Scum integral type vacuum atomization powdering method and system based on temperature control pre-alloying

Abstract

The invention discloses a temperature control pre-alloying-based scum integral vacuum atomization powder preparation method and system. The method comprises the following steps: smelting an alloy in a vacuum or protective atmosphere; an Sb-Bi-based activator is added to the surface of the melt, and scum is agglomerated through a metallurgical reaction to form an integrated porous slag cake; performing temperature control pre-alloying, namely cooling the melt to 150-200 DEG C below a liquidus, preserving heat, and quickly heating to a pouring temperature, so that volatile elements are dissolved in a matrix in a solid manner; during pouring, the whole slag cake is intercepted through the inverted-cone-shaped air pressure gas ring, and pure melt flows out through holes of the inverted-cone-shaped air pressure gas ring; and finally, vacuum ultrasonic atomization powder preparation is carried out. The system comprises a smelting chamber, an activating agent adding device, a temperature control unit, a pouring intercepting unit and an atomizing chamber which are used for implementing the steps. According to the method, through cooperation of slag cake integration and element pre-alloying locking, the contradiction between slag removal and volatilization control under high-temperature smelting is solved, and efficient continuous production of powder with high purity and high component consistency is achieved.

Description

Technical Field

[0001] This invention relates to the field of metallurgy and powder preparation technology, specifically to a method and system for integral vacuum atomization powder preparation of slag based on temperature-controlled pre-alloying. Background Technology

[0002] Nickel-based superalloys, such as Inconel 718, the Rene series, and RAE 600, are widely used in aerospace engine hot-end components, gas turbine blades, and high-end chemical equipment due to their excellent high-temperature strength, creep resistance, and oxidation resistance. High-quality pre-alloyed powders are key raw materials for the subsequent manufacture of high-performance dense parts using advanced forming technologies such as hot isostatic pressing and selective laser melting.

[0003] Currently, the mainstream process for producing such pre-alloyed powders is vacuum induction melting combined with gas atomization technology. However, this process has long faced inherent technical bottlenecks due to their mutual coupling, which severely restrict the purity, compositional consistency, and production efficiency of the powder.

[0004] First, there is a direct conflict between the high-temperature melting requirements of the alloy and the effective removal conditions for slag. To ensure the full melting and uniform diffusion of all alloying elements, the melting temperature typically needs to reach or exceed 1600℃. However, at this high temperature, the melt viscosity is low and the convective mass transfer is vigorous, which is not conducive to the floating, collision, and aggregation of high-melting-point non-metallic inclusions such as Al2O3 and TiN. Conversely, lowering the temperature to promote inclusion removal cannot meet the requirements for complete liquefaction and homogenization of the alloy. This makes it difficult to achieve both melt purity and compositional homogeneity in a single melting process.

[0005] Secondly, the homogenization process of alloying elements under high-temperature conditions is accompanied by serious losses of volatile elements. Microalloying elements such as Mg and Mn, which are crucial to alloy performance, have high vapor pressures under high-temperature vacuum and are prone to escape from the melt. This not only leads to uncontrolled target composition and low element yield (loss rates often exceed 15% in industrial practice), but also causes the generated volatiles to contaminate equipment, affect vacuum levels, and form harmful fumes. In existing technologies, such as the pre-alloyed atomization powdering method disclosed in patent CN113385650B, pre-alloying is performed by adding intermediate alloys. Although this aims to improve distribution, it still takes place during the high-temperature main melting stage and fails to change the thermodynamic behavior of volatile elements. Therefore, its effect on suppressing volatilization and improving uniformity is limited, and element segregation problems (such as Mn segregation >8%) remain prominent.

[0006] Furthermore, the multi-step, intermittent processes developed to address the aforementioned issues significantly increase equipment complexity and production costs. Traditionally, to separately address the challenges of purity and composition control, multiple processes such as vacuum induction melting and electroslag remelting are often employed, resulting in lengthy production processes and high energy consumption. In the pursuit of continuous atomization production, fine, dispersed slag easily clogs the nozzles or casting systems (clogging rates can reach over 12%), or penetrates traditional filters, becoming inclusion defects in the powder, leading to production interruptions and reduced yield.

