Surface buffering chemical polishing process for whole superconducting cavity

Abstract

The invention discloses a surface buffer chemical polishing process for a whole superconducting cavity, which comprises the following steps: pretreating the superconducting cavity, fixing the superconducting cavity in a tool clamp of a chemical buffer treatment device in a vertical manner, injecting a buffer chemical polishing solution into the superconducting cavity, and starting an external cooling water circulation system at the same time, carrying out primary buffer chemical polishing; then the polishing solution is discharged from the superconducting cavity and recycled, secondary thickness measurement is conducted on the superconducting cavity, the superconducting cavity is turned over and fixed into the tool clamp in the vertical mode again to be subjected to secondary buffer chemical polishing, and the superconducting cavity is cleaned and dried; and then third-time thickness measurement is carried out, the product is placed in a vacuum furnace to be subjected to medium-temperature annealing, quality detection and classification, and through control and cooperation of multiple links and application of improvement of an external cooling water circulation system, the polishing quality and reliability and consistency of cavity performance are remarkably improved. And the buffer chemical polishing quality of the surface of the superconducting cavity 30 is obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical polishing, and in particular to a surface buffer chemical polishing process for the entire superconducting cavity. Background Art

[0002] In the fields of superconducting accelerators, particle acceleration devices, and high-energy physics experiments, the superconducting cavity is one of the key components, and its performance is crucial to the energy improvement and operating efficiency of the entire system. The smoothness and consistency of the internal surface of the superconducting cavity directly affect the acceleration field strength and quality factor that the cavity can achieve when working at high frequencies. Therefore, high-quality, controllable, and uniform surface treatment technology has very broad application prospects in related industries and scientific research fields. At present, in order to make the performance of the superconducting cavity meet the expected requirements, the industry generally uses surface processing processes such as chemical buffered polishing (BCP) for inner wall treatment. The reliability of this type of process and the improvement of polishing quality play an important role in the performance and economy of the overall device.

[0003] In the prior art, the typical method of chemical buffer polishing of a superconducting cavity is usually to fix the cavity vertically and inject a chemical buffer solution in a specific proportion to uniformly corrode the inner wall. However, due to the complex internal structure of the superconducting cavity, the fluidity of the acid in the cavity is poor when placed vertically, and the solution temperature in local areas, especially in the upper end, is prone to being too high, resulting in uneven corrosion of the inner wall and obvious differences in the polishing effect. In this process, local excessive corrosion may cause irreversible damage to the cavity, seriously affecting performance stability and practical life. Although existing technical solutions have attempted to improve the above problems by controlling the injection time and flow rate of the chemical solution, adjusting the direction of the cavity and other measures, it has always been difficult to completely solve the pain points of insufficient polishing uniformity and reliability.

[0004] In view of this, it is necessary to improve the chemical buffer polishing technology of superconducting cavity in the prior art to solve the technical problem of poor stability of its internal surface quality. Summary of the invention

[0005] The purpose of the present invention is to provide a surface buffer chemical polishing process for the entire superconducting cavity to solve the above technical problems.

[0006] To achieve this object, the present invention adopts the following technical solutions: A surface buffer chemical polishing process for the entire superconducting cavity, comprising: Step S1, pre-treating the superconducting cavity to be treated, wherein the pre-treatment includes leak detection and surface condition inspection, followed by first thickness measurement and surface cleaning by ultrasonic wave; Step S2, fixing the pretreated superconducting cavity in a fixture of the chemical buffer treatment device in a vertical manner, injecting a buffered chemical polishing solution into the superconducting cavity, and simultaneously starting an external cooling water circulation system, cooling the superconducting cavity from top to bottom through a spray device in the external cooling water circulation system, so that the temperature of the inner and outer surfaces of the superconducting cavity is balanced, thereby performing the first buffered chemical polishing; Step S3, draining and recovering the polishing solution used after the first buffered chemical polishing is completed from the superconducting cavity, cleaning the superconducting cavity with ultrapure water, then measuring the thickness of the superconducting cavity for the second time, and turning the superconducting cavity over; Step S4, fixing the flipped superconducting cavity in the fixture in a vertical manner again, injecting the buffered chemical polishing solution and operating the external cooling water circulation system again to perform a second buffered chemical polishing, then draining and recovering the polishing solution and washing the superconducting cavity with ultrapure water, and then drying it; Step S5, measuring the thickness of the dried superconducting cavity for the third time, placing it in a vacuum furnace for medium-temperature annealing, and performing quality inspection and classification on the superconducting cavity after annealing, thereby completing the overall surface buffer chemical polishing process.

