Low-oxygen ultrafine tantalum powder and its preparation method

Abstract

This invention provides a low-oxygen ultrafine tantalum powder and its preparation method, relating to the field of tantalum powder preparation technology. The oxygen content of this tantalum powder is less than 2000 ppm, and the difference between the particle size D90 and D50 is 2-5 μm, indicating a narrow particle size distribution, uniform powder, fine particle size, and stable performance. This meets the requirements of metallurgical-grade powders with higher requirements for particle size and oxygen content. Furthermore, by subjecting tantalum ingots to two hydrogenation processes to make tantalum brittle, and by selecting appropriate sieve meshes and controlling ball milling time during crushing and powdering, the particle size of the tantalum powder meets the requirements. Impurities introduced during ball milling are removed by acid washing, and the powder is dried to obtain ultrafine tantalum powder. Subsequent low-temperature dehydrogenation and oxygen reduction yields low-oxygen ultrafine tantalum powder.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tantalum powder preparation, and particularly relates to a low-oxygen ultrafine tantalum powder and a preparation method thereof. BACKGROUND

[0002] Tantalum is a rare metal and is regarded as an emerging strategic metal. Due to the high melting point, high dielectric constant, good hardness, high plasticity, excellent thermal and electrical conductivity, wide working temperature range, high reliability, anti-shock and long service life of tantalum capacitors, tantalum has a wide application prospect in many high-tech fields.

[0003] Metallurgical tantalum powder is mainly used for preparing various tantalum materials, sputtering targets for barrier layers between integrated circuit copper lines and silicon, alloy additives and the medical industry. The quality of metallurgical grade tantalum powder is mainly evaluated from physical properties and chemical composition, including particle size distribution, particle morphology, chemical impurities, bulk specific gravity and the like. Generally, only D50 of the metallurgical grade tantalum powder is specially required, but in special application scenarios, D50, D90 and oxygen content of the metallurgical grade tantalum powder are simultaneously required. Generally, the tantalum powder with a fine particle size has relatively active performance and is easily reacted with oxygen, nitrogen and the like at room temperature, so that the oxygen content in the tantalum powder is increased. Although the oxygen content can be reduced through deoxidization, the deoxidization process causes sintering of the material, so that the particle size of the material is increased, resulting in certain limitations in industrial production of the low-oxygen ultrafine tantalum powder.

[0004] In the prior art, a high-purity tantalum powder and a preparation method thereof are disclosed in Chinese Patent Application No. 201480016668.3. The GDMS analysis purity of the tantalum powder is greater than 99.995%, the oxygen content is not higher than 1000ppm, the nitrogen content is not higher than 50ppm, the hydrogen content is not higher than 20ppm, the magnesium content is not greater than 5ppm, and the particle size D50 is less than 25um. In the patent, the particle size of the tantalum powder is less than 25um, and D50 is large. However, it is well known to those skilled in the art that when D50 is less than 10um, the specific surface area of the tantalum powder is large, and the tantalum powder is easily adsorbed with oxygen in the air, so that the oxygen content is high. Therefore, it is necessary to provide a tantalum powder with small particle size and low oxygen content and a preparation method thereof. SUMMARY

[0005] Therefore, the application provides a low-oxygen ultrafine tantalum powder.

[0006] It is also necessary to provide a preparation method of the low-oxygen ultrafine tantalum powder.

[0007] The technical scheme adopted by the application to solve the technical problems is as follows:

[0008] The low-oxygen ultrafine tantalum powder has an oxygen content less than 2000ppm, and the difference between the particle size D90 and D50 of the tantalum powder is 2-5um.

[0009] Preferably, the particle size D50 of the tantalum powder is 3-5um.

[0010] Preferably, the particle size D90 of the tantalum powder is 6-9um.

[0011] The preparation method of the low-oxygen superfine tantalum powder as described above is prepared by the following steps:

[0012] S1: The high-purity tantalum ingot is subjected to twice hydrogenation treatment, and the second hydrogenation temperature is 100-400℃ lower than the first hydrogenation temperature, so as to increase the contact area of the high-purity tantalum ingot after film removal and hydrogen, ensure complete hydrogenation, and obtain high-fragility high-purity tantalum powder after hydrogenation;

[0013] S2: The high-fragility high-purity tantalum powder after hydrogenation is subjected to powdering, ball milling, acid washing, filter washing, and drying to obtain a first tantalum powder crude product;

[0014] S3: A reducing agent is added to the first tantalum powder crude product, and then the first tantalum powder crude product is subjected to dehydrogenation and oxygen reduction at 700-900℃ to obtain a second tantalum powder crude product;

[0015] S4: The second tantalum powder crude product is subjected to acid washing, filter washing, and drying to obtain a low-oxygen superfine tantalum powder.