[0007] Therefore, to address the aforementioned problems, this invention provides a method and system for integral vacuum atomization powder production of slag based on temperature-controlled pre-alloying. Through the synergy of two core technologies—"metallurgical modification of the melt surface to promote the aggregation of slag into an integral slag cake" and "time-sequential precise temperature control to achieve pre-alloying and locking of volatile elements"—the method continuously and sequentially solves the problems of slag removal and volatilization control within the same vacuum system. Furthermore, it utilizes the integral slag cake to achieve blockage-free interception casting, ultimately realizing the integrated and continuous preparation of high-efficiency, high-yield, and high-purity nickel-based high-temperature alloy powder. Summary of the Invention

[0008] The purpose of this invention is to provide a method and system for integral vacuum atomization powder preparation of slag based on temperature-controlled pre-alloying, so as to achieve a method and system for efficient, continuous and integrated preparation of pre-alloyed powder with high purity and high compositional uniformity.

[0009] The objective of this invention is achieved through the following technical solution: A method for integral vacuum atomization powdering of slag based on temperature-controlled pre-alloying includes the following steps performed in sequence: S1. Under vacuum or inert atmosphere protection, nickel-based superalloy raw materials are melted in a melting crucible to form an alloy melt; S2. Slag integration treatment: Sb-Bi-based surfactant is added to the surface of the alloy melt, and the melt is stirred by a stirring device to agglomerate and metallurgically modify the high melting point slag on the surface of the melt, forming a porous integral slag cake. S3. Temperature-controlled pre-alloying treatment: The melt is cooled to a temperature range of 150~200℃ below its liquidus temperature and held at that temperature to allow volatile elements to dissolve in the matrix; then the temperature is increased to the casting temperature at a rate of not less than 15℃ / min. S4. Integral slag cake interception and casting: The melt is cast into the tundish for transfer and heat preservation, and then the melt flows through the gas ring set at the gate; during casting, the integral slag cake is intercepted by the gas ring, and the pure melt flows downstream through the pores of the slag cake and the inner cavity of the gas ring. S5. Vacuum ultrasonic atomization: The pure melt that has been poured is atomized to obtain high-temperature alloy powder.

[0010] Preferably, the nickel-based superalloy raw materials include, but are not limited to, grades such as IN718 and RAE600, wherein the total content of volatile elements (such as Mg and Mn) can be greater than 1.5 wt%, so as to demonstrate the outstanding advantages of this method in processing such high-requirement alloys.

[0011] Preferably, the surface activator is an Sb-Bi based alloy with a melting point of approximately 630°C, capable of rapid spreading on the surface of the melt. The addition amount is 0.05~0.12 wt% of the alloy melt weight. The key to this step is that the activator chemically reacts with oxides such as Al₂O₃ on the melt surface to generate adhesive compounds such as AlSb₂O₃, which act as a "binder" to bridge and bind the fine slag particles together.

[0012] More preferably, the mass ratio of Sb to Bi in the surfactant is (6:4) to (8:2), which can form a suitable eutectic structure and optimize the activation effect.

[0013] More preferably, the surface activator further contains the rare earth element Ce, with an addition amount of 0.005~0.02wt% of the alloy melt weight. The addition of rare earth Ce can significantly improve the toughness and thermal stability of the final integral slag cake, preventing it from breaking during subsequent interception.

[0014] Preferably, the integral slag cake formed in step S2 has a specific porous structure with a porosity of 30% to 40%, a compressive strength greater than 10 MPa, and a diameter typically ranging from 6 to 12 mm. This structure can effectively adsorb and contain slag while ensuring sufficient permeability to allow the melt to pass through smoothly.

[0015] Preferably, the cooling process can be carried out at a relatively fast rate, for example, not less than 40°C / min, so as to quickly enter the pre-alloying window and reduce the process time.

