A method for preparing low interstitial impurity alloy powder based on large-size hydrogenatable alloy scrap

Abstract

The present application belongs to the technical field of preparation of low-interstitial impurity titanium alloy powder, and particularly relates to a method for preparing low-interstitial impurity alloy powder based on large-size hydrogenatable alloy waste, comprising the following steps: S1: cleaning the surface of the block-shaped waste, and drying the obtained alloy block for standby; S2: placing the alloy block in a hydrogenation furnace, vacuumizing, and then heating to a set temperature; S3: hydrogenating the material; S4: dehydrogenating the material; S5: secondary hydrogenating the material; S6: after repeating steps S3-S5 for multiple times, taking out the hydride for mechanical crushing, and sieving out hydride powder of a required particle size; S7: placing the hydride powder in a vacuum furnace, vacuumizing, heating to a set temperature, and keeping the temperature; S8: immediately introducing high-purity argon into the furnace and keeping the positive pressure in the furnace, and obtaining low-interstitial impurity alloy powder after the furnace is cooled to room temperature. The present application can realize low-cost and efficient recycling of large-size hydrogenatable alloy waste, and prepare high-quality alloy fine powder with low-interstitial impurities.

Description

Technical Field

[0001] This invention belongs to the field of preparation technology of low-gap impurity titanium alloy powder, specifically relating to a method for preparing low-gap impurity alloy powder based on large-size hydrogenatable alloy waste. Background Technology

[0002] Titanium alloys, as high-performance, corrosion-resistant, and heat-resistant metallic structural materials, have wide applications in aerospace, aviation, and medical fields. However, the production and processing of titanium alloys generate a large amount of waste and scrap, making the treatment and utilization of this waste a significant issue. The main methods for recycling titanium waste are generally to remelt it into titanium alloys or to produce other titanium products. However, titanium waste is difficult to process, and some companies lack advanced smelting equipment and recycling technologies, resulting in low recycling efficiency and inconsistent product quality. Furthermore, waste recycling requires a series of complex processes, leading to high costs, making it less economical than using virgin titanium directly. This discourages many companies from investing in titanium waste recycling technologies. Therefore, it is necessary to develop new recycling technologies to improve the recycling efficiency, product quality, and economic benefits of titanium waste.

[0003] Hydrogenation-dehydrogenation is a traditional process for preparing titanium alloy powder with low interstitial impurities. However, this process requires raw materials that are uniform, fine pieces with a large specific surface area to increase the reaction contact area between the material and hydrogen at high temperatures, thereby improving the hydrogenation effect. However, titanium scrap is generally a dense block, resulting in low reaction efficiency with hydrogen at high temperatures. Poor hydrogenation also increases the difficulty of mechanical crushing, significantly increasing the risk of interstitial impurities such as oxygen and nitrogen in the material. Secondary cutting of the scrap further prolongs the process, increases production costs, and accumulates impurities, thus requiring technological innovation.

[0004] "Preparation of Uranium-Zirconium Alloy Powder by Hydrogenation-Dehydrogenation Method", Xiong Yifu, Zhang Pengcheng, Jing Wenyong, Ba Jingwen, Zhang Guikai, Rare Metals Materials and Engineering, Vol. 43, No. 11, Publication Date: 20141130. This paper discloses the preparation of uranium-zirconium alloy powder by hydrogenation-dehydrogenation method, and the microstructure was observed by XRD and SEM. The results show that the pretreatment before powder preparation is very important and directly affects the hydrogenation performance of uranium-zirconium alloy. With the increase of hydrogenation-dehydrogenation times, the hydrogen absorption increases accordingly, and the hydrogen absorption reaches a stable value after 10 activations. XRD and SEM morphology observation of the powder after dehydrogenation treatment at 650℃ shows that U-10%Zr (mass fraction) powder is a simple γ phase without phase transformation. With the increase of hydrogenation-dehydrogenation times, the proportion of intermediate particle size (100-150 μm) gradually increases. However, this scheme utilizes the bulk expansion and bursting phenomenon that occurs in uranium-zirconium alloys under different temperature and pressure conditions to increase the bulk specific surface area before hydrogenation-dehydrogenation powdering. However, this process route is only suitable for a very small number of materials, such as uranium alloys, that are sensitive to temperature and pressure and can produce a bulk expansion and bursting effect. Furthermore, hydrogenation-dehydrogenation generally refers to being carried out in a high-temperature, negative-pressure environment, and the hydrogenation effect is limited and affected by the material size, hydrogen absorption capacity, and specific surface area. This is the limitation of existing technology. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing low-gap impurity alloy powder based on large-size hydrogenizable alloy waste, which addresses the shortcomings of the existing technology. The present invention can realize the low-cost and efficient recycling of large-size hydrogenizable alloy waste and prepare high-quality alloy fine powder with low gap impurities.

