Rhenium alloy spherical powder, preparation method and application
By combining liquid-phase blending and radio-frequency plasma spheroidization with a two-stage hydrogen reduction process, rhenium alloy spherical powder with high sphericity and low oxygen content was prepared. This solved the problems of difficult forming and impurity contamination of rhenium alloy powder in traditional processes, and enabled the 3D printing of high-density rhenium alloy parts, thereby improving material properties and industrialization capabilities.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-13
- Publication Date
- 2026-04-14
AI Technical Summary
Existing technologies make it difficult to prepare rhenium alloy spherical powders with high sphericity, high purity, and low oxygen content. Furthermore, traditional powder sintering processes suffer from problems such as difficulty in controlling porosity, impurity contamination, and difficulty in sintering large blocks, which affect the performance and industrialization process of rhenium alloy parts.
Precursor powder was prepared by liquid-phase blending and vacuum drying, followed by a two-stage hydrogen reduction process of low-temperature deammoniation/impurity removal and high-temperature crystallization/alloying. Then, radio frequency plasma spheroidization was performed to prepare rhenium alloy spherical powder with high sphericity and low oxygen content. Rhenium alloy parts with complex shapes were then prepared by selective laser melting 3D printing technology.
It achieves high sphericity, low oxygen, and high purity of rhenium alloy powder, is compatible with SLM process, has high printing density, and significantly improves high-temperature strength, ductility, and thermal stability. It breaks through the technical bottleneck of refractory rhenium alloy powder preparation and has repeatability and industrialization potential.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of alloy powder technology, and more specifically, to rhenium alloy spherical powder, its preparation method, and its application. Background Technology
[0002] Rhenium alloys are a class of alloys with tungsten or molybdenum as the main element. Taking rhenium-tungsten alloys as an example, tungsten is the metal with the highest melting point (approximately 3422℃), with high density, good thermal conductivity, and high elastic modulus, but it suffers from drawbacks such as low-temperature brittleness, a high ductile-brittle transition temperature (DBTT), and recrystallization brittleness. The addition of rhenium can lower the DBTT of tungsten, improve ductility, and change the yield strength, a phenomenon known as the "rhenium effect." Tungsten-rhenium (W-Re) alloys possess better high-temperature resistance, ductility, low vapor pressure, low electron work function, and a low ductile-brittle transition temperature. They are widely used in high-temperature equipment such as thermionic converters and heaters in space nuclear reactors, rotating anode targets in the core components of medical CT tubes, thermocouples for temperature measurement of hot components in aero-engines, and the first wall structural materials of high-temperature plasma in nuclear fusion devices.
[0003] However, rhenium alloy parts are currently mainly made by powder metallurgy and spark plasma sintering (SPS). In the traditional powder sintering process for manufacturing tungsten rhenium parts, it is difficult to control the porosity and distribution of the parts. In addition, the addition of binders brings impurities to the parts, affecting their performance. Furthermore, it is difficult to sinter large blocks, making it difficult to move towards industrialization.
[0004] In view of this, the present invention is proposed. Summary of the Invention
[0005] The purpose of this invention is to provide rhenium alloy spherical powder, preparation method and application, and to provide a rhenium alloy spherical powder with high sphericity, high purity and low oxygen content.
[0006] This invention is implemented as follows: In a first aspect, the present invention provides a method for preparing rhenium alloy spherical powder, comprising: The precursor powder is obtained by reacting and drying a metal ammonium acid solution containing ammonium perrylate; the metal ammonium acid solution also includes at least one of ammonium molybdate and ammonium tungstate. The precursor powder was subjected to a first stage of hydrogen reduction and a second stage of hydrogen reduction to obtain rhenium alloy pre-alloy powder; the first stage of hydrogen reduction was carried out at 300-450℃ for 1-2 hours, and the second stage of hydrogen reduction was carried out at 700-1100℃ for 1-3 hours. The rhenium alloy pre-alloyed powder is spheroidized by radio frequency plasma to obtain the rhenium alloy spherical powder.
[0007] In an optional embodiment, the reaction temperature is 100-150℃, the reaction time is 2-5h, and the reaction is carried out under stirring conditions at a stirring rate of 100-200rpm. And / or, the solute content in the ammonium metal oxide solution is 30-150 g / ml.
[0008] In an optional embodiment, the rhenium alloy pre-alloyed powder comprises, by mass percentage, 75wt%≤W≤99wt% and 1≤Re≤25wt%. Alternatively, the rhenium alloy pre-alloyed powder comprises, by mass percentage, 60wt%≤Mo≤98wt% and 2≤Re≤40wt%.
