High-voltage tantalum powder and preparation method therefor, and capacitor anode

Abstract

A high-voltage tantalum powder and a preparation method therefor, and a capacitor anode. The preparation method comprises: selecting a tantalum metal blank, wherein the content of impurity C in the tantalum metal blank is less than or equal to 30 ppm, the total content of metal impurities Fe, Ni and Cr is less than or equal to 30 ppm, and the grain size is 1-900 μm; subjecting the tantalum metal blank to a hydrogenation treatment, so as to obtain a hydrogenated material; subjecting the hydrogenated material to a pulverization treatment, so as to obtain a hydrogen-containing tantalum powder; subjecting the hydrogen-containing tantalum powder to acid pickling and impurity removal so as to obtain a hydrogenated and impurity-removed tantalum powder; and subjecting the hydrogenated and impurity-removed tantalum powder to a subsequent treatment, so as to obtain a high-pressure tantalum powder, wherein the subsequent treatment comprises one of or a combination of more of a dehydrogenation treatment, a high-temperature and high-vacuum heat treatment and a reduction and oxygen reduction treatment. Performing the hydrogenation, pulverization and subsequent treatments by using the tantalum metal blank as a raw material effectively improves the breakdown voltage and CV value of a capacitor made of the tantalum powder, and reduces the leakage current of the capacitor.

Description

High-voltage tantalum powder, preparation method thereof, and capacitor anode

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application No. 202311030273.6, filed on August 15, 2023, entitled “A high-voltage tantalum powder, its preparation method and capacitor anode”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present application relates to the field of rare metal technology, and in particular to a high-voltage tantalum powder, a preparation method thereof, and a capacitor anode. Background Art

[0004] High-voltage tantalum powder (including high-reliability tantalum powder with an operating voltage above 35V) is a key raw material for solid tantalum capacitors and liquid tantalum capacitors with an operating voltage of 63V or higher. Currently, the production of this high-voltage tantalum powder both domestically and internationally relies on a refining and purification process, using an electron bombardment-hydrogenation powder production process to increase the purity and quality of the tantalum powder. To further improve the specific capacitance and breakdown voltage of electron-bombarded high-voltage powder, researchers have attempted to study the effects of particle size and shape on the quality of high-voltage tantalum powder based on its physical properties. Research has shown that complex particle shapes are undesirable for high-voltage tantalum powders, as they result in an irregular anode surface, making it difficult for the oxide film to grow uniformly. High stress points at the tips create concentrated electric fields, increasing leakage current and losses, and reducing breakdown voltage. Therefore, researchers are attempting to develop a tantalum powder with a simple particle shape that balances high voltage resistance and high specific capacitance. Therefore, in recent years, some studies have adopted the following methods: (1) controlling the oxygen content below 550 PPM, using ball mills, rod mills, and roller mills to produce tantalum powder with a diameter-to-thickness ratio of 2-60, with at least 70% (by weight) of the powder consisting of flat, flaky particles 3-44 microns in size; and (2) repeatedly performing agglomeration-grinding-sieving-grading treatment, which has the same effect as the agglomeration of high-specific-volume tantalum powder. The goal is to produce a tantalum powder with a particle shape between spherical powder and sodium-based powder and a small sintering shrinkage. Facts have shown that this method of controlling the particle size and shape of electron-bombarded powder and agglomerating it is effective in increasing specific volume and breakdown voltage, but the effect is limited.

[0005] U.S. Patent No. 5,580,367 discloses an improved tantalum flake powder and a method for producing it. This method uses tantalum ingot hydride powder or sodium-reduced powder as raw material to produce large flakes using the aforementioned conventional method. The flakes are then subjected to a hydrogenation treatment and mechanically crushed to reduce their size. This results in a tantalum flake powder with a specific diameter-to-thickness ratio. This agglomerated powder exhibits excellent process properties, such as fluidity, compact strength, and formability, and can be used to produce capacitors with low leakage current and high breakdown voltage. However, this method is complex and requires a long process. Furthermore, repeated mechanical crushing inevitably leads to an increase in metallic impurities, and extensive acid washing results in tantalum powder loss, significantly increasing production costs.

[0006] U.S. Patent No. 4,017,302 discloses a method for preparing high-pressure tantalum metal powder. The specific process involves hydrogenation of tantalum ingots, grinding, grading and screening, dehydrogenation and preheating, crushing through an 80-mesh sieve, agglomeration, crushing, screening through 35 and 250 mesh sieves, mixing -250 mesh and -35 / +25 mesh powders, agglomeration, testing, and final production. The tantalum powder produced by this method is suitable for high-voltage, low-capacity tantalum powder (63V).

[0007] U.S. Patent No. 4,141,719 discloses a method for preparing high-voltage tantalum metal powder. The method involves hydrogenating tantalum ingots, grinding, grading, degassing (at 1200°C), sieving to 35 mesh, and mixing. The resulting tantalum powder has a high bulk density, low oxygen content, high green block strength, and low leakage current in sintered anodes. The tantalum powder produced by this method is particularly suitable for high-voltage, low-capacity tantalum powder (63V).

[0008] U.S. Patent No. 4,555,268 relates to a tantalum flake powder with improved processability. The powder comprises 20-40% tantalum flake powder and 70% tantalum granular powder, heat-treated at 1250°C to 1550°C for 5 to 120 minutes before mixing. This secondary agglomeration of the mixed tantalum powder improves processability. The tantalum powder produced by this method is suitable for medium operating voltages (20V to 35V).

