A method for recycling niobium-tungsten alloy waste

Abstract

The present application belongs to the technical field of refractory alloy waste recycling, and specifically discloses a niobium-tungsten alloy waste recycling method. The method comprises the following steps: firstly, surface decontamination and specification block processing are performed on the multi-source physical form niobium-tungsten alloy waste to eliminate heterogeneous surface impurities and regularize flow field resistance; then, high-activity hydrogen absorption phase change embrittlement is performed in a hydrogenation furnace, and intermediate matrix powder is obtained through mechanical impact crushing and sieving; according to the initial content of zirconium elements in the powder and the selective evaporation burning loss rate of electron beam refining, zirconium-based additives are added directionally and mechanically homogenized; finally, metal bond grain boundaries are reconstructed and most of the harmful interstitial gases are removed through high-vacuum solid-phase activation sintering, and the green body is subjected to at least two times of electron beam high-vacuum multiple refining smelting to obtain a niobium-tungsten alloy ingot with homogeneous composition, low interstitial inclusion and excellent hot working performance. The present method eliminates the pickling process, is green and environmentally friendly, and solves the problems of degradation of volatile elements during remelting and cracking of recycled materials during rolling.

Description

Technical Field

[0001] This invention belongs to the field of refractory alloy waste recycling technology, specifically relating to a method for recycling and processing niobium-tungsten alloy waste. Background Technology

[0002] Niobium-tungsten alloy (NbW5-2) is a novel aerospace material with low density, good high-temperature mechanical properties, and excellent room-temperature machinability. It is widely used in the manufacture of rocket engine nozzles, satellite attitude control engines, and other high-temperature resistant aerospace components. The production process of niobium-tungsten alloys generates a large amount of waste, including machining chips and scrap, accounting for up to 50% of the total waste. Since niobium and tungsten are non-renewable resources, recycling and reusing this waste can significantly improve its utilization value and greatly reduce the consumption of strategic metals such as niobium and tungsten.

[0003] Due to the diverse alloy elements in niobium-tungsten alloy scrap, recycling is quite difficult. Currently, the main methods for processing niobium-tungsten alloy scrap are wet recycling and electron beam remelting. Wet recycling involves dissolving and extracting the niobium-tungsten alloy scrap with acid to obtain high-purity niobium oxide. The niobium oxide is then aluminothermally reduced to obtain smelted niobium, which is then electron beam melted to obtain niobium ingots suitable for rolling. This method involves many steps, high costs, and requires a large amount of acid, making it neither economical nor environmentally friendly. Electron beam remelting involves acid washing to remove impurities from the niobium-tungsten alloy scrap, then fabricating the scrap into electrodes, and directly electron beam melting to obtain niobium-tungsten alloy ingots. The resulting niobium-tungsten alloy ingots have uneven distribution of alloy elements, particularly Zr content along the length of the ingot. Their processing performance is also poor, and they are prone to cracking during hot forging or hot rolling, making it difficult to produce uniform, high-quality niobium-tungsten alloy materials. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for recycling and processing niobium-tungsten alloy waste, the specific technical solution of which is as follows: A method for recycling and processing niobium-tungsten alloy waste, characterized by comprising the following steps: S1. Surface cleaning and block-forming treatment of niobium-tungsten alloy waste; S2. The treated niobium-tungsten alloy waste is placed in a hydrogenation furnace for hydrogenation treatment. Then the hydrogenated and embrittled waste is crushed and sieved to obtain intermediate matrix powder. S4. Determine the composition of the intermediate matrix powder, and based on the initial zirconium content in the intermediate matrix powder and the preset burn-off rate of subsequent refining and melting, introduce zirconium-based additives into the intermediate matrix powder for directional composition compensation mixing to obtain alloy mixed powder with controlled composition. S5. The alloy mixture powder is pressed into shape and then vacuum sintered to obtain an alloy billet; S6. The alloy billet is subjected to multiple high-vacuum refining and melting processes to obtain a niobium-tungsten alloy ingot with uniform composition.

[0005] Preferably, in step S1, the surface cleaning and block-forming treatment specifically includes: If the niobium-tungsten alloy waste is niobium-tungsten car shavings waste, it is ultrasonically cleaned for 5-30 minutes using a mixture of degreasing cleaning agent and water. After cleaning, it is rinsed with water, dried, and then compressed into small pieces with length, width, and height dimensions ≤ 400mm × 100mm × 100mm using a hydraulic baler. If the niobium-tungsten alloy scrap is niobium-tungsten offcut scrap, it is cut into small pieces with a length ≤400mm and a width ≤250mm, and then ultrasonically cleaned for 5~30min with a mixture of degreasing cleaning agent and water. After cleaning, it is rinsed with water and dried.

