixture of 69% HN0 ₃ solution and 40% HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1: 20) Pickling to remove metal impurities, drying and sieving to obtain a flake original powder. The physical properties of the obtained flake original powder and the chemical impurity content are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 Then, it will be 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HN0 ₃ acid, drying, The sieve powder was passed through a 50 mesh sieve to obtain Sample C. The main properties and chemical impurity content of sample C are shown in Table 2.

 Example 4:

The content of impurities in the raw materials is determined by the reduction of sodium as raw materials: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, and cyclohexanol was added as a surfactant. The amount of cyclohexanol added was 1.5% by weight of the tantalum powder, and 150 kg of steel balls of φ4ππη were selected. Ensure that the ball mill barrel, stirring pulp and steel balls are rust-free and clean. 10 kg of the weighed powder was added to a ball mill barrel of a ball mill for ball milling, the ball mill was rotated at 130 rpm, and the ball milling time was 20 hours to form a tablet. The ball milled powder is prepared by mixing mixed acid of HN0 ₃ and HF (from a concentration of 69% HN0 ₃ solution and a 40% concentration HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1. : 20) Pickling to remove metal impurities, drying and sieving to obtain a flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 Then, it will be 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HNO ₃ acid, dry, sieve the powder to completely pass through a 50 mesh sieve to obtain sample D. The main properties and chemical impurity content of sample D are shown in Table 2.

 Example 5

The content of impurities in the raw materials is determined by the reduction of sodium as raw materials: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Ethanol as milling media, is added as a surfactant, polyethylene glycol, polyethylene glycol added in an amount of 1.5% by weight of tantalum powder, the choice of the ball φ6πιιη 150K _g. Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. The weighed powder 10K _{g was} added to a ball mill barrel of a ball mill for ball milling, the ball mill speed was 130 rpm, and the ball milling time was 20 hours to form a sheet. The ball milled powder is prepared by mixing mixed acid of HN0 ₃ and HF (from a concentration of 69% HN0 ₃ solution and a 40% concentration HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1. : 20) Pickling to remove metal impurities, drying and sieving to obtain a flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder was heat-treated under vacuum for 1150 for 60 minutes, and then broken. To -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 mesh, and then 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HNO ₃ acid, dry, sieve the powder to completely pass the 50 mesh sieve to obtain sample E. The main properties and chemical impurity content of sample E are shown in Table 2.

 Example 6:

The content of impurities in the raw materials is determined by the reduction of sodium as raw materials: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, isopropanol and methyl ethyl ketone were added as surfactants, and the amounts of isopropanol and methyl ethyl ketone added were 5% and 1.5%, respectively, of the weight of the tantalum powder. A steel ball of φ6ππη is used in an amount of 150 kg. Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. The weighed S 10 Kg was placed in a ball mill barrel of a ball mill for ball milling, the ball mill was rotated at 130 rpm, and the ball milling time was 20 hours to form a sheet. The ball milled powder is prepared by mixing a mixed acid of HN0 ₃ and HF (from a concentration of 69% HN0 ₃ solution and a 40% concentration HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1. : 20 ) Pickling removes metal impurities, drying and sieving to obtain flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 Then, it will be 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HNO ₃ acid, dry and sieve the powder to completely pass the 50 mesh sieve to obtain sample F. The main properties and chemical impurity content of sample F are shown in Table 2.

 Example 7

The content of impurities in the raw materials is determined by the reduction of sodium as raw materials: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, and polyethylene glycol was added as a surfactant. The amount of polyethylene glycol added was 15% by weight of the tantalum powder. Use φ6πιιη steel ball 150K _g . Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. The weighed powder 10K _{g was} added to a ball mill barrel of a ball mill for ball milling, the ball mill speed was 130 rpm, and the ball milling time was 20 hours to form a sheet. The ball milled powder is mixed with HN0 ₃ and HF (formed by adding 69% HN0 ₃ solution, 40% HF solution to water). The volume ratio of HN0 ₃ solution, HF solution and water is 4:1:20), pickling to remove metal impurities, drying and sieving to obtain flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 Then, it will be 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HNO ₃ acid, dry and sieve the powder to completely pass the 50 mesh sieve to obtain sample G. The main properties and chemical impurity content of sample G are shown in Table 2.

