A method for manufacturing a distributor for high uniformity electric propulsion

Abstract

This invention relates to a method for manufacturing a distributor for high-uniformity electric propulsion, belonging to the field of metal printing, and includes the following steps: loading high-temperature alloy powder into a printing device; placing a cleaned substrate in the printing device and leveling it; setting the printing parameters as follows: laser power 280W, scanning speed 1200mm / s, layer thickness 0.03mm, to print in one step a device base with a fixed column, a gas supply column, and an anode column, a first perforated plate, a second perforated plate, and a vortex perforated plate with several circumferential spiral flow channels inside and vortex holes on the end face connected to the spiral flow channels; removing the printed product from the device and cleaning off any residual powder; annealing the cleaned product in a furnace by heating it to 900℃ and holding it at that temperature for 3 hours. This invention has the advantages of integrated forming through additive manufacturing, overcoming the limitations of traditional manufacturing processes on structural complexity, increasing the path and residence time of neutral atoms in the discharge channel, and increasing the probability of collisional ionization.

Description

Technical Field

[0001] This invention relates to the field of metal printing technology, and in particular to a method for manufacturing a distributor for high uniformity electric propulsion. Background Technology

[0002] Hall thrusters are currently the most researched and widely used spacecraft electric propulsion technology in the world. They mainly consist of a cathode, discharge chamber, magnetic poles, anode / gas distributor, propellant delivery pipeline, and support structure. The ionization of the working propellant inside the discharge channel of a Hall thruster is the most important process in its operation. Electrons collide with neutral atoms to produce ions, which are then accelerated in the electric field generated by the thermal potential and ejected from the discharge channel, ultimately generating thrust.

[0003] In Hall thrusters, the gas distributor is located within the discharge chamber. Neutral gaseous propellant enters the discharge chamber via the propellant delivery pipeline and the gas distributor. The gas distributor is typically required to homogenize the neutral gas. In existing technologies, conventional gas distributors, including single-layer orifice plates, double-layer orifice plates, inner cover plates, and outer cover plates, all require electron beam welding. This results in numerous weld seams and frequent disassembly and reassembly during the welding process. Furthermore, the gas distributor contains many thin-walled components, making it highly susceptible to deformation during the later weld seams, increasing the difficulty of subsequent welding and compromising weld quality.

[0004] Furthermore, xenon is present in small amounts in the atmosphere, while krypton is ten times more abundant and much cheaper to produce. Currently, a significant proportion of Hall thrusters use krypton as their propellant. However, krypton has characteristics such as small atomic radius, high first ionization energy, and high atomic velocity, resulting in poor ionization performance.

[0005] Therefore, to address the above shortcomings, there is a need to provide a manufacturing method for a distributor with high uniformity in electric propulsion. Summary of the Invention

[0006] (a) Technical problems to be solved The technical problem to be solved by this invention is to address the issues of numerous welds and low welding quality in traditional gas distributors.

[0007] (II) Technical Solution To solve the above-mentioned technical problems, the present invention provides a method for manufacturing a distributor for high uniformity electric propulsion, comprising the following steps: Ⅰ. Load the high-temperature alloy powder into the printing equipment, place the cleaned substrate into the printing equipment and level it; II. Set the printing parameters as follows: laser power 280W, scanning speed 1200mm / s, layer thickness 0.03mm, so as to print in one go a device base with a fixed column, a gas supply column and an anode column, a first orifice plate, a second orifice plate and a vortex orifice plate with several circumferential spiral channels inside and vortex holes on the end face that are connected to the spiral channels. Ⅲ. After printing and forming, remove the product from the equipment and clean off any residual powder; place the cleaned product in an oven and heat it to 900℃ for 3 hours for annealing. IV. Separate the molded part from the substrate by wire cutting, and then polish the molded part to make the surface roughness Ra1.5μm.

[0008] As a further explanation of the present invention, preferably, the high-temperature alloy powder needs to be dried before being loaded into the printing equipment to ensure its flowability.

[0009] As a further explanation of the present invention, preferably, argon gas is circulated inside the printing device to prevent powder oxidation.

[0010] As a further explanation of the present invention, preferably, after the molded part is separated from the substrate, residual powder is further removed by high-pressure water gun or ultrasonic vibration.

[0011] As a further explanation of the present invention, preferably, the polishing method is electrochemical polishing.

[0012] As a further explanation of the present invention, preferably, X-rays are used to perform quality inspection on the polished molded parts to ensure that there are no defects such as pores, incomplete fusion, or cracks inside the molded parts.

[0013] As a further explanation of the present invention, preferably, there is a first buffer cavity between the inner seat of the molded part and the first perforated plate, a second buffer cavity between the first perforated plate and the second perforated plate, and a third buffer cavity between the second perforated plate and the swirl perforated plate. The first buffer cavity, the second buffer cavity and the third buffer cavity are interconnected through channels. The first buffer cavity is connected to the air supply column, and the third buffer cavity is connected to the spiral flow channel through channels.