[0006] Preferably, in step S2, the hydrogenation treatment temperature is 500~800℃ and the time is 60~120min; the crushing and sieving is performed using an 80-mesh screen.

[0007] Preferably, step S4 specifically includes: S41. Mix the intermediate matrix powders from different batches together, and take samples to test the content of each element in the matrix powder after batch mixing; S42. Based on the initial Zr element content obtained from the test, add zirconium-based additives to the powder to adjust the total Zr element mass percentage after mixing to be in the range of 2.8%~3.4%, and then mix again for 60~180 min.

[0008] Preferably, the zirconium-based additive is selected from Zr powder, zirconium hydride powder, etc. At least one of the compound sustained-release agents.

[0009] Preferably, the The composite slow-release agent also contains 1% to 5% of its mass of pre-alloyed Nb powder.

[0010] Preferably, the In the compound sustained-release agent, the mass percentage of ZrC is 30wt%~50wt%.

[0011] Preferably, the following steps are included between steps S2 and S4: S3. The intermediate matrix powder is subjected to vacuum dehydrogenation treatment to obtain dehydrogenated intermediate matrix powder, wherein the parameters of the vacuum dehydrogenation treatment are: vacuum furnace temperature 650~850℃, vacuum degree ≥ The heat preservation time is 60~150 minutes.

[0012] Preferably: In step S5, the pressing is cold isostatic pressing with a pressure of 100 MPa and a holding time of 60 min; the vacuum sintering temperature is 1600~2300℃. In step S6, the high-vacuum refining and melting is electron beam melting, with the melting process repeated at least twice, and the high vacuum level during melting is not lower than [missing information]. .

[0013] Preferably, the The compound sustained-release agent is prepared through the following steps: S10. Using zirconium source powder and solid carbon source as raw materials, the molar ratio of Zr element to C element is controlled at (1.8~2.2):1 to mix them to obtain reaction precursor powder; S20. The reaction precursor powder is placed in a mixed atmosphere of hydrogen and argon, and subjected to reaction sintering and hydrogenation treatment at 800~1100℃ for 2~4 hours to obtain the sintered product. S30. The sintered product is ball-milled and sieved, and the particle size of the sieved material is matched with the particle size of the intermediate matrix powder in step S2.

[0014] This invention involves directly cleaning and hydrogenating niobium-tungsten alloy waste into powder, then pressing and sintering it into niobium-tungsten alloy bars, and finally smelting them into niobium-tungsten alloy ingots. This eliminates the intermediate acid washing process, resulting in niobium-tungsten alloy ingots with uniform composition and excellent subsequent processing performance, superior to those obtained from virgin materials. The processed niobium-tungsten alloy plates meet all standard requirements. This method is environmentally friendly, requiring no hydrofluoric acid, concentrated nitric acid, or other acids, making it a green recycling method. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art are briefly introduced below.

[0016] Figure 1 This is a photograph of the niobium-tungsten alloy ingot prepared in Example 1 of the present invention. Figure 2 This is a physical image of the niobium-tungsten alloy ingot prepared in Example 2 of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0018] This embodiment provides a method for recycling and processing niobium-tungsten alloy waste.

[0019] Specifically, the method for recycling and processing niobium-tungsten alloy waste includes the following steps: The first step (Step S1) involves surface cleaning and block forming of the niobium-tungsten alloy scrap. For niobium-tungsten machining shavings that easily retain cutting oil and have a loose, porous shape, ultrasonic cleaning agents are used to deeply remove machining oil, followed by hydraulic packing to limit their porous volume. For blocky niobium-tungsten scrap, mechanical shearing is first used to interrupt their continuous long dimensions, followed by ultrasonic surface degreasing. This process transforms scrap of different physical forms into standardized blocks with both high cleanliness and regular geometric density, which improves the uniformity of the flow field in the hydrogenation furnace and the continuity of large-scale loading.

[0020] The second step (step S2) involves placing the processed niobium-tungsten alloy waste in a hydrogenation furnace for hydrogenation treatment. The hydrogenated and embrittled waste is then crushed and sieved to obtain intermediate matrix powder. Hydrogenation utilizes the physical property of metals absorbing hydrogen under specific temperature and pressure, resulting in lattice expansion and phase transformation embrittlement. By controlling the hydrogen pressure and thermodynamic temperature within the hydrogenation furnace, hydrogen atoms diffuse into the niobium-tungsten alloy matrix, causing brittle hydride phases to precipitate in situ and solidify the lattice distortion energy, thereby reducing the material's fracture toughness. Subsequently, a brittle crushing device is used to apply mechanical impact force to the hydrogen-embrittled blocks, causing them to disintegrate and crush along the embrittled grain boundaries. The powder is then sieved through a standard mesh sieve to control the particle size distribution range and isolate macroscopic inclusions, obtaining the intermediate matrix powder.

