Method for detecting boron nitride ceramic cavity of hall thruster

Abstract

The application provides a boron nitride ceramic cavity detection method for a Hall thruster, characterized in that: a high-temperature environment during normal operation of the thruster is simulated by a vacuum furnace, the boron nitride ceramic cavity is heated and then cooled to room temperature, the surface crack condition of the boron nitride ceramic cavity is fully detected by using a multi-angle X-ray flaw detector and a magnifying glass, the screening before assembly of the boron nitride ceramic cavity is realized, and the unqualified boron nitride ceramic cavity with surface cracks is removed, so that the reliability and safety of the Hall thruster can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of space electric propulsion technology, and more specifically, to a method for detecting the boron nitride ceramic cavity of a Hall thruster. Background Technology

[0002] Electric propulsion technology, as an advanced space propulsion technology, has been widely used in various space applications, including attitude control, north-south position holding, orbit transfer, atmospheric damping compensation, and main propulsion for deep space exploration. Especially in deep space exploration missions, electric propulsion technology, with its high specific impulse and long lifespan, can significantly reduce propellant usage and increase the spacecraft's payload ratio, demonstrating significant advantages.

[0003] The boron nitride ceramic cavity is one of the key components of a Hall thruster, directly affecting the plasma sheath layer on the inner wall of the discharge chamber, temperature distribution, and material sputtering characteristics. Therefore, it not only determines the thruster's lifespan but also directly impacts its efficiency. During production, processing, and transportation, boron nitride ceramic materials can develop microcracks. These microcracks may propagate during the high-temperature operation of the thruster and exposure to harsh mechanical environments, causing damage to the ceramic cavity. This severely affects the performance, lifespan, and reliability of the Hall thruster. Therefore, employing appropriate boron nitride ceramic cavity inspection methods to eliminate defective ceramics is extremely important.

[0004] In the existing ceramic cavity inspection process, the ceramic cavity is only subjected to X-ray flaw detection once in the axial direction and once in the radial direction at room temperature, which makes it difficult to detect micro-cracks in advance. Summary of the Invention

[0005] This application provides a method for detecting boron nitride ceramic cavities in Hall thrusters. By simulating the high-temperature environment of Hall thruster operation, the thermal effect on the boron nitride ceramic cavity is amplified, and then multi-angle X-ray flaw detection and magnification are used to inspect the surface of the boron nitride ceramic cavity, thereby detecting microcracks in the boron nitride ceramic cavity parts in advance before assembly.

[0006] This application provides a method for detecting the boron nitride ceramic cavity of a Hall thruster, comprising the following steps:

[0007] Step 1: Dimensionally inspect the boron nitride ceramic cavity;

[0008] Step 2: Use a magnifying glass to inspect the surface cracks of the boron nitride ceramic cavity that has passed the dimensional inspection;

[0009] Step 3: Place the boron nitride ceramic cavity that has passed the surface crack inspection into the vacuum furnace;

[0010] Step 4: Heat the boron nitride ceramic cavity to the operating temperature of the Hall thruster discharge chamber using a vacuum furnace and maintain the temperature.

[0011] Step 5: Stop heating the vacuum furnace and maintain the vacuum inside the furnace to allow the boron nitride ceramic cavity to cool to room temperature;

[0012] Step 6: Repeat steps 4 to 5 to cycle the boron nitride ceramic cavity after it has cooled to room temperature. After cycling the heating and cooling multiple times, remove the boron nitride ceramic cavity from the vacuum furnace.

[0013] Step 7: Inspect the surface cracks of the removed boron nitride ceramic cavity using a magnifying glass;

[0014] Step 8: Perform multi-angle flaw detection on the boron nitride ceramic cavity that has passed the surface crack detection using an X-ray flaw detector. The conditions for passing the inspection are: no cracks are present; or no linear or strip-shaped defects are present; or the cumulative defect length does not exceed a certain threshold.

[0015] Furthermore, in steps 2, 7, and 8, if cracks are detected in the boron nitride ceramic cavity, the test result is deemed unqualified.