[0009] In an optional embodiment, the hydrogen flow rate in both the first stage of hydrogen reduction and the second stage of hydrogen reduction is 1-5 L / min; And / or, both the first stage of hydrogen reduction and the second stage of hydrogen reduction are performed under a vacuum of less than 10. -3 The experiment was conducted under the condition of Pa.
[0010] In an optional embodiment, the heating rate of the first stage of hydrogen reduction is 5-10 °C / min; And / or, the heating rate of the second stage hydrogen reduction is 5-10℃ / min; And / or, after the second stage of hydrogen reduction, the temperature is first lowered to below 500°C at a rate of 5-10°C / min, and then further lowered to below 50°C in the furnace.
[0011] In an optional embodiment, in the radio frequency plasma spheroidization step, the plasma edge gas flow rate is 40-75 L / min, and the plasma edge gas is a mixture of hydrogen and argon with a volume ratio of 0.05-0.15:1; the power of the plasma spheroidization device is 15-100 kW; the powder feed rate is 0.1-100 g / min; the flow rate of the center gas is 10-25 L / min, and the center gas is argon; the reaction chamber pressure is 12.5-15 psi. And / or, the plasma spheroidizing treatment is performed at a temperature of 8000-12000℃ and a reaction pressure of 0.01-0.15MPa.
[0012] Secondly, the present invention provides a rhenium alloy spherical powder with a particle size of 15-53 μm, a powder sphericity ≥95%, an oxygen content ≤70ppm, and a purity ≥99.99%.
[0013] Thirdly, the present invention provides a method for 3D printing using rhenium alloy spherical powder as described in any one of the preceding claims, comprising: selectively melting the rhenium alloy spherical powder with a laser to form rhenium alloy printed parts.
[0014] In an optional implementation, the power of the laser selective melting forming is 250-400W, the scanning speed is 200-700mm / s, the laser strip spacing is 0.05-0.15mm, and the powder thickness is 30-60µm; And / or, the power of laser selective melting is 300-400W, the scanning speed is 400-600mm / s, the laser strip spacing is 0.07-0.12mm, and the powder thickness is 10-50µm; And / or, the density of the rhenium alloy printed parts is ≥99%.
[0015] Fourthly, the present invention provides a rhenium alloy printed part, which is prepared by the 3D printing method of rhenium alloy spherical powder described in the foregoing embodiments.
[0016] The present invention has the following beneficial effects: This application employs liquid-phase blending followed by vacuum drying to prepare the precursor, avoiding component segregation and impurity introduction that are prone to occur with spray drying. This ensures that alloying elements are uniformly mixed at the atomic level, laying the foundation for the subsequent formation of high-solid-solid-content pre-alloyed powder. Furthermore, the two-stage hydrogen reduction process—low-temperature deammoniation / impurity removal followed by high-temperature crystallization / alloying—significantly improves reduction efficiency and phase purity, effectively eliminating NH4 compared to single-stage reduction. + The residual WO3 / MoO3 intermediate oxides are used to obtain pre-alloyed powder with lower oxygen content and more uniform grain size. Overall, this method overcomes the technical bottlenecks in the preparation of refractory rhenium alloy powder, namely "uneven composition, high oxygen content, poor sphericity, and difficulty in SLM forming", and has the advantages of repeatability, controllable parameters, and industrialization potential. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.
[0018] Selective laser melting (SLM) provides a new approach for the fabrication of complex-shaped rhenium alloy parts. To improve the mechanical properties of rhenium alloys, this invention focuses on optimizing raw material powders. It prepares precursor powders through wet chemical methods and high-temperature hydrogen reduction, and then prepares low-oxygen, high-purity spherical tungsten-rhenium powders by combining radio frequency plasma spheroidization technology. Finally, it uses selective laser melting (SLM) 3D printing technology to fabricate complex-shaped rhenium alloy parts.
[0019] This invention provides a method for preparing rhenium alloy spherical powder, comprising: The precursor powder is obtained by reacting and drying a metal ammonium acid solution containing ammonium perrylate; the metal ammonium acid solution also includes at least one of ammonium molybdate and ammonium tungstate. The precursor powder was subjected to a first stage of hydrogen reduction and a second stage of hydrogen reduction to obtain rhenium alloy pre-alloy powder; the first stage of hydrogen reduction was carried out at 300-450℃ for 1-2 hours, and the second stage of hydrogen reduction was carried out at 700-1100℃ for 1-3 hours. The rhenium alloy pre-alloyed powder is spheroidized by radio frequency plasma to obtain the rhenium alloy spherical powder.