[0014] (III) Beneficial Effects The above-described technical solution of the present invention has the following advantages: 1. This invention adopts additive manufacturing integrated molding, which breaks through the limitations of traditional manufacturing processes on structural complexity, realizes the manufacturing of the distributor's 3-layer gas buffer chamber and 4 3-layer complex swirling gas outlet structures, thereby improving gas uniformity and solving the problem of poor ionization characteristics of existing krypton working fluid Hall thrusters; 2. This invention uses additive manufacturing to form a single unit, reducing connection interfaces and potential leakage points, thus significantly improving the reliability of the components; 3. This invention adopts additive manufacturing integrated molding, which simplifies the production process and greatly shortens the product development and production cycle compared to the traditional design of combining 7 parts into one direct manufacturing. At the same time, it reduces the cost of raw materials, mold development, assembly tooling and component assembly. Attached Figure Description

[0015] Figure 1 This is a structural diagram of the molded part of the present invention; Figure 2 This is a rear view of the molded part of the present invention; Figure 3 This is a cross-sectional view of the molded part of the present invention; Figure 4 yes Figure 3 A magnified view of A in the middle.

[0016] In the figure: 1. Base; 11. Fixed column; 12. Gas supply column; 13. Anode column; 2. First orifice plate; 3. Second orifice plate; 4. Swirl orifice plate; 41. Swirl hole; 5. Spiral flow channel; 51. First buffer chamber; 52. Second buffer chamber; 53. Third buffer chamber. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] A method for manufacturing a distributor for high uniformity electric propulsion includes the following steps: I. Design the process model, including but not limited to design model optimization, adding process allowances, part printing orientation, and support structure design. The final design should resemble... Figures 1 to 4 The model structure includes a base 1 with a fixed column 11, a gas supply column 12, and an anode column 13; a first orifice plate 2; a second orifice plate 3; and a vortex orifice plate 4 with several circumferential spiral channels 5 inside and vortex holes 41 on its end face that communicate with the spiral channels 5. A first buffer cavity 51 is located between the base 1 and the first orifice plate 2; a second buffer cavity 52 is located between the first orifice plate 2 and the second orifice plate 3; and a third buffer cavity 53 is located between the second orifice plate 3 and the vortex orifice plate 4. The first buffer cavity 51, the second buffer cavity 52, and the third buffer cavity 53 are interconnected through channels. The first buffer cavity 51 is connected to the gas supply column 12, and the third buffer cavity 53 is connected to the spiral channels 5 through channels. The model is then imported into the equipment for data slicing and printing process parameter settings.

[0019] II. The printing material is high-temperature alloy powder, preferably 316L stainless steel conforming to the institute's standards. Common high-temperature alloy materials such as aluminum alloy and titanium alloy can also be used. The powder is dried before being loaded into the printing equipment to ensure its flowability. The substrate surface is cleaned to remove surface oil and dirt, then loaded into the equipment for leveling. After leveling, the equipment is purged. Argon gas is used for protection during the printing process to prevent oxidation.

[0020] III. Use the equipment to print the parts with a laser power of 280W, a scanning speed of 1200mm / s, and a layer thickness of 0.03mm. Monitor the print quality during the printing process to ensure smooth operation. After printing, remove the parts from the forming chamber. Clean the surface, internal channels, and support components of the parts to remove any remaining powder. For parts with complex internal cavities, after separating the part from the substrate, it is recommended to further remove any remaining powder using methods such as high-pressure water jets or ultrasonic vibration to ensure that no foreign matter remains inside the parts.

[0021] IV. Due to the complex metallurgical process involved in selective laser melting (SLM), metal powder melts, solidifies, and cools instantaneously under the scanning of a high-speed laser beam. This inevitably generates significant residual stress within the formed part and easily leads to defects such as porosity and poor fusion, thus affecting the microstructure and mechanical properties of the sample. Heat treatment is a crucial means of controlling the microstructure and mechanical properties of SLM-formed parts. Therefore, the formed parts printed from 316L stainless steel need to be annealed at 900℃ for 3 hours.

[0022] V. The parts are removed from the substrate using wire cutting. After wire cutting, excess support parts are removed, and the surface is then polished to improve surface quality. For complex internal flow channel structures, electrochemical polishing is generally used. The surface roughness after polishing needs to reach Ra1.5μm. Then, the areas where allowances are added are machined to ensure the accuracy of their mounting positions.

[0023] After processing, the parts are inspected for surface and internal quality. Surface quality is inspected using fluorescence detection to ensure that there are no defects such as microcracks on the surface. Internal quality is generally inspected using X-rays. The allowable level of internal quality of the formed parts refers to the Class B requirements in HB5430-2011 to ensure that there are no defects such as pores, lack of fusion, and cracks inside.

[0024] Compared to traditional methods that require multiple electron beam welding of single or double-layer perforated plates and inner and outer cover plates, resulting in numerous welds, frequent disassembly and assembly, severe welding deformation of thin-walled parts, and inconsistent welding quality, the dispenser manufactured using the above method achieves a seamless, continuous structure with zero welds for all flow channels and connecting structures. This eliminates defects such as welding deformation, weld cracks, and incomplete welding at the source, significantly improving part dimensional consistency and assembly qualification rate. At the same time, it eliminates the weld, the most critical fatigue weakness of aerospace products, and its vibration resistance and high and low temperature cycling performance far exceed those of welded parts.

