Preparation method of niobium alloy spherical powder

Abstract

The invention relates to the field of preparation of metal spherical powder, in particular to a preparation method of niobium alloy spherical powder, and a spherical powder preparation process including coarse powder recycling is constructed by integrating plasma rotating electrode powder preparation and induction plasma spheroidizing processes. The fine powder accounts for more than 99% of 15-53 [mu] m and can be directly used for 3D printing, and the coarse powder is more than or equal to 53 [mu] m; and carrying out hydrogenation, ball milling, secondary screening, induction plasma spheroidizing and vacuum dehydrogenation on the coarse powder, and mixing the coarse powder with the fine powder to obtain the final niobium alloy spherical powder. According to the technology, efficient preparation of the high-quality niobium alloy spherical powder is achieved, the proportion of the finished product 15-53-micron fine powder is larger than or equal to 96%, the fine powder yield is larger than or equal to 85%, the oxygen content is smaller than or equal to 250 ppm, the spheroidization rate is larger than or equal to 95%, and the technology is suitable for powder bed laser melting additive manufacturing and suitable for the fields of aerospace, nuclear power, military industry and the like.

Description

TECHNICAL FIELD

[0001] The application relates to the field of metal spherical powder preparation, in particular to a preparation method of niobium alloy spherical powder. BACKGROUND

[0002] As a relatively light refractory metal, niobium has high melting point, high specific strength, low vapor pressure, excellent cold working performance and acid and alkali corrosion resistance, and small thermal neutron capture cross section. Its alloys (such as niobium-tungsten alloy, niobium-zirconium alloy, niobium-hafnium alloy, etc.) have become important structural and functional materials in the fields of aerospace (such as high-temperature components of engines), nuclear industry (such as reactor structural components), chemical industry (such as complex thin-walled functional components), etc. With the rapid development of these fields, the market demand for niobium alloy components has also increased rapidly, and the traditional forming method of niobium alloy components is powder metallurgy, which is difficult to realize the efficient production of complex shape or thin-walled components. As a kind of layer-by-layer solidification and stacking moldless integrated forming technology (such as powder bed laser melting additive manufacturing process), the additive manufacturing technology has obvious advantages in the manufacturing of complex shape or thin-walled components, with the advantages of flexible design, short manufacturing cycle, high material utilization rate, wide application range and high forming precision. The performance requirements for raw materials are very high.

[0003] For example, when niobium alloy spherical powder is used as the raw material of the powder bed laser melting additive manufacturing process, in order to meet the adaptability of the 3D printing process and to make the printed parts have fewer defects, the particle size of the niobium alloy spherical powder is usually 15-53 μm (particle size that is too coarse is easy to cause poor interlayer bonding, and particle size that is too fine is easy to agglomerate and block the powder feeding channel), the oxygen content is ≤250 ppm (high oxygen content will cause the component to be brittle and cracked), and the spheroidization rate is ≥95% (to ensure the powder flowability and uniformity of powder laying).

[0004] However, the current mainstream preparation process of niobium alloy spherical powder often has many defects, and it is difficult to efficiently and low-cost produce niobium alloy spherical powder with excellent performance as the raw material of the powder bed laser melting additive manufacturing process.

[0005] Specifically, the current mainstream preparation process of niobium alloy spherical powder mainly includes the following two kinds: 1. Plasma rotating electrode powder preparation process This process uses a forged and machined niobium alloy rod as raw material to directly obtain spherical powder through a plasma rotating electrode device. The core advantage is high powder preparation efficiency, but the prepared spherical powder has problems such as large particle size and wide particle size distribution range (usually 20-150 μm). The yield of 15-53 μm fine powder suitable for powder bed laser melting 3D printing is usually less than 25%, and the waste of coarse powder is serious, which is difficult to meet the demand of cost control of additive manufacturing.

[0006] 2. Induction plasma spheroidization powder production process (e.g., CN120480204A) Using prepared niobium alloy billets as raw materials, non-spherical powder with suitable particle size is obtained through pretreatment processes such as hydrogenation, crushing, grinding, and sieving. Then, spherical niobium alloy powder is prepared using an induction plasma spheroidizing powder-making device. It is worth noting that although the yield of fine powder of 15-53μm exceeds 80% and the spheroidization rate is >93%, the crushing, grinding, and sieving processes are time-consuming, and the oxygen increase in the powder is large, with the oxygen content only controlled at <500ppm. At the same time, the induction plasma spheroidizing process itself has low powder-making efficiency (the powder production capacity of a single 80kW powder-making device is less than 2kg per hour).

