High pressure tantalum powder, method of making same, and capacitor anode

Abstract

The application provides high-pressure tantalum powder, a preparation method thereof, and a capacitor anode. The preparation method of the high-pressure tantalum powder comprises the following steps: 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 mu m; performing hydrogenation treatment on the tantalum metal blank to obtain a hydrogenated material; performing powdering treatment on the hydrogenated material to obtain hydrogen-containing tantalum powder; performing acid pickling and impurity removal on the hydrogen-containing tantalum powder to obtain hydrogenated and impurity-removed tantalum powder; and performing subsequent treatment on the hydrogenated and impurity-removed tantalum powder to obtain high-pressure tantalum powder, wherein the subsequent treatment comprises one or a combination of multiple kinds of treatment, such as dehydrogenation treatment, high-temperature and high-vacuum heat treatment, and reduction and oxygen reduction treatment.

Description

Technical Field

[0001] This application relates to the field of rare metal technology, specifically to a high-voltage tantalum powder, its preparation method, and a capacitor anode. Background Technology

[0002] High-voltage tantalum powder (including high-reliability tantalum powder with operating voltages above 35V) is a key raw material for solid tantalum capacitors and liquid tantalum capacitors with operating voltages of 63V or higher. Currently, both domestically and internationally, the production of this type of high-voltage tantalum powder employs refining and purification methods, specifically electron bombardment-hydrogenation powdering processes, to improve the purity and quality of the tantalum powder. To further improve the specific capacitance and breakdown voltage of electron bombardment high-voltage powder, researchers have attempted to study the influence of particle size and shape on the quality of high-voltage tantalum powder by examining its physical properties. Studies have shown that the particle shape of high-voltage tantalum powder should not be complex, as complex particle shapes lead to irregular anode surfaces, making it difficult for the oxide film to grow uniformly. High-stress points at the tips of the particles concentrate the electric field, resulting in increased leakage current and losses, and a lower breakdown voltage. Therefore, researchers are attempting to develop a tantalum powder with a simple particle shape that can better balance high voltage resistance and high specific capacitance. Therefore, in recent years, some studies have adopted the following methods: (1) controlling the oxygen content to be below 550 PPM, using ball mills, rod mills, and double roller mills to extrude tantalum powder with a diameter-to-thickness ratio of 2-60, and at least 70% (by weight) of the powder being composed of flat, flaky particles of 3-44 micrometers; (2) repeatedly performing agglomeration-grinding-grading treatment, the effect of which is consistent with the agglomeration of high specific volume tantalum powder. It is hoped that tantalum powder with a particle shape between spherical powder and sodium-based raw powder and a small sintering shrinkage rate can be obtained. Facts have shown that this method of controlling the particle size and shape of electron bombardment powder and performing agglomeration treatment is effective in improving specific volume and breakdown voltage, but the effect is limited.

[0003] US Patent 5580367 discloses an improved flake tantalum powder and a method for producing it. The method involves using tantalum ingot hydrogenation powder or sodium reducing powder as raw materials, producing large flakes using conventional methods, then subjecting these flakes to hydrogenation treatment followed by mechanical crushing to reduce their size. This results in flake tantalum powder with a specific diameter-to-thickness ratio. This characteristic gives the agglomerated powder good processing properties, such as flowability, briquette strength, and formability, and allows for the production of capacitors with low leakage current and high breakdown voltage. However, this method is clearly complex and has a long process route. Furthermore, the repeated mechanical crushing inevitably increases metal impurities, and the extensive acid washing results in tantalum powder loss, significantly increasing production costs.

[0004] US Patent 4017302 discloses a method for preparing high-pressure tantalum metal powder. The specific process includes tantalum ingot hydrogenation, grinding, grading and sieving, dehydrogenation preheating treatment, crushing and passing through an 80-mesh sieve, agglomeration, crushing, passing through a 35-mesh and 250-mesh sieve, then mixing -250-mesh and -35 / +25-mesh powders and re-agglomerating, testing, and product. The tantalum powder prepared by this method is particularly suitable for high-pressure, low-capacity tantalum powder (63V).

[0005] US Patent 4141719 discloses a method for preparing high-pressure tantalum metal powder. The method involves hydrogenating tantalum ingots, grinding, classifying, degassing (1200°C), sieving (to a 35-mesh screen), and mixing. The resulting tantalum powder has a high bulk density, low oxygen content, high bulk strength, and low leakage current in the sintered anode. The tantalum powder prepared by this method is particularly suitable for high-pressure, low-capacity tantalum powder (63V).

[0006] US Patent 4555268 relates to a flake-shaped tantalum powder with improved processing properties. The powder contains 20-40% flake-shaped tantalum powder and 70% granular tantalum powder, and is heat-treated at 1250°C to 1550°C for 5-120 minutes before mixing. The mixed tantalum powder undergoes secondary agglomeration, improving processing properties. The tantalum powder prepared by this method is suitable for medium operating voltages (20V-35V).

[0007] US Patent 4740238 relates to a tantalum powder containing flake-like particles. The specific process for producing this tantalum powder includes: tantalum powder degassing, flake preparation (ball milling, wet milling), acid washing, sieving, phosphorus doping, primary heat treatment, grinding and sieving, phosphorus doping, secondary heat treatment, grinding and sieving, and Mg reduction. The tantalum powder prepared by this method is suitable for medium operating voltages (20V–35V).

