Method for efficiently preparing niobium material and niobium material prepared by method

Abstract

The invention belongs to the technical field of powder metallurgy, and particularly relates to a method for efficiently preparing a niobium material and the niobium material prepared through the method.The method comprises the steps that niobium pentoxide and carbon black are fully mixed and react for a first time length, a first mixed material is obtained, hydrogen is introduced into a graphite carbon tube furnace, and a second mixed material is obtained; carrying out primary carbonization and secondary carbonization on the first mixture in the furnace to obtain niobium carbide; the ball mill carries out ball milling on the niobium carbide until the niobium carbide is proper in particle size, flat in particle shape and uniform in particle size distribution, and the particle size range is-100-300 meshes; the niobium carbide and niobium pentoxide are fully mixed and react for a second time period to obtain a second mixture, the second mixture is granulated to obtain a second mixture with the particle size of 2-4 [mu] m / g, propylene alcohol is used as an adhesive, cold press molding treatment is performed to obtain a pre-sintered niobium strip, and the pre-sintered niobium strip is subjected to multi-stage low-temperature treatment to remove low-temperature impurities, so that the niobium carbide / niobium pentoxide composite material is obtained. And redundant carbon and oxygen are removed through high-temperature treatment, qualified niobium strips with the purity being 99.98% or above are obtained, the process steps are simplified, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of powder metallurgy, and particularly relates to a method for efficiently preparing niobium materials and the niobium materials prepared by this method. Background Art

[0002] Niobium, as a rare high-melting metal, is an important structural material and also a functional material with excellent properties. It has good low-temperature plasticity, and is resistant to high temperature, corrosion, and has high strength. It also has characteristics such as low-temperature superconductivity. These properties make niobium widely used in high-tech fields such as steel, energy, superalloys, superconductivity, nuclear reactions, aerospace, and electronics.

[0003] Niobium bar products are strip products made of high-purity metallic niobium, which can be used as additives for iron-based, nickel-based, and zirconium-based superalloys to improve their strength properties. Niobium and niobium alloys are high-temperature resistant materials. Among the four "space metals" in aerospace, tungsten, molybdenum, tantalum, and niobium, niobium alloys have the best comprehensive performance, showing good plasticity and excellent processing and welding properties. In recent years, with the continuous development of the aviation and aerospace industries, the application scope of niobium-containing alloys has been further expanded and is widely used in structural components and heat protection system materials of aircraft and rocket engines.

[0004] Currently, in industrial production, the vacuum carbothermal reduction method is used to produce niobium bars. There are two carbon reduction processes. One is the direct reduction method, that is, using carbon to directly reduce niobium pentoxide to produce metallic niobium (Nb2O5 + 5C = 2Nb + 5CO↑). This process has the disadvantages of large shrinkage, large fluctuations in the C / O ratio that are difficult to control, low output, and loose texture of the niobium bars. Therefore, currently, the indirect reduction method is generally used, that is, first preparing niobium carbide, and then using niobium carbide to reduce niobium oxide to produce metallurgical-grade niobium powder. The niobium powder obtained by this method has relatively high carbon and oxygen contents and needs to remove the excess carbon and oxygen to obtain qualified niobium bar products. The overall reaction formula of the indirect reduction method is: (Nb2O5 + 7C = 2NbC + 5CO↑; Nb2O5 + 5NbC = 7Nb + 5CO↑). The specific process is: first, mix niobium oxide and carbon, and then perform primary carbonization → secondary carbonization → primary reduction → hydrogenation → powder making → dehydrogenation → adjusting the carbon and oxygen ratio → forming → secondary reduction → niobium bars. However, this process has the problems of a long production cycle and low working efficiency. Summary of the Invention

[0005] In view of this, the present invention provides a method for efficiently preparing niobium materials and the niobium materials prepared by this method to solve the technical problems of the long production cycle and low working efficiency of the indirect reduction method process when using the vacuum carbothermal reduction method to produce niobium bars in the prior art.