[0007] Therefore, how to prepare high-quality niobium alloy spherical powder quickly and efficiently as a raw material for powder bed laser melting additive manufacturing, improve the industrial mass production efficiency of this raw material while reducing its industrial mass production cost, and completely break the key constraints restricting the industrialization of niobium alloy additive manufacturing, has always been a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to address the shortcomings of existing technologies by disclosing a method for preparing niobium alloy spherical powder. This method includes steps such as plasma rotating electrode powder preparation, sieving, hydrogenation, grinding and secondary sieving, inductive plasma spheroidization, and dehydrogenation. The final spherical powder has a target particle size of 15-53 μm with a powder yield of ≥85%, an oxygen content of ≤250 ppm, and a spheroidization rate of ≥95%. It also has high production efficiency, fully meets the requirements of powder bed laser melting additive manufacturing process, and satisfies the application of niobium alloy additive manufacturing technology in aerospace, nuclear power, military and other fields.

[0009] The objective of this invention is achieved through the following approach: A method for preparing niobium alloy spherical powder includes the following steps: 1) Plasma rotating electrode powder making and sieving A plasma rotating electrode powder preparation method was used to process niobium alloy rods. The electrode current was 1300–2100 A, and the rod rotation speed was 18000–30000 r / min, resulting in spherical powder. After sieving, fine powder <53 μm and coarse powder ≥53 μm were obtained. The fine powder <53 μm was used as part of the finished niobium alloy spherical powder. In the fine powder <53 μm, the powder with a particle size in the range of 15–53 μm accounted for more than 99% of the mass and could be directly used in powder bed laser melting additive manufacturing (3D printing). The coarse powder ≥53 μm required further processing to be converted into fine powder that meets the requirements of additive manufacturing.

[0010] 2) Hydrogenation, ball milling, and secondary sieving Take coarse powder with a diameter of ≥53μm, hydrogenate it to obtain hydrogenated coarse powder; ball mill it to obtain powder with a diameter of ≤80μm; sieve it to obtain powder with a diameter of 15-60μm; wherein, the mass of the obtained powder with a diameter of 15-60μm accounts for ≥85% of the total mass of all powder with a diameter of ≤80μm processed in this step (i.e., the mass ratio of powder with a diameter of 15-60μm is ≥85%).

[0011] 3) Induced plasma spheroidization Inductive plasma spheroidization is used to spheroidize powders with a particle size of 15–60 μm. The spheroidization power is 30–80 kW and the feeding rate is 35–120 g / min, resulting in fine powder with a particle size of <53 μm after spheroidization. Among the fine powder with a particle size of 15–53 μm, the percentage of powder with a particle size in the range of 15–60 μm in this step is ≥95%, and the spheroidization rate of the fine powder with a particle size of <53 μm after spheroidization is ≥95%.

[0012] 4) Dehydrogenation and Mixing After spheroidization, the <53μm fine powder is dehydrogenated, and the dehydrogenated <53μm fine powder is mixed with the <53μm fine powder obtained in step 1) to obtain the <53μm niobium alloy spherical powder product. In this <53μm niobium alloy spherical powder product, the mass proportion of powder with a size of 15~53μm is ≥96%, and the fine powder yield is ≥85%.

[0013] Through the above-mentioned ball milling, sieving, and spheroidizing, the final powder can be formed into fine powder that meets the requirements.

[0014] Preferably, the electrode current is 1500-1900A, the bar rotation speed is 23000-28000r / min, the spheroidizing power is 50-75kW, and the feeding rate is 50-100g / min.

[0015] More preferably, the electrode current is 1600-1800A, the bar rotation speed is 24000-27000r / min, the spheroidizing power is 60-70kW, and the feeding rate is 60-90g / min.