[0008] Chinese patent application CN1004614A relates to a method for producing spherical tantalum powder and the product thereof. The method involves feeding tantalum powder into a plasma reaction zone using a carrier gas, spraying it into a vacuum chamber for cooling to form spherical tantalum powder, acid washing, and heat treatment at 1000–1250°C. This tantalum powder has a withstand voltage of 300–450V. However, the tantalum powder prepared by this method has a specific volume of only 500–800 microfarads / gram and extremely poor formability. Summary of the Invention

[0009] This application provides a high-voltage tantalum powder, its preparation method, and a capacitor anode to further improve the specific capacitance and breakdown voltage of capacitors made of tantalum powder.

[0010] The first aspect of this application provides a method for preparing high-pressure tantalum powder, the method comprising: selecting a tantalum metal billet, wherein the impurity C content in the tantalum metal billet is ≤30ppm, the total content of metallic impurities Fe, Ni and Cr is ≤30ppm, and the grain size is 1μm-900μm; subjecting the tantalum metal billet to hydrogenation treatment to obtain hydrogenated material; subjecting the hydrogenated material to pulverization treatment to obtain hydrogen-containing tantalum powder; subjecting the hydrogen-containing tantalum powder to acid washing to remove impurities to obtain hydrogenated and impurity-removed tantalum powder; subjecting the hydrogenated and impurity-removed tantalum powder to subsequent processing to obtain high-pressure tantalum powder, wherein the subsequent processing includes one or more combinations of dehydrogenation treatment, high-temperature and high-vacuum heat treatment, and reduction and deoxidation treatment.

[0011] In any embodiment of the first aspect, the grain size of the tantalum metal billet is 1μm-450μm, preferably 1μm-350μm, and more preferably 10μm-150μm.

[0012] In any embodiment of the first aspect, the mass content of hydrogen in the hydrogenated material is greater than or equal to 0.3%, preferably greater than or equal to 0.5%.

[0013] In any embodiment of the first aspect, 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.

[0014] 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 one or more of the following conditions: 1) using zirconia balls as the milling medium, preferably with a diameter of 1 mm to 5 mm, more preferably 2 mm to 4 mm; 2) using wet stirred ball milling, preferably using water or an organic solvent as the dispersion medium; 3) using a surfactant as a grinding aid; preferably, the grinding aid is butanone and / or isopropanol; preferably, the amount of grinding aid added is 0.5% to 5% of the weight of the hydrogenated material, more preferably 1% to 4%, more preferably 1.8% to 3.6%.

[0015] In any embodiment of the first aspect, the acid used for pickling and impurity removal includes one or more of sulfuric acid, hydrochloric acid, nitric acid, hydrogen peroxide, and hydrofluoric acid.

[0016] The second aspect of this application provides a high-pressure tantalum powder, wherein the total content of metallic 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 loose packing density is 1.8g / cm³. 3 -4.0g / cm 3 The preferred value is 1.95 g / cm³. 3 -3.55g / cm 3Further preferred value is 2.2 g / cm³. 3 -3.5g / cm 3 ;2) The specific surface area of ​​BET is 0.1m². 2 / g-1.0m 2 / g, preferably 0.2m 2 / g-0.7m 2 / g, further preferably 0.2m 2 / g-0.6m 2 / g; 3), fluidity ≤50s / 50g, preferably fluidity ≤40s / 50g, more preferably fluidity ≤35s / 50g, and even more preferably fluidity <20s / 50g.

[0017] In any embodiment of the second aspect, the anode of the electrolytic capacitor made of high-voltage tantalum powder has a specific capacitance of 6500μF·V / g-23000μF·V / g and a breakdown voltage of 200V-300V, preferably 200V-285V, when the applied voltage is 150V-300V.

[0018] The third aspect of this application provides a high-pressure tantalum powder, which is prepared using any of the preparation methods of the first aspect.

[0019] The fourth aspect of this application provides a capacitor anode made of tantalum powder, which is the high-voltage tantalum powder provided in any embodiment of the second or third aspect described above. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0021] Figure 1 A schematic flowchart of a method for preparing high-pressure tantalum powder according to one embodiment of this application is shown.

[0022] Figure 2 A metallographic photograph of the tantalum metal billet of Embodiment 1 of this application is shown.

[0023] Figure 3 A metallographic photograph of the tantalum metal billet of Embodiment 2 of this application is shown.

[0024] Figure 4 A metallographic photograph of the tantalum metal billet of Embodiment 3 of this application is shown.

[0025] Figure 5A metallographic photograph of the tantalum metal billet of Embodiment 4 of this application is shown.

[0026] Figure 6 A metallographic photograph of the tantalum metal billet of Embodiment 5 of this application is shown.

[0027] Figure 7 A metallographic photograph of the tantalum metal billet of Embodiment 6 of this application is shown.

[0028] Figure 8 A metallographic photograph of the tantalum metal billet of Embodiment 7 of this application is shown.

[0029] Figure 9 A metallographic photograph of the tantalum metal billet of Comparative Example 1 of this application is shown. Detailed Implementation

[0030] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments is used to illustrate the principles of this application, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0031] As analyzed in the background section of this application, there are various methods for preparing tantalum powder for high-voltage applications. However, most of these methods use electron-bombarded tantalum ingots as raw materials to improve the purity of the tantalum powder. To further improve the specific capacitance and breakdown voltage of the electron-bombarded high-voltage powder, the particle size and shape of the tantalum powder are controlled through tantalum ingot hydrogenation powder preparation. It has been shown that this method of controlling the particle size and shape of electron-bombarded powder and performing agglomeration treatment is effective in improving specific capacitance and breakdown voltage, but the effect is limited.