[0006] This solution is achieved through the following technical measures: a method for preparing low-gap impurity alloy powder based on large-size hydrogenatable alloy waste, which includes the following steps:

[0007] S1: Clean the surface of the blocky waste material to remove impurities, and then dry the resulting alloy block for later use.

[0008] S2: Place the alloy block in the hydrogenation furnace, evacuate the vacuum, and heat it to the set temperature;

[0009] S3: High-purity hydrogen gas is introduced into the furnace to positive pressure and kept at a constant temperature to hydrogenate the material;

[0010] S4: Start the mechanical pump unit to extract hydrogen from the furnace and keep it warm, so that the material can be dehydrogenated;

[0011] S5: High-purity hydrogen gas is introduced into the furnace to positive pressure and kept at a constant temperature to allow the material to undergo secondary hydrogenation;

[0012] S6: After repeating steps S3-S5 multiple times, remove the hydride for mechanical crushing and sieve out the hydride powder of the required particle size.

[0013] S7: Place the sieved hydride powder in a vacuum furnace, evacuate the vacuum, heat to the set temperature and keep warm to complete the dehydrogenation process;

[0014] S8: After dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace and positive pressure is maintained inside the furnace. After the furnace cools to room temperature, low-interstitial-impurity alloy powder is obtained.

[0015] Preferably, the hydrogenatable alloy scrap is 15-30g of TC4 titanium scrap with an average thickness of 30-50mm, 45-60g of Nb521 scrap with an average thickness of 20-40mm, or 15-30kg of zirconium alloy scrap with an average thickness of 20-40mm.

[0016] Preferably, in step S1, the surface of the blocky waste is cleaned with an oil-removing cleaning agent and then acid-washed to remove impurities from the surface of the waste. The oil-removing cleaning agent is an organic solvent or an alkaline cleaning agent.

[0017] Preferably, in step S2, the vacuum is evacuated to 1*10 -3 After heating to 650℃-850℃ at pressures below MPa, the temperature is increased.

[0018] Preferably, in step S3, high-purity hydrogen is introduced into the furnace and the hydrogen partial pressure is maintained at 1-2 MPa for 20-45 minutes.

[0019] Preferably, in step S4, the mechanical pump group is turned on to extract hydrogen from the furnace, and the vacuum degree inside the furnace is maintained within 0.1 MPa and then kept at that temperature for 15-20 minutes.

[0020] Preferably, in step S5, high-purity hydrogen is introduced into the furnace and the hydrogen partial pressure is maintained at 1-2 MPa for 20-45 minutes.

[0021] Preferably, in step S6, after repeating steps S3-S5 three times, heating is stopped, the hydrogenation furnace is cooled to room temperature, the remaining hydrogen in the furnace is extracted, and high-purity argon is introduced to atmospheric pressure. The hydride is then removed, and the hydride is mechanically ball-milled under argon protection and sieved to obtain hydride powder with a D50 of 20-30 μm.