[0016] Preferably, in the S1 step, the holding temperature of the first hydrogenation treatment is 1000-1100℃, and the holding time is 4-6h; and the holding temperature of the second hydrogenation treatment is 700-900℃, and the holding time is 8-12h.

[0017] Preferably, in the S1 step, the high-purity tantalum ingot is only contacted with hydrogen gas and not contacted with other gases during the twice hydrogenation process.

[0018] Preferably, in the S1 step, the heating rate of the first hydrogenation treatment is 20-30℃ / min, and the heating rate of the second hydrogenation treatment is 5-10℃ / min.

[0019] Preferably, in the S3 step, the reducing agent is magnesium powder, and the addition amount of the magnesium powder is 0.5-2.0% of the weight of the first tantalum powder crude product.

[0020] Preferably, in the S3 step, the heating rate of the dehydrogenation and oxygen reduction is 10-20℃ / min, and argon gas is introduced for protection during the heating process.

[0021] Preferably, in the S2 step, the powdering is specifically: the high-fragility high-purity tantalum powder after hydrogenation is crushed, and high-fragility high-purity tantalum powder after hydrogenation with a mesh size of 100-400 is obtained through screening.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] The low-oxygen superfine tantalum powder provided by the application has an oxygen content less than 2000 ppm, a difference between D90 and D50 of the tantalum powder of 2-5 um, indicating a narrow particle size distribution, uniform powder, fine particle size of the tantalum powder, stable performance, and can meet the application field of metallurgical grade powder with higher requirements for particle size and oxygen content.

[0024] The application also provides a preparation method of the low-oxygen superfine tantalum powder, which comprises the following steps: twice hydrogenation of a tantalum ingot to make the tantalum brittle, crushing to powder, selection of a suitable mesh size, control of the ball milling time, and control of the particle size of the tantalum powder to meet the requirements; acid washing to remove impurities introduced in the ball milling process, drying to obtain the superfine tantalum powder; and low-temperature dehydrogenation and oxygen reduction to obtain the low-oxygen superfine tantalum powder.

[0025] The application removes the tantalum pentoxide layer on the surface of the high-purity tantalum ingot through the first hydrogenation, keeps the surface of the high-purity tantalum ingot clean, generates a hydride layer through the hydrogenation reaction of the high-purity tantalum ingot and hydrogen, transmits hydrogen through the hydride layer, increases the reaction rate at high temperature, and makes the generated hydride layer no longer adhere to the surface, so that cracks and fissures appear, the contact area of the high-purity tantalum ingot is further increased, and the high-purity tantalum ingot becomes small particles; then the second hydrogenation is performed, the second hydrogenation is performed at a lower temperature under the condition of saving energy, the second hydrogenation increases the contact area of the metal and hydrogen, ensures that the hydrogenation is complete, the tantalum powder is brittle, and the powder with a smaller and more uniform particle size is prepared.

[0026] The high-purity tantalum ingot is a body-centered cubic crystal, and the hydrogenated tantalum (TaH) after hydrogen absorption is a body-centered cubic lattice. The first hydrogenation enables hydrogen to quickly enter the interlattice position, so that the original lattice is expanded and broken, and then the second hydrogenation is performed, the contact area is further increased, and the tantalum ingot is peeled off layer by layer, and finally the tantalum powder with a smaller particle size is formed. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a particle size distribution graph of the low-oxygen superfine tantalum powder sample D of Example 1.

[0028] Figure 2 It is a particle size distribution graph of the low-oxygen superfine tantalum powder sample d of Example 2.

[0029] Figure 3 It is a particle size distribution graph of the comparative tantalum powder sample A of Comparative Example 1.

[0030] Figure 4 It is a particle size distribution graph of the comparative tantalum powder sample B of Comparative Example 2.

[0031] Figure 5 It is a particle size distribution graph of the comparative tantalum powder sample C of Comparative Example 3.

[0032] Figure 6 Figure 4 is a particle size distribution graph of the comparative tantalum powder sample E.

[0033] Figure 7 Figure 5 is a scanning electron microscope graph of the low-oxygen ultrafine tantalum powder sample D of Example 1.