[0020] This application employs liquid-phase blending followed by vacuum drying to prepare the precursor, avoiding component segregation and impurity introduction that are prone to occur with spray drying. This ensures that alloying elements are uniformly mixed at the atomic level, laying the foundation for the subsequent formation of high-solid-solid-content pre-alloyed powder. Furthermore, the two-stage hydrogen reduction process—low-temperature deammoniation / impurity removal followed by high-temperature crystallization / alloying—significantly improves reduction efficiency and phase purity, effectively eliminating NH4 compared to single-stage reduction. + The residual WO3 / MoO3 intermediate oxides are used to obtain pre-alloyed powder with lower oxygen content and more uniform grain size. Overall, this method overcomes the technical bottlenecks in the preparation of refractory rhenium alloy powder, namely "uneven composition, high oxygen content, poor sphericity, and difficulty in SLM forming", and has the advantages of repeatability, controllable parameters, and industrialization potential.
[0021] In an optional embodiment, the reaction temperature is 100-150℃, the reaction time is 2-5h, and the reaction is carried out under stirring conditions at a stirring rate of 100-200rpm. The combination of moderate temperature, reasonable reaction time, and stirring rate enables the precursor to achieve deep mixing and chemical bonding preparation of tungsten, molybdenum, and rhenium components at the molecular / ionic scale, significantly improving the alloying efficiency and phase purity in the subsequent hydrogen reduction stage. It also provides a raw material base with uniform composition, moderate particle size, and good dispersibility for radio frequency plasma spheroidization, ultimately supporting the reproducible preparation of high-density, high-performance rhenium alloy additive manufacturing parts.
[0022] In an optional embodiment, the solute content in the ammonium metal oxide solution is 30-150 g / ml; this is beneficial for uniform dispersion of the reaction system and fine and controllable precipitation of the precursor, providing a reliable raw material basis for obtaining rhenium alloy powder with uniform composition, good flowability, and excellent spheroidization response.
[0023] In an optional embodiment, the rhenium alloy pre-alloyed powder comprises, by mass percentage, 75wt%≤W≤99wt% and 1≤Re≤25wt%; this composition range covers the synergistic requirements of aerospace hot-end components and nuclear energy converters for high-temperature strength, ductility, and ductile-brittle transition temperature. Low Re content (1–5wt%) focuses on grain boundary strengthening and recrystallization inhibition; high Re content (15–25wt%) significantly activates the "rhenium effect," improving plasticity and creep resistance. The wide range design accommodates performance tuning for different service scenarios, while still ensuring solid solution homogeneity and SLM forming stability under this process.
[0024] Alternatively, the rhenium alloy pre-alloyed powder, by mass percentage, comprises 60wt%≤Mo≤98wt% and 2≤Re≤40wt%. This formulation is suitable for applications such as medical targets and high-temperature sensors that have differentiated requirements for density, thermal conductivity, and electron emission characteristics. Medium to low Mo ratios (60–80wt%) enhance high-temperature strength and thermal shock resistance; high Mo ratios (>90wt%) balance processability and cost. The extended Re content gradient effectively controls the room-temperature brittleness and high-temperature softening behavior of the Mo matrix, broadening the application boundaries of refractory alloys in precision functional components.
[0025] In an optional implementation, the hydrogen flow rate in both the first and second stages of hydrogen reduction is 1-5 L / min, which helps to ensure the stability of the atmosphere and the consistency of mass transfer in the two reduction processes, and avoids powder splashing or uneven reduction caused by sudden changes in airflow.
[0026] In an optional embodiment, both the first stage of hydrogen reduction and the second stage of hydrogen reduction are performed under a vacuum degree of less than 10. -3 The process is carried out under Pa conditions, which helps to eliminate interfering gases, ensures efficient impurity removal of hydrogen in the low-temperature section and deep alloying in the high-temperature section, and synergistically realizes the controllable conversion of precursor into high-purity, low-oxygen, uniform solid solution pre-alloyed powder, providing a clean and highly active raw material prerequisite for subsequent spheroidization and SLM forming.
[0027] In an optional embodiment, the heating rate of the first stage of hydrogen reduction is 5-10 °C / min.
[0028] In an optional embodiment, the heating rate of the second stage hydrogen reduction is 5-10 °C / min.