[0032] To further improve the specific capacitance and breakdown voltage of capacitors made of tantalum powder, the first embodiment of this application provides a method for preparing high-voltage tantalum powder, such as... Figure 1 As shown, the preparation method includes: selecting a tantalum metal billet, wherein the impurity C content in the tantalum metal billet is ≤30ppm (preferably ≤20ppm), the total content of metallic 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; acid washing the hydrogen-containing tantalum powder to remove impurities, to obtain hydrogenated impurity-removed tantalum powder; and further processing the hydrogenated impurity-removed tantalum powder to obtain high-pressure tantalum powder, wherein the further processing includes one or more combinations of dehydrogenation treatment, high-temperature high-vacuum heat treatment, and reduction deoxidation treatment.

[0033] The excessively large grain size of tantalum metal billets results in a small BET specific surface area for the hydrogen-containing tantalum powder obtained after pulverization, leading to a low specific capacitance. High purity of the tantalum metal billet, with high levels of impurities such as carbon, iron, nickel, and chromium, increases leakage current and reduces reliability. This application uses tantalum metal billets with impurity C content ≤30ppm, total impurity Fe, Ni, and Cr content ≤30ppm, and a grain size of 1μm-900μm as raw materials for hydrogenation, pulverization, and post-treatment. This effectively improves the breakdown voltage and CV value (specific capacitance) of capacitors made from tantalum powder and reduces leakage current. The aforementioned hydrogenation, impurity removal, and post-treatment improve the flowability and electrical properties of the tantalum metal billet. Therefore, the high-voltage tantalum powder prepared in this way is easier to manufacture into capacitors, and the breakdown voltage and CV value of the capacitors are significantly improved, while leakage current is effectively controlled. The preparation method of this application, after the raw materials meet the above conditions, can be carried out by referring to conventional processes for hydrogenation, impurity removal and post-treatment. Therefore, the process is simple and highly controllable, with low safety risks and wide applicability.

[0034] In some implementations, after high-pressure tantalum powder is sieved, high-pressure tantalum powder passing through 50 mesh is selected as the raw material for subsequent electrode fabrication.

[0035] The grain size of tantalum metal billets was determined by the comparative method in GB / T6394 "Method for Determination of Average Grain Size of Metals".

[0036] The tantalum metal billet used in this application can be tantalum ingot, tantalum rod, tantalum wire, and / or other tantalum materials. This tantalum metal billet can be prepared using known methods or derived from known products. There are many methods for preparing this tantalum metal billet. For example, during the processing of the tantalum metal billet, any chemical substance that is beneficial to grain refinement can be added in the required proportion as a grain refiner, such as one or more of phosphorus, nitrogen, boron, silicon, yttrium, etc.; the grain size can also be controlled by adjusting the tantalum material processing technology, such as sintering temperature and / or holding time; the grain refinement can also be achieved by reprocessing the tantalum material, such as heat treatment and machining processes. Alternatively, a combination of the above processing methods can be used to achieve the purpose of grain refinement.

[0037] Experiments have shown that smaller grain size of tantalum metal billet is more conducive to improving the CV value of capacitor, but the improvement effect on leakage current is affected; increasing the grain size of tantalum metal billet is beneficial to improving the leakage current of capacitor, but the improvement effect on CV value is affected. In order to simultaneously reduce the leakage current of tantalum powder and improve its CV value, in some embodiments of this application, the grain size of tantalum metal billet is 1μm-450μm, preferably 1μm-350μm, and more preferably 10μm-150μm.

[0038] Hydrogenation can be implemented using conventional processes. Hydrogenation utilizes the characteristic that the maximum hydrogen absorption capacity of tantalum metal and tantalum alloys varies at different temperatures. 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 as the temperature decreases, the higher the temperature at which hydrogen flow is stopped, the lower the hydrogen content; conversely, 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 to maintain the temperature. The holding time varies depending on the size of the tantalum metal and tantalum alloy placed in the hydrogenation container (larger pieces require longer times). Then, hydrogen flow is stopped to allow the tantalum metal and tantalum alloy to fully and uniformly absorb hydrogen.

[0039] In some embodiments of this application, the hydrogen content in the hydride is greater than or equal to 0.3%, preferably greater than or equal to 0.5%. This is to avoid insufficient hydrogen embrittlement of the hydride, which would make fine crushing difficult during the pulverization process. The aforementioned hydrogen content ensures that the tantalum hydride ingot maintains good hydrogen embrittlement, allowing the tantalum hydride ingot 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, but in practice, the hydrogen content will not exceed this saturation level.

[0040] In some embodiments, the hydrogen supply is stopped at any temperature ≤200℃ during hydrogenation, which can be any temperature between 150℃ and 200℃; or any temperature between 100℃ and 200℃; or any temperature between 50℃ and 100℃, preferably any temperature between 50℃ and 150℃. This effectively controls the hydrogen content in the hydrogenated material, preventing it from being too low.

