High-purity rhenium powder and method for producing the same

Abstract

The application belongs to the technical field of metal powder preparation, and particularly relates to high-purity rhenium powder and a preparation method thereof. The high volatility of rhenium oxide is utilized, efficient volatilization of rhenium oxide is realized under vacuum conditions, and the high activity of hydrogen radio frequency plasma is utilized to rapidly and completely reduce the rhenium oxide vapor into high-purity rhenium powder, so that the reduction reaction efficiency is significantly improved, efficient and clean preparation of rhenium powder is realized, the problem of impurity introduction in the traditional reduction method can be avoided, and the product purity and particle size can meet the application requirement of high-end fields.

Description

Technical Field

[0001] This invention belongs to the field of metal powder preparation technology, specifically relating to a high-purity rhenium powder and its preparation method. Background Technology

[0002] Rhenium is a rare refractory metal with excellent properties such as high melting point, corrosion resistance, wear resistance, and thermal shock resistance. It has irreplaceable application value in high-end fields such as aerospace, nuclear energy, electronics, and chemical industry. Especially in fields such as high-temperature alloy modification, semiconductor packaging, and nuclear reactor components, extremely high requirements are placed on the purity and particle size of rhenium powder. Typically, high-purity rhenium powder with a purity of ≥99.99% and good dispersibility at the nanoscale or submicron level is required.

[0003] Currently, the main methods for preparing high-purity rhenium powder include hydrogen reduction, carbothermic reduction, and plasma spheroidization. Among these, the hydrogen reduction method often involves the direct reaction of ammonium perrhenate or rhenium oxide with hydrogen at high temperatures, which suffers from low reaction efficiency, easy product agglomeration, uneven particle size distribution, and the easy introduction of impurities. The carbothermic reduction method requires the addition of reducing agents such as carbon black, which can easily lead to excessive carbon content in the product, affecting the purity of the rhenium powder. The plasma spheroidization method often uses coarse rhenium powder as raw material for subsequent processing, resulting in cumbersome process steps, high energy consumption, and difficulty in further improving product purity.

[0004] Furthermore, rhenium oxide exhibits excellent evaporability. While existing technologies have attempted to utilize the volatilization properties of rhenium oxide to prepare rhenium-related products, these methods often combine traditional heating and volatilization with conventional hydrogen reduction. This approach suffers from low volatilization efficiency, incomplete reduction, and susceptibility to contamination by impurities such as oxygen and moisture, hindering the efficient and large-scale preparation of high-purity rhenium powder. Therefore, developing a simple, highly controllable, high-purity, and well-dispersible method for preparing high-purity rhenium powder has become a pressing technical challenge in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a high-purity rhenium powder and its preparation method. The rhenium powder obtained by the method provided by this invention has high purity and good dispersibility.

[0006] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing high-purity rhenium powder, comprising the following steps: Rhenium oxide solid was evaporated under vacuum to obtain rhenium oxide vapor. The rhenium oxide vapor is reduced by radio frequency plasma in a hydrogen-containing atmosphere to obtain the high-purity rhenium powder; the purity of the high-purity rhenium powder is not less than 99.99%.

[0007] Preferably, the evaporation conditions include: heating power of 30~80kW, volatilization temperature of 1200~1800℃, heat preservation time of 2~4h, and working pressure of 10~103Pa.

[0008] Preferably, the method for preparing the rhenium oxide solid includes: decomposing ammonium perrylate crystals to obtain the rhenium oxide solid.

[0009] Preferably, the purity of the ammonium perrylate crystals is ≥99.9%; The decomposition conditions include: a temperature of 380~850℃ and a holding time of 2~6h; the decomposition is carried out in an oxygen-containing atmosphere with a flow rate of 100~200mL / min.

[0010] Preferably, the oxygen-containing atmosphere comprises a mixture of air and oxygen, wherein the volume ratio of oxygen to air in the mixture is 0.1 to 0.5:1.

[0011] Preferably, the hydrogen-containing atmosphere includes argon and hydrogen; the purity of the hydrogen is ≥99.999%, and the flow rate is 0.4~5 L / min; the purity of the argon is ≥99.999%, and the flow rate is 5~40 L / min.

[0012] Preferably, the power of the radio frequency plasma is 5~20kW.

[0013] Preferably, after reduction, the process further includes cooling and collection; The cooling process includes sequential primary cooling and secondary cooling; The temperature of the primary cooling stage is 800~1000℃, and the temperature of the secondary cooling stage is 200~300℃; The cooling rate is ≥105 K / s.

[0014] Preferably, the yield of the high-purity rhenium powder is ≥99%.

[0015] The present invention also provides high-purity rhenium powder prepared by the preparation method described above, wherein the high-purity rhenium powder has a particle size of 50~200nm and a sphericity of ≥95%.