[0029] The above heating rate ensures that the stepwise reactions such as ammonium salt decomposition and intermediate oxide reduction are carried out fully, while avoiding excessively rapid temperature rise that could lead to powder cracking or component segregation.
[0030] In an optional embodiment, after the second stage of hydrogen reduction, the temperature is first lowered to below 500°C at a rate of 5-10°C / min, and then further lowered to below 50°C in the furnace. This effectively suppresses the non-equilibrium precipitation or microcracks of the high-temperature phase during rapid cooling, promotes grain stress release and structural relaxation, and improves the phase stability, chemical homogeneity, and melt response consistency of the pre-alloyed powder during the subsequent spheroidization process.
[0031] In an optional embodiment, in the radio frequency plasma spheroidizing step, the plasma edge gas flow rate is 40-75 L / min, and the plasma edge gas is a mixture of hydrogen and argon with a volume ratio of 0.05-0.15:1, preferably 0.15:1; the power of the plasma spheroidizing device is 15-100 kW; the powder feed rate is 0.1-100 g / min; the flow rate of the center gas is 10-25 L / min, and the center gas is argon; the reaction chamber pressure is 12.5-15 psi.
[0032] By limiting the aforementioned parameters within a reasonable range during the radio frequency plasma spheroidization step, it is beneficial to ensure sufficient droplet spheroidization and rapid quenching, resulting in rhenium alloy powder with high sphericity, low oxygen, and high density, significantly improving the uniformity of SLM powder spreading and the stability of the molten pool. It is particularly noteworthy that the introduction of H2 edge gas during the radio frequency plasma spheroidization process, at ultra-high temperatures of 8000–12000 K, not only enhances heat conduction and promotes spheroidization driven by the surface tension of the molten droplets, but also utilizes the strong affinity of H for O to achieve "in-situ deoxidation," equivalent to a third deep reduction. This facilitates achieving powder oxygen content as low as 60–70 ppm, purity of 99.99%, and sphericity ≥95%.
[0033] In an optional embodiment, the plasma spheroidization treatment is carried out at a temperature of 8000-12000℃ and a reaction pressure of 0.01-0.15MPa.
[0034] The ultra-high temperature of 8000–12000℃ is conducive to ensuring the instantaneous complete melting of the refractory W / Mo–Re system, with surface tension dominating spheroidization; the pressure range of 0.01–0.15MPa takes into account both the stability of the plasma torch and the droplet flight / cooling kinetics—too low a pressure leads to excessive heat dissipation and insufficient spheroidization, while too high a pressure inhibits droplet contraction. The synergistic effect of temperature and pressure is conducive to achieving efficient spheroidization and internal densification of high-melting-point alloy powders, providing a key raw material basis for SLM with excellent flowability, high packing density, and consistent molten pool response.
[0035] The present invention also provides a rhenium alloy spherical powder with a particle size of 15-53 μm, a powder sphericity ≥95%, an oxygen content ≤70ppm, and a purity ≥99.99%.
[0036] The rhenium alloy spherical powder prepared in this application has the characteristics of high sphericity, low oxygen, and high purity, and has excellent flowability and powder uniformity. It is suitable for SLM process, with a printing density of over 99.4%, and a dense and non-porous microstructure, which significantly improves high-temperature strength, ductility and thermal stability.
[0037] The present invention also provides a method for 3D printing using rhenium alloy spherical powder as described in any one of the foregoing claims, comprising: selectively melting the rhenium alloy spherical powder with a laser to form rhenium alloy printed parts.
[0038] In an optional implementation, the power of laser selective melting forming is 250-400W, the scanning speed is 200-700mm / s, the laser strip spacing is 0.05-0.15mm, and the powder thickness is 30-60µm. It is adapted to the high melting point and high thermal conductivity characteristics of tungsten-based materials. The medium-high power and medium-speed scanning balance the melting depth and heat dissipation. The relatively wide strip spacing and powder thickness take into account the forming efficiency and interlayer bonding, effectively suppressing cracking and spheroidization, and ensuring the dense metallurgical bonding and dimensional stability of thick-walled / load-bearing components.
[0039] In an optional implementation, the power of laser selective melting is 300-400W, the scanning speed is 400-600mm / s, the laser strip spacing is 0.07-0.12mm, and the powder thickness is 10-50µm. Optimized for the low melting point and high thermal expansion coefficient of molybdenum-based materials, the slightly higher scanning speed and finer strip / powder control can suppress grain coarsening and deformation caused by heat accumulation, and improve the forming accuracy and surface quality of precision structures such as thin walls and complex flow channels.