[0006] To achieve the above object, the present application adopts the following solutions:

[0007] A method for efficiently preparing niobium material comprises the following steps:

[0008] S10. The niobium pentoxide and carbon black are fully mixed and reacted for a first time to obtain a first mixture, wherein the mass ratio of niobium pentoxide to carbon black is 10: (3 to 3.5);

[0009] S20. introducing hydrogen into the graphite carbon tube furnace, and performing primary carbonization and secondary carbonization on the first mixture in the graphite carbon tube furnace to obtain niobium carbide having a nitrogen content of less than 400 ppm;

[0010] S30. The niobium carbide is mechanically milled using a ball mill to obtain niobium carbide having a particle size of 1.5 μm / g to 3.0 μm / g, a flat particle shape, a uniform particle size distribution, and a particle size range of -100 to 300 mesh;

[0011] S40. The ball-milled niobium carbide and niobium pentoxide are fully mixed and reacted for a second time to obtain a second mixture, wherein the mass ratio of the niobium carbide to the niobium pentoxide is (2 to 3): (1 to 1.8);

[0012] S50. Granulating the second mixed material to obtain a second mixed material with a particle size of 2 μm / g to 4 μm / g;

[0013] S60. Drying the second mixture;

[0014] S70. Using propylene glycol as a binder, and adding it to the second mixture after drying, and cold pressing to obtain a pre-bonded niobium bar;

[0015] S80. The pre-bonded niobium bar is placed in a high-temperature reduction furnace, firstly subjected to multiple low-temperature treatments to remove low-temperature impurities, and then subjected to high-temperature treatments to remove excess carbon and oxygen, to obtain a qualified niobium bar with a purity of more than 99.9%.

[0016] Preferably, the purity of niobium pentoxide is ≥99.50%, the purity of carbon black is ≥98.0%, and the particle size of carbon black is -100 mesh.

[0017] Preferably, the first duration is the same as the second duration, both being 10 hours to 12 hours.

[0018] Preferably, the hydrogen flow rate is 0.3m 3 / h to 0.5m 3 / h.

[0019] Preferably, the heating temperature of the graphite carbon tube furnace is 1800°C to 2200°C.

[0020] Preferably, the added amount of propyl alcohol is 1.3% to 1.5%.

[0021] Preferably, the temperature of the drying treatment is 150°C to 250°C, and the duration of the drying treatment is 20 min to 60 min.

[0022] Preferably, the multi-stage low-temperature treatment includes a first-stage low-temperature treatment, a second-stage low-temperature treatment, and a third-stage low-temperature treatment. The first-stage low-temperature treatment is: rising from room temperature to 900°C to 1100°C at one time, with a heating time of 1.9 h to 2.1 h, and maintaining the temperature until the vacuum degree in the furnace is 28 Pa to 32 Pa; the second-stage low-temperature treatment is: rising from 900°C to 1000°C to 1200°C to 1400°C at one time, with a heating time of 1.9 h to 2.1 h, and maintaining the temperature until the vacuum degree in the furnace is 18 Pa to 22 Pa; the third-stage low-temperature treatment is: rising from 1200°C to 1400°C to 1750°C to 1850°C at one time, with a heating time of 1.9 h to 2.1 h, and maintaining the temperature until the vacuum degree in the furnace is 9 Pa to 11 Pa; the high-temperature treatment is: rising from 1750°C to 1850°C to 1900°C to 2100°C at one time, with a heating time of 1.9 h to 2.1 h, and maintaining the temperature until the vacuum degree in the furnace is 4 Pa to 6 Pa.

[0023] Preferably, the multi-stage low-temperature treatment includes a first-stage low-temperature treatment, a second-stage low-temperature treatment, and a third-stage low-temperature treatment. The first-stage low-temperature treatment is: rising from room temperature to 1000°C at one time, with a heating time of 2 h, and maintaining the temperature until the vacuum degree in the furnace is 30 Pa; the second-stage low-temperature treatment is: rising from 1000°C to 1300°C at one time, with a heating time of 2 h, and maintaining the temperature until the vacuum degree in the furnace is 20 Pa; the third-stage low-temperature treatment is: rising from 1300°C to 1800°C at one time, with a heating time of 2 h, and maintaining the temperature until the vacuum degree in the furnace is 10 P; the high-temperature treatment is: rising from 1800°C to 2000°C at one time, with a heating time of 2 h, and maintaining the temperature until the vacuum degree in the furnace is 5 Pa.