[0041] The aforementioned pulverization process refers to mechanically crushing and pulverizing hydrogenated materials (such as tantalum blocks) that exhibit good hydrogen embrittlement properties obtained through hydrogenation treatment. The pulverization method is not limited and can be performed using air jet milling equipment or ball milling equipment. To avoid excessively small particle size of the hydrogen-containing tantalum powder, which would result in excessively high surface energy and easy oxidation, in some embodiments, the particle size of the aforementioned hydrogen-containing tantalum powder is 1μm ≤ D. V 50≤15μm, preferably 1μm≤D of hydrogen-containing tantalum powder V 50≤10μm.

[0042] In some embodiments, the pulverization process includes one or more of ball milling, impact treatment, and extrusion treatment; the ball milling process satisfies any one or more of the following conditions: 1) using zirconia balls as the milling medium, preferably with a diameter of 1 mm to 5 mm, more preferably 2 mm to 4 mm; 2) using wet stirred ball milling, preferably using water or an organic solvent as the dispersion medium; 3) using a surfactant as a grinding aid; preferably, the grinding aid is butanone and / or isopropanol; preferably, the amount of grinding aid added is 0.5% to 5% of the weight of the hydrogenated material, more preferably 1% to 4%, and more preferably 1.8% to 3.6%.

[0043] For example, the aforementioned pulverization process first uses mechanical methods to crush the material to a size that can pass through a 100-mesh sieve, followed by wet-mixed ball milling, for example using zirconia balls as the milling medium and water or an organic solvent as the dispersion medium, continuously ball milling until D is achieved. V 50≤15μm, D is preferred V 50≤10μm. Due to the high hardness of tantalum hydride powder, grinding with ordinary stainless steel balls will cause severe wear to the stainless steel balls, allowing a large amount of metallic impurities to mix into the material, resulting in a high impurity content. To solve this problem and improve the purity of the final product, it is preferable to use zirconia balls with higher hardness instead of stainless steel balls for grinding.

[0044] To achieve a finer and more uniform particle size distribution, smaller grinding media are preferred, such as those with a diameter of 1mm-5mm, preferably 2mm-4mm. This is because smaller diameter grinding media allow for a larger filling volume in the grinding chamber, increasing the impact and friction of the media, while also increasing the contact area. This increased grinding area also contributes to finer pulverization. Surprisingly, it was found that using grinding media with a diameter of 1mm-5mm, preferably 2mm-4mm, generally achieves better grinding results.

[0045] During ball milling, it is difficult to avoid generating ultrafine powders with a particle size of less than 0.1 μm. These powders are often prone to oxidation or even spontaneous combustion. Furthermore, the finer the powder particles, the larger their surface area and the greater their surface free energy, leading to re-agglomeration of fine particles, which is detrimental to micro-grinding. For ease of grinding, it is preferable to add a surfactant as a grinding aid to the dispersion medium. Surfactants can adhere to the surface of tantalum powder particles, forming a protective layer, which passivates the surface of the material particles during micro-grinding and ultra-fine ball milling. This effectively inhibits the oxidation of ultrafine powders during ball milling and subsequent processing, improving product quality. Preferred grinding aids are butanone and / or isopropanol. More preferably, the amount of grinding aid added is 0.5%-5% of the weight of the hydrogenated material, more preferably 1%-4%, and even more preferably 1.8%-3.6%.

[0046] After pulverization, the hydrogen-containing tantalum powder is acid-washed to remove impurities. Acid washing can reduce impurities in the tantalum powder, such as oxygen, carbon, iron, nickel, chromium, etc. The implementation of acid washing can refer to the conventional acid washing process for tantalum powder. In some embodiments, the acids used for acid washing include one or more of sulfuric acid, hydrochloric acid, nitric acid, mixed acids, hydrogen peroxide, and hydrofluoric acid.

[0047] When the hydrogenated and acid-washed tantalum powder obtained after the above-mentioned hydrogenation treatment and impurity removal is directly used to manufacture capacitor anode blocks, its fine particle size and poor flowability cause difficulties in filling the corners of the mold cavity during the anode block forming process, resulting in chipped edges and corners of the formed block. It also easily forms an arching effect, leading to poor density and reduced strength of the blank. Furthermore, the fine particle size causes uneven pore structure distribution and low porosity in the formed block, hindering electrolyte penetration during the anode block energizing process. Uneven current distribution leads to uneven oxide film thickness growth, resulting in partial electric field concentration, increased current density, and increased leakage current and losses. Regarding capacitance, the small pores between fine particles are detrimental to capacitance extraction during subsequent capacitor manufacturing. Additionally, the high content of impurities such as oxygen, hydrogen, and sulfur in this hydrogenated tantalum powder affects the electrical performance of the capacitor, particularly increasing leakage current. These impurities become nucleation sites for the crystallization of the anodic oxide film during the anodizing process, causing defects in the oxide film and ultimately increasing leakage current and reducing flashover voltage. By combining any one or more of the above-mentioned processes, such as pelletizing, high-temperature and high-vacuum heat treatment, and magnesium reduction and deoxygenation treatment, the problems caused by poor powder flowability, the presence of fine powder particles, and high content of impurities such as oxygen, hydrogen, and fluorine can be effectively overcome.