[0040] In an optional embodiment, the density of the rhenium alloy printed parts is ≥99%.
[0041] The present invention also provides a rhenium alloy printed part, which is prepared by the 3D printing method of rhenium alloy spherical powder described in the foregoing embodiments.
[0042] The features and performance of the present invention will be further described in detail below with reference to embodiments.
[0043] Example 1 This embodiment discloses a method for preparing rhenium alloy spherical powder and its 3D printing method, including the following steps: (1) Preparation of precursor powder The target tungsten-rhenium alloy composition is W-25wt.%Re. High-purity ammonium metatungstate (AMT, Aladdin, purity ≥99.95%) and ammonium perrhenate (NH4ReO4, purity ≥99.9%) were used as raw materials. The mixture was dissolved in deionized water (150g / L). The solution was heated in a magnetic stirrer while stirring and mixing. The temperature was raised to 120℃ and the stirring speed was 150rpm. After the solute reacted fully for 3 hours, the water was evaporated in a vacuum drying oven to obtain a uniform precursor mixed powder.
[0044] (2) Hydrogen reduction The precursor mixture powder obtained in step (1) was placed in a tube furnace and subjected to two-stage reduction with high-purity hydrogen gas at a flow rate of 2 L / min. The temperature was increased to 450°C at 10°C / min and held for 1 h. Then, the temperature was increased to 1100°C at 10°C / min and held for 2 h. The temperature was then decreased to 500°C at 5°C / min and finally cooled to room temperature with the furnace to obtain tungsten-rhenium pre-alloyed powder.
[0045] (3) Radio frequency plasma spheroidization Radio frequency plasma spheroidization treatment of tungsten-rhenium alloy powder: First, the radio frequency plasma spheroidization equipment was turned on. The reaction chamber, powder feeder, and powder collector of the radio frequency plasma spheroidization powder preparation device were purified by repeated vacuuming and argon purging. The carrier gas argon flow rate was set to 3.0 L / min, the powder feeding rate to 40 g / min, the central argon flow rate to 20 L / min, the plasma edge gas to be a mixture of argon and hydrogen with a flow rate of 60 L / min, the reaction chamber pressure to 15 psi, and the plasma power to 40 kW. Subsequently, the tungsten-rhenium alloy powder was fed into the high-temperature zone at the center of the plasma torch using the carrier gas. Under the action of surface tension, highly spherical droplets were formed, which were then rapidly cooled to form spherical particles. The spherical tungsten-rhenium alloy powder was washed 3-4 times in deionized water and then dried at 100°C for 1 hour under a nitrogen atmosphere.
[0046] The 3D printing method using the tungsten-rhenium alloy spherical powder prepared in this embodiment includes the following steps: (1) 3D printing Tungsten-rhenium alloy powder with a thickness of 15-53µm is selected and formed by selective laser melting 3D printing to obtain the 3D printed tungsten-rhenium alloy product. The powder thickness is 30µm, the laser power is 300W, the laser scanning speed is 500mm / s, and the laser strip spacing is 0.08mm, for selective laser melting forming.
[0047] Example 2 This embodiment discloses a method for preparing rhenium alloy spherical powder and its 3D printing method, including the following steps: (2) Preparation of precursor powder The target tungsten-rhenium alloy composition is W-15wt.%Re. High-purity ammonium metatungstate (AMT, Aladdin, purity ≥99.95%) and ammonium perrhenate (NH4ReO4, purity ≥99.9%) were used as raw materials. The mixture was dissolved in deionized water (120g / L). The solution was heated in a magnetic stirrer while being stirred and mixed. The heating temperature was 120℃ and the stirring speed was 150rpm. After the solute reacted fully for 3 hours, the water was evaporated in a vacuum drying oven to obtain a uniform precursor mixed powder.
[0048] (2) Hydrogen reduction The precursor mixture powder obtained in step (1) was placed in a tube furnace and high-purity hydrogen was introduced for two-stage reduction at a flow rate of 2 L / min. The temperature was increased to 400℃ at 10℃ / min and held for 1 h. Then, the temperature was increased to 1000℃ at 10℃ / min and held for 2 h. The temperature was then decreased to 500℃ at 5℃ / min and finally cooled to room temperature with the furnace to obtain tungsten-rhenium pre-alloyed powder.