 Example 8

The content of impurities in the raw materials is determined by the reduction of sodium as raw materials: O < 2000 ppm, C < 20 ppm, N < 150 ppm, Fe < 20 ppm. Anhydrous ethanol was used as a ball milling medium, and benzoic acid was added as a surfactant. The amount of benzoic acid added was 10% by weight of the tantalum powder. A steel ball of φ3ππη was used in an amount of 150 Kg. Ensure that the ball mill barrel, stirring pulp and steel balls are rust-free and clean. The weighed powder lOKg was added to a ball mill barrel of a ball mill for ball milling, the ball mill was rotated at 130 rpm, and the ball milling time was 20 hours to form a tablet. The ball milled powder is prepared by mixing mixed acid of HN0 ₃ and HF (from a concentration of 69% HN0 ₃ solution and a 40% concentration HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1. : 20) Pickling to remove metal impurities, drying and sieving to obtain a flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 Then, it will be 900. C deoxidation treatment, and finally remove the magnesium oxide and excess magnesium with a concentration of 20% (mass%) of HNO ₃ acid, dry and sieve the powder to completely pass the 50 mesh sieve to obtain sample H. The main properties and chemical impurity content of sample H are shown in Table 2.

 Comparative Example 9:

The content of impurities in the raw materials is as follows: O<2000ppm, C<20ppm, N<150ppm, Fe<20ppm. Using anhydrous ethanol as the ball milling medium, without adding any surfactant, φ4ππη steel ball 150K _{g was selected} . Ensure that the ball mill barrel, mixing slurry and steel balls are rust-free and clean. Weigh the weighed S 10Kg into the ball mill barrel of the ball mill. The ball mill, the ball mill rotates at 130 rpm, and the ball milling time is 20 hours to form a sheet. The powder after ball milling is prepared by mixing mixed acid of HN0 ₃ and HF (from a mixture of 69% HN0 ₃ solution and 40% HF solution), and the volume ratio of HN0 ₃ solution, HF solution and water is 4:1. : 20 ) Pickling removes metal impurities, drying and sieving to obtain flake original powder. The physical properties and chemical impurity content of the obtained flake original powder are shown in Table 1. The above-mentioned flake original powder is treated by vacuum treatment at 1150 for 60 minutes, and then broken to -50 mesh, and then subjected to secondary heat treatment and deoxidation treatment, specifically carried out under vacuum for 1300 treatment for 60 minutes, and then broken to -50 mesh, 900 ° C and then subjected to deoxidation treatment, the final concentration of 20% (by mass percent) HN0 ₃ acid remove magnesium oxide and excess magnesium, drying, sifting completely through a 50 mesh screen to obtain a sample I. The main properties and chemical impurity content of sample I are shown in Table 2.

 Table 1: Physical properties and chemical impurities of flake raw powder

表 2: 最终样品主要性能及化学杂质含量

Table 2: Main properties and chemical impurities of the final sample

样品 F 2.05 1.55 48.92 2070 30 26 6 5 86 样品 G 2.18 1.62 50.02 1980 32 29 5 5 90 样品 H 2.01 1.72 53.02 2210 25 34 4 3 88 样品 I 2.74 1.85 52.14 2800 72 75 10 10 75 注： 当用目 示粉末的粒度时， 在目数之前的 "+" 或 "-" 号分 别表示 "不通过"或 "通过" 所述目数的筛网。 例如 "-325目"表示通 过 325 目筛网， 而 "+325 目" 表示不通过 325 目筛网。 "-200— +325 目 " 表示通过了 200目筛网而未通过 325目筛网。

Sample F 2.05 1.55 48.92 2070 30 26 6 5 86 Sample G 2.18 1.62 50.02 1980 32 29 5 5 90 Sample H 2.01 1.72 53.02 2210 25 34 4 3 88 Sample I 2.74 1.85 52.14 2800 72 75 10 10 75 Note: When using the instructions When the particle size of the powder, the "+" or "-" sign before the mesh number indicates the mesh of "not pass" or "pass" the mesh. For example, "-325 mesh" means passing through a 325 mesh screen, while "+325 mesh" means not passing through a 325 mesh screen. "-200-+325 mesh" means passing through a 200 mesh screen without passing through a 325 mesh screen.

The samples A to I obtained in the above examples were compression molded, the pressed density was 5.0 g/cm ³ , the core powder weight was 0.15 g, and the test was carried out in accordance with the standard (GBT 3137-2007 钽 powder electrical property test method). The sintered block was obtained by sintering at 1400 ° C for 30 minutes in a vacuum furnace of T ³ Pa to obtain a sintered block. The sintered block was energized at a voltage of 0.01 V in a phosphoric acid solution having a concentration of 0.01% by mass to obtain a capacitor. The anodes were measured and their electrical performance indicators are listed in Table 3.