[0025] Furthermore, traditional turning and casting processes cannot form complex integrated structures such as three-stage buffer cavities and inclined swirling orifices. General 3D printing technologies also suffer from problems such as high roughness of internal channels, residual powder, and poor fusion. This invention, however, uses specific metal powders and achieves integrated forming of complex internal cavities through customized printing parameters, specialized powder cleaning, and electrochemical polishing of the internal channels. The surface roughness of the internal channels can reach Ra1.5μm, with no residual material, significantly improving the uniformity of channel resistance. Simultaneously, a dual-inspection system ensures the absence of internal defects in the internal channels, fully meeting the high reliability requirements of aerospace in orbit. Combined with a customized 900℃ / 3h annealing process, residual stress from the selective laser melting forming process is effectively eliminated. Compared to general 3D printed parts without heat treatment, deformation during subsequent processing and assembly is reduced by more than 80%. At the same time, the use of institute-grade 316L stainless steel achieves an optimal balance of strength and toughness, with yield strength and fatigue resistance superior to welded parts and general 3D printed parts, making it suitable for long-term service under extreme aerospace conditions.

[0026] In summary, this invention overcomes the limitations of traditional manufacturing processes such as turning and casting on structural complexity. Using metal 3D printing, it fabricates a swirling orifice plate 4 with a spiral flow channel 5. Combined with a three-stage buffer chamber and swirling orifices 41, the propellant undergoes three rounds of buffering and pressure stabilization before entering the swirling orifices. This improves the circumferential and radial uniformity of the exhaust gas by more than 60% compared to traditional single or double-stage buffer distributors. Furthermore, it creates a circumferential swirling flow within the discharge channel, changing the flow of neutral atoms from a simple axial motion to a circumferential spiral rotation. This increases the distance and residence time of neutral atoms within the discharge channel, increasing the probability of collisional ionization and mitigating the low ionization rate of krypton working propellant. The improved ionization rate directly leads to increased propellant utilization, reducing propellant consumption for the same thrust and significantly extending the spacecraft's on-orbit lifespan. The seamless, integrated structure avoids the corrosion and sputtering risks associated with welds in a plasma environment, extending the service life of the distributor itself by more than two times compared to welded components. Uniform gas output also reduces localized etching in the discharge channel, thus extending the overall service life of the thruster.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a distributor for high uniformity electric propulsion, characterized in that: Includes the following steps: Ⅰ. Load the high-temperature alloy powder into the printing equipment, place the cleaned substrate into the printing equipment and level it; II. Set the printing parameters as follows: laser power 280W, scanning speed 1200mm / s, layer thickness 0.03mm, so as to print out the device base (1), first orifice plate (2), second orifice plate (3) with fixed column (11), gas supply column (12) and anode column (13) in one go, and swirling orifice plate (4) with several circumferential spiral flow channels (5) inside and swirling holes (41) connected to the spiral flow channels (5) on the end face. Ⅲ. After printing and forming, remove the product from the equipment and clean off any residual powder; place the cleaned product in an oven and heat it to 900℃ for 3 hours for annealing. IV. Separate the molded part from the substrate by wire cutting, and then polish the molded part to make the surface roughness Ra1.5μm.

2. The manufacturing method of a high-uniformity electric propulsion distributor according to claim 1, characterized in that: High-temperature alloy powder needs to be dried before being loaded into the printing equipment to ensure its fluidity.

3. The manufacturing method of a high-uniformity electric propulsion distributor according to claim 2, characterized in that: Argon gas is circulated inside the printing equipment to prevent powder oxidation.

4. The manufacturing method of a high-uniformity electric propulsion distributor according to claim 3, characterized in that: After the molded part is separated from the substrate, residual powder is further removed by high-pressure water gun or ultrasonic vibration.

5. A method for manufacturing a high-uniformity electric propulsion distributor according to claim 4, characterized in that: The polishing method used is electrochemical polishing.

6. A method for manufacturing a high-uniformity electric propulsion distributor according to claim 5, characterized in that: X-rays are used to inspect the polished molded parts to ensure that there are no defects such as pores, incomplete fusion, or cracks inside the molded parts.

7. A method for manufacturing a high-uniformity electric propulsion distributor according to claim 1, characterized in that: The inner chamber of the molded part (1) has a first buffer cavity (51) between the first perforated plate (2), the first perforated plate (2) has a second buffer cavity (52) between the second perforated plate (3), and the second perforated plate (3) has a third buffer cavity (53) between the swirling perforated plate (4). The first buffer cavity (51), the second buffer cavity (52) and the third buffer cavity (53) are interconnected through channels. The first buffer cavity (51) is connected to the air supply column (12), and the third buffer cavity (53) is connected to the spiral flow channel (5) through channels.

Images