[0016] Preferably, the pre-alloying temperature window (e.g., approximately 1250℃±20℃ for RAE600 alloy) needs to be selected within the region where the γ-Ni matrix phase is stably precipitated. The purpose of heat preservation is to allow volatile elements such as Mg and Mn to fully diffuse and dissolve in the γ-Ni matrix, forming a supersaturated solid solution. Preferably, the diffusion distance is controlled within ≤0.5μm, thereby achieving microscopic homogenization and "locking" of elements.

[0017] Preferably, the rate of the reheating stage is crucial and should be no less than 15°C / min (e.g., 18°C / min). Rapid heating can shorten the total residence time of the melt in the volatile temperature range, effectively suppressing the secondary volatilization of elements and the oxidation tendency of the melt.

[0018] Preferably, the preset casting temperature can be set according to the specific alloy grade, for example, in the range of 1500~1580℃.

[0019] Preferably, the casting system includes an air ring with a cone angle of 70° to 80°. This structure provides good mechanical constraint on the overall slag cake.

[0020] Preferably, the sidewall of the gas ring is provided with an inert gas channel for applying a controllable lateral gas pressure to the integral slag cake covering the gate, with a pressure range of 0.02~0.1MPa.

[0021] More preferably, the applied gas pressure is 0.05~0.08 MPa. This pressure can maintain the stability of the slag cake structure, preventing it from being dispersed or crushed by the melt, without completely sealing the pores from which the melt flows out.

[0022] Preferably, a high-precision thermocouple (such as Pt-Rh type) may be embedded in the gas ring for real-time monitoring and control of the temperature in the gating area, with a temperature control accuracy of ±5℃, to ensure the stability of the thermal state during the casting process.

[0023] Preferably, the atomization process is carried out under a vacuum or high-purity inert atmosphere, and the working vacuum degree of the atomization chamber is preferably no higher than 10 Pa (e.g., 8 Pa) to minimize powder oxidation.

[0024] Preferably, a tightly coupled ultrasonic atomizer is used, with an ultrasonic frequency preferably of 20~30kHz and a power density preferably of 2.0~2.5W / mm². 2 This method aims to obtain high-quality powder with high sphericity, narrow particle size distribution, and few satellite particles. Experiments show that this method can significantly reduce the powder satellite rate from about 18% in traditional vacuum induction atomization to about 2.1%.

[0025] This application also claims an atomization powdering system for implementing the above-described temperature-controlled pre-alloyed slag integral vacuum atomization powdering method, comprising: A melting chamber, which contains a melting crucible 1 for melting alloy raw materials; The activator adding device 5 is used to quantitatively add a surface activator to the surface of the alloy melt in the melting crucible 1; A stirring device 4 is installed inside or above the smelting crucible 1 to stir the melt and promote the agglomeration of slag. A temperature control unit, connected to the heating device and the temperature sensing element, is used to execute the temperature control program as described in claim 1; The intermediate ladle 2 is located downstream of the pouring flow path of the melting crucible 1 and is used to receive and transfer the heat-holding melt. The casting interception unit includes an air ring 3 located at the outlet of the intermediate ladle 2. The air ring 3 has an inverted conical structure and is provided with an air ring gas pipeline 6 and an air ring gas hole 8 connected to an external gas source, which are used to apply controllable gas pressure to the intercepted slag cake. The air ring 3 is also provided with a temperature measuring hole 7 for installing a real-time temperature measuring element. The vacuum atomization chamber is connected to the outlet of the casting interception unit and contains an ultrasonic atomizer and a powder collection tank.

[0026] Preferably, the gas pressure provided by the gas ring gas pipeline 6 can be adjusted within the range of 0.02~0.1 MPa; and / or, the temperature measuring element provided in the temperature measuring hole 7 is signal-connected to the temperature control unit.

[0027] Preferably, the following components are included: Melting crucible 1 – for controlling the melting temperature and pouring of the product required for production; tundish 2 – for pouring the molten dry pot into the tundish for transfer and heat preservation, providing solution for the atomizer; gas ring 3 – for limiting scum to ensure solution purity and measuring the real-time temperature of the solution flowing through it; stirring device 4 – for stirring the solution after adding activator to remove scum and ultimately cause the scum to agglomerate; activator adding device 5 – for adding activator to complete the scum agglomeration step; gas ring gas pipeline 6 – for blowing scum through gas holes; and temperature measuring hole 7 – for real-time monitoring of the solution fluid temperature and precise temperature control.