[0016] Compared with the prior art, the beneficial effects of the present invention include: This invention utilizes the high volatility of rhenium oxide to achieve efficient volatilization of rhenium oxide under vacuum conditions. Then, by utilizing the high activity of hydrogen radio frequency plasma, the rhenium oxide vapor is rapidly and completely reduced into high-purity rhenium powder, which significantly improves the reduction reaction efficiency and achieves efficient and clean preparation of rhenium powder. It also avoids the problem of impurity introduction in traditional reduction methods, ensuring that the purity and particle size of the product meet the application requirements of high-end fields. Detailed Implementation

[0017] This invention provides a method for preparing high-purity rhenium powder, comprising the following steps: Rhenium oxide solid was evaporated under vacuum to obtain rhenium oxide vapor. The rhenium oxide vapor is reduced using radio frequency plasma in a hydrogen-containing atmosphere to obtain the high-purity rhenium powder; the purity of the high-purity rhenium powder is not less than 99.99%.

[0018] The present invention evaporates rhenium oxide solid under vacuum conditions to obtain rhenium oxide (Re2O7) vapor.

[0019] In this invention, the method for preparing the rhenium oxide solid preferably includes: decomposing ammonium perrylate crystals to obtain the rhenium oxide solid. In this invention, the purity of the ammonium perrylate crystals is preferably ≥99.9%; the decomposition conditions preferably include: a temperature of 380~850℃, specifically 380℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, and 850℃; a holding time of 2~6h, specifically 2h, 3h, 4h, 5h, and 6h; the decomposition is preferably carried out in an oxygen-containing atmosphere, and the flow rate of the oxygen-containing atmosphere is preferably 100~200mL / min; the oxygen-containing atmosphere preferably includes a mixture of air and oxygen, and the volume ratio of oxygen to air in the mixture is preferably 0.1~0.5:1, specifically 0.1:1, 0.2:1, 0.3:1, 0.4:1, and 0.5:1. In this invention, the decomposition is preferably carried out in a rotary roasting furnace, and the rotation speed of the rotary roasting furnace is preferably 3~5rpm. In this invention, by employing a rotary roasting furnace, the rotation of the furnace can ensure that the ammonium rhenium oxide crystals are heated evenly, avoiding local overheating that could lead to the formation of impurities. The introduction of an oxygen-containing mixed gas can promote the forward decomposition reaction, thereby improving the production efficiency and purity of rhenium oxide.

[0020] In this invention, the reaction equations involved in the decomposition process are as follows: 4NH4ReO4+3O2=2Re2O7+2N2+8H2O.

[0021] In this invention, the preferred evaporation conditions include: a heating power of 30-80 kW, specifically 30 kW, 40 kW, 50 kW, 60 kW, 70 kW, or 80 kW; a volatilization temperature of 1200-1800℃, specifically 1200℃, 1300℃, 1400℃, 1500℃, 1600℃, 1700℃, or 1800℃; a holding time of 2-4 hours, more preferably 3 hours; and a working pressure of 10-10... 3Pa, specifically 10 Pa, 100 Pa, or 1000 Pa. In this invention, the evaporation is preferably carried out in a vacuum induction furnace; before evaporation, the vacuum induction furnace is preferably evacuated to ensure effective removal of impurities such as oxygen and moisture from the furnace, preventing secondary oxidation of rhenium oxide, and promoting the volatilization of rhenium oxide. In this invention, by carrying out evaporation under vacuum conditions, it is ensured that impurities such as oxygen and moisture in the furnace are effectively removed, preventing secondary oxidation of rhenium oxide, and promoting the volatilization of rhenium oxide; rapid and uniform heating of rhenium oxide can be achieved, improving volatilization efficiency, while the vacuum environment effectively avoids impurity contamination and ensures the purity of the rhenium oxide gas phase.

[0022] After obtaining the rhenium oxide vapor, the present invention reduces the rhenium oxide vapor using radio frequency plasma under a hydrogen-containing atmosphere to obtain the high-purity rhenium powder.

[0023] In this invention, the hydrogen-containing atmosphere preferably comprises argon and hydrogen; the purity of the hydrogen is preferably ≥99.999%, and the flow rate is preferably 0.4~5 L / min, specifically 0.4 L / min, 0.5 L / min, 1 L / min, 2 L / min, 3 L / min, 4 L / min, or 5 L / min; the purity of the argon is preferably ≥99.999%, and the flow rate is preferably 5~40 L / min, specifically 5 L / min, 10 L / min, 20 L / min, 30 L / min, or 40 L / min. In this invention, during the reduction process, the amount of hydrogen-containing atmosphere is preferably excessive to ensure sufficient reduction of rhenium oxide vapor. In this invention, before the reaction, it is also preferable to remove impurities such as moisture and oxygen from the hydrogen to prevent the introduction of byproducts.