[0016] Furthermore, the temperature range inside the vacuum furnace is from room temperature to 600°C, and the pressure range is ≤5×10-1Pa.

[0017] Furthermore, the X-ray flaw detector's multi-angle flaw detection includes axial flaw detection and radial flaw detection.

[0018] Furthermore, during axial flaw detection, multiple images are stitched together to allow X-rays to cover the entire end face of the boron nitride ceramic cavity for imaging and detection.

[0019] Furthermore, during radial flaw detection, a rotating imaging method is used. The film is placed inside the boron nitride ceramic cavity, and the X-ray source is rotated along the annular direction to perform multiple imaging tests on the boron nitride ceramic cavity.

[0020] Furthermore, in step 4, the heating rate is higher than 6℃ / min, and the holding time is greater than or equal to 0.5 hours.

[0021] Furthermore, in step 6, the heating and cooling cycles are repeated 2-5 times.

[0022] Furthermore, the accuracy of the X-ray flaw detector is less than or equal to 80 μm.

[0023] Furthermore, in step 4, the operating temperature of the Hall thruster discharge chamber is 500°C to 600°C.

[0024] The present invention provides a method for detecting boron nitride ceramic cavities in Hall thrusters. By simulating the high-temperature environment during normal operation of the thruster in a vacuum furnace, the boron nitride ceramic cavity is first heated and then cooled to room temperature. A multi-angle X-ray flaw detector and a magnifying glass are used to fully detect surface cracks in the boron nitride ceramic cavity. This method can screen boron nitride ceramic cavities before assembly, eliminating unqualified boron nitride ceramic cavities with surface cracks, and effectively improving the reliability and safety of Hall thrusters. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings:

[0026] Figure 1 This is a schematic diagram of axial flaw detection performed according to the Hall thruster boron nitride ceramic cavity detection method provided in the embodiments of this application;

[0027] Figure 2 This is a schematic diagram of radial flaw detection performed according to the Hall thruster boron nitride ceramic cavity detection method provided in the embodiments of this application;

[0028] Figure 3 This is a schematic diagram of the starting point for radial flaw detection and imaging based on the Hall thruster boron nitride ceramic cavity detection method provided in the embodiments of this application. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0032] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0033] In addition, the term "multiple" should mean two or more.

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0035] The boron nitride ceramic cavity 1 is one of the key components of the Hall thruster, which determines the lifespan of the thruster and affects its working efficiency. However, the boron nitride ceramic material may develop micro-cracks when the thruster operates at high temperatures and is subjected to harsh mechanical environments. As the cracks propagate, they can cause damage to the ceramic cavity, which in severe cases can affect the performance, lifespan, and reliability of the Hall thruster.

[0036] The boron nitride ceramic cavity detection method for Hall thrusters provided in this application involves detecting surface cracks in the boron nitride ceramic cavity 1 before it is assembled into the Hall thruster. A vacuum furnace is then used to simulate the normal operating temperature of the Hall thruster. The high and low temperature variations simulate the working environment faced by the boron nitride ceramic cavity 1. Finally, a magnifying glass and X-ray flaw detector are used to detect whether cracks exist on the surface of the boron nitride ceramic cavity 1 under simulated environmental conditions. This method achieves the detection and screening of the boron nitride ceramic cavity 1 before assembly, preventing cracks from appearing in the boron nitride ceramic cavity 1 during the operation of the Hall thruster after assembly, thus ensuring the reliability of the Hall thruster's operation.

[0037] To achieve the above objectives, this application provides a method for detecting the boron nitride ceramic cavity of a Hall thruster, comprising the following steps:

[0038] Step 1: Dimensionally inspect the boron nitride ceramic cavity;

[0039] Step 2: Use a magnifying glass to inspect the surface cracks of the boron nitride ceramic cavity that has passed the dimensional inspection;

[0040] Step 3: Place the boron nitride ceramic cavity that has passed the surface crack inspection into the vacuum furnace;

[0041] Step 4: Heat the boron nitride ceramic cavity to the operating temperature of the Hall thruster discharge chamber using a vacuum furnace and maintain the temperature.