[0034] Figure 8 Figure 6 is a scanning electron microscope graph of the low-oxygen ultrafine tantalum powder sample d of Example 2.

[0035] Figure 9 Figure 7 is a scanning electron microscope graph of the comparative tantalum powder sample A.

[0036] Figure 10 Figure 8 is a scanning electron microscope graph of the comparative tantalum powder sample B.

[0037] Figure 11 Figure 9 is a scanning electron microscope graph of the comparative tantalum powder sample C.

[0038] Figure 12 Figure 10 is a scanning electron microscope graph of the comparative tantalum powder sample E. DETAILED DESCRIPTION

[0039] The technical solutions and technical effects of the embodiments of the present application are further described in detail below in combination with the drawings of the present application.

[0040] A low-oxygen ultrafine tantalum powder, the oxygen content of the tantalum powder being less than 2000 ppm, and the difference between the particle size D90 and D50 of the tantalum powder being 2-5 um.

[0041] Further, the particle size D50 of the tantalum powder is 3-5 um.

[0042] Further, the particle size D90 of the tantalum powder is 6-9 um.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] The present application provides a low-oxygen ultrafine tantalum powder, the oxygen content of the tantalum powder being less than 2000 ppm, and the difference between the particle size D90 and D50 of the tantalum powder being 2-5 um, which indicates that the particle size distribution is narrow, the powder is uniform, the particle size of the tantalum powder is fine, and the performance is stable, and the low-oxygen ultrafine tantalum powder can meet the requirements of the application field of metallurgical grade powder with higher requirements for particle size and oxygen content.

[0045] The preparation method of the low-oxygen ultrafine tantalum powder as described above is prepared by the following steps:

[0046] S1: the high-purity tantalum ingot is subjected to twice hydrogenation treatment, the second hydrogenation temperature being 100-400 DEG C lower than the first hydrogenation temperature, so as to increase the contact area between the metal and hydrogen after the film of the high-purity tantalum ingot is removed, and ensure that the hydrogenation is thorough, and obtain the high-fragility high-purity tantalum powder after hydrogenation;

[0047] S2: obtaining a first crude tantalum powder by powdering, ball milling, acid washing, filter washing and drying the high-purity tantalum powder after hydrogenation;

[0048] S3: adding a reducing agent to the first crude tantalum powder, and then dehydrogenating and deoxidizing the first crude tantalum powder at 700-900°C to obtain a second crude tantalum powder;

[0049] S4: obtaining a low-oxygen ultra-fine tantalum powder by acid washing, filter washing and drying the second crude tantalum powder.

[0050] Specifically, the high-purity tantalum ingot refers to a tantalum ingot with a tantalum content of 99.995% or more.

[0051] Specifically, in S2, the ball milling can be performed by using a ball mill, the ball milling time is 2-8h, the stirring speed is 100-150r / min, and the ball-to-material ratio is 1:3-5; the acid washing is performed by using a mixed acid of nitric acid and hydrofluoric acid to remove Fe, Ni, Cr, C, Si and other metal impurities, the mixed acid is prepared by mixing nitric acid with a mass concentration of 65%, hydrofluoric acid with a mass concentration of 40% and water, and the ratio of the nitric acid solution, the hydrofluoric acid solution and the water is 6:2:15-5:1:25; the filter washing is performed by placing the material after acid washing in a filter washing tank, first washing with cold water until the conductivity is less than 30μs / cm, then washing with hot water until the conductivity is less than 30μs / cm, and then discharging; and the drying is performed by drying the filter-washed material at a temperature of 100-150°C for 10-15h, and then sieving the dried material to 100-200 meshes.

[0052] Specifically, in S4, the acid washing is performed by using a mixed acid of nitric acid and hydrofluoric acid to remove Fe, Ni, Cr, C, Si and other metal impurities, the mixed acid is prepared by mixing nitric acid with a mass concentration of 65%, hydrofluoric acid with a mass concentration of 40% and water, and the ratio of the nitric acid solution, the hydrofluoric acid solution and the water is 6:2:15-5:1:25; the filter washing is performed by placing the material after acid washing in a filter washing tank, first washing with cold water until the conductivity is less than 20μs / cm, then washing with hot water until the conductivity is less than 20μs / cm, and then discharging; and the drying is performed by drying the filter-washed material at a temperature of 100-150°C for 10-15h, and then sieving the dried material to 100-200 meshes to obtain the low-oxygen ultra-fine tantalum powder.