[0024] In this invention, the power of the radio frequency plasma is preferably 5~20kW, specifically 5kW, 10kW, 15kW, or 20kW. By controlling the above power, a stable hydrogen radio frequency plasma can be formed in the reaction region. This hydrogen radio frequency plasma has the advantages of high activity and no electrode contamination. The active hydrogen particles it generates can significantly improve the reduction reaction efficiency, achieving complete reduction of rhenium oxide, while avoiding the problem of impurity introduction in traditional reduction methods.

[0025] In this invention, the reaction equations involved in the reduction process are as follows: Re2O7(g) + H / H + →Re(s)+H2O(g).

[0026] In this invention, after reduction, the process preferably includes cooling and collection; the cooling preferably includes a primary cooling and a secondary cooling performed sequentially; the temperature of the primary cooling is preferably 800~1000℃, and the temperature of the secondary cooling is preferably 200~300℃; the cooling rate is preferably ≥10. 5 K / s, further preferably (1~1.5) 10 5 K / s. In this invention, rhenium vapor is rapidly condensed into solid particles by controlling the cooling conditions, while simultaneously inhibiting particle growth and agglomeration.

[0027] In this invention, the collection is preferably carried out using a combination of a cyclone separator and a bag filter. After collection, the invention also preferably includes drying. The drying process is not particularly limited and can be any method known to those skilled in the art; drying can remove trace amounts of adsorbed moisture.

[0028] In this invention, the yield of the high-purity rhenium powder is preferably ≥99%.

[0029] The present invention also provides high-purity rhenium powder prepared by the preparation method described above, wherein the high-purity rhenium powder has a particle size of 50-200 nm and a sphericity of ≥95%; the high-purity rhenium powder has good dispersibility and no agglomeration. In the present invention, the purity of the high-purity rhenium powder is not less than 99.99%, the oxygen content is preferably not more than 50 ppm, and the carbon content is preferably not more than 30 ppm.

[0030] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0031] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0032] Example 1 20g of ammonium perrylate crystals with a purity of 99.9% were placed in the furnace tube of a rotary roasting furnace, and the exhaust port of the furnace tube was connected to a sealed collection structure. After the furnace door was closed, a mixture of oxygen and air with a volume ratio of 0.1:1 was introduced into the furnace tube at a flow rate of 100mL / min. After 10min of gas introduction, the rotary roasting furnace was turned on, and the furnace tube was rotated at a speed of 5rpm. The heating temperature was controlled at 850℃ and the holding time was 2h to allow the ammonium perrylate to decompose completely and generate rhenium oxide solid. The rhenium oxide solid produced by decomposition was transferred to a vacuum induction furnace, and the furnace was evacuated to a vacuum level of 5 × 10⁻⁶.- 3 The heating device was turned on at 30 kW, raising the furnace temperature to 1200℃. The temperature was maintained for 4 hours to allow volatilization. The working pressure was adjusted to 10 Pa to obtain rhenium oxide vapor. This rhenium oxide vapor was then introduced into a radio frequency plasma reaction chamber, along with 99.999% pure hydrogen gas at a flow rate of 0.4 L / min and 99.999% pure argon gas at a flow rate of 5 L / min. The plasma generator power was controlled at 5 kW for reduction to obtain rhenium elemental vapor. A multi-stage cooling method was used, with a first-stage cooling temperature of 800℃, a second-stage cooling temperature of 200℃, and a cooling rate of 10... 5 The rhenium vapor is rapidly condensed at K / s; it is then collected by a combination of cyclone separator and bag filter, and dried to obtain high-purity rhenium powder.

[0033] The high-purity rhenium powder prepared in this embodiment has a purity of 99.99%, an oxygen content of 48 ppm, a carbon content of 28 ppm, a particle size distribution of 50~200 nm, a particle sphericity of ≥95%, good dispersibility, no obvious agglomeration, and a collection efficiency of 99.2%.

[0034] Example 2 50g of ammonium perrylate crystals with a purity of 99.95% were placed in the furnace tube of a rotary roasting furnace, and the exhaust port of the furnace tube was connected to a sealed collection structure. After the furnace door was closed, a mixture of oxygen and air with a volume ratio of 0.3:1 was introduced into the furnace tube at a flow rate of 150mL / min. After 10min of gas introduction, the rotary roasting furnace was turned on, and the furnace tube was rotated at a speed of 4rpm. The heating temperature was controlled at 600℃ and the holding time was 4h to allow the ammonium perrylate to decompose completely and generate rhenium oxide solid. The rhenium oxide solid produced by decomposition was transferred to a vacuum induction furnace, and the furnace was evacuated to a vacuum level of 5 × 10⁻⁶. - 3 Pa, turn on the heating device, control the heating power to 50kW, raise the furnace temperature to 1500℃, keep it at the temperature for 2 hours for volatilization, adjust the working pressure to 100Pa, and obtain rhenium oxide vapor; The obtained rhenium oxide vapor was introduced into a radio frequency plasma reaction chamber, along with 99.999% pure hydrogen gas at a flow rate of 3 L / min and 99.999% pure argon gas at a flow rate of 30 L / min. The plasma generator power was controlled at 10 kW to perform reduction, yielding rhenium elemental vapor. A multi-stage cooling method was employed, with a first-stage cooling temperature of 900℃, a second-stage cooling temperature of 250℃, and a cooling rate of 1.5. 10 5 The rhenium vapor is rapidly condensed at K / s; it is then collected by a combination of cyclone separator and bag filter, and dried to obtain high-purity rhenium powder.