[0024] The niobium material prepared by the method for efficiently preparing niobium material according to any one of the above.

[0025] In the above-mentioned method for efficiently preparing niobium materials, when the first mixture is subjected to primary carbonization and secondary carbonization in a graphite carbon tube furnace, hydrogen is introduced into the graphite carbon tube furnace, and the hydrogen reacts with the organic matter in the first mixture to reduce the oxygen atoms in the organic matter and combines with the hydrogen to generate water, thereby removing the oxygen, avoiding the phenomenon of failure to form or cracking and delamination of the pressed embryo due to the excessively high proportion of oxides in the subsequent cold pressing process, thereby improving the forming rate; in the carbon thermal reduction method, graphite is used as a reducing agent and the reaction is carried out at a high temperature, which can effectively remove impurity nitrogen, and the hydrogen atmosphere avoids the mixing of nitrogen in the air, so that the nitrogen in the first mixture can be removed to obtain niobium carbide with a nitrogen content of less than 400ppm, so as to improve the purity of the finished product; the obtained blocky niobium carbide is ball-milled to a particle size of 1.5μm / g to 3.0μm / g, a flat particle shape, a uniform particle size distribution, and a particle size range of -100 to 300 Purpose: Niobium is carburized to increase the contact area and reaction efficiency of the reduction reaction, thereby ensuring that the reduction reaction is fully carried out; the granulation process aggregates the fine powder into particles, effectively solving the problems of poor fluidity and uneven particles of traditional powders, thereby improving the subsequent cold pressing forming rate, which not only improves production efficiency, but also ensures the uniform distribution of materials during the forming process, and further optimizes the density and mechanical properties of the product; and propylene glycol is used as a binder, which can quickly dissolve into part of the metal powder (niobium) to make the bonding stronger, and can further improve the forming rate during cold pressing, and its volatilization rate is faster than that of water, and it can be dried quickly after the bonding operation to form a bonding connection, further improving work efficiency, even if it is not completely volatilized at room temperature, it will be completely removed by low-temperature sintering, and will not affect the purity of the niobium bar due to the generation of impurities; low-temperature impurities are removed by multi-stage low-temperature treatment, and then excess carbon and oxygen are removed by high-temperature treatment to obtain qualified niobium bars.

[0026] In summary, the method for efficiently preparing niobium materials provided by the present invention simplifies the traditional process steps, that is, the steps of hydrogenation, powder making, dehydrogenation, carbon adjustment, oxygen ratio adjustment and secondary reduction are omitted, the production cycle is shortened, the production efficiency is improved, and the impurity content of the prepared niobium bars is low, all of which meet the national standards, and niobium bars with a purity of more than 99.98% and a forming rate of more than 95% can be prepared. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present application, the present application will be described in more detail below. And the preferred embodiments of the present application are given. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0029] In a specific embodiment, a method for efficiently preparing niobium materials includes the following steps:

[0030] S10. Thoroughly mix niobium pentoxide and carbon black and react for a first duration to obtain a first mixture, where the mass ratio of niobium pentoxide to carbon black is 10:(3 to 3.5);

[0031] S20. Introduce hydrogen into a graphite carbon tube furnace, and perform primary carbonization and secondary carbonization on the first mixture in the graphite carbon tube furnace to obtain niobium carbide with a nitrogen content of less than 400 ppm;

[0032] S30. Mechanically ball-mill the niobium carbide using a ball mill to obtain niobium carbide with a particle size of 1.5 μm / g to 3.0 μm / g, flat particle shape, uniform particle size distribution, and a particle size range of -100 to 300 mesh;

[0033] S40. Thoroughly mix the ball-milled niobium carbide and niobium pentoxide and react for a second duration to obtain a second mixture, where the mass ratio of niobium carbide to niobium pentoxide is (2 to 3):(1 to 1.8);

[0034] S50. Perform granulation treatment on the second mixture to obtain a second mixture with a particle size of 2 μm / g to 4 μm / g;

[0035] S60. Perform drying treatment on the second mixture;

[0036] S70. Use propanol as a binder, add it to the second mixture after drying treatment, and perform cold pressing and forming treatment to obtain a pre-sintered niobium bar;

[0037] S80. Place the pre-sintered niobium bar in a high-temperature reduction furnace, first remove low-temperature impurities through multi-stage low-temperature treatment, and then remove excess carbon and oxygen through high-temperature treatment to obtain a qualified niobium bar with a purity of over 99.9%.