[0022] Preferably, in step S7, the sieved hydride powder is placed in a vacuum furnace and evacuated to a vacuum level of 1*10. -3 After the pressure is below MPa, heat to 650℃-700℃ and hold for 120-300 minutes.

[0023] Preferably, in step S8, after dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace to a pressure of 1 MPa.

[0024] The beneficial effects of this invention are as follows: By causing drastic changes in the partial pressure of hydrogen in the furnace, this invention induces repeated hydrogenation-dehydrogenation phase transitions in the material from the surface inwards, generating numerous microscopic defects and promoting the mass exchange rate. Macroscopically, the significant volume change caused by the phase transition leads to the continuous initiation and propagation of cracks in the material, exposing fresh surfaces to participate in the hydrogenation reaction process, thus promoting the hydrogenation effect on large-sized materials. Furthermore, the repeated adsorption and desorption of hydrogen continuously absorbs interstitial impurities within the material. After mechanical crushing, screening, and dehydrogenation, high-purity argon gas is immediately introduced into the furnace at high temperature to a positive pressure, allowing the powder to be passivated by high-purity argon gas before a dense oxide film forms. The method and steps of this invention enable low-cost and efficient recycling of large-sized hydrogenizable alloy waste and the preparation of high-quality alloy fine powder with low interstitial impurities. Furthermore, this invention involves repeated hydrogenation-dehydrogenation cycles on large-sized hydrogenatable alloy waste under high temperature and positive pressure. Through a hydrogenation-dehydrogenation phase transformation occurring from the surface to the interior of the material, internal mass transport is activated, significantly increasing the specific surface area and enhancing hydrogen embrittlement resistance. The secondary dehydrogenation in this invention causes a significant change in the macroscopic volume of the material, resulting in cracks of varying sizes both internally and on the surface; microscopically, numerous defects appear in the crystals, greatly improving the efficiency of subsequent hydrogenation. Therefore, this invention possesses outstanding substantive features and significant progress compared to existing technologies, and its beneficial effects are readily apparent. Detailed Implementation

[0025] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0026] A method for preparing low-interstitial-impurity alloy powder based on large-size hydrogenatable alloy waste, comprising the following steps:

[0027] S1: Clean the surface of the blocky waste to remove impurities: After cleaning the surface of the blocky waste with an oil-removing cleaning agent and then acid washing to remove impurities, the resulting alloy block is dried for later use. The oil-removing cleaning agent is an organic solvent (such as alcohol, ketone, ester, etc.). The oil stains are dissolved by using an organic solvent for cleaning. Alternatively, an alkaline cleaning agent (such as sodium hydroxide solution) can be used. The surface of the blocky waste is immersed in a sodium hydroxide solution to chemically remove the oil stains using alkalinity.

[0028] S2: Place the alloy block in the hydrogenation furnace, evacuate the vacuum, and heat to the set temperature: evacuate the vacuum to 1*10. -3 After heating to 650℃-850℃ at pressure below MPa;

[0029] S3: Introduce high-purity hydrogen into the furnace to positive pressure and maintain the temperature: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1-2 MPa, maintain the temperature for 20-45 minutes to hydrogenate the material;

[0030] S4: Turn on the mechanical pump set to extract hydrogen from the furnace and keep it at a constant temperature; turn on the mechanical pump set to extract hydrogen from the furnace, keep the vacuum in the furnace below 0.1MPa, and keep it at a constant temperature for 15-20 minutes to dehydrogenate the material.

[0031] S5: Introduce high-purity hydrogen into the furnace to positive pressure and maintain the temperature: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1-2 MPa, maintain the temperature for 20-45 minutes, so that the material is hydrogenated a second time.