[0053] Further, in the S1 step, the holding temperature of the first hydrogenation treatment is 1000-1100°C for 4-6h, and the holding temperature of the second hydrogenation treatment is 700-900°C for 8-12h.

[0054] Further, before hydrogenation, sealing and vacuum replacement are required.

[0055] Further, in the S1 step, the high-purity tantalum ingot is only contacted with hydrogen during the two hydrogenation processes, and is not contacted with other gases.

[0056] Further, in the S1 step, the heating rate of the first hydrogenation treatment is 20-30℃ / min, so as to provide sufficient energy to make hydrogen atoms destroy the oxide layer on the surface of the tantalum powder, and the heating rate of the second hydrogenation treatment is 5-10℃ / min.

[0057] Further, in the S3 step, the reducing agent is magnesium powder, and the added amount of the magnesium powder is 0.5-2.0% of the weight of the first tantalum powder crude product.

[0058] Further, in the S3 step, the heating rate of the dehydrogenation and oxygen reduction is 10-20℃ / min, and argon is introduced during the heating process. Since the first tantalum powder crude product prepared in the application has a fine particle size, a large specific surface area and a low temperature during the dehydrogenation and oxygen reduction process, the material will not be sintered, and the magnesium oxide particles will not be wrapped, so that the dehydrogenation and oxygen reduction are carried out together, which will not affect the product quality, and can reduce the production cost and improve the production cycle.

[0059] Further, in the S2 step, the powder preparation is as follows: the high-purity tantalum powder with high brittleness after hydrogenation is crushed, and the high-purity tantalum powder with high brittleness after hydrogenation with a size of 100-400 meshes is obtained through screening.

[0060] The use of the application is introduced through the following examples. Example 1:

[0061] S1: The high-purity tantalum ingot is loaded into a special reaction bomb, sealed and replaced after being evacuated, and then first hydrogenated: the reaction bomb is placed in a high-temperature furnace for heating, hydrogen is introduced during the heating process, the heating rate is 15℃ / min, the highest holding temperature is 1100℃, the holding time is 4-6h, and the power is stopped after the heating and holding are completed, and then the temperature is reduced; second hydrogenation: after the furnace body is powered off for 12 hours, the second hydrogenation is carried out, the second heating rate is 10℃ / min, the highest temperature is 800℃, and the holding time is 10h, hydrogen is continuously introduced during the whole process, the power is stopped after the heating and holding are completed, and then the furnace is discharged, and the high-purity tantalum powder with high brittleness after hydrogenation is obtained;

[0062] S2: The hydrogenated high brittleness high purity tantalum powder is crushed by a jaw crusher, sieved through a 100 mesh sieve, and stirred and ground by a ball mill. The ball milling time is 2-8 h, the stirring machine speed is 100-150 r / min, and the ball-to-material ratio is 1:3-5. A mixture of nitric acid and hydrofluoric acid is used to wash the ground material to remove Fe, Ni, Cr, C, Si and other metal impurities. The mixture is prepared by mixing 65% nitric acid and 40% hydrofluoric acid with water. The ratio of the nitric acid solution, the hydrofluoric acid solution and water is 6:2:15-5:1:25. The washed material is placed in a filter washing tank and washed with cold water until the conductivity is less than 30 μs / cm, then hot water is used for washing until the conductivity is less than 30 μs / cm, and the material is discharged. The filtered material is dried at a temperature of 100-150°C for 10-15 h, sieved through a 100-200 mesh sieve, ground, washed with acid, filtered, and dried to obtain a first tantalum powder crude product.

[0063] S3: Magnesium powder is added to the first tantalum powder crude product at a weight ratio of 0.5%, mixed uniformly, and then loaded into a special reaction bomb. After sealing and vacuum replacement, the bomb is placed in a high-temperature furnace for heating. The heating rate is 20°C / min, and argon gas is introduced for protection during the heating process. The temperature during the heating process is 800°C. After the heating is completed, the power is turned off for cooling, the bomb is taken out of the furnace, and a second tantalum powder crude product is obtained.