[0038] When preparing niobium materials, the niobium materials prepared in this embodiment are specifically niobium bars. First, niobium pentoxide and carbon black are mixed and reacted. Using the reducibility of carbon black, niobium pentoxide is partially reduced to generate an intermediate product with a certain carbon content, preparing for the subsequent carbonization process. The purities of the niobium pentoxide and carbon black used need to meet national standards to avoid affecting the quality of the obtained niobium bars. Then, hydrogen is introduced into the graphite carbon tube furnace. Under a hydrogen atmosphere, the remaining oxygen is removed through the primary carbonization and secondary carbonization processes to improve the purity of the niobium bars produced subsequently. After carbonization, massive niobium carbide is obtained. Therefore, the particle size of niobium carbide needs to be refined through a ball milling process to obtain niobium carbide particles with a particle size of 1.5 μm / g to 3.0 μm / g, flat particle shape, and uniform particle size distribution. The niobium carbide particles with a particle size range of -100 to 300 mesh are screened. Ball milling the massive niobium carbide into niobium carbide particles can improve its uniformity, which is convenient for subsequent mixing and reaction on the one hand and can improve the forming rate during subsequent cold pressing on the other hand. Next, the niobium carbide and niobium pentoxide are mixed and reacted again for further purification. In this embodiment, the granulation treatment of the second mixture is specifically as follows: The second mixture and appropriate water are placed in an inclined and rotating disc. Under the combined action of gravity, centrifugal force, and friction, the material undergoes rolling and rubbing motions and forms spherical particles, obtaining a mixture with a particle size of 2 μm / g to 4 μm / g, preferably a mixture with a particle size of 3 μm / g, thereby improving the fluidity and uniformity of the niobium carbide and unreacted niobium pentoxide particles (powders). Through the granulation treatment, the particle size of the second mixture is uniform, which is convenient for subsequent processing on the one hand and can improve the forming rate during subsequent cold pressing on the other hand. At this time, it needs to be dried to remove the moisture in the second mixture, prevent the niobium bars obtained in the next step of pressing from being too loose due to a large water content, and improve the stability and controllability in subsequent processing. Propanol is added to the second mixture for cold pressing to form a pre-sintered niobium bar with a certain shape and strength. Propanol can quickly dissolve into some metal powders (niobium), making the adhesion stronger, which can further improve the forming rate during cold pressing. Moreover, its evaporation speed is faster than that of water and can be dried relatively quickly after the adhesion operation to form an adhesive connection, further improving work efficiency. And its evaporation process is relatively stable and will not cause defects on the adhesion surface due to too fast evaporation. Compared with some other organic solvents such as benzene and formaldehyde, it has lower toxicity. When used under appropriate ventilation conditions, it has less harm to human health, is relatively safe to use, and also meets some requirements in terms of environmental protection. Even if it does not evaporate completely at room temperature, it will be removed completely during low-temperature sintering and will not generate impurities due to it, thus not affecting the purity of the niobium bars.In this embodiment, a hydraulic press with a pressure of 200 MPa to 400 MPa is used, and the pressure is maintained for 1.5 min to press a pre-sintered niobium bar with dimensions of 21 ± 3 × 21 ± 3 × 450 ± 50 mm. It should be noted that those skilled in the art can determine the shape and size of the product according to actual needs; finally, the pre-sintered niobium bar is placed in a high-temperature reduction furnace, and low-temperature impurities are removed through multi-stage low-temperature treatment first, and then excess carbon and oxygen are removed through high-temperature treatment to obtain a qualified niobium bar with a purity of more than 99.98%.