[0016] Through long-term practical verification by the applicant, it has been found that the range of values ​​for the key process parameters in this invention is directly related to the core performance of the prepared powder, with the specific effects as follows: 1. Plasma rotating electrode powder preparation process The bar stock rotation speed and electrode current are the core parameters affecting powder particle size and fine powder yield, and different value ranges correspond to significantly different effects: When the bar rotation speed is <18000 r / min, the molten droplets cannot detach from the bar in time due to insufficient centrifugal force, resulting in larger powder particle size. The yield of fine powder <53μm is very low, and most powder still requires subsequent hydrogenation, grinding, crushing, spheroidizing and other processes, which cannot reflect the high efficiency of plasma rotating electrode powder making process. When the bar rotation speed is >30000 r / min, the speed is close to the upper limit of equipment operation, the equipment is overloaded, and the excessive centrifugal force makes the bar prone to edge flipping (i.e. the incompletely melted part at the front end of the bar deforms under the action of centrifugal force, but cannot completely detach from the bar, resulting in a significant increase in the diameter of the front end). The stability of the production process is significantly reduced, continuous and efficient powder making cannot be achieved, and it is easy to cause equipment wear and raw material waste. When 18000r / min < bar stock speed < 30000r / min, the equipment can operate basically stably, and the molten droplets can form spherical powder under reasonable centrifugal force. When 23000r / min < bar stock speed < 28000r / min, the powder particle size distribution is more concentrated, the average powder particle size is reduced, and the yield of fine powder <53μm is further improved, effectively reducing the time, energy consumption and cost of subsequent processing steps, while the equipment operation is also more stable. When 24000 r / min < bar speed < 27000 r / min, the powder particle size distribution reaches the optimal state, the yield of fine powder < 53 μm is the highest, and the proportion of powder with target particle size of 15~53 μm can be stably maintained at a high level. This part of the powder can be directly adapted to the powder bed laser melting additive manufacturing process without additional optimization, and the overall powder production efficiency and raw material utilization rate are optimal.

[0017] In addition, the influence of electrode current is consistent with the bar stock rotation speed. That is, when it exceeds the range of 1300 to 2100 A, the production stability decreases and the fine powder yield is extremely low. When it is in the range of 1500 to 1900 A, the powder particle size and yield are gradually optimized. When it is in the range of 1600 to 1800 A, the overall performance of the powder is the best.

[0018] 2. Induction Plasma Spheroidization Process Spheroidizing power and feeding rate are the core parameters affecting powder spheroidization rate, and different value ranges correspond to significantly different effects: When the spheroidizing power is <30kW or the feeding rate is >120g / min, the powder particles cannot be fully and uniformly melted, and a large portion of the powder cannot be spheroidized, resulting in a decrease in sphericity and a significant reduction in the spheroidization rate, failing to meet the requirement of a finished product spheroidization rate ≥95%. When the spheroidizing power is >80kW or the feeding rate is <35g / min, the energy supply inside the induction plasma torch is too high, and the powder is heated to a higher temperature, causing the powder to not solidify before reaching the lower part of the spheroidizing chamber, resulting in molten powder adhering to the wall surface, affecting the smooth progress of spheroidization, and causing significant damage to the equipment.

[0019] When 30kW < spheroidizing power < 80kW and 35g / min < feeding rate < 120g / min, the equipment can operate stably and most powders can be spheroidized; when 50kW < spheroidizing power < 75kW and 50g / min < feeding rate < 100g / min, the powder spheroidization rate is further improved. When 60kW < spheroidizing power < 70kW and 60g / min < feeding rate < 90g / min, a stable spheroidization rate of ≥ 95% can be achieved.

[0020] In step 1), the mass fraction of niobium in the niobium alloy rod is ≥90%.

[0021] In step 1), the sieving process uses a 270-mesh sieve with an aperture of 53 μm.

[0022] In step 2), the hydrogenation process is as follows: hydrogenation temperature 400-600℃, hydrogenation time 4-6h, and hydrogen pressure 1.2-1.3atm.

[0023] In step 2), the ball milling time is 10 to 12 hours.

[0024] In step 2), the sieving process uses a 250-mesh sieve with a aperture of 60μm.

[0025] In step 4), the dehydrogenation process is as follows: vacuum dehydrogenation, with a vacuum degree ≤ 0.01 Pa and a dehydrogenation temperature of 700~800℃.