[0021] The third step (step S4) involves determining the composition of the intermediate matrix powder. Based on the initial zirconium content in the intermediate matrix powder and the preset burn-off rate for subsequent refining and melting, zirconium-based additives are introduced into the intermediate matrix powder for directional compositional compensation mixing, resulting in a compositionally controlled alloy mixture powder. This directional compositional compensation mixing is based on full-element quantitative chemical analysis and a melting pyrodynamic loss model. Because the vapor pressure of zirconium is higher than that of niobium and tungsten under the high temperature, high vacuum, and strong flow field of electron beam refining and melting, it undergoes selective vaporization and evaporation in the molten pool. By pre-determining the actual initial residual zirconium mass concentration in each batch of intermediate matrix powder and combining it with a specific instantaneous high-temperature kinetic preset burn-off rate, the target compensation amount required to achieve the final grade is calculated. The introduced zirconium-based additives are quantitatively controlled and then spatially dispersed in the intermediate matrix powder using a mechanical mixing device to form an alloy mixture powder, avoiding localized component segregation and enrichment.

[0022] Step 4 (S5) involves pressing the alloy powder mixture into a compact shape, followed by vacuum sintering to obtain an alloy billet. Pressing forces the dispersed powder particles to undergo elastic-plastic deformation through external physical constraints, eliminating bridging gaps between particles and constructing mechanical bonds to form a shaped body with a specific geometry and initial green strength. The subsequent vacuum sintering is a vacuum thermal activation treatment performed at a solid-state temperature below the alloy's melting point. Under high temperature and high vacuum, surface energy at the contact points of the powder particles is released, and atoms undergo grain boundary diffusion and volume diffusion, promoting the growth of the sintering neck, reducing pore size, and expelling atoms outward from the grain boundaries. The original mechanical interfaces between the powder particles are transformed into stable metallic bond grain boundaries. At this point, different elements within the alloy begin to undergo solid-state diffusion and homogenization, thus obtaining the alloy billet.

[0023] Step 5 (Step S6) involves multiple high-vacuum refining and melting processes on the alloy billet to obtain a niobium-tungsten alloy ingot with uniform composition. High-vacuum refining and melting utilizes a high-energy electron beam to bombard the alloy billet, creating a high-temperature dynamic remelting pool within a water-cooled copper crystallizer. Under the synergistic effect of ultra-high vacuum and the extreme temperature of the molten pool, interstitial impurities and metallic impurities with high vapor pressure dissolved in the waste material undergo thermal decomposition or vaporization, thus being removed by the vacuum pumping system. By designing multiple melting paths, the remelted metal undergoes repeated convective mixing and solute redistribution within the molten pool, thereby eliminating macroscopic segregation and ensuring a uniform distribution of all alloying elements along the axial and radial directions of the ingot, ultimately solidifying into a niobium-tungsten alloy ingot.

[0024] Benefically, this embodiment directly cleans and hydrogenates niobium-tungsten alloy waste into powder, then presses and sinters it into niobium-tungsten alloy bars, and finally melts them into niobium-tungsten alloy ingots. This eliminates the intermediate acid washing process, resulting in niobium-tungsten alloy ingots with uniform composition and excellent subsequent processing performance, superior to those obtained from virgin materials. The processed niobium-tungsten alloy plates meet all standard requirements. This method is environmentally friendly, as it eliminates the need for hydrofluoric acid, concentrated nitric acid, or other acids, making it a green recycling method.

[0025] Furthermore, the specific operation method and material path for surface cleaning and block-forming treatment in step S1 are as follows: When the niobium-tungsten alloy scrap to be processed is characterized by easily adhering mechanical cutting oil stains and a continuous, porous, and fluffy morphology, the pretreatment focus is on removing oil stains from hidden pores and increasing the loading density. Specifically, the niobium-tungsten scrap is completely immersed in an ultrasonic cleaning tank. The cleaning medium in the tank is a mixture of degreasing cleaning agent and clean water, with the volume ratio of cleaning agent to clean water controlled at 1:20. The ultrasonic generator is activated, and the ultrasonic cleaning time is controlled within the range of 5 to 30 minutes. During this period, the micro-jets and shock waves generated by the ultrasonic cavitation effect force the solidified oil stains inside the porous folds of the scrap to detach from the metal surface and enter the emulsion. After the ultrasonic treatment, the scrap is removed and rinsed continuously with clean water 2 to 3 times to thoroughly remove residual liquid, followed by heating and drying to remove water. The dried automotive waste is fed into a metal hydraulic baler, where it is compressed at a high ratio by applying multiple external physical pressures to confine and shape it into dense, standardized small blocks. The length, width, and height of each block are no greater than 400 mm × 100 mm × 100 mm.