[0049] (3) Radio frequency plasma spheroidization Radio frequency plasma spheroidization treatment of tungsten-rhenium alloy powder: First, the radio frequency plasma spheroidization equipment was turned on. The reaction chamber, powder feeder, and powder collector of the radio frequency plasma spheroidization powder preparation device were purified by repeated vacuuming and argon purging. The carrier gas argon flow rate was set to 3.0 L / min, the powder feeding rate to 35 g / min, the central argon flow rate to 20 L / min, the plasma edge gas to be a mixture of argon and hydrogen with a flow rate of 65 L / min, the reaction chamber pressure to 15 psi, and the plasma power to 35 kW. Subsequently, the tungsten-rhenium alloy powder was fed into the high-temperature zone at the center of the plasma torch using the carrier gas. Under the action of surface tension, highly spherical droplets were formed, which were then rapidly cooled to form spherical particles. The spherical tungsten-rhenium alloy powder was washed 3-4 times in deionized water and then dried at 100°C for 1 hour under a nitrogen atmosphere.
[0050] The tungsten-rhenium alloy powder has a sphericity of 97.5%, a purity of 99.99%, is dense and non-porous, and has an oxygen content of 62 ppm.
[0051] The 3D printing method using the aforementioned tungsten-rhenium alloy spherical powder includes the following steps: (1) 3D printing Tungsten-rhenium alloy powder with a thickness of 15-53µm is selected and formed by selective laser melting 3D printing to obtain the 3D printed tungsten-rhenium alloy product. The powder thickness is 30µm, the laser power is 350W, the laser scanning speed is 600mm / s, and the laser strip spacing is 0.08µm, for selective laser melting forming.
[0052] The density of the tungsten-rhenium alloy printed sample is 99.50%.
[0053] Example 3 This embodiment discloses a method for preparing rhenium alloy spherical powder and its 3D printing method, including the following steps: (3) Preparation of precursor powder The target molybdenum-rhenium alloy composition is Mo-40wt.%Re. High-purity ammonium dimolybdate (ADT, Aladdin, purity ≥99.95%) and ammonium perrhenate (NH4ReO4, purity ≥99.9%) were used as raw materials. The mixture was dissolved in deionized water (120g / L). The solution was heated in a magnetic stirrer while being stirred and mixed. The heating temperature was 120℃ and the stirring speed was 150rpm. After the solute reacted fully for 3 hours, the water was evaporated in a vacuum drying oven to obtain a uniform precursor mixed powder.
[0054] (2) Hydrogen reduction The precursor mixture powder obtained in step (1) was placed in a tube furnace and high-purity hydrogen was introduced for two-stage reduction at a flow rate of 2 L / min. The temperature was increased to 450°C at 10°C / min and held for 1 h. Then the temperature was increased to 1000°C at 10°C / min and held for 2 h. The temperature was then decreased to 500°C at 5°C / min and finally cooled to room temperature with the furnace to obtain tungsten-rhenium pre-alloyed powder.
[0055] (3) Radio frequency plasma spheroidization Radio frequency plasma spheroidization treatment of molybdenum-rhenium alloy powder: First, the radio frequency plasma spheroidization equipment was turned on. The reaction chamber, powder feeder, and powder collector of the radio frequency plasma spheroidization powder preparation device were purified by repeated vacuuming and argon purging. The carrier gas argon flow rate was set to 4.0 L / min, the powder feeding rate to 40 g / min, the central argon flow rate to 20 L / min, the plasma edge gas to be a mixture of argon and hydrogen with a flow rate of 60 L / min, the reaction chamber pressure to 15 psi, and the plasma power to 40 kW. Subsequently, the molybdenum-rhenium alloy powder was fed into the high-temperature zone at the center of the plasma torch using the carrier gas. Under the action of surface tension, highly spherical droplets were formed, which were then rapidly cooled to form spherical particles. The spherical molybdenum-rhenium alloy powder was washed 3-4 times in deionized water and then dried at 100°C for 1 hour under a N2 protective atmosphere.
[0056] The 3D printing method using the aforementioned prepared molybdenum-rhenium alloy spherical powder includes the following steps: (1) 3D printing Molybdenum-rhenium alloy powder with a thickness of 15-53µm was selected and formed using selective laser melting 3D printing technology to obtain the 3D printed molybdenum-rhenium alloy product. The powder thickness was 40µm, the laser power was 400W, the laser scanning speed was 400mm / s, and the laser strip spacing was 80µm, during selective laser melting forming.