[0007] Optionally, the buffered chemical polishing solution is a mixed solution of phosphoric acid and nitric acid, and the ratio of the mixed solution is 85% phosphoric acid: 65% nitric acid: 40% phosphoric acid = 2:1:1.

[0008] Optionally, the step S1 specifically includes: Step S11, performing an initial integrity inspection on the superconducting cavity to be processed. During the initial inspection, the superconducting cavity is placed in a clean room environment, and visual inspection is performed on its universal interface, vacuum port and connection weld position to determine whether there are obvious cracks, pits or welding defects on the cavity surface, and the outer surface of the superconducting cavity is initially wiped and cleaned; Step S12, performing a leak test on the superconducting cavity that has passed the initial inspection, connecting the superconducting cavity to the adjustable pressurization system through an airtight connecting pipe, gradually filling the interior of the superconducting cavity with high-purity helium and maintaining it within a predetermined pressure range for a predetermined time, using a mass spectrometer leak detector to perform a gas probe scan around the cavity to determine whether there is a tiny leak in the cavity wall and the peripheral connection parts, and if a leak is found, its location information is recorded; Step S13, after the leak detection is qualified, the surface condition of the inner surface of the superconducting cavity is inspected, and the inner surface of the cavity is scanned and photographed in all directions by an industrial endoscope combined with a digital imaging analysis system, and the local protrusions, depressions, scratches or stains on the surface are marked and digitized through image processing software to identify abnormal surface data.

[0009] Optionally, after step S13, the following steps are further included: Step S14, after the surface condition inspection, use an ultrasonic thickness gauge to perform a first multi-point distribution thickness measurement on the inner wall thickness of the superconducting cavity to obtain first cavity wall thickness distribution data; wherein the multi-point distribution thickness measurement point layout is performed according to several radial and axial regions, specifically including at least 4 thickness measurement points uniformly distributed in the circumference of the cavity, and at least 3 thickness measurement points selected at different height positions in the axial direction; Step S15, cleaning the surface of the superconducting cavity after the first thickness measurement is completed, placing the superconducting cavity in an ultrasonic cleaning machine, injecting ultrapure water filtered by 0.1 μm into the cleaning tank, controlling the cleaning water temperature between 20°C and 30°C, and adjusting the position of the ultrasonic head according to the surface abnormality data to focus on cleaning the abnormal surface position.

[0010] Optionally, the step S2 specifically includes: Step S21, transporting the pre-treated superconducting cavity to a chemical buffer treatment device, fixing it vertically in a fixture, and adjusting the verticality and coaxiality of the superconducting cavity by fine-tuning the support structure during fixing; Step S22, after the position of the superconducting cavity is fixed, the parameters of the liquid injection system are set, the buffered chemical polishing solution is configured according to a predetermined ratio and stored in a solution storage tank, and the buffered chemical polishing solution is gradually injected into the superconducting cavity at a preset flow rate through an adjustable speed metering pump.

[0011] Optionally, after step S23, the following steps are further included: Step S23, while the buffered chemical polishing solution is injected, the external cooling water circulation system is started for cooling, the cooling water that has been subjected to temperature reduction treatment is injected into the cooling water tank, and after being pressurized by the water circulation pump group, the water is continuously sprayed from top to bottom on the outer surface of the superconducting cavity through the spray device; Step S24, while the cooling process is in progress, the temperature distribution of the superconducting cavity is monitored in real time through the multi-point temperature sensors and the online data acquisition system arranged outside the superconducting cavity, and the temperature monitoring data is fed back to the control module; when the temperature monitoring data shows that the temperature inside the superconducting cavity has a local upward trend, the control module automatically fine-tunes the cooling water spraying amount or the polishing solution injection rate; Step S25, after the first buffer chemical polishing reaches the preset polishing time, the operation of the liquid injection system and the external cooling water circulation system is stopped.