[0026] When the niobium-tungsten alloy scrap to be processed is large-sized niobium-tungsten offcuts, the focus of pretreatment is to block physical interference and remove surface oil. Specifically, large pieces or long strips of scrap are first forcefully cut using a mechanical shearing machine to reduce their size to small pieces no more than 400 mm in length and 250 mm in width, thereby increasing the specific surface area and eliminating mechanical interference during subsequent transfer and furnace loading. Then, the cut pieces are completely immersed in an ultrasonic cleaning tank with the above-mentioned ratio (cleaning agent to water volume ratio 1:20) for 5-30 minutes of ultrasonic cleaning, using acoustic energy to remove grease from solid boundaries. After ultrasonic treatment, the pieces are removed, rinsed 2-3 times with water, and dried.

[0027] Furthermore, the detailed operation of the hydrogenation treatment and pulverization and classification process in step S2 is as follows: The standardized blocks obtained after pretreatment are densely packed into the hydrogenation furnace. The furnace body is sealed, and the vacuum system is activated to evacuate the furnace to a basic pressure below 1 Pa to purge the reactive gases from the original furnace chamber. Then, hydrogen gas with a purity of not less than 99.99% is introduced into the furnace to maintain a constant positive pressure. The heating elements are activated, and the internal temperature of the hydrogenation furnace is raised to the range of 500-800℃. At this temperature, hydrogen atoms have an extremely high solid-phase diffusion coefficient, allowing them to rapidly penetrate the surface of the blocks and diffuse into the interstitial positions within the metal lattice. This temperature is maintained, and the reaction continues for 60-120 minutes, allowing the metal matrix to fully react with the hydrogen atoms and precipitate a brittle hydride phase with high distortion energy in situ. This locks dislocation movement, resulting in a significant increase in the ductile-brittle transition temperature of the material. After the holding period, the heating is turned off, and the material is allowed to cool to room temperature in the hydrogen atmosphere. The embrittled material is then transferred to a ball mill or air jet mill, where mechanical impact and frictional shear forces are applied to break it apart along the grain boundaries. The crushed material is then fed into a standard sieving device with an 80-mesh screen for particle size classification. The fine powder material that passes through the screen is collected to obtain an intermediate matrix powder with a narrow particle size distribution.

[0028] Furthermore, the specific operation of step S4 is as follows: Step S41 involves a large-scale batch physical mixing of intermediate matrix powders obtained from different batches of hydrogenation embrittlement powdering process or vacuum dehydrogenation process. After uniform mixing, the batched matrix powder is sampled using a multi-point random sampling method, and the mass percentage of each major element and interstitial element in the batched matrix powder is accurately detected using inductively coupled plasma optical emission spectrometry (ICP-OES) or a high-frequency infrared carbon-sulfur analyzer. The initial matrix content of zirconium and oxygen in the powder is recorded at this point.

[0029] Step S42: Based on the detected initial zirconium content and the preset high-temperature burn-off rate of zirconium during subsequent high-vacuum refining and melting processes, calculate the net mass of zirconium that needs to be added. Add a zirconium-based additive to the powder so that the total zirconium mass percentage after introducing the additive and remixing is within the range of 2.8% to 3.4%. This zirconium-based additive is selected from at least one of pure elemental zirconium powder, zirconium hydride powder, and a composite slow-release agent.

[0030] When a composite slow-release agent is selected as the zirconium-based additive, the composite slow-release agent is a substance with a core-shell structure or a homogeneous composite structure, wherein zirconium carbide ( The mass percentage of zirconium hydride is limited to 30wt%~50wt%, with the remainder mainly consisting of zirconium hydride. Furthermore, to eliminate potential poor wettability or compositional segregation at local phase interfaces caused by the introduction of heterogeneous phases, a small amount of pre-alloyed niobium powder (1%–5% by weight) can be pre-alloyed in the composite slow-release agent. This pre-alloyed niobium powder is in a solid solution state or highly dispersed within the composite slow-release agent. The quantitatively calculated zirconium-based additive is then added to a double-cone mixer and mixed again with the intermediate matrix powder for 60–180 min. Utilizing the three-dimensional cross-rolling effect of the double cones, the composite slow-release agent, zirconium powder, or zirconium hydride powder is driven to achieve dispersion in the interparticle gaps of the intermediate matrix powder, ultimately obtaining a compositionally controlled alloy mixture powder.

[0031] Beneficially, this embodiment uses batch testing and reverse calculation of zirconium element compensation based on refining burn loss to lock the total zirconium content after adjustment between 2.8% and 3.4%, laying the material foundation for finally obtaining niobium-tungsten alloy ingots with grades that meet the standards and have minimal compositional fluctuations.