[0009] U.S. Patent No. 4,740,238 relates to a tantalum powder containing flaky powder. The specific process for producing this tantalum powder includes: degassing, flaking (ball milling, wet milling), pickling, screening, phosphorus doping, primary heat treatment, grinding and screening, phosphorus doping, secondary heat treatment, grinding and screening, and magnesium reduction. The tantalum powder produced by this method is suitable for medium operating voltages (20V to 35V).

[0010] Chinese patent application CN1004614A relates to a method for forming spherical tantalum powder and its product. The tantalum powder is fed into a plasma reaction zone using a carrier gas, sprayed into a vacuum tank for cooling, and then formed into spherical tantalum powder. The powder is then acid-washed and heat-treated at 1000-1250°C. The tantalum powder has a withstand voltage of 300-450V. The tantalum powder produced by this method has a specific capacitance of only 500-800 μF / g and exhibits extremely poor formability.

[0011] Summary of the Invention

[0012] The present application provides a high-voltage tantalum powder, a preparation method thereof, and a capacitor anode to further improve the specific capacitance and breakdown voltage of capacitors made of tantalum powder.

[0013] The first aspect of the present application provides a method for preparing high-pressure tantalum powder, which comprises: selecting a tantalum metal billet, wherein the impurity C content in the tantalum metal billet is ≤30 ppm, the total content of metal impurities Fe, Ni and Cr is ≤30 ppm, and the grain size is 1 μm-900 μm; performing hydrogenation treatment on the tantalum metal billet to obtain a hydrogenated material; performing pulverization treatment on the hydrogenated material to obtain hydrogen-containing tantalum powder; performing acid washing and impurity removal on the hydrogen-containing tantalum powder to obtain hydrogenated impurity-removed tantalum powder; performing subsequent treatment on the hydrogenated impurity-removed tantalum powder to obtain high-pressure tantalum powder, wherein the subsequent treatment comprises a combination of one or more of dehydrogenation treatment, high-temperature and high-vacuum heat treatment, and reduction and oxygen reduction treatment.

[0014] In any embodiment of the first aspect, the grain size of the tantalum metal billet is 1 μm-450 μm, preferably 1 μm-350 μm, and more preferably 10 μm-150 μm.

[0015] In any embodiment of the first aspect, the mass content of hydrogen in the hydrogenation material is greater than or equal to 0.3%, preferably greater than or equal to 0.5%.

[0016] In any embodiment of the first aspect, the hydrogen-containing tantalum powder has a thickness of 1 μm≤D V 50≤15μm, preferably 1μm≤D of hydrogen-containing tantalum powder V 50≤10μm.

[0017] In any embodiment of the first aspect, the pulverization treatment includes one or more of ball milling, impact treatment and extrusion treatment; the ball milling treatment satisfies any one or more of the following conditions: 1) zirconia balls are used as ball milling media, preferably the diameter of the zirconia balls is 1 mm-5 mm, more preferably 2 mm-4 mm; 2) wet agitated ball milling is used, preferably water or an organic solvent is used as a dispersion medium in the wet agitated ball milling; 3) a surfactant is used as a grinding aid; preferably the grinding aid is butanone and / or isopropyl alcohol; preferably, the amount of the grinding aid added is 0.5%-5% of the weight of the hydrogenated material, preferably 1%-4%, more preferably 1.8%-3.6%.

[0018] In any embodiment of the first aspect, the acid used for pickling and impurity removal includes a mixed acid formed by one or more of sulfuric acid, hydrochloric acid, and nitric acid, hydrogen peroxide, and hydrofluoric acid.

[0019] A second aspect of the present application provides a high-pressure tantalum powder, wherein the total content of metal impurities Fe, Ni and Cr is ≤30ppm, and the C content is ≤30ppm; and the high-pressure tantalum powder satisfies at least one of the following conditions: 1) the bulk density is 1.8g / cm 3 -4.0g / cm 3 , preferably 1.95 g / cm 3 -3.55g / cm 3 , more preferably 2.2 g / cm 3 -3.5g / cm 3 ; 2), BET specific surface area is 0.1m 2 / g-1.0m 2 / g, preferably 0.2m 2 / g-0.7m 2 / g, more preferably 0.2m 2 / g-0.6m 2 / g; 3), fluidity ≤ 50s / 50g, preferably fluidity ≤ 40s / 50g, more preferably fluidity ≤ 35s / 50g, further preferably fluidity < 20s / 50g.

[0020] In any embodiment of the second aspect, the electrolytic capacitor anode made of high-voltage tantalum powder has a specific capacitance of 6500μF·V / g-23000μF·V / g and a breakdown voltage of 200V-300V when the energizing voltage is 150V-300V, preferably a breakdown voltage of 200V-285V.

[0021] A third aspect of the present application provides a high-pressure tantalum powder, which is prepared by any one of the preparation methods of the first aspect.

[0022] A fourth aspect of the present application provides a capacitor anode made of tantalum powder, wherein the tantalum powder is the high-voltage tantalum powder provided in any embodiment of the second or third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0024] FIG1 shows a schematic flow chart of a method for preparing high-voltage tantalum powder provided in one embodiment of the present application.

[0025] FIG2 shows a metallographic photograph of the tantalum metal billet of Example 1 of the present application.

[0026] FIG3 shows a metallographic photograph of the tantalum metal billet of Example 2 of the present application.

[0027] FIG4 shows a metallographic photograph of the tantalum metal billet of Example 3 of the present application.

[0028] FIG5 shows a metallographic photograph of the tantalum metal billet of Example 4 of the present application.

[0029] FIG6 shows a metallographic photograph of the tantalum metal billet of Example 5 of the present application.