[0039] Furthermore, to ensure the quality of the prepared niobium material (niobium bar), the purity of the raw materials used needs to meet the following standards: the purity of niobium pentoxide ≥ 99.50%, the purity of carbon black ≥ 98.0%, and the particle size of carbon black is -100 mesh to prepare a high-purity niobium bar.

[0040] Specifically, the first duration is the same as the second duration, both being 10 h to 12 h. At this reaction duration, the mixing material can react more fully.

[0041] In a preferred embodiment, the hydrogen flow rate is 0.3 m 3 / h to 0.5 m 3 / h. In a hydrogen atmosphere, hydrogen reacts with the organic matter in the first mixture, reducing the oxygen atoms in the organic matter and combining with hydrogen to form water, thereby removing oxygen to improve the purity of the prepared niobium bar. When the hydrogen flow rate is controlled at 0.3 m 3 / h to 0.5 m 3 / h, the effect is better.

[0042] In a specific embodiment, the heating temperature of the graphite carbon tube furnace is 1800 °C to 2200 °C.

[0043] In another preferred embodiment, the addition amount of propanol is 1.3% to 1.5%.

[0044] Specifically, the temperature of the drying treatment is 150 °C to 250 °C, and the duration of the drying treatment is 20 min to 60 min.

[0045] In a preferred embodiment, the multi-stage low-temperature treatment includes a first-stage low-temperature treatment, a second-stage low-temperature treatment, and a third-stage low-temperature treatment. The first-stage low-temperature treatment is: rising from room temperature to 900°C to 1100°C at one time, with a heating time of 1.9h to 2.1h, and holding until the vacuum degree in the furnace is 28Pa to 32Pa; the second-stage low-temperature treatment is: rising from 900°C to 1000°C to 1200°C to 1400°C at one time, with a heating time of 1.9h to 2.1h, and holding until the vacuum degree in the furnace is 18Pa to 22Pa; the third-stage low-temperature treatment is: rising from 1200°C to 1400°C to 1750°C to 1850°C at one time, with a heating time of 1.9h to 2.1h, and holding until the vacuum degree in the furnace is 9Pa to 11Pa; the high-temperature treatment is rising from 1750°C to 1850°C to 1900°C to 2100°C at one time, with a heating time of 1.9h to 2.1h, and holding until the vacuum degree in the furnace is 4Pa to 6Pa.

[0046] The above accurately controlled reduction sintering temperature can make the C / O ratio fluctuate within a controllable range, that is, the C / O ratio fluctuates less, thereby improving the stability and consistency of the product, reducing defects caused by improper temperature control, and improving the quality of niobium bars. For example, if the sintering temperature is too low, the material density is insufficient, and the strength and hardness decrease; if the sintering temperature is too high, the material sintering is distorted, and over-sintering expansion occurs, specifically manifested as defects such as pores and cracks.

[0047] Preferably, the multi-stage low-temperature treatment includes a first-stage low-temperature treatment, a second-stage low-temperature treatment, and a third-stage low-temperature treatment. The first-stage low-temperature treatment is: rising from room temperature to 1000°C at one time, with a heating time of 2h, and holding until the vacuum degree in the furnace is 30Pa; the second-stage low-temperature treatment is: rising from 1000°C to 1300°C at one time, with a heating time of 2h, and holding until the vacuum degree in the furnace is 20Pa; the third-stage low-temperature treatment is: rising from 1300°C to 1800°C at one time, with a heating time of 2h, and holding until the vacuum degree in the furnace is 10P; the high-temperature treatment is rising from 1800°C to 2000°C at one time, with a heating time of 2h, and holding until the vacuum degree in the furnace is 5Pa.

[0048] The present invention also provides a niobium material prepared by the method for efficiently preparing niobium material described above. The purity of this niobium material is above 99.9%, and it has a relatively high hardness.

[0049] The following further illustrates the technical solutions and technical effects of the present invention through specific experimental examples. It should be noted that the following experimental examples are only for further explaining the present invention and do not limit the technical solutions of the present invention.