[0032] Furthermore, step S3 is included between steps S2 and S4. Step S3 involves loading the intermediate matrix powder obtained in step S2, which has undergone hydrogenation embrittlement and crushing and has been sieved through an 80-mesh screen, into a vacuum dehydrogenation furnace. The pumping system is then activated to maintain the vacuum level inside the furnace. Under a high vacuum state, the vacuum furnace temperature is then heated to the range of 650~850℃ and held for 60~150 min. Under this high vacuum, the hydrogen partial pressure difference generated by the high vacuum drives the hydrogen atoms originally dissolved in the interstitial spaces of the niobium-tungsten lattice to diffuse outward in the reverse direction and dissociate and desorb. This reduces the hydrogen content of the powder to an extremely low level before the introduction of zirconium-based additives, preventing the brittle hydrogen phase from interfering with subsequent composition control and mixing uniformity.

[0033] The specific process of step S5 is as follows: The alloy powder, after composition adjustment in step S4 (total zirconium content adjusted to 2.8%~3.4%), was loaded into a negative mold and transferred to a cold isostatic press. Cold isostatic pressing was performed under a balanced axial and radial hydrostatic pressure of 100 MPa, with a holding time of 60 min. Subsequently, the alloy block was transferred to a high-temperature vacuum sintering furnace for solid-state vacuum sintering in the ultra-high temperature range of 1600~2300℃.

[0034] The specific process of step S6 is as follows: The alloy billet (sintered bar) is placed as the base material in an electron beam (EB) melting furnace. The high vacuum unit is started to ensure that the background high vacuum level in the melting chamber is strictly no less than [a certain value]. The electron gun is activated to extract a high-energy electron beam that is focused and bombards the surface of the material, causing it to remelt as a whole and establishing a dynamic remelting pool within the crystallizer. The overall remelting and refining process is repeated ≥2 times. Under the ultra-high temperature and high vacuum environment of the molten pool, zirconium, which is normally prone to instantaneous vaporization and boiling, is forced to undergo a slow melting and kinetic release process within the ZrC high-temperature phase. This suppresses the instantaneous vacuum evaporation loss of zirconium, significantly reducing the zirconium burn-off rate during the smelting process from the conventional 40%~55% to 20%~35%. Simultaneously, the slowly dissolving zirconium atoms and trace amounts of carbon atoms act as highly efficient "carbon-oxygen scavengers" in the molten pool, rapidly converting residual heterogeneous interstitial oxygen elements in the melt into low-density oxide micro-slag in situ. With the help of the strong thermal convection field of the molten pool, these micro-slags are rapidly driven to float and aggregate into slag, which is then removed in situ at the edge of the crystallizer. After smelting, directional solidification is carried out to finally obtain niobium-tungsten alloy ingots with minimal compositional fluctuations (fluctuation <0.1% in the upper and lower parts), elimination of local segregation, and excellent hot working performance.

[0035] Furthermore, the specific preparation process of the composite sustained-release agent is as follows: In step S10, elemental zirconium powder or zirconium hydride powder is used as the zirconium source powder, and graphite powder or phenolic resin cracked carbon is used as the solid carbon source. The powder is mixed, and the molar ratio of the main Zr element to C element in the mixture is controlled within the range of (1.8~2.2):1. The mixture is then homogenized to obtain the reaction precursor powder. Next, in step S20, the reaction precursor powder is placed in a mixed protective / reaction atmosphere of hydrogen and argon, and subjected to reaction sintering and in-situ hydrogenation treatment at a temperature field of 800~1100℃ for 2~4 hours. Finally, in step S30, the sintered product is transferred to a ball mill for crushing, grinding, and sieving. By controlling the airflow classification or sieving parameters, the final D50 particle size is controlled within 2~15μm to ensure that the microparticle size of the composite slow-release agent matches the intermediate matrix powder obtained by sieving through an 80-mesh sieve in step S2, preventing macroscopic segregation caused by specific gravity or particle size separation during mixing.

[0036] Specific embodiments are provided below. These embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the present invention in any way.

[0037] Preparation Example 1 Weigh 182.4 g of elemental Zr powder and 12.0 g of high-purity graphite carbon powder. Put the weighed powders into a three-dimensional oscillating mixer, introduce high-purity argon gas into the mixer until the air is exhausted, then lock the mixing tank and mix continuously at a speed of 45 r / min for 6 h to obtain the reaction precursor powder.