[0030] FIG7 shows a metallographic photograph of the tantalum metal billet of Example 6 of the present application.

[0031] FIG8 shows a metallographic photograph of the tantalum metal billet of Example 7 of the present application.

[0032] FIG9 shows a metallographic photograph of the tantalum metal blank of Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0033] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The detailed description of the following examples is used to illustrate the principles of the present application, but is not intended to limit the scope of the present application, i.e., the present application is not limited to the described embodiments.

[0034] As analyzed in the background of this application, there are various methods for producing tantalum powder for high-voltage applications. However, most methods use electron-bombarded tantalum ingots as the raw material to increase the purity of the tantalum powder. To further increase the specific capacitance and breakdown voltage of the electron-bombarded high-voltage powder, the particle size and shape of the tantalum powder are controlled by hydrogenating the tantalum ingots. While this method of controlling the particle size and shape of the electron-bombarded powder and performing agglomeration treatment is effective in increasing the specific capacitance and breakdown voltage, the results are limited.

[0035] In order to further improve the specific capacitance and breakdown voltage of capacitors made of tantalum powder, the first embodiment of the present application provides a method for preparing high-voltage tantalum powder, as shown in Figure 1. The preparation method includes: selecting a tantalum metal billet, the impurity C content in the tantalum metal billet is ≤30ppm (preferably ≤20ppm), the total content of metal impurities Fe, Ni and Cr is ≤30ppm (preferably ≤20ppm), and the grain size is 1μm-900μm; hydrogenating the tantalum metal billet to obtain a hydrogenated material; pulverizing the hydrogenated material to obtain hydrogen-containing tantalum powder; pickling and removing impurities from the hydrogen-containing tantalum powder to obtain hydrogenated impurity-removed tantalum powder; and performing subsequent treatment on the hydrogenated impurity-removed tantalum powder to obtain high-voltage tantalum powder, and the subsequent treatment includes one or more combinations of dehydrogenation treatment, high-temperature and high-vacuum heat treatment, and reduction and deoxidation treatment.

[0036] The grain size of the tantalum metal blank is too large, and the BET specific surface area of ​​the hydrogen-containing tantalum powder obtained after pulverization is too small, so the specific volume of the tantalum powder finally obtained is low; the purity of the tantalum metal blank, such as the content of metal impurities such as carbon, iron, nickel, and chromium, is high, the leakage current of the product increases, and the reliability is reduced. This application uses tantalum metal blanks with an impurity C content of ≤30ppm, a total content of metal impurities Fe, Ni and Cr of ≤30ppm, and a grain size of 1μm-900μm as raw materials for hydrogenation, pulverization and post-treatment, which effectively improves the breakdown voltage and CV value (specific volume) of capacitors made of tantalum powder, and reduces its leakage current. The above-mentioned hydrogenation, impurity removal and post-treatment improve the fluidity and electrical properties of the tantalum metal blank, so that the high-voltage tantalum powder prepared thereby is easier to make into capacitors, and the breakdown voltage and CV value of the capacitors are fully improved, and the leakage current is effectively controlled. In the preparation method of the present application, after the raw materials meet the above conditions, hydrogenation, impurity removal and post-treatment can be carried out by referring to conventional processes. Therefore, the process is simple and highly controllable, the production process has low safety risks and wide applicability.

[0037] In some embodiments, after the high-voltage tantalum powder is sieved, the high-voltage tantalum powder that passes 50 mesh is selected as the raw material for subsequent electrode production.

[0038] The grain size of tantalum metal billet is determined according to the comparison method in GB / T6394 "Method for determination of average grain size of metals".

[0039] The tantalum metal blank used in this application may be a tantalum ingot, tantalum rod, tantalum wire, and / or other tantalum material. The tantalum metal blank may be prepared using known methods or from known products. There are many methods for preparing the tantalum metal blank. For example, any chemical substance that is beneficial to grain refinement may be added as a refiner in a desired proportion during the processing of the tantalum metal blank, such as one or more of phosphorus, nitrogen, boron, silicon, yttrium, etc.; grain size may also be controlled by adjusting the tantalum material processing process, such as sintering temperature and / or holding time; grain refinement may also be achieved by reprocessing the tantalum material, such as heat treatment and machining. Alternatively, a combination of the above processing methods may be used to achieve grain refinement.

[0040] Experiments have found that smaller tantalum metal ingot grain size improves the capacitor's CV value, but this reduces the effect of improving leakage current. Increasing the tantalum metal ingot grain size also improves the capacitor's leakage current, but reduces the effect of improving CV value. To simultaneously reduce the leakage current of tantalum powder and improve its CV value, in some embodiments of the present application, the tantalum metal ingot has a grain size of 1 μm to 450 μm, preferably 1 μm to 350 μm, and more preferably 10 μm to 150 μm.

[0041] Hydrogenation can be carried out with reference to conventional processes. Hydrogenation utilizes the characteristic that the maximum hydrogen absorption capacity of tantalum metal and tantalum alloys varies at different temperatures, and the hydrogen content of tantalum metal is controlled by adjusting the hydrogenation process. Since the maximum hydrogen absorption capacity of tantalum metal and tantalum alloys increases with decreasing temperature, the higher the temperature at which hydrogen flow is stopped, the lower the hydrogen content, and the lower the temperature at which hydrogen flow is stopped, the higher the hydrogen content. Generally, after the temperature drops to the temperature at which hydrogen flow is stopped, hydrogen flow is continued for a period of time. The holding time varies depending on the size of the tantalum metal and tantalum alloy loaded into the hydrogenation container (larger blocks require longer time). Then, hydrogen flow is stopped to ensure that the tantalum metal and tantalum alloy absorb hydrogen fully and evenly.