[0028] Due to the application of the above technical solution, the present invention has the following beneficial effects compared with the prior art: 1. This invention achieves a balance between high melt cleanliness and zero process blockage. Through a metallurgical reaction induced by a surface activator, fine, dispersed slag aggregates into a stable, integral porous slag cake with a specific porosity. This slag cake, in conjunction with the inverted conical air pressure locking gate, achieves filterless physical interception of the melt. This innovative mechanism fundamentally solves the problems of gate blockage and powder contamination caused by slag fragments in traditional processes, making the gate blockage rate approach zero in continuous multi-heat production of RAE600 alloy, thus ensuring the continuity and stability of production. 2. This invention improves the yield and compositional uniformity of volatile elements. The core innovation of this invention, the "temperature-controlled pre-alloying" process, promotes the full dissolution of volatile elements such as Mg and Mn into the alloy matrix through precise "cooling-holding-rapid reheating" temperature cycles within a window that is far below the conventional melting temperature and conducive to the stability of the γ-Ni phase. This process achieves "pre-locking" at the atomic scale, thereby making them exhibit extremely low volatility tendencies during the subsequent unavoidable high-temperature casting and atomization stages. This method can increase the yield of key volatile elements from about 82% in traditional processes to over 99.5%, and control the compositional fluctuation deviation within an extremely narrow range of ±0.02wt%, ensuring high consistency between powder batches. 3. This invention achieves efficient and continuous integrated production of complex metallurgical targets. It seamlessly connects and continuously completes the two core tasks of "high-temperature slag removal" and "volatilization suppression," which are traditionally contradictory and require separate processing, within a single vacuum system through a time-sequential process design. This integrated process design eliminates the cumbersome and energy-intensive nature of traditional multi-unit remelting processes, significantly shortening the production cycle of a single furnace. For example, it can be optimized from more than 110 minutes in the traditional process to about 85 minutes, greatly improving equipment utilization and overall production efficiency. 4. This invention significantly optimizes the physical quality of the final alloy powder. The high-temperature alloy powder prepared by this invention exhibits excellent performance in terms of sphericity, particle size distribution concentration, and low defect rate. In particular, the proportion of "satellite ball" defects caused by the collision and adhesion of atomized droplets in the powder is greatly reduced, for example, from about 18% in the traditional vacuum induction gas atomization process to about 2.1%. This provides a crucial high-quality raw material foundation for the subsequent preparation of high-performance dense components using advanced technologies such as additive manufacturing and hot isostatic pressing. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, some of the drawings in the following description are some embodiments of the present invention. For those skilled in the art, other drawings can be made based on these drawings without creative effort.

[0030] Figure 1 This is a technical roadmap of Embodiment 1 of the present invention; Figure 2 This is a distribution diagram of the melting chamber in Embodiment 1 of the present invention; Figure 3 This is a diagram of the scum control system in Embodiment 1 of the present invention; Figure 4 This is a three-dimensional view of the gas ring at the gate in Embodiment 1 of the present invention; Among them, 1-melting crucible; 2-intermediate ladle; 3-gas ring; 4-stirring device; 5-activator adding device; 6-gas ring gas pipeline; 7-temperature measuring hole; 8-gas ring gas hole. Detailed Implementation

[0031] To provide a clearer understanding of the technical features, objectives, and effects of this invention, specific implementation schemes are now described in detail.

[0032] The present invention will be further described below with reference to embodiments, but the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0033] Example 1 See appendix Figure 1 ~Appendix Figure 4 This embodiment provides a method for integral vacuum atomization powder preparation of slag based on temperature-controlled pre-alloying (preparation of RAE600 high-temperature alloy powder), including: Raw materials: The master alloy composition is Ni-18Cr-5Fe-1.5Ti-0.8Al-1.8Mn-0.5Mg (weight percentage). The activator is an Sb-Bi-Ce alloy, wherein the mass ratio of Sb:Bi is 7:3, and it contains 5% Ce.