[0026] The advantages of this invention are: This invention utilizes a plasma rotating electrode for rapid powder production, precisely screening the powder (<53μm) through a 270-mesh sieve to obtain fine powder suitable for direct 3D printing (of which, fine powder with a particle size of 15-53μm accounts for >99%). Only the coarse powder (≥53μm) undergoes further processing: First, the coarse powder (≥53μm) is hydrogenated to obtain brittle hydrides, facilitating subsequent ball milling. Second, after ball milling and sieving, irregular powder of 15-60μm is obtained, followed by inductive plasma spheroidization to obtain spherical powder of <53μm fine powder. Finally, hydrogen is removed from the powder through dehydrogenation. This process significantly improves the fine powder yield (the proportion of 15-53μm fine powder in the total powder). Compared with traditional plasma rotating electrode powder production processes, the method described in this invention achieves a fine powder yield of ≥85%, significantly reducing raw material waste and realizing efficient utilization of raw materials.

[0027] In addition, compared with the traditional induction plasma spheroidization powder production process, this process takes less time for crushing, grinding and sieving, has higher powder production efficiency, and effectively controls the oxygen increase of the powder during the process. The final fine powder has a lower oxygen content (powder oxygen content ≤250ppm). When the powder is used in additive manufacturing, it can effectively avoid component embrittlement and cracking, improve component performance, and optimize powder performance while improving powder production efficiency.

[0028] According to the applicant's testing, the performance indicators of the spherical powder prepared by the method described in this invention are as follows: ① The yield of 15-53μm fine powder is ≥85% (Detection method: The particle size distribution of spherical powder is detected by a Macchick S3500 laser particle size analyzer, and the ratio of the mass of 15-53μm powder to the initial total powder mass (i.e., the total powder mass obtained by plasma rotating electrode powder preparation) is calculated). ② The sphericity of the powder produced in the plasma rotating electrode powder preparation process is ≥99%; ③ The spheroidization rate of the powder produced in the inductive plasma spheroidization process is ≥95%; ④ The powder produced in the plasma rotating electrode powder preparation stage and the powder produced in the inductive plasma spheroidization stage are mixed, and the spheroidization rate of the resulting product is ≥95% (Detection method: under FEI Inspect F50 scanning electron microscope at 200x magnification, three fields of view of the same size are randomly selected, the ratio of spherical particles to total particles in each field of view is counted, and the average of the three is taken as the final spheroidization rate). ⑤ Powder oxygen content ≤250ppm (Test standard: based on GB / T 15076.14-2008 "Determination of Oxygen Content by Chemical Analysis Methods for Tantalum and Niobium").

[0029] This process can stably and efficiently produce niobium alloy spherical powder with high yield, high sphericity, and low oxygen content. It is suitable for additive manufacturing of niobium alloy components in aerospace, chemical, military, and nuclear power industries, and has broad application prospects. Attached Figure Description

[0030] Fig. 1 This is a flowchart of the method for preparing niobium alloy spherical powder in this invention; Fig. 2 This is a scanning electron microscope image of niobium alloy spherical powder prepared by the plasma rotating electrode in step 1) of this invention; Fig. 3 This is a scanning electron microscope image of niobium alloy spherical powder prepared by inductive plasma spheroidization in step 3) of this invention. Detailed Implementation

[0031] like Figs. 1 to 3 As shown, a method for preparing niobium alloy spherical powder includes the following steps: 1) Plasma rotating electrode powder preparation Using niobium alloy rods with a diameter of 50 mm (niobium content ≥90% by mass) as raw material, a plasma rotating electrode powder-making device is used to melt and atomize the niobium alloy rods. The process parameters are: electrode current 1300–2100 A, preferably 1500–1900 A, more preferably 1600–1800 A; rod rotation speed 18000–30000 r / min, preferably 23000–28000 r / min, more preferably 24000–27000 r / min. The plasma melts the end of the rod, and the molten droplets separate from the rod under centrifugal force, quickly forming spherical niobium alloy powder. Compared with the traditional plasma rotating electrode powder-making process, this method significantly shortens the powder-making time, significantly reduces the oxygen adsorption time of niobium alloy powder during the preparation process, and effectively reduces the oxygen increment.

[0032] 2) Screening Niobium alloy spherical powder was sieved using a 270-mesh sieve with a aperture of 53 μm to obtain fine powder <53 μm and coarse powder ≥53 μm.

[0033] 3) Hydrogenation Coarse powder with a diameter of ≥53μm is placed in a hydrogenation furnace for hydrogenation treatment. The treatment is carried out continuously for 4 to 6 hours at a temperature of 400 to 600℃ and a hydrogen atmosphere of 1.2 to 1.3 atm. The niobium alloy reacts with hydrogen to form brittle hydrides, resulting in hydrogenated coarse powder suitable for subsequent grinding processes.