[0038] The uniformly mixed reaction precursor powder was removed and evenly spread in a molybdenum boat inside a high-temperature vacuum hydrogen-filled furnace. The furnace door was closed, and the vacuum pump was started to evacuate the furnace to a vacuum level. Pa. Then, heat at a rate of 10℃ / min until the furnace temperature reaches 950℃, at which point heating is stopped. Maintain this temperature and introduce high-purity oxygen into the furnace. A mixture of gas and high-purity Ar gas (volume ratio 1:1) was prepared, and the positive pressure inside the furnace was maintained at 0.05 MPa by adjusting the inlet valve. Under this mixed atmosphere, the furnace underwent constant-temperature hydrogen reaction sintering and hydrogenation treatment for 3 hours to obtain the sintered product.

[0039] After the reaction is complete, the heating power and vent valve are turned off, and the furnace is cooled to room temperature under argon protection. The sintered product in the molybdenum boat is removed from the furnace and transferred to a fully enclosed ball mill for mechanical crushing. It is then sieved through an 80-mesh screen, and the undersize material is collected to finally obtain ZrC-. Composite sustained-release powder. Chemical analysis showed that the ZrC content in this composite sustained-release powder was 42 wt%.

[0040] Example 1

[0041] Collect 5.0 kg of niobium-tungsten automotive waste. Prepare the cleaning solution: Add the degreasing cleaner and water to the ultrasonic cleaner at a volume ratio of 1:20 and mix thoroughly. Completely immerse the 5.0 kg of niobium-tungsten automotive waste in the cleaning solution and ultrasonically clean for 20 minutes. After ultrasonic cleaning, remove the waste and rinse it three times with clean water. The cleaned automotive waste is then fed into a metal hydraulic baler and compressed into small pieces with dimensions of 120 mm × 50 mm × 50 mm, and then placed in an oven to dry.

[0042] The dried waste material is placed into a tubular hydrogen-filling furnace. After evacuating the furnace by starting the vacuum pump, high-purity hydrogen is introduced into the furnace. The gas flow was controlled, and the hydrogen pressure inside the furnace was maintained at 0.1 MPa. The temperature was then raised to 650℃ and held at this temperature for 90 minutes for hydrogenation. After cooling to room temperature, the material was removed from the furnace. The embrittled waste was transferred to a fully enclosed ball mill for ball milling and crushing, and then sieved through an 80-mesh screen. The sieved powder was then transferred to a vacuum furnace for dehydrogenation treatment. The dehydrogenation parameters were set as follows: furnace temperature 750℃, vacuum level maintained at... The mixture was heated to a pressure above Pa and dehydrogenated for 120 min. After cooling, intermediate matrix powder was obtained. Sampling and testing revealed the following mass percentages of elements in this batch of intermediate matrix powder: W 4.94%, Mo 1.99%, Zr 1.8%, Ta 0.28%, C 0.0093%, O 0.12%, N 0.0084%, and H 0.0019%.

[0043] 78.5 g of ultrafine pure Zr powder with an average particle size of 15 μm was directly added to the above intermediate matrix powder. The mixture was then placed into a small double cone mixer and dried for 120 min to obtain an alloy mixed powder.

[0044] The mixed alloy powder was placed into a rectangular elastic sleeve and sealed. It was then placed in a cold isostatic press and pressed at 100 MPa for 60 minutes. After depressurization, the powder was removed to obtain a green billet. This green billet was then transferred to a high-temperature vacuum sintering furnace, and the vacuum system was activated to achieve the required vacuum level. Pa was heated to 1950℃ at a heating rate of 15℃ / min, and sintered under this vacuum high-temperature condition for 4 h to obtain a silver-gray high-density alloy billet strip.

[0045] The sintered alloy billet was used as a consumable electrode and hoisted into a small electron beam (EB) melting furnace. The vacuum system was then activated, and the base vacuum level of the melting chamber was increased to [value missing]. At a pressure of Pa, the electron gun is activated. The electron gun beam current and voltage are adjusted to focus the electron beam onto the bottom of the alloy strip for continuous remelting. The molten material drips continuously into a water-cooled copper crystallizer for solidification. This electron beam remelting and refining process is repeated twice, and finally, a high-quality niobium-tungsten alloy recycled ingot is obtained by drawing.

[0046] Example 2

[0047] The raw material pretreatment, hydrogenation embrittlement, ball milling and sieving, and dehydrogenation process steps and equipment used in this embodiment are the same as in Example 1, thereby obtaining an intermediate matrix powder with the same composition (wherein the mass percentage of each element is: W 4.94%, Mo 1.99%, Zr 1.8%, Ta 0.28%, C 0.0093%, O 0.12%, N 0.0084%, and H 0.0019%).