[0042] In some embodiments of the present application, the mass content of hydrogen in the hydride material is greater than or equal to 0.3%, preferably greater than or equal to 0.5%. This is to avoid the hydrogen content being too low, resulting in the hydride material having insufficient hydrogen embrittlement and difficulty in fine crushing during the pulverization process. The above hydrogen content can enable the metallic tantalum hydride block material to maintain good hydrogen embrittlement, allowing the tantalum hydride block to be fully crushed to the desired particle size, thereby improving production efficiency and yield. It should be noted that hydrogen saturation may occur in the hydride material, but the actual hydrogen content will not exceed this saturation.

[0043] In some embodiments, the hydrogen flow is stopped at any temperature ≤ 200°C during the hydrogenation treatment, and can be any temperature between 150°C and 200°C; any temperature between 100°C and 200°C; any temperature between 50°C and 100°C; and preferably any temperature between 50°C and 150°C. This effectively controls the mass content of hydrogen in the hydrogenated material and prevents it from being too low.

[0044] The above-mentioned pulverization treatment refers to the mechanical crushing of the hydrogenated material (such as tantalum block) with good hydrogen embrittlement obtained by hydrogenation treatment into powder. There is no restriction on the pulverization method and it can be crushed by air flow crushing equipment or ball milling equipment. In order to avoid the hydrogen-containing tantalum powder having too small particle size and resulting in too large surface energy and easy oxidation, in some embodiments, the hydrogen-containing tantalum powder has a particle size of 1 μm ≤ D V 50≤15μm, preferably 1μm≤D of hydrogen-containing tantalum powder V 50≤10μm.

[0045] In some embodiments, the pulverization treatment includes one or more of ball milling, impact treatment and extrusion treatment; the ball milling treatment satisfies any one or more of the following conditions: 1) zirconia balls are used as ball milling media, preferably the diameter of the zirconia balls is 1 mm-5 mm, more preferably 2 mm-4 mm; 2) wet agitation ball milling is used, preferably water or an organic solvent is used as a dispersion medium in the wet agitation ball milling; 3) a surfactant is used as a grinding aid; preferably the grinding aid is butanone and / or isopropyl alcohol; preferably, the amount of the grinding aid added is 0.5%-5% of the weight of the hydrogenated material, preferably 1%-4%, more preferably 1.8%-3.6%.

[0046] For example, the above pulverization treatment is first mechanically crushed to a size that can pass through a 100-mesh sieve and then wet-mixed ball milling is used, for example, using zirconia balls as the milling medium and water or an organic solvent as the dispersion medium, and continuous ball milling is performed until D V 50≤15μm, preferably D V 50 ≤ 10 μm. Due to the high hardness of tantalum hydride powder, grinding with standard stainless steel balls can cause severe wear on the balls, introducing large amounts of metallic impurities into the material, resulting in a high impurity content. To address this issue and improve the purity of the final product, it is preferred to use harder zirconia balls rather than stainless steel balls for grinding.

[0047] To achieve a finer and more uniform particle size distribution, it's preferable to use smaller grinding balls for grinding, such as those with diameters of 1mm-5mm, preferably 2mm-4mm. This is because smaller grinding media fill the grinding chamber with a larger volume, increasing the impact and friction of the grinding media. This also increases the contact area of ​​the grinding media, which in turn aids in finer grinding. Surprisingly, it has been found that grinding balls with diameters of 1mm-5mm, preferably 2mm-4mm, generally achieve better grinding results.

[0048] During the ball milling process, it is difficult to avoid the generation of ultrafine powders with a particle size of less than 0.1 μm. These powders are often easily oxidized or even spontaneously combust. At the same time, since the finer the powder particle size, the larger its surface area and the greater its surface free energy, the fine particles will re-agglomerate, which is not conducive to micronization. In order to facilitate the pulverization, it is preferred to add a surfactant as a grinding aid to the dispersion medium. Because the surfactant can adhere to the surface of the tantalum powder particles to form a protective layer, the surface of the material particles is passivated while the micronized ball ultrafine grinding is carried out, which can effectively inhibit the oxidation of the ultrafine powder during the ball milling and subsequent processing, thereby improving the product quality. The preferred grinding aid is butanone and / or isopropyl alcohol. More preferably, the amount of grinding aid added is 0.5%-5% of the weight of the hydrogenated material, preferably 1%-4%, and more preferably 1.8%-3.6%.

[0049] After pulverization, the hydrogen-containing tantalum powder is pickled for impurity removal. Pickling for impurity removal can reduce impurities in the tantalum powder, such as oxygen, carbon, iron, nickel, chromium, etc. The implementation of pickling for impurity removal can refer to the conventional pickling for impurity removal process of tantalum powder. In some embodiments, the acid used for pickling for impurity removal includes a mixed acid formed by one or more of sulfuric acid, hydrochloric acid, and nitric acid, hydrogen peroxide, and hydrofluoric acid.