[0042] Step 5: Stop heating the vacuum furnace and maintain the vacuum inside the furnace to allow the boron nitride ceramic cavity to cool to room temperature;

[0043] Step 6: Repeat steps 4 to 5 to perform cyclic heating and cooling on the boron nitride ceramic cavity 1 after it has cooled to room temperature. After multiple cycles of cyclic heating and cooling, remove the boron nitride ceramic cavity 1 from the vacuum furnace.

[0044] Step 7: Inspect the surface cracks of the removed boron nitride ceramic cavity using a magnifying glass;

[0045] Step 8: Perform multi-angle flaw detection on the boron nitride ceramic cavity that has passed the surface crack detection using an X-ray flaw detector. The X-ray flaw detector is used to detect the fine cracks on the surface of the boron nitride ceramic cavity 1. The qualified conditions for the detection are: no cracks exist; or no linear or strip-shaped defects exist; or the cumulative defect length does not exceed a certain threshold.

[0046] Furthermore, in steps 2, 7, and 8, if a crack is detected in the boron nitride ceramic cavity, the boron nitride ceramic cavity is deemed unqualified.

[0047] Furthermore, the temperature range inside the vacuum furnace is from room temperature to 600°C, and the pressure range is ≤5×10⁻⁶. -1 Pa.

[0048] Furthermore, in step 8, the X-ray flaw detector performs multi-angle flaw detection, including axial flaw detection and radial flaw detection.

[0049] Furthermore, during axial flaw detection, multiple images are stitched together to allow X-rays to cover the entire end face of the boron nitride ceramic cavity for imaging and detection.

[0050] Furthermore, during radial flaw detection, a rotating imaging method is used. The film is placed inside the boron nitride ceramic cavity, and the X-ray source is rotated along the annular direction to perform multiple imaging tests on the boron nitride ceramic cavity.

[0051] Specifically, such as Figures 1 to 3 As shown, the Hall thruster boron nitride ceramic cavity detection method provided according to an embodiment of this application includes the following steps:

[0052] Step 1: Perform dimensional inspection on the boron nitride ceramic cavity 1;

[0053] Step 2: Use a 50μm precision magnifying glass to inspect the surface cracks of the boron nitride ceramic cavity 1 that has passed the dimensional inspection. This magnifying glass is used to detect larger cracks on the surface of the boron nitride ceramic cavity 1.

[0054] Step 3: Place the boron nitride ceramic cavity 1, which has passed the surface crack inspection, into a vacuum furnace for heating. The temperature range inside the vacuum furnace is room temperature to 600℃, and the pressure range is ≤5×10⁻⁶. -1 Pa;

[0055] Step 4: Heat the boron nitride ceramic cavity to the operating temperature of the Hall thruster discharge chamber using a vacuum furnace at a heating rate higher than 6℃ / min and hold for 0.5 hours;

[0056] Step 5: Stop heating the vacuum furnace and maintain the vacuum inside the furnace to allow the boron nitride ceramic cavity 1 to cool to room temperature;

[0057] Step 6: Repeat steps 4-5 to cycle the heating and cooling of the boron nitride ceramic cavity 1 after it has cooled to room temperature. After 2-5 cycles of heating and cooling, remove the boron nitride ceramic cavity 1 from the vacuum furnace.

[0058] Step 7: Surface crack detection of the removed boron nitride ceramic cavity 1 is performed using a 50μm precision 10x magnifying glass;

[0059] Step 8: Perform multi-angle flaw detection on the boron nitride ceramic cavity 1 that has passed the surface crack detection using an 80μm precision X-ray flaw detector. The X-ray flaw detector is used to detect fine cracks on the surface of the boron nitride ceramic cavity 1. The qualified conditions for the inspection are: there are no linear or strip-shaped defects, and the cumulative defect length does not exceed 1.2mm.