 Table 3: Electrical comparison

 In Table 3, SHD (%) represents the shrinkage ratio of the capacitor anode block in the radial direction, and SHV (%) represents the volume shrinkage ratio of the capacitor anode block.

It can be clearly seen from the comparison of the data in Table 3 that the addition of different surfactants during the ball milling process improves the tableting efficiency and the final product performance compared to the absence of the surfactant. It can also be seen from the data in Table 3 that the electrolytic capacitor anode made of the tantalum powder obtained by the present invention has a high specific volume and a low leakage current at a high sintering temperature and a high energizing voltage.

 Although specific embodiments of the invention have been described in detail, those skilled in the art will understand. Various modifications and alterations may be made to those details in accordance with the teachings of the invention, which are within the scope of the invention. The full scope of the invention is indicated by the appended claims and any equivalents thereof.

Claims

Rights request A wet ball milling method for powdered powder, characterized in that the grinding aid used in the method contains a ball milling medium and a surfactant.  The wet ball milling method according to claim 1, wherein said surfactant is used in an amount of from 0.001 to 50% by weight based on the weight of the cerium powder, preferably from 1 to 50%, from 1.5 to 50% or from 10 to 50% by weight.  The wet ball milling method according to claim 1 or 2, wherein the surfactant is selected from the group consisting of oleic acid, benzoic acid, methyl ethyl ketone, polyethylene glycol, isopropyl alcohol, cyclohexanol, sodium hexametaphosphate, and trimerization. Sodium phosphate or a combination thereof;  Preferably, the surfactant is selected from the group consisting of oleic acid, cyclohexanol, polyethylene glycol, isopropyl alcohol, methyl ethyl ketone, benzoic acid or a combination thereof.  The wet ball milling method according to any one of claims 1 to 3, wherein the ball milling medium is water or an organic solvent (e.g., anhydrous ethanol).  The wet ball milling method according to any one of claims 1 to 4, wherein the surfactant is oleic acid, and the amount thereof is 10 to 50% by weight of the tantalum powder (for example, 10%, 20%, 50%);  Or wherein the surfactant is cyclohexanol or polyethylene glycol, and the amount thereof is 0.5 to 2.5% by weight of the tantalum powder, preferably 1% to 2% by weight of the tantalum powder, more preferably the weight of the tantalum powder. 1.5%.  6. A grinding aid for wet ball milling, comprising a ball milling medium and a surfactant, wherein the ball milling medium is water or an organic solvent (e.g., absolute ethanol), and the surfactant is selected from the group consisting of oleic acid. , benzoic acid, butanone, polyethylene glycol, isopropanol, cyclohexanol, sodium hexametaphosphate, sodium tripolyphosphate or a combination thereof;  Preferably, the surfactant is selected from the group consisting of oleic acid, cyclohexanol, polyethylene glycol, isopropyl alcohol, methyl ethyl ketone, benzoic acid or a combination thereof.  The grinding aid according to claim 6, wherein the surfactant is used in an amount of from 0.001 to 50% by weight based on the weight of the niobium powder, preferably from 1 to 50%, from 1.5 to 50% or from 10 to 50% by weight. 8. The grinding aid according to claim 6, wherein the surfactant is oleic acid in an amount of 10 to 50% by weight of the tantalum powder (for example, 10%, 20%, 50%); Alternatively, wherein the surfactant is selected from the group consisting of isopropanol, butanone, benzoic acid, cyclohexanol, polyethylene glycol or a combination thereof in an amount of from 0.5 to 15% by weight of the cerium powder.  A flaky powder prepared by the wet ball milling method according to any one of claims 1 to 5;  Preferably, the sheet-like metal impurity is >J: ∑Fe+M+Cr<50 ppm, and C is 3⁄4: <50 ppm.  10. A high-reliability high-capacity electrolytic capacitor for a, wherein the flaky bismuth powder according to claim 9 is subjected to a treatment of granulation, high-temperature high-vacuum heat treatment, and M-oxygen treatment; The combined treatment of the treatments is obtained. An electrolytic capacitor anode made of the tantalum powder according to claim 10; preferably, the electrolytic capacitor anode has a specific capacitance of 5000-6000 (^FV/ _g , and an energizing voltage of 50 -270V.