[0050] When the hydrogenated, impurity-removed tantalum powder obtained after the hydrogenation treatment and acid washing is directly used to make capacitor anode blocks, its fine particles and poor fluidity make it difficult to fill the mold corners during the capacitor anode block molding process, resulting in missing edges and corners in the molded blocks. It also easily forms an arch bridge effect, resulting in poor compactness and reduced block strength. Furthermore, the fine powder particles lead to uneven pore structure distribution and low porosity in the molded blocks, hindering electrolyte penetration during the anode block energization process. The uneven current distribution leads to uneven thickness of the oxide film, causing partial electric field concentration, resulting in increased current density, leakage current, and losses. Regarding capacity, the small inter-particle pores between the fine powder particles hinder capacity extraction during the subsequent capacitor manufacturing process. Furthermore, the hydrogenated, impurity-removed tantalum powder contains high levels of impurities such as oxygen, hydrogen, and fluorine. Increased levels of these impurities can affect the electrical performance of the capacitor, particularly increasing leakage current. This is because impurities in the tantalum powder serve as nucleation centers for crystallization of the anodic oxide film during the anodic oxidation process, causing defects in the oxide film. This ultimately leads to increased leakage current and reduced flash voltage. The problems caused by poor powder fluidity, the presence of fine powder particles, and high content of impurities such as oxygen, hydrogen and fluorine can be effectively overcome by treating the powder with a combination of any one or more of the above-mentioned processes of pelletizing, high-temperature and high-vacuum heat treatment, and magnesium reduction and oxygen reduction treatment.

[0051] Dehydrogenation, high-temperature, high-vacuum heat treatment, and reduction and oxygen reduction are all commonly used processes in tantalum powder processing. Therefore, the above-mentioned treatment processes in this application can refer to conventional processes. In some embodiments, the above-mentioned treatments can be performed sequentially. In some embodiments, the dehydrogenation treatment is to place the hydrogen-containing tantalum powder in a sealed furnace filled with argon and heated to 700-900°C for 60-200 minutes, then cool it out of the furnace and sieve it.

[0052] To reduce material shrinkage and surface side reactions during high-temperature, high-vacuum heat treatment, in some embodiments, any chemical substance that inhibits shrinkage and reduces specific surface area loss during high-temperature sintering of the tantalum powder can be added as a sintering inhibitor in the desired proportion. For example, one or more of phosphorus, nitrogen, and boron can be added during the high-temperature, high-vacuum heat treatment. The high-temperature, high-vacuum heat treatment temperature is generally controlled between 1000°C and 1600°C, and the temperature is maintained for 15 to 200 minutes. After the high-temperature, high-vacuum heat treatment, the tantalum powder is pelletized and granulated. After sintering, the tantalum powder is cooled and passivated to produce agglomerated tantalum blocks, which are then crushed. The magnesium reduction and oxygen reduction treatment can be conventional oxygen reduction. For example, it can be carried out in the following manner: generally, a small amount of a reducing agent having an affinity for oxygen greater than that of tantalum for oxygen, such as alkaline earth metals, rare earth metals and their hydrides, is mixed into the material to be treated. The most commonly used method is to mix the material to be treated with metallic magnesium powder accounting for 0.2%-6.0% of the weight of the material to be treated, and then heat it under vacuum or under the protection of an inert gas (preferably an inert gas), keeping it warm at 800°C-900°C for 1 hour-3 hours, then evacuate the material, and keep it warm under vacuum conditions for another 2 hours-6 hours; then cool it, passivate it, and remove magnesium to obtain high-pressure tantalum powder.

[0053] In a second embodiment of the present application, a high-pressure tantalum powder is provided, wherein the total content of metal impurities Fe, Ni and Cr in the high-pressure tantalum powder is ≤30 ppm (preferably ≤20 ppm), and the C content is ≤30 ppm (preferably ≤20 ppm); and the high-pressure tantalum powder satisfies at least one of the following conditions: a bulk density of 1.8 g / cm 3 -4.0g / cm 3 , preferably 1.95 g / cm 3 -3.55g / cm 3 , more preferably 2.2 g / cm 3 -3.5g / cm 3 ; 2), BET specific surface area is 0.1m 2 / g-1.0m 2 / g, preferably 0.2m 2 / g-0.7m 2 / g, more preferably 0.2m 2 / g-0.6m 2 / g; 3), fluidity ≤ 50s / 50g, preferably fluidity ≤ 40s / 50g, more preferably fluidity ≤ 35s / 50g, and further preferably fluidity < 20s / 50g. High-voltage tantalum powder that meets the above conditions has a high CV value and breakdown voltage, and has low leakage current, meeting the requirements for use in high-reliability and high-specific capacitance electrolytic capacitors.

[0054] In some embodiments, the electrolytic capacitor anode made of the above-mentioned high-voltage tantalum powder has a specific capacitance of 6500μF·V / g-23000μF·V / g when the energizing voltage is 150V-270V, preferably a specific capacitance of 7000μF·V / g-20000μF·V / g, and a breakdown voltage of 200V-300V, preferably a breakdown voltage of 200V-285V.

[0055] In a third embodiment of the present application, a high-voltage tantalum powder is provided. The high-voltage tantalum powder is prepared by the preparation method of any of the above-mentioned embodiments of the present application. The high-voltage tantalum powder prepared in the present application has a high CV value and breakdown voltage, and has a low leakage current, meeting the requirements for use in high-reliability and high-specific capacitance electrolytic capacitors.

[0056] In a third embodiment of the present application, a capacitor anode is provided. The capacitor anode is made of tantalum powder, and the tantalum powder is any one of the high-voltage tantalum powders provided in the second embodiment or the third embodiment of the present application.

[0057] The following examples and comparative examples will further illustrate the beneficial effects of the present application, but the scope of the present invention is not limited to these examples.

[0058] The analysis equipment and models of various parameters involved in this application are shown in Table 1.

[0059] Table 1

[0060] In addition, the bulk density (SBD) was determined according to GB / T1479.1 Funnel method, Part 1: Funnel method; the flowability (Flow) was determined according to GB / T1482 Hall flowmeter; the specific surface area of ​​metal powders was determined according to GB / T13390: Nitrogen adsorption method; and the grain size was determined according to the comparison method in GB / T6394 Determination of average grain size of metals.