[0032] S6: Repeat steps S3-S5 multiple times (preferably 3 times), then take out the hydride for mechanical crushing and sieve out the hydride powder with the required particle size: stop heating, let the hydrogenation furnace cool to room temperature, extract the remaining hydrogen in the furnace and introduce high-purity argon to atmospheric pressure, then take out the hydride, mechanically ball mill the hydride under argon protection and sieve out the hydride powder with D50 of 20-30um;

[0033] S7: Place the sieved hydride powder in a vacuum furnace, evacuate, heat to the set temperature, and hold. -3 After the pressure is below MPa, heat to 650℃-700℃ and hold for 120-300 minutes to complete the dehydrogenation.

[0034] S8: After dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace and the furnace is kept under positive pressure. After the furnace is cooled to room temperature, low-interstitial-impurity alloy powder is obtained. It is preferable to introduce high-purity argon gas into the furnace to 1 MPa.

[0035] The hydrogenatable alloy scrap is 15-30g of TC4 titanium scrap with an average thickness of 30-50mm, 45-60g of Nb521 scrap with an average thickness of 20-40mm, or 15-30kg of zirconium alloy scrap with an average thickness of 20-40mm. The invention will be further described in detail below through specific embodiments.

[0036] Example 1

[0037] TC4 titanium alloy powder is prepared from recycled bulk titanium waste.

[0038] S1: The surface of 20kg TC4 titanium waste with an average thickness of 40mm is cleaned with an oil-removing cleaning agent and then pickled to remove impurities from the surface of the waste. The resulting alloy block is then dried for later use.

[0039] S2: Place the alloy block in the hydrogenation furnace and evacuate to a vacuum level of 1*10. -3After heating to 700℃ at pressure below MPa;

[0040] S3: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1 MPa, keep it at this temperature for 30 minutes to hydrogenate the material;

[0041] S4: Turn on the mechanical pump set to extract hydrogen from the furnace, keep the vacuum in the furnace below 0.1MPa, and hold for 15 minutes to dehydrogenate the material.

[0042] S5: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1MPa. Keep the temperature for 30 minutes to allow the material to undergo secondary hydrogenation.

[0043] S6: After repeating steps S3-S5 (hydrogenation-dehydrogenation-hydrogenation) 3 times, stop heating, allow the hydrogenation furnace to cool to room temperature, extract the remaining hydrogen in the furnace and introduce high-purity argon to atmospheric pressure, take out the hydride, mechanically ball mill the hydride under argon protection and sieve out the hydride powder with D50 of 20-30um.

[0044] S7: Place the sieved hydride powder in a vacuum furnace and evacuate to 1*10. -3 After the pressure is below MPa, heat to 650℃ and hold for 120 minutes to complete the dehydrogenation.

[0045] S8: After dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace to 1 MPa. After the furnace is cooled to room temperature, TC4 titanium alloy fine powder with low interstitial impurities is obtained (O content less than 1800 ppm; N content less than 500 ppm).

[0046] Example 2

[0047] Nb521 alloy powder is prepared from the recycling of bulk Nb521 waste.

[0048] S1: The surface of 50kg Nb521 waste with an average thickness of 30mm is cleaned with an oil-removing cleaning agent and then pickled to remove impurities from the surface of the waste. The resulting alloy block is then dried for later use.

[0049] S2: Place the alloy block in the hydrogenation furnace and evacuate to a vacuum level of 1*10. -3 After heating to 850℃ at pressure below MPa;

[0050] S3: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1.5 MPa, hold for 40 minutes to hydrogenate the material;

[0051] S4: Turn on the mechanical pump set to extract hydrogen from the furnace, keep the vacuum in the furnace below 0.1MPa, and then keep it at that temperature for 20 minutes to dehydrogenate the material.

[0052] S5: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1.5 MPa, keep it at the temperature for 40 minutes to allow the material to undergo secondary hydrogenation.

[0053] S6: After repeating steps S3-S5 (hydrogenation-dehydrogenation-hydrogenation) 4 times, stop heating, allow the hydrogenation furnace to cool to room temperature, extract the remaining hydrogen in the furnace and introduce high-purity argon to atmospheric pressure, take out the hydride, mechanically ball mill the hydride under argon protection and sieve out the hydride powder with D50 of 20-30um.