[0034] An atomization powdering system for realizing an integral vacuum atomization powdering method for slag based on temperature-controlled pre-alloying includes: A melting chamber, which contains a melting crucible 1 for melting alloy raw materials; The activator adding device 5 is used to quantitatively add a surface activator to the surface of the alloy melt in the melting crucible 1; A stirring device 4 is installed inside or above the smelting crucible 1 to stir the melt and promote the agglomeration of slag. A temperature control unit, connected to the heating device and the temperature sensing element, is used to execute the temperature control program as described in claim 1; The intermediate ladle 2 is located downstream of the pouring flow path of the melting crucible 1 and is used to receive and transfer the heat-holding melt. The casting interception unit includes an air ring 3 located at the outlet of the intermediate ladle 2. The air ring 3 has an inverted conical structure and is provided with an air ring gas pipeline 6 and an air ring gas hole 8 connected to an external gas source, which are used to apply controllable gas pressure to the intercepted slag cake. The air ring 3 is also provided with a temperature measuring hole 7 for installing a real-time temperature measuring element. The vacuum atomization chamber is connected to the outlet of the casting interception unit and contains an ultrasonic atomizer and a powder collection tank.

[0035] Melting Crucible 1 - Controls the melting temperature and pouring of products required for production; Tundish 2 - Melting dry pot, poured into the tundish for transfer and heat preservation, providing solution for the atomizer; Gas Ring 3 - Limits scum to ensure solution purity and measures the real-time temperature of the solution flowing through it; Stirring Device 4 - Stirs the solution after adding activator to remove scum and ultimately cause scum to agglomerate; Activator Adding Device 5 - Used to add activator to complete the scum agglomeration step; Gas Ring Gas Pipeline 6 - Gas ring gas pipe purges scum through gas holes; Temperature Measuring Hole 7 - Real-time monitoring of solution fluid temperature for precise temperature control.

[0036] Preparation steps: S1 melting: Place the master alloy raw material in melting crucible 1, evacuate to 5 Pa and then fill with high-purity argon to -0.05 MPa (gauge pressure); start induction heating, raise the temperature to 1600℃ and hold for 20 minutes to make the alloy completely melt and initially homogenize.

[0037] S2 slag integral treatment: Sb-Bi-Ce activator, accounting for 0.09 wt% of the total weight of the melt, was added to the surface of the melt through activator addition device 5; stirring device 4 was started and stirred continuously at 5 kW for 10 minutes; it was observed that the slag on the surface of the melt gradually aggregated and darkened in color, eventually forming an integral slag cake with a diameter of about 8 mm and a gray-black surface; it was verified that the porosity of the slag cake was about 38%.

[0038] S3 temperature-controlled pre-alloying treatment: The melt temperature is reduced from 1600℃ to 1250℃ at a rate of 50℃ / min using a temperature control unit; it is then held at 1250℃ for 15 minutes; subsequently, the melt is reheated to a casting temperature of 1580℃ at a rate of 18℃ / min.

[0039] S4 Integral Slag Cake Interception Casting: The casting valve is opened, and the melt is poured into the tundish 2 for a brief transfer and heat preservation, and then flows into the gas ring 3; the integral slag cake above the melt is intercepted by the inverted conical structure of the gas ring 3; at the same time, argon gas side pressure of 0.06 MPa is applied to the slag cake through the gas ring gas pipeline 6 and gas hole 8, so that it stably covers the top of the flow channel; the temperature of the melt is monitored in real time by the thermocouple in the temperature measuring hole 7; the pure melt flows into the guide pipe through the slag cake pores.

[0040] S5 Vacuum Ultrasonic Atomization: The melt flows through the guide tube into the vacuum atomization chamber (indoor pressure 8 Pa), where it is broken into droplets by an ultrasonic atomizer with a power of 22kW and a frequency of 25 kHz. The droplets then solidify into powder and fall into the powder collection tank.