[0048] Dehydrogenation treatment, high-temperature high-vacuum heat treatment, and reduction deoxygenation treatment are all commonly used processes in tantalum powder processing. Therefore, the above-mentioned processing techniques in this application can all refer to conventional processes. In some embodiments, the above-mentioned treatments can be performed sequentially. In some embodiments, the dehydrogenation treatment involves placing the hydrogen-containing tantalum powder in a sealed furnace, purging it with argon, heating it to 700-900°C, holding it at that temperature for 60-200 minutes, and then cooling it before removing it from the furnace and sieving it.

[0049] 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 of tantalum powder during high-temperature sintering can be added as a sintering inhibitor in the required proportion, such as one or more of phosphorus, nitrogen, and boron. The high-temperature, high-vacuum heat treatment temperature is generally controlled between 1000℃ and 1600℃, held for 15-200 minutes. This high-temperature, high-vacuum heat treatment causes the tantalum powder to pelletize and granulate. After sintering, cooling and passivation treatment are performed to obtain agglomerated tantalum blocks, which are then crushed. Magnesium reduction and oxygen reduction treatment can be a conventional oxygen reduction process. For example, this can be done as follows: Generally, a small amount of reducing agent with a greater affinity for oxygen than tantalum for oxygen, such as alkaline earth metals, rare earth metals and their hydrides, is mixed into the material to be treated. The most common method is to mix 0.2%-6.0% by weight of magnesium powder into the material to be treated. Then, the material is heated under vacuum or inert gas protection (preferably inert gas) and held at 800℃-900℃ for 1-3 hours. Then, a vacuum is drawn and the material is held under vacuum for another 2-6 hours. Finally, the material is cooled, passivated, and magnesium is removed to obtain high-pressure tantalum powder.

[0050] In a second embodiment of this application, a high-pressure tantalum powder is provided, wherein the total content of metallic impurities Fe, Ni, and Cr is ≤30ppm (preferably ≤20ppm), and the C content is ≤30ppm (preferably ≤20ppm); and the high-pressure tantalum powder satisfies at least one of the following conditions: loose packing density is 1.8 g / cm³. 3 -4.0g / cm 3 The preferred value is 1.95 g / cm³. 3 -3.55g / cm 3 Further preferred value is 2.2 g / cm³. 3 -3.5g / cm 3 ;2) The specific surface area of ​​BET is 0.1m². 2 / g-1.0m 2 / g, preferably 0.2m 2 / g-0.7m 2 / g, further preferably 0.2m 2 / g-0.6m 2 / g; 3), flowability ≤ 50s / 50g, preferably flowability ≤ 40s / 50g, more preferably flowability ≤ 35s / 50g, and even more preferably flowability < 20s / 50g. High-voltage tantalum powder that meets the above conditions has a high CV value and breakdown voltage, and has a low leakage current, meeting the requirements for use in high-reliability, high-specific-capacitance electrolytic capacitors.

[0051] In some embodiments, the anode of the electrolytic capacitor made of the aforementioned high-voltage tantalum powder has a specific capacitance of 6500μF·V / g-23000μF·V / g, preferably 7000μF·V / g-20000μF·V / g, and a breakdown voltage of 200V-300V, preferably 200V-285V, when the applied voltage is between 150V and 270V.

[0052] In a third embodiment of this application, a high-voltage tantalum powder is provided, which is prepared by the preparation method of any of the above embodiments of this application. The high-voltage tantalum powder prepared in this application has a high CV value and breakdown voltage, and a low leakage current, meeting the requirements for use in high-reliability, high-specific-capacitance electrolytic capacitors.

[0053] In the third embodiment of this application, a capacitor anode is provided, which is made of tantalum powder, and the tantalum powder is any of the high-voltage tantalum powders provided in the second or third embodiment of this application.

[0054] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples, but the scope of the present invention is not limited to these embodiments.

[0055] The analytical equipment and models of the various parameters involved in this application are shown in Table 1.

[0056] Table 1

[0057]

[0058] In addition, the determination of loose bulk density (SBD) is based on GB / T1479.1 funnel method, Part 1: funnel method; the determination of flowability is based on GB / T1482 Hall flowmeter; the determination of specific surface area of ​​metal powder is based on GB / T13390 nitrogen adsorption method; and the determination of grain size is based on the comparative method in GB / T6394 method for determining the average grain size of metals.

[0059] Example 1

[0060] Step 1): Sodium-reduced tantalum powder was selected as the raw material, with ∑Fe+Ni+Cr=10ppm and C content of 14ppm. It was placed into an elastic mold, sealed, and then placed in the high-pressure cylinder of an isostatic press. A tantalum rod was formed under pressure of 180MPa. The formed tantalum rod was sintered in a graphite furnace at 2000℃ for 240min to obtain tantalum metal billet A. The chemical impurity content is shown in Table 2, and the metallographic structure is shown in [image missing]. Figure 2 .

[0061] Step 2): The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is controlled at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is lowered and the hydrogen pressure is controlled 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 supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0062] Step 3) The hydrogenated material is then coarsely crushed using a jaw crusher to obtain tantalum powder that can completely pass through an 80-mesh sieve. The tantalum powder is then ball-milled for 1.5 hours with anhydrous ethanol as the milling medium and methyl ethyl ketone (MEK) and isopropanol as grinding aids (MEK is added at 1.0% of the weight of the hydrogenated material, and isopropanol is added at 3.0% of the weight of the hydrogenated material) using 3mm diameter zirconia balls as the milling medium, to obtain hydrogen-containing tantalum powder with Dv50 < 15μm. After sieving, hydrogen-containing tantalum powder with 1μm ≤ DV50 ≤ 15μm and a hydrogen content of 0.497% is obtained.