[0054] S7: Place the sieved hydride powder in a vacuum furnace and evacuate to 1*10. -3 After the pressure is below MPa, heat to 700℃ and hold for 240 minutes to complete the dehydrogenation.

[0055] S8: After dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace to 1 MPa. After the furnace is cooled to room temperature, fine Nb521 alloy powder with low interstitial impurities is obtained (O content less than 2000 ppm; N content less than 500 ppm).

[0056] Example 3

[0057] Zr-2.5%Nb alloy powder was prepared from bulk Zr-2.5%Nb waste.

[0058] S1: The surface of 20kg Zr-2.5%Nb waste with an average thickness of 30mm is cleaned with an oil-removing cleaning agent and then pickled to remove impurities from the surface of the waste. The resulting alloy block is then dried for later use.

[0059] S2: Place the alloy block in the hydrogenation furnace and evacuate to a vacuum level of 1*10. -3 After heating to 750℃ at pressure below MPa;

[0060] S3: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1.5 MPa, keep it at this temperature for 20 minutes to hydrogenate the material;

[0061] S4: Turn on the mechanical pump set to extract hydrogen from the furnace, keep the vacuum in the furnace below 0.1MPa, and then keep it at that temperature for 20 minutes to dehydrogenate the material.

[0062] S5: Introduce high-purity hydrogen into the furnace and maintain the hydrogen partial pressure at 1.5 MPa, keep it at this temperature for 20 minutes to allow the material to undergo secondary hydrogenation.

[0063] S6: After repeating steps S3-S5 (hydrogenation-dehydrogenation-hydrogenation) twice, stop heating, allow the hydrogenation furnace to cool to room temperature, extract the remaining hydrogen in the furnace and introduce high-purity argon to atmospheric pressure, take out the hydride, mechanically ball mill the hydride under argon protection and sieve out hydride powder with D50 of 20-30um.

[0064] S7: Place the sieved hydride powder in a vacuum furnace and evacuate to 1*10. -3 After the pressure is below MPa, heat to 700℃ and hold for 240 minutes to complete the dehydrogenation.

[0065] S8: After dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace to 1 MPa. After the furnace is cooled to room temperature, a fine Zr-2.5% Nb alloy powder with low interstitial impurities is obtained (O content less than 1600 ppm; N content less than 300 ppm).

[0066] As can be seen from the above embodiments:

[0067] 1. This invention causes a drastic change in the partial pressure of hydrogen in the furnace, which causes the material to undergo repeated hydrogenation-dehydrogenation phase transitions from the surface to the interior at the microscopic level, generating a large number of microscopic defects and promoting the mass exchange rate; at the macroscopic level, the significant volume change caused by the phase transition leads to the continuous initiation and expansion of cracks in the material, exposing fresh surfaces to participate in the hydrogenation reaction process, thus promoting the hydrogenation effect of large-sized materials.

[0068] 2. This invention can continuously absorb interstitial impurities in materials through repeated adsorption and desorption of hydrogen;

[0069] 3. After mechanical crushing, screening and dehydrogenation, the present invention immediately introduces high-purity argon gas into the furnace at high temperature to positive pressure, so that the powder is passivated by high-purity argon gas before a dense oxide film is formed, thereby improving the oxidation resistance of the powder after exposure and reducing the content of interstitial impurities in the powder.

[0070] 4. The method and steps of the present invention can realize the low-cost and high-efficiency recycling of large-size hydrogenizable alloy waste and prepare high-quality alloy fine powder with low interstitial impurities.

[0071] Technical features not described in this invention can be implemented using existing technologies and will not be elaborated upon here. This invention is not limited to the specific embodiments described above; any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of this invention should also fall within the protection scope of this invention.