[0061] Example 1

[0062] Step 1) Sodium-reduced tantalum powder is selected as a raw material, wherein ∑Fe+Ni+Cr=10ppm and C content is 14ppm. The powder is loaded into an elastic mold, sealed, and placed in a high-pressure cylinder of an isostatic press. A pressure of 180 MPa is used to press-form the powder to obtain a tantalum rod. The formed tantalum rod is sintered in a graphite furnace at a sintering temperature of 2000°C and a holding time of 240 min to obtain a tantalum metal billet A. The chemical impurity content is shown in Table 2, and the metallographic structure photograph is shown in Figure 2.

[0063] Step 2) The tantalum metal billet is placed in a hydrogenation container of a hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The heat is maintained for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5 MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 200°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0064] In step 3), the hydrogenated material is coarsely crushed using a jaw crusher to a tantalum powder that can completely pass through an 80-mesh sieve. The tantalum powder is ball-milled using anhydrous ethanol as a ball milling medium, butanone and isopropanol as grinding aids (butanone is added in an amount of 1.0% by weight of the hydrogenated material, and isopropanol is added in an amount of 3.0% by weight of the hydrogenated material), and zirconia balls with a diameter of 3 mm as a ball milling medium. Wet agitation ball milling is performed for 1.5 hours to obtain a hydrogenated tantalum powder with a Dv50 of less than 15 μm. After screening, a hydrogenated tantalum powder with a Dv50 of 1 μm ≤ 15 μm and a hydrogen content of 0.497% is obtained.

[0065] In step 4), the sieved hydrogenated tantalum powder is washed with a mixed acid of HNO3 and HF (the volume ratio of HNO3, HF and water is 4:1:20) to remove metal impurities, dried and sieved to obtain hydrogenated impurity-removed tantalum powder.

[0066] Step 5) The hydrogenated impurity-removed tantalum powder is placed in a sealed furnace filled with argon and heated to 900°C for 180 minutes for dehydrogenation treatment, then cooled and taken out of the furnace and sieved. The dehydrogenated tantalum powder is subjected to high temperature and high vacuum heat treatment and deoxidation treatment, specifically in the following steps: -3 The powder was heated to 1300°C under a vacuum of 1.5 Pa and held for 60 minutes, then jaw crushed to a size below 50 mesh. 2% magnesium chips were added to the tantalum powder and heated to 900°C in an argon atmosphere in a sealed furnace for 2 hours. The powder was then evacuated and held for another 3 hours under vacuum before being cooled, passivated, and removed from the furnace. Finally, the powder was acid-washed with 20% HNO3 to remove magnesium oxide and excess magnesium. The powder was then dried and sieved to pass through a 50-mesh sieve to obtain high-pressure tantalum powder A. Its chemical impurity content is shown in Table 3.

[0067] The high-pressure tantalum powder A is pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard.-3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0068] Example 2

[0069] In step 1), sodium-reduced tantalum powder, the same as in Example 1, was used as the raw material, with ∑Fe+Ni+Cr=10ppm and a C content of 14ppm. The powder was placed into an elastic mold, sealed, and placed in the high-pressure cylinder of an isostatic press. The molded tantalum rod was press-formed at a pressure of 180 MPa. The formed tantalum rod was sintered in a graphite furnace at a temperature of 2200°C and a holding time of 240 minutes to obtain tantalum metal billet B. The chemical impurity content is shown in Table 2, and a metallographic microstructure photograph is shown in Figure 3.

[0070] Step 2) The tantalum metal billet is placed in a hydrogenation container of a hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The heat is maintained for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5 MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 100°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0071] Repeat step 3) of Example 1 to obtain hydrogen-containing tantalum powder with a particle size of 1 μm≤DV50≤15 μm and a hydrogen content of 0.517%.

[0072] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder. Repeat step 5) of Example 1 to obtain high-pressure tantalum powder B. The chemical impurity content of the powder is shown in Table 3.

[0073] The high-pressure tantalum powder B is pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0074] Example 3

[0075] In step 1), sodium-reduced tantalum powder, the same as in Example 1, was selected as the raw material, with ∑Fe+Ni+Cr=10ppm and a C content of 14ppm. The powder was placed into an elastic mold, sealed, and placed in the high-pressure cylinder of an isostatic press. The molded tantalum rod was then sintered in a vertical melting furnace at 2400°C for 240 minutes to obtain a tantalum metal billet C. The chemical impurity content of the tantalum metal billet is shown in Table 2, and a metallographic microstructure photograph is shown in Figure 4.

[0076] Step 2) The tantalum metal billet is placed in a hydrogenation container of a hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The heat is maintained for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5 MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 100°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0077] Repeat step 3 of Example 1 to obtain hydrogen-containing tantalum powder with a particle size of 1 μm≤DV50≤15 μm and a hydrogen content of 0.612%.

[0078] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0079] Repeat step 5) of Example 1 to obtain high-voltage tantalum powder C. The chemical impurity content of the powder is shown in Table 3.

[0080] The high-pressure tantalum powder C is pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0081] Example 4

[0082] Step 1) The tantalum metal blank is a commercially available high-purity tantalum rod with the grade Ta1. The chemical impurity content and grain size are shown in Table 2, and the metallographic structure photograph is shown in Figure 5.

[0083] Step 2) The tantalum metal billet is placed in a hydrogenation container of a hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The heat is maintained for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5 MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 100°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0084] Repeat step 3) of Example 1 to obtain hydrogen-containing tantalum powder with a size of 1 μm≤DV50≤15 μm and a hydrogen content of 0.412%.