[0041] Test results: 72 furnaces were run continuously with zero gate blockage.

[0042] Chemical composition analysis (ICP-OES) of the powder sample showed that the Mn content deviated from the designed composition (1.8 wt%) by +0.01 wt%, and the Mg content was greater than 99.3%.

[0043] The morphology of at least 1000 powder particles was analyzed using scanning electron microscopy (SEM), and the proportion of satellite spheres was calculated to be 2.1%.

[0044] The Hall flow rate of the powder was 15.3 s / 50 g, and the loose packing density was 4.25 g / cm³. 3 This indicates that the powder has good flowability.

[0045] Example 2 This embodiment provides a method for integral vacuum atomization powder preparation of slag based on temperature-controlled pre-alloying (preparation of IN718 high-temperature alloy powder), including: Raw materials: Commercial IN718 master alloy (Ni-19Cr-18Fe-5.1Nb-3.0Mo-1.0Ti-0.5Al, by weight percentage). Activator is an Sb-Bi alloy (Sb:Bi=7:3), Ce-free.

[0046] Preparation steps: S1 Melting: Under argon protection, heat the raw material to 1580℃ to melt it, and hold it at that temperature for 15 minutes.

[0047] S2 scum integrated treatment: 0.07 wt% Sb-Bi activator is added through the activator addition device, and the stirring device is started to stir for 8 minutes to form an integral scum cake with a diameter of about 7 mm.

[0048] S3 temperature-controlled pre-alloying treatment: Cool down to 1220℃ (about 170℃ below its liquidus line), hold for 12 minutes, and then heat up to 1550℃ at a rate of 20℃ / min.

[0049] S4 integral slag cake interception casting: After the melt is transferred through the tundish, it flows through a gas ring with a cone angle of 70° and is intercepted and cast by applying a stable gas pressure of 0.04MPa.

[0050] S5 Vacuum Ultrasonic Nebulization: Nebulization is performed using a nebulizer with a frequency of 22 kHz at a pressure of 10 Pa in the nebulization chamber.

[0051] Test Results: No gate blockage occurred. The yields of easily oxidized elements such as Al and Ti both exceeded 99%. The proportion of powder satellite balls was 3.5%. The powder oxygen content was 120 ppm, which is at a low level.

[0052] Example 3 This embodiment provides a method for integral vacuum atomization powder production of slag based on temperature-controlled pre-alloying (preparation of customized alloy powder with high Mn content), including: Raw materials: The custom alloy composition is Ni-15Cr-2.5Mn-2.0Mg (by weight). The activator is an Sb-Bi-Ce alloy, wherein the mass ratio of Sb:Bi is 7:3, and it contains 5% Ce.

[0053] Preparation steps: S1 melting: Melt at 1620℃ and hold at that temperature.

[0054] S2 scum integrated treatment: 0.12wt% activator is added to form a large-sized (approximately 10mm) scum cake.

[0055] S3 temperature-controlled pre-alloying treatment: Implements stricter temperature control: rapidly cools to 1200℃, holds for 20 minutes to ensure sufficient solid solution of Mn and Mg, and then rapidly rises to 1590℃ at a rate of 25℃ / min for casting.

[0056] S4 integral slag cake interception casting: A relatively high air pressure of 0.08MPa is used to stabilize the large-sized slag cake at the air ring.

[0057] S5 Vacuum Ultrasonic Atomization: Standard Atomization.

[0058] Test Results: The process was stable and clog-free. The yield of Mn reached 99.5%, and the yield of Mg reached 99.0%, with precise composition control. No visible inclusions were found in the powder.

[0059] Comparative Example 1 This comparative example is based on Example 1 above, and the similarities with Example 1 above will not be repeated.

[0060] In this comparative example: Step S2: No Sb-Bi-Ce activator is added, and no scum integrated treatment procedure is performed.

[0061] Step S3: Omit the temperature-controlled pre-alloying cycle (i.e., cooling-holding-reheating procedure) of the present invention; after completing the S1 melting, directly maintain the temperature at 1600℃ for 30 minutes (simulating the high-temperature pre-alloying and holding time of the traditional process), and then perform casting.