[0064] S4: The second tantalum powder crude product is washed with a mixture of nitric acid and hydrofluoric acid to remove Fe, Ni, Cr, C, Si and other metal impurities. The mixture is prepared by mixing 65% nitric acid and 40% hydrofluoric acid with water. The ratio of the nitric acid solution, the hydrofluoric acid solution and water is 6:2:15-5:1:25. The washed material is placed in a filter washing tank and washed with cold water until the conductivity is less than 20 μs / cm, then hot water is used for washing until the conductivity is less than 20 μs / cm, and the material is discharged. The filtered material is dried at a temperature of 100-150°C for 10-15 h, sieved through a 100 mesh sieve, and a low-oxygen ultra-fine tantalum powder sample D is obtained. Example 2:

[0065] S1: A high-purity tantalum ingot is loaded into a special reaction bomb, sealed and vacuum replaced, and then subjected to first hydrogenation. The bomb is placed in a high-temperature furnace for heating. Hydrogen gas is introduced during the heating process, and the heating rate is 15°C / min. The maximum holding temperature is 1100°C, and the holding time is 4-6 h. After the heating and holding are completed, the power is turned off for cooling, and a hydrogenated high brittleness high purity tantalum powder is obtained.

[0066] S2: The hydrogenated high brittleness high purity tantalum powder is crushed by a jaw crusher, sieved through a 100 mesh sieve, and a low-oxygen ultra-fine tantalum powder sample d is obtained.

[0067] Comparative Example 1

[0068] S1: Put high-purity tantalum ingot into a special reaction bomb, seal and replace after evacuation, put the reaction bomb into a high-temperature furnace for heating, pass hydrogen during the heating process, the heating rate is 20℃ / min, the highest holding temperature is 1100℃, the holding time is 5h, hydrogen is continuously passed throughout the process, after the end of heating and holding, stop power and cool down, take out of the furnace, get high-purity tantalum powder after hydrogenation with high brittleness;

[0069] The other steps are the same as Example 1, and comparative tantalum powder sample A is obtained.

[0070] Comparative Example 2

[0071] S1: Put high-purity tantalum ingot into a special reaction bomb, seal and replace after evacuation, put the reaction bomb into a high-temperature furnace for heating, pass hydrogen during the heating process, the heating rate is 15℃ / min, the highest holding temperature is 1000℃, the holding time is 5h, hydrogen is continuously passed throughout the process, after the end of heating and holding, stop power and cool down, take out of the furnace, get high-purity tantalum powder after hydrogenation with high brittleness;

[0072] The other steps are the same as Example 1, and comparative tantalum powder sample B is obtained.

[0073] Comparative Example 3

[0074] S1: Put high-purity tantalum ingot into a special reaction bomb, seal and replace after evacuation, put the reaction bomb into a high-temperature furnace for heating, pass hydrogen during the heating process, the heating rate is 10℃ / min, the highest holding temperature is 1000℃, the holding time is 5h, hydrogen is continuously passed throughout the process, after the end of heating and holding, stop power and cool down, take out of the furnace, get high-purity tantalum powder after hydrogenation with high brittleness;

[0075] The other steps are the same as Example 1, and comparative tantalum powder sample C is obtained.

[0076] Comparative Example 4

[0077] S1: Put high-purity tantalum ingot into a special reaction bomb, seal and replace after evacuation, put the reaction bomb into a high-temperature furnace for heating, pass hydrogen during the heating process, the heating rate is 15℃ / min, the highest holding temperature is 700℃, the holding time is 5h, hydrogen is continuously passed throughout the process, after the end of heating and holding, stop power and cool down, take out of the furnace, get high-purity tantalum powder after hydrogenation with high brittleness;

[0078] The other steps are the same as Example 1, and comparative tantalum powder sample E is obtained.

[0079] The low-oxygen superfine tantalum powder sample D, the low-oxygen superfine tantalum powder sample d, the comparative tantalum powder sample A, the comparative tantalum powder sample B, the comparative tantalum powder sample C and the comparative tantalum powder sample E are respectively subjected to impurity content detection, particle size distribution detection and scanning electron microscope detection, wherein the instruments for detection are shown in Table 1, the sample chemical impurity content detection results are shown in Table 2, the particle size distribution graphs are shown in Figures 1-6 and the scanning electron microscope graphs are shown in Figures 7-12 .