[0085] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0086] Repeat step 5) of Example 1 to obtain high-voltage tantalum powder D. The chemical impurity content thereof is shown in Table 3.

[0087] The high-pressure tantalum powder D is pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0088] Example 5

[0089] In step 1), the tantalum metal blank is a commercially available high-purity tantalum ingot with the grade Ta1. The chemical impurity content and grain size thereof are shown in Table 2, and the metallographic structure photograph is shown in FIG6 .

[0090] Step 2) The tantalum metal billet is placed in a hydrogenation container of a hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The heat is maintained for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5 MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 100°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0091] Repeat step 3 of Example 1 to obtain hydrogen-containing tantalum powder having a diameter of 1 μm ≤ DV50 ≤ 15 μm and a hydrogen content of 0.494%.

[0092] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0093] Repeat step 5) of Example 1 to obtain high-voltage tantalum powder E. The chemical impurity content of the powder is shown in Table 3.

[0094] The high-pressure tantalum powder E was pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0095] Example 6

[0096] The same sodium-reduced tantalum powder as in Example 1 was selected as a raw material, wherein ∑Fe+Ni+Cr=10ppm and C content was 14ppm. The powder was loaded into an elastic mold, sealed, and placed in a high-pressure cylinder of an isostatic press. A pressure of 210 MPa was applied to form the powder under pressure to obtain a tantalum rod. The formed tantalum rod was sintered in a vertical melting furnace at a sintering temperature of 2800°C and a holding time of 360 min to obtain a tantalum metal billet F. The chemical impurity content is shown in Table 2.

[0097] The subsequent operations were the same as those in Example 1, and the obtained high-voltage tantalum powder F was used to make a capacitor anode in the same manner as in Example 1.

[0098] Example 7

[0099] The same sodium-reduced tantalum powder as in Example 1 was selected as a raw material, wherein ∑Fe+Ni+Cr=10ppm and C content was 14ppm. The powder was loaded into an elastic mold, sealed, and placed in a high-pressure cylinder of an isostatic press. A pressure of 210 MPa was applied to form the tantalum rod. The formed tantalum rod was sintered in a vertical melting furnace at a sintering temperature of 2800°C and a holding time of 480 min to obtain a tantalum metal billet G. The chemical impurity content is shown in Table 2.

[0100] The subsequent operations were the same as those in Example 1, and the obtained high-voltage tantalum powder G was used to make a capacitor anode in the same manner as in Example 1.

[0101] Comparative Example 1

[0102] In step 1), the tantalum metal blank (comparison blank 1) is a commercially available high-purity tantalum ingot with the grade Ta1. The chemical impurity content thereof is shown in Table 2, and the metallographic structure photograph is shown in FIG8 .

[0103] Repeat step 2) of Example 1 to obtain a hydrogenated material with good hydrogen embrittlement resistance.

[0104] Repeat step 3 of Example 1) to prepare tantalum hydride powder with a diameter of 1 μm ≤ DV50 ≤ 15 μm and a hydrogen content of 0.394%.

[0105] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0106] Repeat step 5) of Example 1 to obtain comparative sample 1. The chemical impurity content thereof is shown in Table 3.

[0107] Comparative sample 1 was pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0108] Comparative Example 2

[0109] The tantalum metal blank is a commercially available high-purity tantalum ingot with the grade Ta1 (comparison blank 2), and the chemical impurity content thereof is shown in Table 2.

[0110] The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C and kept warm. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5MPa. The billet is kept warm for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 100°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is taken out of the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0111] The hydride material is then crushed into tantalum hydride powder with Dv50 < 15 μm.

[0112] The crushed tantalum hydride powder is pickled with a mixed acid of HNO3 and HF (the volume ratio of HNO3, HF and water is 4:1:20) to remove metal impurities, dried and sieved to obtain tantalum hydride powder.

[0113] The hydrogenated impurity-removed tantalum powder was placed in a sealed furnace filled with argon and heated to 900°C for 180 minutes for dehydrogenation. The powder was then cooled, removed from the furnace, and sieved. The dehydrogenated tantalum powder was then subjected to high-temperature, high-vacuum heat treatment and deoxidation. Specifically, the powder was treated at 1300°C under vacuum for 60 minutes, then crushed to -50 mesh, and deoxidized at 900°C. Finally, the powder was acid-washed with 20% HNO3 to remove magnesium oxide and excess magnesium. The powder was then dried and sieved to pass through a 50-mesh sieve, yielding Comparative Sample 2. Its chemical impurity content is shown in Table 3.

[0114] Comparative sample 2 was pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0115] Comparative Example 3

[0116] The tantalum metal blank is a commercially available tantalum rod with the brand name Ta3 (comparative blank 3), and the chemical impurity content thereof is shown in Table 2.

[0117] The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C and kept warm. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5MPa. The billet is kept warm for 15 hours. The temperature is then lowered and the hydrogen pressure is maintained at 1.3-1.5MPa to allow the tantalum ingot to fully absorb hydrogen and react with hydrogen. After the temperature drops to 100°C, the hydrogen flow is stopped. When the temperature is lower than 40°C, the billet is taken out of the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0118] Repeat step 3 of Example 1) to prepare tantalum hydride powder with a diameter of 1 μm ≤ DV50 ≤ 15 μm and a hydrogen content of 0.494%.

[0119] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0120] Repeat step 5) of Example 1 to obtain comparative sample 3. The chemical impurity content thereof is shown in Table 3.