[0012] Optionally, the step S3 specifically includes: Step S31, directingly discharging the buffered chemical polishing solution in the superconducting cavity through a drainage pipeline, wherein the drainage pipeline is connected to a solution collection container, and during the discharging process, the solution recovery rate is monitored by a flow meter; Step S32, after the polishing solution is discharged, the interior of the superconducting cavity is cleaned multiple times by a spray device of an ultrasonic cleaning machine; Step S33, after the ultrapure water cleaning is completed, the inner wall of the superconducting cavity is purged, and then the thickness of the inner wall of the superconducting cavity is measured for the second time in a multi-point distribution by using an ultrasonic thickness gauge to obtain second thickness distribution data of the cavity wall; Step S34, after completing the second thickness measurement, the superconducting cavity is flipped 180° as a whole by the flipping tool and fixed in the tooling fixture, and the state information of the superconducting cavity after flipping is recorded; the superconducting cavity state information includes the flipping angle, the centering degree of the re-fixed position and the stress sensing data during the flipping process.

[0013] Optionally, the step S5 specifically includes: Step S51, using an ultrasonic thickness gauge to perform a third multi-point distribution thickness measurement on the inner wall thickness of the dried superconducting cavity to obtain third thickness distribution data of the cavity wall, and obtaining a processing quality index of chemical polishing by comparing the difference between the first thickness distribution data of the first thickness measurement, the second thickness distribution data of the second thickness measurement, and the third thickness distribution data and analyzing the thickness fluctuation; Step S52, placing the superconducting cavity that has completed the third thickness measurement into a vacuum furnace for medium-temperature annealing; the temperature range of the medium-temperature annealing is set between 200° C. and 600° C. and maintained at a constant temperature for 2 to 6 hours, and during the annealing process, the cavity temperature distribution is monitored in real time by an integrated infrared thermometer and a thermocouple, and the operating parameters of the vacuum furnace are regulated by the cavity temperature distribution data; Step S53, after annealing is completed, the superconducting cavity is transferred from the vacuum furnace to the measuring workbench, the electrical performance parameters of the superconducting cavity are tested, and the superconducting cavity is divided into quality grades based on the obtained processing quality index, and the superconducting cavities of each quality grade are classified and stored to complete the overall surface buffer chemical polishing process.

[0014] Optionally, the external cooling water circulation system comprises a tooling support, a receiving cavity for accommodating the superconducting cavity is provided in the middle of the tooling support, and an annular cooling liquid channel is provided on the outer side of the tooling support; A spray device is arranged above the tooling bracket, and a cooling water collecting tray is arranged below the tooling bracket, so that the cooling water sprayed from top to bottom by the spray device can flow into the cooling water collecting tray through the coolant channel for recovery.

[0015] Optionally, the spray device is provided with a water circulation pump group and a cold water tank respectively, and the water circulation pump group is connected to the cold water tank and the spray device, respectively, for pumping cooling water from the cold water tank to the spray device; the cold water tank is connected to the cooling water collecting tray, for realizing the reflux of cooling water.

[0016] Compared with the prior art, the present invention has the following beneficial effects: firstly, by pre-treating the superconducting cavity with leak detection, surface condition inspection, initial thickness measurement and ultrasonic cleaning, the superconducting cavity is fixed in a vertical manner and injected with a buffered chemical polishing solution, and at the same time, the cavity is uniformly cooled from top to bottom by an external cooling water circulation system through a spray device, so that during the first buffered chemical polishing process, the acid liquid can achieve relatively uniform corrosion under the condition of temperature balance; after completing the first polishing, the cavity is cleaned, thickness measured and turned over, the liquid injection and cooling operations are repeated, the turned cavity is polished for the second time, and after polishing, it is cleaned and dried again to ensure that the inner surface of the cavity meets the established surface treatment requirements; the dried cavity is re-thickness measured and medium-temperature annealed, which can effectively remove harmful hydrogen elements generated in the process, and finally the cavity is quality inspected and classified; the method significantly improves the reliability and consistency of the polishing quality and cavity performance through the control and coordination of multiple links and the application of the improved external cooling water circulation system, and significantly improves the buffered chemical polishing quality of the superconducting cavity surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0019] Figure 1 This is one of the schematic flow diagrams of the surface buffer chemical polishing process of this embodiment; Figure 2 This is one of the schematic flow diagrams of the surface buffer chemical polishing process of this embodiment; Figure 3 is a schematic diagram of the system layout of the external cooling water circulation system of this embodiment; Figure 4 The external cooling water circulation system of this embodiment Figure 3 Schematic diagram of the cross-sectional structure at AA in the middle. DETAILED DESCRIPTION