[0048] The difference between this embodiment and Embodiment 1 lies in the feeding components and subsequent parameters in the component control step, as detailed below: The intermediate matrix powder obtained after dehydrogenation of the above-mentioned waste was added with the material prepared in Preparation Example 1. - 82.5 g of composite slow-release agent powder was then added to a small double-cone mixer and dried for 120 min to obtain alloy mixed powder.

[0049] Subsequently, the mixed alloy powder was subjected to cold isostatic pressing (100 MPa, 60 min) under the same process conditions as in Example 1 to obtain green billets; then the green billets were transferred into a high-temperature vacuum sintering furnace and sintered under the same vacuum degree ( Heated to 1950℃ at a controlled temperature and heating rate of Pa, and sintered at that temperature for 4 h; finally, the sintered alloy billet was used as a consumable electrode and hoisted into a small electron beam (EB) melting furnace, with a background vacuum of [missing information - likely a specific value]. Under the condition of Pa, two consecutive remelting and refining processes were carried out, and finally high-grade niobium-tungsten alloy recycled ingots were obtained by drawing.

[0050] Comparative Example 1 The raw material pretreatment, hydrogenation embrittlement, ball milling and sieving, and dehydrogenation process steps and equipment used in this comparative example are exactly the same as those in Example 1, thereby obtaining intermediate matrix powder with the same composition.

[0051] The only difference between this comparative example and Example 1 is that no ultrafine pure Zr powder or blending agent is added in the component control step. The intermediate matrix powder obtained after dehydrogenation is directly put into a small double cone mixer for drying and mixing for 120 min.

[0052] Subsequently, following the same process conditions as in Example 1, cold isostatic pressing (100 MPa, 60 min) was performed sequentially to obtain green billet strips; alloy billet strips were obtained by heat sintering under vacuum high temperature conditions (1950 ℃, 4 h) using the same parameters; finally, the billet strips were hoisted into a small electron beam (EB) melting furnace as consumable electrodes, and two remelting and refining processes were performed consecutively, and finally drawn to obtain recycled ingots.

[0053] Comparative Example 2 The raw material pretreatment, hydrogenation embrittlement, ball milling and sieving, and dehydrogenation processes and equipment used in this comparative example are the same as in Example 1, thereby obtaining an intermediate matrix powder with the same composition. The only difference between this comparative example and Example 2 is the composition control step, specifically as follows: 34.6 g of high-purity ZrC powder with an average particle size of 1.5 μm was added separately to the above intermediate matrix powder. The mixture was then placed into a small double-cone mixer and dried and mixed for 120 min to obtain an alloy mixed powder. Subsequently, following the same process conditions as in Example 1, cold isostatic pressing and high-temperature vacuum sintering were performed sequentially. Finally, the sintered alloy billet strip was subjected to two consecutive electron beam remelting refining processes under the same parameters and drawn to obtain a recycled ingot.

[0054] Comparative Example 3 The raw material pretreatment, hydrogenation embrittlement, ball milling and sieving, and dehydrogenation processes and equipment used in this comparative example are the same as in Example 1, thereby obtaining an intermediate matrix powder with the same composition. The difference between this comparative example and Example 2 lies only in the feed composition in the composition control step, specifically as follows: 34.6 g of ZrC powder (average particle size 1.5 μm) was added to the above intermediate matrix powder, and... 47.9 g of powder (average particle size 2.0 μm) was directly mechanically and physically mixed with the other two materials. The mixture was then placed into a small double-cone mixer and dried for 120 min to obtain the alloy powder. Subsequently, following the same process conditions as in Example 1, the powder underwent cold isostatic pressing, high-temperature vacuum sintering, and finally, the sintered alloy billet was subjected to two consecutive electron beam remelting refining processes under the same parameters, followed by drawing to obtain a recycled ingot.

[0055] The samples prepared in the above embodiments and comparative examples were tested as follows: 1. Chemical composition and microscopic segregation testing Test method: Along the longitudinal centerline of the high-grade niobium-tungsten alloy recycled ingots prepared in each embodiment and comparative example, samples were taken at the top (10% from the top), middle (50% from the center), and bottom (10% from the bottom) of the ingot.

[0056] Testing equipment: Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to accurately determine the mass percentage of zirconium (Zr); a carbon-sulfur analyzer was used to determine the mass percentage of carbon (C); and an oxygen-nitrogen-hydrogen analyzer was used to determine the mass percentage of oxygen (O). Segregation was quantitatively evaluated by comparing the elemental concentration fluctuations at the top, middle, and bottom of the sample.

[0057] 2. Room Temperature Mechanical Property Test Method: Standard tensile specimens were machined from the center of each ingot according to GB / T 228.1. Testing Equipment: An electronic universal testing machine was used to conduct tensile tests at room temperature (25℃) with a loading rate of 1 mm / min. Recording Indicators: The tensile strength (…) was measured separately. The results were measured for elongation at break (A) and the average value of each sample was taken after three tests.