[0121] Comparative sample 3 was pressed into a shape with a density of 6.5 g / cm 3 The core powder weighs 1g and is tested according to the standard. -3 The sintered block was sintered in a vacuum furnace at 1.50 Pa for 30 minutes according to the sintering conditions in Table 4. The block was then energized in a 0.01% by volume phosphoric acid solution at the energizing voltages specified in Table 4 to produce a capacitor anode. The electrical properties of the capacitor are listed in Table 4.

[0122] Table 2: Main chemical impurity content and grain size of tantalum metal billets

[0123] Table 3: Main impurity content and other properties of high-voltage tantalum powder

[0124] Table 4: Specific capacitance and leakage current of electrolytic capacitor anodes obtained from different high-voltage tantalum powders sintered under different conditions

[0125] From the data of the above embodiments and comparative examples, it can be seen that when the impurity C content of the tantalum metal billet is controlled to be ≤30ppm, the total content of metal impurities Fe, Ni and Cr is less than or equal to 30ppm, and the grain size is 1μm-900μm, the preparation method of the present application is used to obtain high-voltage tantalum powder. The electrolytic capacitor anode made of the high-voltage tantalum powder has a specific capacitance of 7000μF·V / g-25000μF·V / g and a breakdown voltage of 200V-285V when the energizing voltage is 150V-270V, achieving a high specific capacitance and a low leakage current. Moreover, by comparing the CV values ​​of the high-voltage tantalum powder, it can be seen that the CV value gradually decreases with the increase of the grain size; in particular, when comparing high-voltage tantalum powder A, high-voltage tantalum powder F and high-voltage tantalum powder G, it can be found that the CV value gradually decreases and the leakage current gradually decreases with the increase of the grain size.

[0126] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for preparing high-voltage tantalum powder, characterized in that: The preparation method comprises: Selecting a tantalum metal blank, wherein the impurity C content in the tantalum metal blank is ≤30ppm, the total content of metal impurities Fe, Ni and Cr is ≤30ppm, and the grain size is 1μm-900μm; Performing a hydrogenation treatment on the tantalum metal blank to obtain a hydrogenated material; Powdering the hydrogenated material to obtain hydrogen-containing tantalum powder; The hydrogen-containing tantalum powder is pickled and impurities are removed to obtain hydrogenated impurity-removed tantalum powder; The hydrogenated impurity-removed tantalum powder is subsequently treated to obtain high-pressure tantalum powder, and the subsequent treatment includes one or more combinations of dehydrogenation treatment, high-temperature and high-vacuum heat treatment, and reduction and oxygen reduction treatment.

2. The preparation method according to claim 1, characterized in that: The grain size of the tantalum metal blank is 1 μm-450 μm, preferably 1 μm-350 μm, and more preferably 10 μm-150 μm.

3. The preparation method according to claim 1 or 2, characterized in that: The mass content of hydrogen in the hydrogenation material is greater than or equal to 0.3%, preferably greater than or equal to 0.5%.

4. The preparation method according to any one of claims 1 to 3, characterized in that The hydrogen-containing tantalum powder has a thickness of 1 μm≤D V 50≤15μm, preferably 1μm≤D V 50≤10μm.

5. The preparation method according to claim 4, characterized in that: The pulverization treatment includes one or more of ball milling, impact treatment and extrusion treatment; the ball milling treatment satisfies any one or more of the following conditions: 1) Using zirconium oxide balls as ball milling media, preferably the diameter of the zirconium oxide balls is 1 mm-5 mm, more preferably 2 mm-4 mm; 2) using wet stirring ball milling, preferably using water or an organic solvent as a dispersion medium in the wet stirring ball milling; 3) Using a surfactant as a grinding aid; preferably, the grinding aid is butanone and / or isopropanol; preferably, the amount of the grinding aid added is 0.5%-5% by weight of the hydrogenated material, preferably 1%-4%, more preferably 1.8%-3.6%.

6. The preparation method according to any one of claims 1 to 5, characterized in that The acid used for pickling and impurity removal includes a mixed acid formed by one or more of sulfuric acid, hydrochloric acid, and nitric acid, hydrogen peroxide, and hydrofluoric acid.

7. A high-voltage tantalum powder, characterized in that: The total content of metal impurities Fe, Ni and Cr in the high-voltage tantalum powder is ≤30ppm, and the C content is ≤30ppm; and the high-voltage tantalum powder satisfies at least one of the following conditions: 1), bulk density is 1.8g / cm 3 -4.0g / cm 3 , preferably 1.95 g / cm 3 -3.55g / cm 3 , more preferably 2.2 g / cm 3 -3.5g / cm 3 ; 2), BET specific surface area is 0.1m 2 / g-1.0m 2 / g, preferably 0.2m 2 / g-0.7m 2 / g, more preferably 0.2m 2 / g-0.6m 2 / g; 3) Fluidity ≤ 50 s / 50 g, preferably fluidity ≤ 40 s / 50 g, more preferably fluidity ≤ 35 s / 50 g, and further preferably fluidity < 20 s / 50 g.

8. The high-voltage tantalum powder according to claim 7, characterized in that: The electrolytic capacitor anode made of the high-voltage tantalum powder has a specific capacitance of 6500μF·V / g-23000μF·V / g and a breakdown voltage of 200V-300V when the energizing voltage is 150V-300V, and preferably has a breakdown voltage of 200V-285V.

9. A high-voltage tantalum powder, characterized in that: The high-voltage tantalum powder is prepared by the preparation method described in any one of claims 1 to 6.

10. A capacitor anode made of tantalum powder, characterized in that: The tantalum powder is the high-pressure tantalum powder according to any one of claims 7 to 9.

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