[0034] If the coarse powder is not hydrogenated, it will be too tough and cannot be effectively broken down if it is directly ground in the subsequent step 4). The hydrogenation treatment causes the niobium alloy to react with hydrogen to form brittle hydrides, which can significantly improve the grinding performance of coarse powder with a diameter of ≥53μm and ensure the smooth progress of the grinding process in step 4).

[0035] 4) Ball milling and secondary screening The hydrogenated coarse powder was ball-milled using a ball milling device at a speed of 400 r / min for 10–12 h until the powder particle size was ≤80 μm. Then, a 250-mesh sieve with a 60μm aperture is used to sieve the powder with a diameter of ≤80μm to obtain powder with a diameter of 15-60μm.

[0036] 5) Induced plasma spheroidization Powder with a particle size of 15–60 μm is subjected to induction plasma spheroidization treatment. The process parameters are as follows: spheroidization power 30–80 kW, preferably 50–75 kW, more preferably 60–70 kW; feeding rate 35–120 g / min, preferably 50–100 g / min, more preferably 60–90 g / min. The strong thermal effect of high-temperature plasma fully and uniformly melts the 15–60 μm powder particles. Under the influence of the surface tension of the molten particles, precise control of the powder particle size and uniform and regularized morphology are achieved, resulting in spherical fine powder with a particle size of <53 μm after spheroidization.

[0037] 6) Dehydrogenation and Mixing After spheroidization, the <53μm fine powder is placed in a vacuum furnace and dehydrogenated under vacuum conditions ≤0.01Pa and temperature conditions of 700-800℃. This process efficiently removes residual hydrogen in the <53μm spherical fine powder in gaseous form, while simultaneously isolating the fine powder from air oxidation, preventing oxidation of the fine powder with oxygen during the dehydrogenation process. This ensures that the oxygen content of the fine powder is stably controlled at ≤250ppm, ultimately yielding <53μm fine powder with qualified hydrogen content and no oxidation pollution after dehydrogenation.

[0038] Subsequently, the <53μm fine powder after dehydrogenation is thoroughly mixed with the <53μm fine powder obtained by sieving in step 2) to finally obtain the <53μm niobium alloy spherical powder product. The mass ratio of 15-53μm powder in the finished product is ≥96%, and the fine powder yield is ≥85%, which fully meets the core requirements of powder particle size and performance for powder bed laser melting additive manufacturing.

[0039] The following is an example of implementing the method described above: Example 1

[0040] 1. Plasma rotating electrode powder preparation Using niobium-zirconium (Nb-1%Zr) alloy rods with a diameter of 50 mm as raw material, the niobium alloy rods were processed using a plasma rotating electrode device. During processing, the electrode current was 1800 A and the rod rotation speed was 24000 r / min, resulting in spherical niobium alloy powder.

[0041] 2. Screening The niobium alloy spherical powder was sieved using a 270-mesh sieve with a aperture of 53μm, and the niobium alloy spherical powder was divided into two parts: ≥53μm and <53μm.

[0042] Fine powder with a diameter of <53μm is part of the finished niobium spherical powder product. Among them, fine powder with a diameter of 15-53μm accounts for ≥99% and can be directly used for 3D printing. Coarse powder with a diameter of ≥53μm requires subsequent processing.

[0043] 3. Hydrogenation Coarse powder with a particle size of ≥53μm was placed in a hydrogenation furnace for hydrogenation treatment. The hydrogenation temperature was controlled at 400℃, the hydrogen pressure at 1.2atm, and the hydrogenation time at 6h to obtain hydrogenated coarse powder.

[0044] 4. Grinding and secondary sieving The hydrogenated coarse powder was ground using a ball mill for 10 hours at a speed of 400 r / min until the powder particle size was ≤80 μm. Then, the ≤80 μm powder was sieved using a 250-mesh sieve with a 60 μm aperture to obtain powder of 15–60 μm, which accounted for 85% of the mass of the sieved powder.

[0045] 5. Induced plasma spheroidization Powder with a particle size of 15–60 μm was subjected to induction plasma spheroidization treatment at a power of 60 kW and a feed rate of 60 g / min to obtain fine powder with a particle size of <53 μm after spheroidization. In this fine powder with a particle size of <53 μm, 95% of the powder has a particle size range of 15–53 μm, and the spheroidization rate is ≥95%.