[0063] Step 4): The sieved hydrogen-containing 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 and impurity-removed tantalum powder.

[0064] Step 5): The hydrogenated and impurity-removed tantalum powder is placed in a sealed furnace, heated to 900°C with argon, and held for 180 minutes for dehydrogenation treatment. After cooling, it is removed from the furnace and sieved. The dehydrogenated tantalum powder is then subjected to high-temperature, high-vacuum heat treatment and deoxidation treatment, specifically implemented by... -3 The tantalum powder was heated to 1300℃ under vacuum and held for 60 minutes, then crushed to below 50 mesh. 2% magnesium shavings were added to the tantalum powder, and the mixture was heated to 900℃ in an argon atmosphere in a sealed furnace and held for 2 hours. Then, a vacuum was applied, and the mixture was held under vacuum for another 3 hours before cooling and passivation. The powder was then removed from the furnace and finally acid-washed with 20% HNO3 to remove magnesium oxide and excess magnesium. After drying and sieving, the powder was ensured to pass completely through a 50-mesh sieve to obtain high-pressure tantalum powder A. The chemical impurity content is shown in Table 3.

[0065] High-pressure tantalum powder A was pressed into shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0066] Example 2

[0067] Step 1) Using the same sodium-reduced tantalum powder as in Example 1 as the raw material, its ∑Fe+Ni+Cr=10ppm and C content is 14ppm. It is placed into an elastic mold, sealed, and then placed in the high-pressure cylinder of an isostatic press. A pressure of 180MPa is applied to form the tantalum rod. The formed tantalum rod is sintered in a graphite furnace at a temperature of 2200℃ for 240min to obtain tantalum metal billet B. The chemical impurity content is shown in Table 2, and the metallographic structure photograph is shown in [Table 2]. Figure 3 .

[0068] Step 2): The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is controlled at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is lowered and the hydrogen pressure is controlled 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 supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0069] Repeat step 3) of Example 1 to obtain hydrogen-containing tantalum powder with a particle size of 1μm≤DV50≤15μm and a hydrogen content of 0.517%.

[0070] Repeat step 4) of Example 1 to obtain hydrogenated tantalum powder. Repeat step 5) of Example 1 to obtain high-pressure tantalum powder B. The chemical impurity content is shown in Table 3.

[0071] High-pressure tantalum powder B was pressed into shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0072] Example 3

[0073] Step 1) Using the same sodium-reduced tantalum powder as in Example 1 as the raw material, its ∑Fe+Ni+Cr=10ppm and C content is 14ppm. It is placed into an elastic mold, sealed, and then placed in the high-pressure cylinder of an isostatic press. A pressure of 180MPa is applied to form the tantalum rod. The formed tantalum rod is sintered in a vertical melting furnace at a sintering temperature of 2400℃ for 240min to obtain tantalum metal billet C. The chemical impurity content is shown in Table 2, and the metallographic structure photograph is shown in [Table 2]. Figure 4 .

[0074] Step 2): The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is controlled at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is lowered and the hydrogen pressure is controlled 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 supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0075] Repeat step 3 of Example 1 to obtain hydrogen-containing tantalum powder with a particle size of 1μm≤DV50≤15μm and a hydrogen content of 0.612%.

[0076] Repeat step 4 of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0077] Repeat step 5) of Example 1 to obtain high-pressure tantalum powder C. Its chemical impurity content is shown in Table 3.

[0078] Tantalum powder C under high pressure was pressed into shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0079] Example 4

[0080] Step 1) The tantalum metal billet 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 photographs are shown in [Table 2]. Figure 5 .

[0081] Step 2): The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is controlled at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is lowered and the hydrogen pressure is controlled 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 supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0082] Repeat step 3) of Example 1 to obtain hydrogen-containing tantalum powder with a hydrogen content of 0.412% and a diameter of 1μm≤DV50≤15μm.

[0083] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0084] Repeat step 5) of Example 1 to obtain high-pressure tantalum powder D. Its chemical impurity content is shown in Table 3.

[0085] High-pressure tantalum powder D was pressed into shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0086] Example 5

[0087] Step 1), the tantalum metal billet is a commercially available high-purity tantalum ingot with the grade Ta1. Its chemical impurity content and grain size are shown in Table 2, and the metallographic structure photographs are shown below. Figure 6 .

[0088] Step 2): The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C. High-purity hydrogen is introduced and the hydrogen pressure is controlled at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is lowered and the hydrogen pressure is controlled 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 supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0089] Repeat step 3 of Example 1 to obtain hydrogen-containing tantalum powder with a diameter of 1μm ≤ DV50 ≤ 15μm and a hydrogen content of 0.494%.

[0090] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0091] Repeat step 5) of Example 1 to obtain high-pressure tantalum powder E. Its chemical impurity content is shown in Table 3.

[0092] High-pressure tantalum powder E was pressed into shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0093] Example 6

[0094] Sodium-reduced tantalum powder, the same as in Example 1, was used as the raw material. Its ∑Fe+Ni+Cr=10ppm and C content was 14ppm. It was placed into an elastic mold, sealed, and then placed in the high-pressure cylinder of an isostatic press. It was pressed and shaped into a tantalum rod under a pressure of 210MPa. The shaped tantalum rod was sintered in a vertical melting furnace at a sintering temperature of 2800℃ and a holding time of 360min to obtain tantalum metal billet F. The chemical impurity content is shown in Table 2.