[0050] Example 1

[0051] Step 1: Thoroughly mix niobium pentoxide (purity ≥ 99.5%) and carbon black (purity > 98%) evenly. The mass ratio of niobium pentoxide to carbon black is 10:3, and the first duration is 10 h to obtain a first mixture, and load the first mixture into a graphite boat;

[0052] Step 2: Place the graphite boat containing the first mixture into a graphite carbon tube furnace, and perform primary carbonization and secondary carbonization under hydrogen conditions. The carbonization temperature is 2000 °C, the carbonization time is 20 minutes / boat, and the hydrogen flow rate is 0.4 m 3 / h to obtain niobium carbide with a nitrogen content of less than 400 ppm;

[0053] Step 3: Use a ball mill to mechanically ball mill the niobium carbide for 2 h to obtain niobium carbide with a particle size range of 200 mesh;

[0054] Step 4: Mix the ball-milled niobium carbide and niobium pentoxide according to a mass ratio of 2:1, and the second duration is 10 h to obtain a second mixture;

[0055] Step 5: Granulate the second mixture to obtain a second mixture with a particle size of 3 μm / g;

[0056] Step 6: Dry the second mixture particles at a temperature of 150 °C to 250 °C for 20 min to 60 min;

[0057] Step 7: Use propanol as a binder, with the addition amount of propanol being 1.5%, and form it under the pressure of a 300 t to 400 t hydraulic press. The pressure holding time is 1.5 min to obtain a pre-sintered niobium bar with dimensions of 21 ± 3 × 21 ± 3 × 450 ± 50 mm;

[0058] Step 8: Place the formed pre-sintered niobium bar in a high-temperature reduction furnace for reduction treatment. The first-stage low-temperature treatment is to rise from room temperature to 1000 °C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 30 Pa; the second-stage heating treatment is to rise from 1000 °C to 1300 °C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 20 Pa; the third-stage low-temperature treatment is to rise from 1300 °C to 1800 °C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 10 Pa, and the high-temperature treatment is to rise from 1800 °C to 2000 °C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 5 Pa.

[0059] Example 2

[0060] Step 1: Thoroughly mix niobium pentoxide (purity ≥ 99.5%) and carbon black (purity > 98%) evenly. The mass ratio of niobium pentoxide to carbon black is 10:3, and the first duration is 11 h to obtain a first mixture, and load the first mixture into a graphite boat;

[0061] Step 2: Place the graphite boat containing the first mixture into a graphite carbon tube furnace, and carry out primary carbonization and secondary carbonization under hydrogen conditions. The carbonization temperature is 2000°C, the carbonization time is 30 minutes / boat, and the hydrogen flow rate is 0.4 m 3 / h, to obtain niobium carbide with a nitrogen content of less than 400 ppm;

[0062] Step 3: Use a ball mill to mechanically ball mill the niobium carbide for 2 h to obtain niobium carbide with a particle size range of 200 mesh;

[0063] Step 4: Mix the ball-milled niobium carbide and niobium pentoxide according to a mass ratio of 2.8:1.5 for 11 h to obtain a second mixture;

[0064] Step 5: Granulate the second mixture to obtain a second mixture with a particle size of 3 μm / g;

[0065] Step 6: Dry the second mixture particles at a temperature of 150°C to 250°C for 20 min to 60 min;

[0066] Step 7: Use propanol as the binder with an addition amount of 1.5%, and mold it under the pressure of a 300 t to 400 t hydraulic press for 1.5 min to obtain a pre-sintered niobium bar with dimensions of 21±3×21±3×450±50 mm;

[0067] Step 8: Place the molded pre-sintered niobium bar in a high-temperature reduction furnace for reduction treatment. The first-stage low-temperature treatment is to rise from room temperature to 1000°C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 30 Pa; the second-stage heating treatment is to rise from 1000°C to 1300°C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 20 Pa; the third-stage low-temperature treatment is to rise from 1300°C to 1800°C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 10 Pa, and the high-temperature treatment is to rise from 1800°C to 2000°C at one time, with a heating time of 2 h, and keep the temperature until the vacuum degree in the furnace is 5 Pa.