[0062] Step S4: The gating system uses a standard straight cylindrical gating gate, without an intermediate tundish or air ring structure.

[0063] Test results: Significant blockage occurred during the casting of the 6th batch, requiring shutdown for cleaning. The Mn element recovery rate in the powder was 82.5%, the proportion of satellite spheres was as high as 18.7%, and the powder contained a large number of inclusions.

[0064] Comparative Example 2 This comparative example is based on Example 1 above, and the similarities with Example 1 above will not be repeated.

[0065] In this comparative example: Step S3: The temperature-controlled pre-alloying cycle of the present invention is omitted. After completing the overall treatment of the slag in S2, the temperature is directly maintained at 1600℃ for 15 minutes (the same as the holding time in Example 1), and then casting is performed.

[0066] Test results: No blockage occurred at the gate. However, the yield of Mn was 87.3% and the yield of Mg was 85.1%, both significantly lower than in Example 1.

[0067] Comparative Example 3 This comparative example is based on Example 1 above, and the similarities with Example 1 above will not be repeated.

[0068] In this comparative example: Step S2: No Sb-Bi-Ce activator is added, and no scum integration treatment procedure is performed; the surface of the melt is naturally formed dispersed scum.

[0069] Test results: Frequent blockages occurred during the casting process, extending the production cycle of a single furnace. The yields of Mn and Mg elements in the powder were relatively high (similar to Example 1), but the number of inclusions in the powder increased significantly.

[0070] The test results of the above embodiments and comparative examples are listed in Table 1.

[0071] Table 1

[0072] As can be seen from Examples 1 to 3, after adopting the complete technical solution of the present invention, no gate blockage occurred in any of the examples, the yield of volatile elements Mn and Mg was stable at over 99%, and the powder satellite ball rate was less than 3.5%, indicating that the present invention has achieved significant results in ensuring production continuity, precise element control, and powder morphology.

[0073] In contrast, Comparative Example 1, employing entirely traditional processes, suffered from severe gate clogging, resulting in a Mn recovery rate of only 82.5% and a satellite ball rate as high as 18.7%, with all indicators significantly inferior to the present invention. While Comparative Example 2 resolved the clogging problem, the lack of temperature-controlled pre-alloying resulted in Mn and Mg recovery rates of only 87.3% and 85.1%, respectively, indicating significant elemental losses. Although Comparative Example 3 controlled elemental volatilization, the absence of integrated slag treatment led to frequent clogging and low powder purity.

[0074] The two core steps of this invention—integrated slag treatment and temperature-controlled pre-alloying treatment—solve two key technical problems: physical interception and blockage, and control of element volatilization. Both are indispensable, and their synergistic effect produces superior technical results compared to a single step. Comparative Example 1 demonstrates the significant disadvantages of traditional high-temperature pre-alloying processes in terms of yield and powder quality. Comparative Examples 2 and 3 clearly verify that omitting any core step of this invention leads to a significant decrease in overall performance, proving the completeness and necessity of the technical solution of this invention. The method of this invention is applicable to various nickel-based superalloy systems, especially for alloys with high volatile element content, enabling near-zero loss element control and stable, continuous production, demonstrating outstanding industrial application value.

[0075] In summary, this invention fundamentally solves the core problems that have long existed in the preparation of high-temperature alloy powders, such as slag blockage, element volatilization, and process interruptions, through the innovative synergistic technology of "integrated slag treatment" and "temperature-controlled pre-alloying treatment". This method enables stable production with near-zero gate blockage in a single continuous process, increases the recovery rate of volatile elements to over 99%, and significantly improves powder morphology and purity. It provides a highly consistent and high-quality raw material guarantee for high-performance additive manufacturing and powder metallurgy, and also possesses outstanding industrial application value.