[0046] 6. Dehydrogenation After spheroidization, the <53μm fine powder was placed in a vacuum furnace for dehydrogenation treatment at a temperature of 700℃ and a vacuum degree of ≤0.01Pa, resulting in dehydrogenated <53μm fine powder.

[0047] The dehydrogenated <53μm fine powder is mixed evenly with the <53μm fine powder obtained by sieving in step 2) to obtain the final niobium alloy spherical powder product.

[0048] The niobium alloy spherical powder product prepared by the method described in Example 1 exhibits excellent core performance indicators: the mass ratio of fine powder in the target particle size range of 15-53 μm is 96.7%, the fine powder yield is 89.2%, the powder spheroidization rate is 95.5%, and the powder oxygen content is 230 ppm. Example 2

[0049] 1. Plasma rotating electrode powder preparation Using Nb521 alloy bars with a diameter of 50 mm (niobium mass fraction > 91%) as raw material, the niobium alloy bars were processed using a plasma rotating electrode device. During processing, the electrode current was 1600 A and the bar rotation speed was 27000 r / min to obtain niobium alloy spherical powder.

[0050] 2. Screening The niobium alloy spherical powder was sieved using a 270-mesh sieve with a aperture of 53μm, and the niobium alloy spherical powder was divided into two parts: ≥53μm and <53μm.

[0051] Fine powder with a diameter of <53μm is part of the finished niobium spherical powder product. Among them, fine powder with a diameter of 15-53μm accounts for ≥99% and can be directly used for 3D printing. Coarse powder with a diameter of ≥53μm requires subsequent processing.

[0052] 3. Hydrogenation Coarse powder with a particle size of ≥53μm was placed in a hydrogenation furnace for hydrogenation treatment. The hydrogenation temperature was controlled at 600℃, the hydrogen pressure at 1.3atm, and the hydrogenation time at 4h to obtain hydrogenated coarse powder.

[0053] 4. Grinding and secondary sieving The hydrogenated coarse powder was ground using a ball mill for 12 hours at a speed of 400 r / min until the powder particle size was ≤80 μm. Then, the ≤80 μm powder was sieved using a 250-mesh sieve with a 60 μm aperture to obtain powder of 15–60 μm, which accounted for 86% of the mass of the sieved powder.

[0054] 5. Induced plasma spheroidization Powder with a particle size of 15–60 μm was subjected to induction plasma spheroidization treatment at a power of 70 kW and a feed rate of 90 g / min to obtain fine powder with a particle size of <53 μm after spheroidization. Of this fine powder with a particle size range of 15–53 μm, 97% had a spheroidization rate of ≥95%.

[0055] 6. Dehydrogenation After spheroidization, the <53μm fine powder was placed in a vacuum furnace for dehydrogenation treatment at a temperature of 800℃ and a vacuum degree of ≤0.01Pa, resulting in dehydrogenated <53μm fine powder.

[0056] The dehydrogenated <53μm fine powder is mixed evenly with the <53μm fine powder obtained by sieving in step 2) to obtain the final niobium alloy spherical powder product.

[0057] The niobium alloy spherical powder product prepared by the method described in Example 2 exhibits excellent core performance indicators: the mass ratio of fine powder in the target particle size range of 15-53 μm is 97.7%, the fine powder yield is 89.9%, the powder spheroidization rate is 95.0%, and the powder oxygen content is 200 ppm. Example 3

[0058] 1. Plasma rotating electrode powder preparation Using Nb521 alloy bars with a diameter of 50 mm (niobium mass fraction > 91%) as raw material, the niobium alloy bars were processed using a plasma rotating electrode device. During processing, the electrode current was 1700 A and the bar rotation speed was 25500 r / min to obtain niobium alloy spherical powder.

[0059] 2. Screening The niobium alloy spherical powder was sieved using a 270-mesh sieve with a aperture of 53μm, and the niobium alloy spherical powder was divided into two parts: ≥53μm and <53μm.

[0060] Fine powder with a diameter of <53μm is part of the finished niobium spherical powder product. Among them, fine powder with a diameter of 15-53μm accounts for ≥99% and can be directly used for 3D printing. Coarse powder with a diameter of ≥53μm requires subsequent processing.