[0068] Example 3

[0069] Step 1: Thoroughly mix niobium pentoxide (purity ≥ 99.5%) and carbon black (purity > 98%) evenly. The mass ratio of niobium pentoxide to carbon black is 10:3.5, and the first duration is 12 h to obtain the first mixture, and load the first mixture into a graphite boat;

[0070] Step 2: Place the graphite boat containing the first mixture into a graphite carbon tube furnace, and carry out primary carbonization and secondary carbonization under hydrogen conditions. The carbonization temperature is 2000°C, the carbonization time is 40 minutes / boat, and the hydrogen flow rate is 0.4 m 3 / h, to obtain niobium carbide with a nitrogen content of less than 400 ppm;

[0071] Step 3: Mechanically ball-mill niobium carbide using a ball mill for 2 h to obtain niobium carbide with a particle size range of 200 mesh.

[0072] Step 4: Mix the ball-milled niobium carbide and niobium pentoxide according to a mass ratio of 3:1.8 for a second duration of 12 h to obtain a second mixture.

[0073] Step 5: Granulate the second mixture to obtain a second mixture with a particle size of 3 μm / g.

[0074] Step 6: Dry the second mixture particles at a temperature of 150°C to 250°C for 20 min to 60 min.

[0075] Step 7: Use propanol as a binder with a propanol addition amount of 1.5%, and form it under a hydraulic press pressure of 300 t to 400 t for a holding pressure time of 1.5 min to obtain a pre-sintered niobium bar with dimensions of 21 ± 3 × 21 ± 3 × 450 ± 50 mm.

[0076] Step 8: Place the formed pre-sintered niobium bar in a high-temperature reduction furnace for reduction treatment. The first-stage low-temperature treatment is to raise the temperature from room temperature to 1000°C at one time, with a heating time of 2 h, and hold the temperature until the vacuum degree in the furnace reaches 30 Pa. The second-stage heating treatment is to raise the temperature from 1000°C to 1300°C at one time, with a heating time of 2 h, and hold the temperature until the vacuum degree in the furnace reaches 20 Pa. The third-stage low-temperature treatment is to raise the temperature from 1300°C to 1800°C at one time, with a heating time of 2 h, and hold the temperature until the vacuum degree in the furnace reaches 10 Pa. The high-temperature treatment is to raise the temperature from 1800°C to 2000°C at one time, with a heating time of 2 h, and hold the temperature until the vacuum degree in the furnace reaches 5 Pa.

[0077] Comparative Example 1

[0078] Adopt the preparation method in the prior art: First, mix niobium oxide and carbon, and then prepare the niobium bar through a process of primary carbonization → secondary carbonization → primary reduction → hydrogenation → powder making → dehydrogenation → adjusting the carbon and oxygen ratio → forming → secondary reduction.

[0079] Detect the impurity content, purity, and forming rate of the niobium bars prepared in Examples 1 to 3 and Comparative Example 1 above. The detection results are shown in Table 1:

[0080] Table 1 Statistical Table of Niobium Bar Detection Results

[0081]

[0082] The data in Table 1 above shows that when using the method for efficiently preparing niobium materials provided by the present invention to prepare niobium bars, not only are the process steps simplified, that is, the steps of hydrogenation, powder making, dehydrogenation, adjusting the carbon-oxygen ratio and secondary reduction are omitted, the production cycle is shortened, the production efficiency is improved, but also the impurity contents of the prepared niobium bars are low and all meet the national standards. The purity of the niobium bars prepared by the three implementation manners listed in Examples 1 to 3 is above 99.98%, and the forming rate of the method provided by the present invention in the cold pressing forming step is higher than that of the existing methods during cold pressing forming.