[0020] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0022] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0023] Combination Figure 1 to Figure 2 As shown, an embodiment of the present invention provides a surface buffer chemical polishing process for the entire superconducting cavity, comprising: Step S1 , pre-treating the superconducting cavity 30 to be treated, the pre-treatment including leak detection and surface condition inspection, followed by the first thickness measurement and surface cleaning by ultrasonic wave.

[0024] First, the superconducting cavity 30 is pretreated to ensure that its structure and surface state meet the ideal basic conditions. Through the leak detection test, it can be determined whether there are tiny leaks in the superconducting cavity 30, thereby avoiding the risk of solution leakage and unnecessary loss during the subsequent chemical polishing. After confirming that there is no leakage, the inner surface of the superconducting cavity 30 is checked to identify the initial defects and unevenness of the surface. Then, by performing the first thickness measurement, the initial thickness data of the inner wall of the cavity can be obtained, laying the foundation for the control and comparison of the subsequent polishing degree. Finally, ultrasonic cleaning technology is used to remove oil and tiny particles attached to the surface, so that the inner wall of the cavity reaches a higher cleanliness and surface quality before entering the chemical polishing stage.

[0025] Step S2, fix the pretreated superconducting cavity 30 vertically in the fixture of the chemical buffer treatment device, inject the buffered chemical polishing solution into the superconducting cavity 30, and simultaneously start the external cooling water circulation system. In the external cooling water circulation system, the superconducting cavity 30 is cooled from top to bottom by the spray device 10 to balance the temperature of the inner and outer surfaces of the superconducting cavity 30, thereby performing the first buffered chemical polishing.

[0026] After the pretreatment is completed, the superconducting cavity 30 is fixed vertically in the fixture of the chemical buffer treatment device to ensure that its spatial position and posture remain stable and consistent during the subsequent polishing process. Subsequently, the buffered chemical polishing solution prepared according to a specific ratio is injected into the cavity so that the solution is in full contact with the inner wall and produces a uniform corrosion and polishing effect. At the same time, the external cooling water circulation system starts to operate, cooling the outside of the cavity by spraying from top to bottom, so that the temperature inside and outside the cavity reaches a relatively balanced state. This can reduce the uneven corrosion caused by local overheating, achieve effective temperature control of the first buffered chemical polishing, and ensure polishing uniformity and surface quality.

[0027] Step S3, draining and recovering the polishing solution used after the first buffered chemical polishing from the superconducting cavity 30, cleaning the superconducting cavity 30 with ultrapure water, then measuring the thickness of the superconducting cavity 30 for the second time, and turning the superconducting cavity 30 over.

[0028] After the first buffered chemical polishing is completed, the reacted polishing solution needs to be discharged from the cavity and recycled to reduce resource waste and potential environmental impact. Subsequently, the superconducting cavity 30 is fully cleaned with ultrapure water to thoroughly remove the chemical components remaining on the inner wall to ensure the neutrality and cleanliness of the cavity surface after the polishing process. After that, the cavity is measured for the second time to compare the data with the first thickness measurement to determine the degree of change in the cavity wall thickness during the polishing process. Finally, by flipping the superconducting cavity 30, the next stage of polishing can be started from different directions and different parts, further improving the uniformity and effect of the overall polishing.

[0029] In step S4, the flipped superconducting cavity 30 is fixed vertically in the fixture again, and the buffered chemical polishing solution is injected and the external cooling water circulation system is operated again to perform a second buffered chemical polishing. After that, the polishing solution is discharged and recovered, and the superconducting cavity 30 is cleaned with ultrapure water, and then dried.