[0060] Step 8, in which multi-angle flaw detection includes axial flaw detection and radial flaw detection, is performed. When performing axial flaw detection, such as... Figure 1 As shown, a multi-image stitching method is used. During the imaging and detection process, the X-rays 3 of the X-ray flaw detector irradiate the entire end face of the boron nitride ceramic cavity 1 along its axial direction. The film 2 of the X-ray flaw detector is positioned below the boron nitride ceramic cavity 1, and the imaging orientation can be marked as needed. For radial flaw detection, such as... Figure 2 As shown, a rotating imaging method is used. The film 2 of the X-ray flaw detector is positioned along the axial direction of the boron nitride ceramic cavity 1 within the inner hole of the boron nitride ceramic cavity 1. The X-ray source rotates in a circumferential direction and performs multiple imaging operations. The starting point of the imaging is as shown... Figure 3 As shown, starting from the shooting point 4, the X-ray source rotates 30° clockwise or counterclockwise each time to take a picture, for a total of 12 shots.

[0061] If a crack is detected on the surface of the boron nitride ceramic cavity 1 during the above-mentioned inspection steps, the boron nitride ceramic cavity 1 is considered unqualified and subsequent assembly with the Hall thruster is prohibited.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for detecting the boron nitride ceramic cavity of a Hall thruster, characterized in that, Includes the following steps: Step 1: Dimensionally inspect the boron nitride ceramic cavity; Step 2: Use a magnifying glass to inspect the surface cracks of the boron nitride ceramic cavity that has passed the dimensional inspection; Step 3: Place the boron nitride ceramic cavity that has passed the surface crack inspection into the vacuum furnace; Step 4: Heat the boron nitride ceramic cavity to the operating temperature of the Hall thruster discharge chamber using a vacuum furnace and maintain the temperature. Step 5: Stop heating the vacuum furnace and maintain the vacuum inside the furnace to allow the boron nitride ceramic cavity to cool to room temperature; Step 6: Repeat steps 4 to 5 to cycle the boron nitride ceramic cavity after it has cooled to room temperature. After cycling the heating and cooling multiple times, remove the boron nitride ceramic cavity from the vacuum furnace. Step 7: Inspect the surface cracks of the removed boron nitride ceramic cavity using a magnifying glass; Step 8: Perform multi-angle flaw detection on the boron nitride ceramic cavity that has passed the surface crack detection using an X-ray flaw detector. The conditions for passing the inspection are: no cracks are present; or no linear or strip-shaped defects are present; or the cumulative defect length does not exceed a certain threshold.

2. The method according to claim 1, characterized in that, If cracks are detected in the boron nitride ceramic cavity in steps 2, 7, and 8, the test result is deemed unqualified.

3. The method according to claim 1, characterized in that, The temperature range inside the vacuum furnace is from room temperature to 600℃, and the pressure range is ≤5×10⁻⁶. -1 Pa.

4. The method according to claim 1, characterized in that, The X-ray flaw detector's multi-angle flaw detection includes axial flaw detection and radial flaw detection.

5. The method according to claim 4, characterized in that, During axial flaw detection, multiple images are stitched together to allow X-rays to cover the entire end face of the boron nitride ceramic cavity for imaging and detection.

6. The method according to claim 4, characterized in that, During radial flaw detection, a rotating imaging method is used. The film is placed inside the boron nitride ceramic cavity, and the X-ray source is rotated in a circumferential direction to take multiple images of the boron nitride ceramic cavity.

7. The method according to claim 1, characterized in that, In step 4, the heating rate is higher than 6℃ / min, and the holding time is greater than or equal to 0.5 hours.

8. The method according to claim 1, characterized in that, In step 6, the heating and cooling cycles are repeated 2-5 times.

9. The method according to claim 1, characterized in that, The accuracy of the X-ray flaw detector is less than or equal to 80μm.

10. The method according to claim 1, characterized in that, In step 4, the operating temperature of the Hall thruster discharge chamber is 500°C to 600°C.

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