[0061] 3. Hydrogenation Coarse powder with a particle size of ≥53μm was placed in a hydrogenation furnace for hydrogenation treatment. The hydrogenation temperature was controlled at 500℃, the hydrogen pressure at 1.2atm, and the hydrogenation time at 5h to obtain hydrogenated coarse powder.

[0062] 4. Grinding and secondary sieving The hydrogenated coarse powder was ground using a ball mill for 11 hours at a speed of 400 r / min until the powder particle size was ≤80 μm. Then, the ≤80 μm powder was sieved using a 250-mesh sieve with a 60 μm aperture to obtain powder of 15–60 μm, which accounted for 85% of the mass of the sieved powder.

[0063] 5. Induced plasma spheroidization Powder with a particle size of 15–60 μm was subjected to induction plasma spheroidization treatment at a power of 65 kW and a feed rate of 75 g / min to obtain fine powder with a particle size of <53 μm after spheroidization. In this fine powder with a particle size of <53 μm, 97% of the powder has a particle size range of 15–53 μm, and the spheroidization rate is ≥95%.

[0064] 6. Dehydrogenation After spheroidization, the <53μm fine powder was placed in a vacuum furnace for dehydrogenation treatment at a temperature of 750℃ and a vacuum degree of ≤0.01Pa, resulting in dehydrogenated <53μm fine powder.

[0065] The dehydrogenated <53μm fine powder is mixed evenly with the <53μm fine powder obtained by sieving in step 2) to obtain the final niobium alloy spherical powder product.

[0066] The niobium alloy spherical powder product prepared by the method described in Example 3 exhibits excellent core performance indicators: the mass ratio of fine powder in the target particle size range of 15-53 μm is 97.6%, the fine powder yield is 89.2%, the powder spheroidization rate is 96.1%, and the powder oxygen content is 240 ppm.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing niobium alloy spherical powder, characterized in that, The method comprises the following steps: 1) processing the niobium alloy rod by using the plasma rotating electrode powdering method, the electrode current is 1300-2100 A, the rod rotating speed is 18000-30000 r / min, and spherical powder is obtained; screening is performed to obtain <53 μm fine powder and ≥53 μm coarse powder respectively; 2) taking the ≥53 μm coarse powder, hydrogenation is performed to obtain hydrogenated coarse powder; ball milling is performed until ≤80 μm powder is obtained; screening is performed to obtain 15-60 μm powder; 3) using the induction plasma spheroidization method, the 15-60 μm powder is spheroidized, the spheroidization power is 30-80 kW, the feeding speed is 35-120 g / min, and <53 μm fine powder after spheroidization is obtained; 4) the <53 μm fine powder after spheroidization is dehydrogenated to obtain <53 μm fine powder after dehydrogenation, and the <53 μm fine powder after dehydrogenation is mixed with the <53 μm fine powder obtained in step 1) to obtain <53 μm niobium alloy spherical powder.

2. The production method according to claim 1, characterized by, The electrode current is 1500-1900 A, the rod rotating speed is 23000-28000 r / min, the spheroidization power is 50-75 kW, and the feeding speed is 50-100 g / min.

3. The production method according to claim 2, characterized by, The electrode current is 1600-1800 A, the rod rotating speed is 24000-27000 r / min, the spheroidization power is 60-70 kW, and the feeding speed is 60-90 g / min.

4. The method of claim 1, wherein, In step 1), the mass fraction of niobium element in the niobium alloy rod is ≥90%.

5. The preparation method according to claim 1, characterized in that, In step 1), the screening is performed by using a 270-mesh sieve with a pore size of 53 μm.

6. The method of claim 1, wherein, In step 2), the hydrogenation treatment mode is as follows: the hydrogenation temperature is 400-600 ℃, the hydrogenation time is 4-6 h, and the hydrogen pressure is 1.2-1.3 atm.

7. The preparation method according to claim 1, characterized in that, In step 2), the ball milling time is 10-12 h.

8. The method of claim 1, wherein, In step 2), the screening is performed by using a 250-mesh sieve with a pore size of 60 μm.

9. The method of claim 1, wherein, In step 4), the dehydrogenation treatment mode is as follows: vacuum dehydrogenation is performed, the vacuum degree is ≤0.01 Pa, and the dehydrogenation temperature is 700-800 ℃.

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