[0095] The subsequent operations are the same as in Example 1, and the obtained high-voltage tantalum powder F is used to make the capacitor anode in the manner described in Example 1.

[0096] Example 7

[0097] Sodium-reduced tantalum powder, the same as in Example 1, was used as the raw material. Its ∑Fe+Ni+Cr=10ppm and C content was 14ppm. It was placed into an elastic mold, sealed, and then placed in the high-pressure cylinder of an isostatic press. It was pressed and shaped into a tantalum rod under a pressure of 210MPa. The shaped tantalum rod was sintered in a vertical melting furnace at a sintering temperature of 2800℃ and a holding time of 480min to obtain tantalum metal billet G. The chemical impurity content is shown in Table 2.

[0098] The subsequent operations are the same as in Example 1, and the obtained high-voltage tantalum powder G is used to make the capacitor anode in the manner described in Example 1.

[0099] Comparative Example 1

[0100] Step 1), the tantalum metal billet (comparison billet 1) is a commercially available high-purity tantalum ingot with the grade Ta1. Its chemical impurity content is shown in Table 2, and the metallographic structure photograph is shown in […]. Figure 8 .

[0101] Repeat step 2) of Example 1 to obtain a hydrogenated material with good hydrogen embrittlement.

[0102] Repeat step 3 of Example 1) 1μm≤DV50≤15μm, tantalum hydride powder with hydrogen content of 0.394%.

[0103] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0104] Repeat step 5) of Example 1 to obtain Comparative Sample 1. Its chemical impurity content is shown in Table 3.

[0105] Comparative sample 1 was pressed into shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0106] Comparative Example 2

[0107] The tantalum metal billet is a commercially available high-purity tantalum ingot with the grade Ta1 (comparison billet 2), and its chemical impurity content is shown in Table 2.

[0108] The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C and held at that temperature. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is 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 it. After the temperature drops to 100°C, the hydrogen supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0109] The hydrogenated material is then crushed into tantalum hydrogenation powder with a Dv50 < 15 μm.

[0110] The crushed tantalum hydride powder was acid-washed with a mixture of HNO3 and HF (volume ratio of HNO3, HF and water is 4:1:20) to remove metal impurities, dried and sieved to obtain purified tantalum hydride powder.

[0111] The hydrogenated tantalum powder was placed in a sealed furnace, heated to 900°C with argon, and held for 180 minutes for dehydrogenation. After cooling, it was sieved. The dehydrogenated tantalum powder underwent high-temperature, high-vacuum heat treatment and deoxidation. Specifically, it was treated at 1300°C under vacuum for 60 minutes, then crushed to -50 mesh, and then deoxidized at 900°C. Finally, it was acid-washed with 20% HNO3 to remove magnesium oxide and excess magnesium, dried, and sieved until it completely passed through a 50-mesh sieve to obtain control sample 2. Its chemical impurity content is shown in Table 3.

[0112] Comparative sample 2 was pressed into a shape with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0113] Comparative Example 3

[0114] The tantalum metal billet is a commercially available tantalum rod with the grade Ta3 (comparison billet 3), and its chemical impurity content is shown in Table 2.

[0115] The tantalum metal billet is placed in the hydrogenation container of the hydrogenation furnace and heated to 800°C and held at that temperature. High-purity hydrogen is introduced and the hydrogen pressure is maintained at 1.3-1.5 MPa. The temperature is maintained for 15 hours. Then the temperature is 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 it. After the temperature drops to 100°C, the hydrogen supply is stopped. When the temperature is below 40°C, the billet is removed from the furnace to obtain a hydrogenated material with good hydrogen embrittlement.

[0116] Repeat step 3 of Example 1) 1μm≤DV50≤15μm, tantalum hydride powder with hydrogen content of 0.494%.

[0117] Repeat step 4) of Example 1 to obtain hydrogenated impurity-removed tantalum powder.

[0118] Repeat step 5) of Example 1 to obtain Comparative Sample 3. Its chemical impurity content is shown in Table 3.

[0119] Comparative sample 3 was pressed into a shape, with a pressing density of 6.5 g / cm³. 3 The core powder weighs 1g and was tested according to standards. (In 10...) -3 Sintering was performed for 30 minutes in a vacuum furnace at Pa according to the sintering conditions in Table 4. The sintered block was then energized in a 0.01% (v / v) phosphoric acid solution at the energizing voltage in Table 4 to obtain the capacitor anode. Its various electrical performance indicators are measured and listed in Table 4.

[0120] Table 2: Main Chemical Impurity Content and Grain Size of Tantalum Metal Billet

[0121] tantalum metal billet Grain size (μm) Fe / ppm Ni / ppm Cr / ppm C / ppm A 14 9 5 3 10 B 30 10 3 3 18 C 60 7 4 3 7 D 101 10 3 3 20 E 113 3 3 3 7 F 320 3 3 3 7 G 450 3 3 3 7 Comparison of billet 1 1000 3 3 3 10 Comparison of billet 2 2000 3 3 3 8 Comparison of billet 3 230 15 10 8 37

[0122] Table 3: Main Impurity Content and Other Properties of High-Pressure Tantalum Powder

[0123]

[0124] Table 4: Specific capacitance and leakage current of the anode of electrolytic capacitors obtained from different high-voltage tantalum powders under different sintering conditions.