[0057] Example 4 This embodiment discloses a method for preparing rhenium alloy spherical powder and its 3D printing method, including the following steps: (1) Preparation of precursor powder The target molybdenum-rhenium alloy composition is Mo-14wt.%Re. High-purity ammonium dimolybdate (ADT, Aladdin, purity ≥99.95%) and ammonium perrhenate (NH4ReO4, purity ≥99.9%) were used as raw materials. The mixture was dissolved in deionized water (100g / L). The solution was heated in a magnetic stirrer while being stirred and mixed. The heating temperature was 120℃ and the stirring speed was 150rpm. After the solute reacted fully for 3 hours, the water was evaporated in a vacuum drying oven to obtain a uniform precursor mixed powder.
[0058] (2) Hydrogen reduction The precursor mixture powder obtained in step (1) was placed in a tube furnace and high-purity hydrogen was introduced for two-stage reduction at a flow rate of 2 L / min. The temperature was increased to 400℃ at 10℃ / min and held for 1 h. Then, the temperature was increased to 900℃ at 10℃ / min and held for 2 h. The temperature was then decreased to 500℃ at 5℃ / min and finally cooled to room temperature with the furnace to obtain tungsten-rhenium pre-alloyed powder.
[0059] (3) Radio frequency plasma spheroidization Radio frequency plasma spheroidization treatment of molybdenum-rhenium alloy powder: First, the radio frequency plasma spheroidization equipment was turned on. The reaction chamber, powder feeder, and powder collector of the radio frequency plasma spheroidization powder preparation device were purified by repeated vacuuming and argon purging. The carrier gas argon flow rate was set to 4.0 L / min, the powder feeding rate to 35 g / min, the central argon flow rate to 20 L / min, the plasma edge gas to be a mixture of argon and hydrogen with a flow rate of 50 L / min, the reaction chamber pressure to 15 psi, and the plasma power to 40 kW. Subsequently, the molybdenum-rhenium alloy powder was fed into the high-temperature zone at the center of the plasma torch using the carrier gas. Under the action of surface tension, highly spherical droplets were formed, which were then rapidly cooled to form spherical particles. The spherical molybdenum-rhenium alloy powder was washed 3-4 times in deionized water and then dried at 100°C for 1 hour under a N2 protective atmosphere.
[0060] The tungsten-rhenium alloy powder has a sphericity of 97.3%, a purity of 99.99%, is dense and non-porous, and has an oxygen content of 65 ppm.
[0061] The 3D printing method using the aforementioned prepared molybdenum-rhenium alloy spherical powder includes the following steps: (1) 3D printing Molybdenum-rhenium alloy powder with a thickness of 15-53µm was selected and formed using selective laser melting 3D printing technology to obtain the 3D printed molybdenum-rhenium alloy product. The powder thickness was 40µm, the laser power was 450W, the laser scanning speed was 500mm / s, and the laser strip spacing was 80µm, during selective laser melting forming. Comparative Example 1 The main difference between this comparative example and Example 2 is that step (2) is carried out by a single-stage reduction method, with the hydrogen reduction temperature at 500°C and the time at 3 hours.
[0062] Comparative Example 2 The main difference between this comparative example and Example 4 is that step (2) is carried out by a single-stage reduction method, with the hydrogen reduction temperature at 600°C and the time at 3 hours.
[0063] Comparative Example 3 The main difference between this comparative example and Example 2 is that the temperature of the first reduction stage in step (2) is 280°C and the time is 1 hour.
[0064] Comparative Example 4 The main difference between this comparative example and Example 2 is that the temperature of the second reduction stage in step (2) is 800°C and the time is 2 hours.
[0065] Comparative Example 5 The main difference between this comparative example and Example 2 is that the heating rate of the two reduction stages in step (2) is 5℃ / min and the cooling rate is 10℃ / min.
[0066] Comparative Example 6 The main difference between this comparative example and Example 2 is that the laser power in the 3D printing molding step is 400W and the laser scanning speed is 300mm / s.
[0067] Test Example 1 The purity, oxygen content, and sphericity of the rhenium alloy spherical powders prepared in the above embodiments and comparative examples were tested, and the test results are shown in Table 1.
[0068] Purity was determined by ICP-AES analysis of the impurity content in rhenium alloy spherical powder, and the results reflected the purity of the rhenium alloy spherical powder.
[0069] Oxygen content was determined by thermogravimetric analysis (TGA), and the results reflected the solid solution and chemical state of oxygen in rhenium alloy spherical powder.