Claims

1. A method for producing a floating-slag bulk vacuum atomized powder based on temperature-controlled pre-alloying, characterized in that, The method comprises the following steps executed in sequence: S1. Melting a raw material of a nickel-based superalloy in a smelting crucible under vacuum or inert atmosphere protection to form an alloy melt; S2. Slag integration treatment: adding a Sb-Bi-based surface activator to the surface of the alloy melt, and stirring the melt by a stirring device to agglomerate and metallurgically modify the high-melting-point slag on the surface of the melt to form a porous integrated slag cake; S3. Temperature-controlled pre-alloying treatment: reducing the melt to a temperature interval of 150-200℃ below the liquidus temperature of the melt for heat preservation to allow the volatile elements to be dissolved in the matrix; then increasing the temperature to the pouring temperature at a rate of not less than 15℃ / min; S4. Integrated slag cake interception pouring: pouring the melt into a tundish for intermediate heat preservation, and then making the melt flow through a gas ring arranged at the pouring gate; during pouring, the integrated slag cake is intercepted by the gas ring, and the pure melt flows to the downstream through the pores of the slag cake and the inner cavity of the gas ring; S5. Vacuum ultrasonic atomization: atomizing the pure melt poured out to obtain a superalloy powder.

2. The temperature controlled pre-alloyed based dross integrated vacuum atomization powder production method according to claim 1, characterized in that, The surface activator is an Sb-Bi alloy, and the addition amount is 0.05-0.12wt% of the weight of the alloy melt, wherein the mass ratio of Sb to Bi is (6:4)-(8:2).

3. The temperature controlled pre-alloyed based dross integral vacuum atomization powder production method according to claim 2, characterized in that, The surface activator further contains a rare earth element Ce, and the addition amount is 0.005-0.02wt% of the weight of the alloy melt.

4. The temperature controlled pre-alloyed based dross integral vacuum atomization powder production method according to claim 1, characterized in that, In step S3, the rate of reducing the melt is not less than 40℃ / min; and the heat preservation time is 10-20 minutes.

5. The temperature controlled pre-alloyed based dross integral vacuum atomization powder production method according to claim 1, characterized in that, In step S4, a lateral gas pressure of 0.02-0.1 MPa is applied to the integrated slag cake to make it stably cover the top of the inverted conical pouring gate.

6. The temperature-controlled pre-alloyed based dross integral vacuum atomization powder production method according to claim 5, characterized in that, The lateral gas pressure is 0.05-0.08 MPa.

7. The temperature controlled pre-alloyed based dross integral vacuum atomization powder production method according to claim 1, characterized in that, In the raw material of the nickel-based superalloy, the total content of the volatile elements Mg and / or Mn is greater than 1.5wt%.

8. An atomization system for realizing the temperature-controlled pre-alloying based bulk vacuum atomization method of floating dross according to any one of claims 1 to 7, characterized in that The method comprises the following steps: a smelting chamber in which a smelting crucible (1) is arranged for smelting alloy raw materials; an activator adding device (5) for quantitatively adding a surface activator to the surface of the alloy melt in the smelting crucible (1); a stirring device (4) arranged in or above the smelting crucible (1) for stirring the melt to promote the agglomeration of the slag; a temperature control unit connected with a heating device and a temperature measuring element for executing the temperature control program of claim 1; a tundish (2) arranged downstream of the pouring flow path of the smelting crucible (1) for receiving and intermediate heat preservation of the melt; a pouring interception unit comprising a gas ring (3) arranged at the outlet of the tundish (2), the gas ring (3) being in an inverted conical structure, and a gas ring gas pipeline (6) and a gas ring gas hole (8) being arranged on the ring body and being in communication with an external gas source for applying a controllable gas pressure to the intercepted integrated slag cake; a temperature measuring hole (7) is further arranged on the gas ring (3) for installing a real-time temperature measuring element; a vacuum atomization chamber connected with the outlet of the pouring interception unit and internally provided with an ultrasonic atomizer; and a powder collection tank.

9. The atomizing pulverizing system according to claim 8, wherein The gas pressure provided by the gas ring gas pipeline (6) can be adjusted in the range of 0.02-0.1 MPa; and / or the temperature measuring element arranged in the temperature measuring hole (7) is signal connected with the temperature control unit.

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