[0080] Table 1

[0081]

[0082] Table 2

[0083]

[0084] It can be known from Table 2, Figures 1 to 12 that the oxygen content of the low-oxygen superfine tantalum powder sample D prepared in the embodiment one is low, and the Fe, Ni, Cr and C impurity contents are low, the smaller the difference between D90 and D50, the narrower the particle size distribution of the tantalum powder and the better the uniformity; and it can be known from the comparison of the low-oxygen superfine tantalum powder sample D, the low-oxygen superfine tantalum powder sample d and the comparative tantalum powder sample A that although the D50 is small in the first hydrogenation, the D90 is large, the larger the difference between D90 and D50, the larger the particle size of the tantalum powder and the poorer the uniformity; and it can be known from the low-oxygen superfine tantalum powder sample d, the comparative tantalum powder sample A, the comparative tantalum powder sample B, the comparative tantalum powder sample C and the comparative tantalum powder sample E that in the first hydrogenation process, the particle size of the tantalum powder is reduced by adjusting the heating rate and the hydrogenation temperature, but the reduction is limited.

[0085] The above only discloses the preferred embodiments of the present application, and of course cannot limit the scope of the rights of the present application, and those skilled in the art can understand that all or part of the processes of the above embodiments are implemented, and equivalent changes are made according to the claims of the present application, which still belong to the scope covered by the present application.

Claims

1. A low-oxygen ultrafine tantalum powder, characterized by, The oxygen content of the tantalum powder is less than 2000 ppm, and the difference between the particle size D90 and D50 of the tantalum powder is 2-5 um. The low-oxygen ultra-fine tantalum powder is prepared by the following steps: S1: twice hydrogenation treatment is performed on the high-purity tantalum ingot, and the second hydrogenation temperature is 100-400 DEG C lower than the first hydrogenation temperature, so that the contact area between the high-purity tantalum ingot and hydrogen is increased after film removal, and the hydrogenation is ensured to be complete, and a high-fragility high-purity tantalum powder after hydrogenation is obtained; In the S1 step, the holding temperature of the first hydrogenation treatment is 1000-1100 DEG C, and the holding time is 4-6 h, so that the hydride layer is generated after the film removal of the high-purity tantalum ingot, and with the increase of the contact area, the hydrogen transmission of the hydride layer is carried out, and at high temperature, the reaction rate is increased, the generated hydride layer is no longer attached to the surface, and cracks and cracks are generated, so that the high-purity tantalum ingot is broken to further increase the contact area, and the high-purity tantalum ingot is changed into small particles; The holding temperature of the second hydrogenation treatment is 700-900 DEG C, and the holding time is 8-12 h; the contact area between the metal and hydrogen is increased, and the hydrogenation is ensured to be complete; S2: the high-fragility high-purity tantalum powder after hydrogenation is powdered, ball milled, pickled, filtered, and dried to obtain a first tantalum powder crude product; S3: a reducing agent is added to the first tantalum powder crude product, and then the first tantalum powder crude product is dehydrogenated and oxygen-reduced at 700-900 DEG C to obtain a second tantalum powder crude product; S4: the second tantalum powder crude product is pickled, filtered, and dried to obtain a low-oxygen ultra-fine tantalum powder.

2. The low-oxygen ultrafine tantalum powder of claim 1, wherein, The particle size D50 of the tantalum powder is 3-5 um.

3. The low-oxygen ultrafine tantalum powder of claim 1 or 2, wherein the oxygen content is 0.0005% or less. The particle size D90 of the tantalum powder is 6-9 um.

4. The low oxygen ultrafine tantalum powder of claim 1, wherein: In the S1 step, the high-purity tantalum ingot is only contacted with hydrogen during the two hydrogenation processes, and is not contacted with other gases.

5. The low oxygen ultrafine tantalum powder of claim 1 wherein: In the S1 step, the heating rate of the first hydrogenation treatment is 20-30 DEG C / min, and the heating rate of the second hydrogenation treatment is 5-10 DEG C / min.

6. The low oxygen ultrafine tantalum powder of claim 1 wherein: In the S3 step, the reducing agent is magnesium powder, and the addition amount of the magnesium powder is 0.5-2.0% of the weight of the first tantalum powder crude product.

7. The low oxygen ultrafine tantalum powder of claim 1 wherein: In the S3 step, the heating rate of the dehydrogenation and oxygen reduction is 10-20 DEG C / min, and argon is introduced for protection during the heating process.

8. The low oxygen ultrafine tantalum powder of claim 1 wherein: In the S2 step, the powdering is specifically: the high-fragility high-purity tantalum powder after hydrogenation is crushed, and the high-fragility high-purity tantalum powder after hydrogenation with a mesh size of 100-400 is obtained by screening.

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