Claims

1. A method for preparing low-interstitial-impurity alloy powder based on large-size hydrogenatable alloy waste, characterized in that, It includes the following steps: S1: Clean the surface of the blocky waste to remove impurities, and then dry the resulting alloy block for later use; the hydrogenatable alloy waste is 15-30kg of TC4 titanium waste with an average thickness of 30-50mm, 45-60kg of Nb521 waste with an average thickness of 20-40mm, or 15-30kg of zirconium alloy waste with an average thickness of 20-40mm; S2: Place the alloy block in a hydrogenation furnace, evacuate the vacuum, and heat it to 650℃-850℃; S3: Introduce high-purity hydrogen into the furnace to positive pressure and keep it at a certain temperature to hydrogenate the material: Introduce high-purity hydrogen into the furnace and keep the hydrogen partial pressure at 1-2 MPa, and keep it at a certain temperature for 20-45 minutes. S4: Start the mechanical pump group to extract hydrogen from the furnace and keep it warm to dehydrogenate the material: Start the mechanical pump group to extract hydrogen from the furnace and keep the vacuum in the furnace below 0.1MPa for 15-20 minutes. The obvious volume change caused by the phase change on a macroscopic scale causes the material to continuously generate cracks and expand, exposing fresh surfaces to participate in the hydrogenation reaction process. S5: Introduce high-purity hydrogen into the furnace to positive pressure and keep it at a certain temperature to hydrogenate the material a second time: Introduce high-purity hydrogen into the furnace and keep the hydrogen partial pressure at 1-2 MPa, keep it at a certain temperature for 20-45 minutes. The second dehydrogenation causes a significant change in the volume of the material macroscopically, resulting in cracks of varying sizes inside and on the surface of the material. S6: After repeating steps S3-S5 multiple times, remove the hydride for mechanical crushing and sieve out the hydride powder of the required particle size. S7: Place the sieved hydride powder in a vacuum furnace, evacuate the vacuum, heat to 650℃-700℃ and keep warm to complete the dehydrogenation. S8: After dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace and positive pressure is maintained inside the furnace. After the furnace cools to room temperature, low-interstitial-impurity alloy powder is obtained.

2. The method for preparing low-interstitial-impurity alloy powder based on large-size hydrogenatable alloy waste according to claim 1, characterized in that, In step S1, the surface of the blocky waste is cleaned with an oil-removing cleaning agent and then acid-washed to remove impurities from the surface of the waste. The oil-removing cleaning agent is an organic solvent or an alkaline cleaning agent.

3. The method for preparing low-interstitial-impurity alloy powder based on large-size hydrogenatable alloy waste according to claim 2, characterized in that, In step S2, the vacuum is evacuated to 1×10⁻⁶. -3 After heating to 650℃-850℃ at pressures below MPa, the temperature is increased.

4. The method for preparing low-gap impurity alloy powder based on large-size hydrogenatable alloy waste according to claim 3, characterized in that, In step S6, after repeating steps S3-S5 three times, heating is stopped, the hydrogenation furnace is cooled to room temperature, the remaining hydrogen in the furnace is extracted, and high-purity argon is introduced to atmospheric pressure. The hydride is then removed, and the hydride is mechanically ball-milled under argon protection and sieved to obtain hydride powder with a D50 of 20-30 μm.

5. The method for preparing low-interstitial-impurity alloy powder based on large-size hydrogenatable alloy waste according to claim 4, characterized in that, In step S7, the sieved hydride powder is placed in a vacuum furnace and evacuated to a vacuum level of 1×10⁻⁶. -3 After the pressure is below MPa, heat to 650℃-700℃ and hold for 120-300 minutes.

6. The method for preparing low-interstitial-impurity alloy powder based on large-size hydrogenatable alloy waste according to claim 5, characterized in that, In step S8, after dehydrogenation is completed, high-purity argon gas is immediately introduced into the furnace to a pressure of 1 MPa.