[0125]

[0126]

[0127] As can be seen from the data in the above embodiments and comparative examples, when the impurity C content of the tantalum metal billet is controlled to be ≤30ppm, the total content of metallic impurities Fe, Ni, and Cr is less than or equal to 30ppm, and the grain size is 1μm-900μm, the high-voltage tantalum powder obtained by the preparation method of this application, and the anode of the electrolytic capacitor made from this high-voltage tantalum powder, have a specific capacitance of 7000μF·V / g-25000μF·V / g and a breakdown voltage of 200V-285V when the applied voltage is 150V-270V, achieving high specific capacitance and low leakage current. Moreover, comparing the CV values ​​of the high-voltage tantalum powder, it can be seen that the CV value gradually decreases with the increase of grain size; especially 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 with the increase of grain size, and the leakage current gradually decreases.

[0128] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing high-pressure tantalum powder, characterized in that, The preparation method includes: Select tantalum metal billet, wherein the impurity C content in the tantalum metal billet is ≤30ppm, the total content of metal impurities Fe, Ni and Cr is ≤30ppm, and the grain size is 1μm-450μm; The tantalum metal billet is subjected to hydrogenation treatment to obtain hydrogenated material; The hydrogenated material is pulverized to obtain hydrogen-containing tantalum powder; The hydrogen-containing tantalum powder is acid-washed to remove impurities, resulting in hydrogenated tantalum powder with impurities removed. The hydrogenated tantalum powder is further processed to obtain high-pressure tantalum powder. The further processing includes one or more of the following: dehydrogenation treatment, high-temperature high-vacuum heat treatment, and reduction deoxygenation treatment.

2. The preparation method according to claim 1, characterized in that, The grain size of the tantalum metal billet is 1μm-350μm.

3. The preparation method according to claim 2, characterized in that, The grain size of the tantalum metal billet is 10μm-150μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The hydrogen content in the hydrogenated material is greater than or equal to 0.3% by mass.

5. The preparation method according to claim 4, characterized in that, The hydrogen content in the hydrogenated material is greater than or equal to 0.5% by mass.

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

7. The preparation method according to claim 6, characterized in that, The hydrogen-containing tantalum powder has a 1μm ≤D V 50≤10μm.

8. The preparation method according to claim 4, characterized in that, The pulverization process includes one or more of ball milling, impact treatment, and extrusion treatment; the ball milling process satisfies any one or more of the following conditions: 1) Zirconia balls were used as the milling media; 2) Wet stirring ball milling is used for treatment; 3) Use surfactants as grinding aids.

9. The preparation method according to claim 8, characterized in that, The diameter of the zirconia spheres is 1mm-5mm.

10. The preparation method according to claim 9, characterized in that, The diameter of the zirconia spheres is 2mm-4mm.

11. The preparation method according to claim 8, characterized in that, Water or organic solvents are used as the dispersion medium in the wet stirred ball milling process.

12. The preparation method according to claim 8, characterized in that, The grinding aid is butanone and / or isopropanol.

13. The preparation method according to claim 8, characterized in that, The amount of grinding aid added is 0.5%-5% of the weight of the hydrogenated material.

14. The preparation method according to claim 13, characterized in that, The amount of grinding aid added is 1%-4% of the weight of the hydrogenated material.

15. The preparation method according to claim 14, characterized in that, The amount of grinding aid added is 1.8%-3.6% of the weight of the hydrogenated material.

16. The preparation method according to any one of claims 1 to 3, characterized in that, The acids used for pickling and impurity removal include one or more of sulfuric acid, hydrochloric acid, nitric acid, mixed acids, hydrogen peroxide, and hydrofluoric acid.

17. The high-pressure tantalum powder prepared by the method according to any one of claims 1 to 16, characterized in that, The total content of metallic impurities Fe, Ni and Cr in the high-pressure tantalum powder is ≤30ppm, and the C content is ≤30ppm; and the high-pressure tantalum powder meets at least one of the following conditions: 1) Loose packing density is 1.95 g / cm³ 3 -3.55g / cm 3 ; 2) The specific surface area of ​​BET is 0.2 m². 2 / g -0.7m 2 / g; 3) Flowability ≤ 40s / 50g.

18. The high-pressure tantalum powder according to claim 17, characterized in that, The high-pressure tantalum powder satisfies at least one of the following conditions: 1) Loose packing density is 2.2 g / cm³ 3 -3.5g / cm 3 ; 2) The specific surface area of ​​BET is 0.2 m². 2 / g -0.6m 2 / g; 3) Flowability ≤35s / 50g.

19. The high-pressure tantalum powder according to claim 18, characterized in that, The flowability of the high-pressure tantalum powder is <20s / 50g.

20. The high-pressure tantalum powder according to any one of claims 17 to 19, characterized in that, The anode of the electrolytic capacitor made of high-voltage tantalum powder has a specific capacitance of 6500 when the applied voltage is between 150V and 300V. -23000 The breakdown voltage is 200V-300V.

21. The high-pressure tantalum powder according to claim 20, characterized in that, The anode of the electrolytic capacitor made of high-voltage tantalum powder has a breakdown voltage of 200 V-285 V when the applied voltage is 150V-300V.

22. 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 17 to 21.

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