[0083] As described above, the above are only specific implementation manners of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A method for efficiently preparing niobium material, characterized in that: The following steps are involved: S10. The niobium pentoxide and carbon black are fully mixed and reacted for a first time to obtain a first mixture, wherein the mass ratio of niobium pentoxide to carbon black is 10: (3 to 3.5); S20. introducing hydrogen into the graphite carbon tube furnace, and performing primary carbonization and secondary carbonization on the first mixture in the graphite carbon tube furnace to obtain niobium carbide having a nitrogen content of less than 400 ppm; S30. The niobium carbide is mechanically milled using a ball mill to obtain niobium carbide having a particle size of 1.5 μm / g to 3.0 μm / g, a flat particle shape, a uniform particle size distribution, and a particle size range of -100 to 300 mesh; S40. The ball-milled niobium carbide and niobium pentoxide are fully mixed and reacted for a second time to obtain a second mixture, wherein the mass ratio of the niobium carbide to the niobium pentoxide is (2 to 3): (1 to 1.8); S50. Granulating the second mixed material to obtain a second mixed material with a particle size of 2 μm / g to 4 μm / g; S60. Drying the second mixture; S70. Using propylene glycol as a binder, and adding it to the second mixture after drying, and cold pressing to obtain a pre-bonded niobium bar; S80. The pre-bonded niobium bar is placed in a high-temperature reduction furnace, firstly subjected to multiple low-temperature treatments to remove low-temperature impurities, and then subjected to high-temperature treatments to remove excess carbon and oxygen, to obtain a qualified niobium bar with a purity of more than 99.9%.

2. The method for efficiently preparing niobium material according to claim 1, characterized in that: The purity of the niobium pentoxide is ≥99.50%, the purity of the carbon black is ≥98.0%, and the particle size of the carbon black is -100 mesh.

3. The method for efficiently preparing niobium material according to claim 1, characterized in that: The first duration is the same as the second duration, which is 10 hours to 12 hours.

4. The method for efficiently preparing niobium material according to claim 1, characterized in that: The hydrogen flow rate is 0.3m 3 / h to 0.5m 3 / h.

5. The method for efficiently preparing niobium material according to claim 1, characterized in that: The heating temperature of the graphite carbon tube furnace is 1800°C to 2200°C.

6. The method for efficiently preparing niobium material according to claim 1, characterized in that: The added amount of propyl alcohol is 1.3% to 1.5%.

7. The method for efficiently preparing niobium material according to claim 1, characterized in that: The temperature of the drying process is 150° C. to 250° C., and the duration of the drying process is 20 min to 60 min.

8. The method for efficiently preparing niobium material according to claim 1, characterized in that: The multi-stage low temperature treatment includes a first stage low temperature treatment, a second stage low temperature treatment and a third stage low temperature treatment. The first stage low temperature treatment is: the room temperature is raised to 900°C to 1100°C at one time, the heating time is 1.9h to 2.1h, and the temperature is kept until the vacuum degree in the furnace is 28Pa to 32Pa; the second stage low temperature treatment is: 900°C to 1000°C is raised to 1200°C to 1400°C at one time, the heating time is 1.9h to 2.1h, and the temperature is kept until the vacuum degree in the furnace is The vacuum degree is 18Pa to 22Pa; the three-stage low-temperature treatment is: 1200℃ to 1400℃ once increased to 1750℃ to 1850℃, the heating time is 1.9h to 2.1h, and the vacuum degree in the furnace is kept at 9Pa to 11Pa; the high-temperature treatment is 1750℃ to 1850℃ once increased to 1900℃ to 2100℃, the heating time is 1.9h to 2.1h, and the vacuum degree in the furnace is kept at 4Pa to 6Pa.

9. The method for efficiently preparing niobium material according to claim 1, characterized in that: The multi-stage low-temperature treatment includes one-stage low-temperature treatment, two-stage low-temperature treatment and three-stage low-temperature treatment. The one-stage low-temperature treatment is: the room temperature is raised to 1000°C once, the heating time is 2 hours, and the vacuum degree in the furnace is kept at 30Pa; the two-stage low-temperature treatment is: 1000°C is raised to 1300°C once, the heating time is 2 hours, and the vacuum degree in the furnace is kept at 20Pa; the three-stage low-temperature treatment is: 1300°C is raised to 1800°C once, the heating time is 2 hours, and the vacuum degree in the furnace is kept at 10P; the high-temperature treatment is raised from 1800°C to 2000°C once, the heating time is 2 hours, and the vacuum degree in the furnace is kept at 5Pa.

10. Niobium material prepared according to the method for efficiently preparing niobium material according to any one of claims 1 to 9.

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