[0035] Testing showed that the high-purity rhenium powder prepared in this embodiment had a purity of 99.992%, an oxygen content of 42 ppm, a carbon content of 28 ppm, a particle size distribution of 100~150 nm, a particle sphericity of ≥96%, good dispersibility, no obvious agglomeration, and a collection efficiency of 99.5%.

[0036] Comparative Example 1 50g of high-purity ammonium perrylate crystals with a purity of 99.99% were selected and pulverized to the required particle size range of 100~150μm by mechanical ball milling; the pulverized ammonium perrylate powder was loaded into a molybdenum reaction boat, and the loading thickness was controlled to be <10mm; The molybdenum reaction boat, loaded with materials, is pushed into the constant temperature zone of the reduction furnace. After the furnace door is sealed, high-purity nitrogen is first introduced to replace the air in the furnace. After the replacement is completed, high-purity hydrogen is introduced into the furnace. The reduction temperature is controlled at 500℃ and the reduction time is 4 hours to carry out the first stage of hydrogen reduction reaction. After the first stage of reduction is completed, the furnace temperature is raised to 900℃ and high-purity hydrogen is continued to be introduced. The reduction time is 2.5 hours to complete the second stage of hydrogen reduction reaction. After the reduction reaction is complete, the molybdenum reaction boat is moved to the cooling zone of the reduction furnace, nitrogen gas is introduced into the furnace, and it is allowed to cool naturally to room temperature (cooling rate less than 10). 5 K / s); the reduction product was taken out, ball-milled and sieved to obtain high-purity rhenium powder.

[0037] The high-purity rhenium powder prepared in this comparative example has a purity of 99.95%, an oxygen content of 88 ppm, and high levels of Fe and Mo impurities. The powder particles are mainly irregular flakes with clear interfaces but poor sphericity, and exhibit varying degrees of agglomeration.

[0038] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing high-purity rhenium powder, characterized in that, Includes the following steps: Rhenium oxide solid was evaporated under vacuum to obtain rhenium oxide vapor. The rhenium oxide vapor is reduced by radio frequency plasma in a hydrogen-containing atmosphere to obtain the high-purity rhenium powder; the purity of the high-purity rhenium powder is not less than 99.99%.

2. The preparation method according to claim 1, characterized in that, The evaporation conditions include: heating power of 30~80kW, volatilization temperature of 1200~1800℃, holding time of 2~4h, and working pressure of 10~10 3 Pa.

3. The preparation method according to claim 1, characterized in that, The method for preparing the rhenium oxide solid includes: decomposing ammonium perrylate crystals to obtain the rhenium oxide solid.

4. The preparation method according to claim 3, characterized in that, The purity of the ammonium perrylate crystals is ≥99.9%; The decomposition conditions include: a temperature of 380~850℃ and a holding time of 2~6h; the decomposition is carried out in an oxygen-containing atmosphere with a flow rate of 100~200mL / min.

5. The preparation method according to claim 4, characterized in that, The oxygen-containing atmosphere comprises a mixture of air and oxygen, wherein the volume ratio of oxygen to air in the mixture is 0.1 to 0.5:

1.

6. The preparation method according to claim 1, characterized in that, The hydrogen-containing atmosphere includes argon and hydrogen; the purity of the hydrogen is ≥99.999%, and the flow rate is 0.4~5 L / min; the purity of the argon is ≥99.999%, and the flow rate is 5~40 L / min.

7. The preparation method according to claim 1, characterized in that, The power of the radio frequency plasma is 5~20kW.

8. The preparation method according to claim 1, characterized in that, The reduction process also includes cooling and collection; The cooling process includes sequential primary cooling and secondary cooling; The temperature of the primary cooling stage is 800~1000℃, and the temperature of the secondary cooling stage is 200~300℃; The cooling rate is ≥10 5 K / s.

9. The preparation method according to claim 1, characterized in that, The yield of the high-purity rhenium powder is ≥99%.

10. The high-purity rhenium powder prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The high-purity rhenium powder has a particle size of 50~200nm and a sphericity of ≥95%.