[0070] Sphericity is a quantitative assessment of the degree to which the powder particle profile matches the ideal spherical surface using image analysis. High sphericity usually means excellent flowability and packing performance.
[0071] Test Example 2 Rhenium alloy spherical powders with a particle size range of 15-53μm prepared in the above embodiments and comparative examples were selected, and after being formed by 3D printing technology, the performance of the printed products was tested and analyzed.
[0072] Density is measured using X-ray CT technology to reflect its mechanical and corrosion resistance properties.
[0073] Table 1
[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing rhenium alloy spherical powder, characterized in that, include: The precursor powder is obtained by reacting and drying a metal ammonium acid solution containing ammonium perrylate; the metal ammonium acid solution also includes at least one of ammonium molybdate and ammonium tungstate. The precursor powder was subjected to a first stage of hydrogen reduction and a second stage of hydrogen reduction to obtain rhenium alloy pre-alloy powder; the first stage of hydrogen reduction was carried out at 300-450℃ for 1-2 hours, and the second stage of hydrogen reduction was carried out at 700-1100℃ for 1-3 hours. The rhenium alloy pre-alloyed powder is spheroidized by radio frequency plasma to obtain the rhenium alloy spherical powder.
2. The method for preparing rhenium alloy spherical powder according to claim 1, characterized in that, The reaction temperature is 100-150℃, the reaction time is 2-5 hours, and the reaction is carried out under stirring conditions at a stirring rate of 100-200 rpm. And / or, the solute content in the ammonium metal oxide solution is 30-150 g / ml.
3. The method for preparing rhenium alloy spherical powder according to claim 1, characterized in that, The rhenium alloy pre-alloyed powder comprises, by mass percentage, 75wt%≤W≤99wt% and 1≤Re≤25wt%. Alternatively, the rhenium alloy pre-alloyed powder comprises, by mass percentage, 60wt%≤Mo≤98wt% and 2≤Re≤40wt%.
4. The method for preparing rhenium alloy spherical powder according to claim 1, characterized in that, The hydrogen flow rate in both the first and second stages of hydrogen reduction is 1-5 L / min. And / or, both the first stage of hydrogen reduction and the second stage of hydrogen reduction are performed under a vacuum of less than 10. -3 The experiment was conducted under the condition of Pa.
5. The method for preparing rhenium alloy spherical powder according to claim 1, characterized in that, The heating rate for the first stage of hydrogen reduction is 5-10℃ / min; And / or, the heating rate of the second stage hydrogen reduction is 5-10℃ / min; And / or, after the second stage of hydrogen reduction, the temperature is first lowered to below 500°C at a rate of 5-10°C / min, and then further lowered to below 50°C in the furnace.
6. The method for preparing rhenium alloy spherical powder according to claim 1, characterized in that, In the radio frequency plasma spheroidizing step, the plasma edge gas flow rate is 40-75 L / min, and the plasma edge gas is a mixture of hydrogen and argon with a volume ratio of 0.05-0.15:1; the power of the plasma spheroidizing device is 15-100 kW; the powder feed rate is 0.1-100 g / min; the flow rate of the central gas is 10-25 L / min, and the central gas is argon; the reaction chamber pressure is 12.5-15 psi. And / or, the plasma spheroidizing treatment is performed at a temperature of 8000-12000℃ and a reaction pressure of 0.01-0.15MPa.
7. A rhenium alloy spherical powder according to any one of claims 1-6, characterized in that, The particle size is 15-53μm, the powder sphericity is ≥95%, the oxygen content is ≤70ppm, and the purity is ≥99.99%.
8. A method for 3D printing using the rhenium alloy spherical powder of claim 7, characterized in that, include: The rhenium alloy spherical powder is melted and shaped by laser selective melting to form rhenium alloy printed parts.
9. The method for preparing rhenium alloy spherical powder according to claim 1, characterized in that, The power of laser selective melting is 250-400W, the scanning speed is 200-700mm / s, the laser strip spacing is 0.05-0.15mm, and the powder thickness is 30-60µm; And / or, the power of laser selective melting is 300-400W, the scanning speed is 400-600mm / s, the laser strip spacing is 0.07-0.12mm, and the powder thickness is 10-50µm; And / or, the density of the rhenium alloy printed parts is ≥99%.
10. A rhenium alloy printed part, characterized in that, It is prepared by the 3D printing method of rhenium alloy spherical powder as described in claim 1.