[0058] The test data is shown in Table 1 below:

[0059] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the technical scope disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for recycling and processing niobium-tungsten alloy waste, characterized in that, Includes the following steps: S1. Surface cleaning and block-forming treatment of niobium-tungsten alloy waste; S2. The treated niobium-tungsten alloy waste is placed in a hydrogenation furnace for hydrogenation treatment. Then the hydrogenated and embrittled waste is crushed and sieved to obtain intermediate matrix powder. S4. Determine the composition of the intermediate matrix powder, and based on the initial zirconium content in the intermediate matrix powder and the preset burn-off rate of subsequent refining and melting, introduce zirconium-based additives into the intermediate matrix powder for directional composition compensation mixing to obtain alloy mixed powder with controlled composition. S5. The alloy mixture powder is pressed into shape and then vacuum sintered to obtain an alloy billet; S6. The alloy billet is subjected to multiple high-vacuum refining and melting processes to obtain a niobium-tungsten alloy ingot with uniform composition.

2. The method for recycling and treating niobium-tungsten alloy waste according to claim 1, characterized in that, In step S1, the surface cleaning and block-forming treatment specifically includes: If the niobium-tungsten alloy waste is niobium-tungsten car shavings waste, it is ultrasonically cleaned for 5-30 minutes using a mixture of degreasing cleaning agent and water. After cleaning, it is rinsed with water, dried, and then compressed into small pieces with length, width, and height dimensions ≤ 400mm × 100mm × 100mm using a hydraulic baler. If the niobium-tungsten alloy scrap is niobium-tungsten offcut scrap, it is cut into small pieces with a length ≤400mm and a width ≤250mm, and then ultrasonically cleaned for 5~30min with a mixture of degreasing cleaning agent and water. After cleaning, it is rinsed with water and dried.

3. The method for recycling and treating niobium-tungsten alloy waste according to claim 1, characterized in that, In step S2, the hydrogenation treatment is carried out at a temperature of 500~800℃ for 60~120 minutes; the crushing and screening is carried out using an 80-mesh screen.

4. The method for recycling and treating niobium-tungsten alloy waste according to claim 1, characterized in that, Step S4 specifically includes: S41. Mix the intermediate matrix powder from different batches together, and take samples to test the content of each element in the matrix powder after batch mixing; S42. Based on the initial Zr element content obtained from the test, add zirconium-based additives to the powder to adjust the total Zr element mass percentage after mixing to be in the range of 2.8%~3.4%, and then mix again for 60~180 min.

5. The method for recycling and treating niobium-tungsten alloy waste according to claim 4, characterized in that, The zirconium-based additive is selected from Zr powder, zirconium hydride powder, etc. At least one of the compound sustained-release agents.

6. The method for recycling and treating niobium-tungsten alloy waste according to claim 5, characterized in that, The The composite slow-release agent also contains 1% to 5% of its mass of pre-alloyed Nb powder.

7. The method for recycling and treating niobium-tungsten alloy waste according to claim 5, characterized in that, The In the compound sustained-release agent, the mass percentage of ZrC is 30wt%~50wt%.

8. The method for recycling and treating niobium-tungsten alloy waste according to claim 5, characterized in that, The steps between S2 and S4 also include the following: S3. The intermediate matrix powder is subjected to vacuum dehydrogenation treatment to obtain dehydrogenated intermediate matrix powder, wherein the parameters of the vacuum dehydrogenation treatment are: vacuum furnace temperature 650~850℃, vacuum degree ≥ The heat preservation time is 60~150 minutes.

9. The method for recycling and processing niobium-tungsten alloy waste according to claim 1, characterized in that: In step S5, the pressing is cold isostatic pressing with a pressure of 100 MPa and a holding time of 60 min; the vacuum sintering temperature is 1600~2300℃. In step S6, the high-vacuum refining and melting is electron beam melting, with the melting process repeated at least twice, and the high vacuum level during melting is not lower than [missing information]. .

10. The method for recycling and treating niobium-tungsten alloy waste according to claim 7, characterized in that, The The compound sustained-release agent is prepared through the following steps: S10. Using zirconium source powder and solid carbon source as raw materials, the molar ratio of Zr element to C element is controlled at (1.8~2.2):1 to mix them to obtain reaction precursor powder; S20. The reaction precursor powder is placed in a mixed atmosphere of hydrogen and argon, and subjected to reaction sintering and hydrogenation treatment at 800~1100℃ for 2~4 hours to obtain the sintered product. S30. The sintered product is ball-milled and sieved, and the particle size of the sieved material is matched with the particle size of the intermediate matrix powder in step S2.

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