[0030] After flipping, the superconducting cavity 30 is fixed in the fixture in a vertical manner again, and the operation of injecting the buffered chemical polishing solution and opening the external cooling water circulation system is repeated, so as to perform a second buffered chemical polishing on the flipped cavity. By repeating this process, the areas that could not be fully processed before or had slight unevenness can be refined again to further improve the flatness and uniformity of the cavity surface. After the second polishing is completed, the solution is discharged and recovered again, and the cavity is thoroughly cleaned with ultrapure water to ensure that there is no residual chemical component attached to its inner wall, and then after appropriate drying treatment, the cavity reaches the ideal initial state for subsequent processes.

[0031] Step S5, the dried superconducting cavity 30 is subjected to a third thickness measurement, and is placed in a vacuum furnace for medium-temperature annealing, and the superconducting cavity 30 after annealing is subjected to quality inspection and classification, and the overall surface buffer chemical polishing process is completed to eliminate the influence of hydrogen elements generated during the buffer chemical polishing process on the performance of the superconducting cavity 30.

[0032] The third thickness measurement is carried out in the dried cavity state to obtain the wall thickness data, and compared with the previous two thickness measurement results to intuitively show the change in cavity wall thickness and the degree of uniformity improvement after two buffered chemical polishing treatments. After that, the superconducting cavity 30 is placed in a vacuum furnace for medium-temperature annealing to remove the adverse effects of hydrogen introduced during the polishing process on the performance of the niobium material, thereby improving the performance stability of the cavity and the quality factor under high-frequency working conditions. After the annealing is completed, the superconducting cavity 30 is strictly quality inspected and classified to ensure that the finished cavity meets the preset performance indicators and application requirements, and thus completes the entire surface buffered chemical polishing process.

[0033] The working principle of the present invention is as follows: first, the superconducting cavity 30 is pre-treated by leak detection, surface condition inspection, initial thickness measurement and ultrasonic cleaning, and then the superconducting cavity 30 is fixed in a vertical manner and injected with a buffered chemical polishing solution. At the same time, the external cooling water circulation system is used to uniformly cool the cavity from top to bottom through the spray device 10, so that during the first buffered chemical polishing process, the acid liquid can achieve relatively uniform corrosion under temperature equilibrium conditions; after the first polishing is completed, the cavity is cleaned, thickness measured and turned over, and the liquid injection and cooling operations are repeated. The turned cavity is polished for the second time, and after polishing, it is cleaned and dried again to ensure that the surface inside the cavity meets the established surface treatment requirements; the dried cavity is re-thickness measured and medium-temperature annealed, which can effectively remove harmful hydrogen elements generated in the process, and finally the cavity is quality inspected and classified; this method significantly improves the reliability and consistency of the polishing quality and cavity performance through the control and coordination of multiple links and the improvement of the application of the external cooling water circulation system, and significantly improves the buffered chemical polishing quality of the surface of the superconducting cavity 30.

[0034] In this embodiment, it is specifically described that the buffered chemical polishing solution is a mixed solution of phosphoric acid and nitric acid, and the ratio of the mixed solution is 85% phosphoric acid: 65% nitric acid: 40% phosphoric acid = 2:1:1.

[0035] It should be noted that the buffered chemical polishing solution is a mixed solution of phosphoric acid and nitric acid, with a specific ratio of 85% phosphoric acid, 65% nitric acid and 40% phosphoric acid, mixed in a ratio of 2:1:1. The composition and proportion of the mixed solution are formulated to optimize the corrosion and polishing effects under acidic conditions. The combination of phosphoric acid and nitric acid can produce a uniform chemical reaction on the surface of the superconducting cavity 30, achieving the desired buffered chemical polishing effect, while controlling the activity of the acid solution to avoid excessive corrosion.

[0036] In this embodiment, it is specifically described that step S1 specifically includes: Step S11, performing a preliminary inspection of the integrity of the superconducting cavity 30 to be processed. During the preliminary inspection, the superconducting cavity 30 is placed in a clean room environment, and its universal interface, vacuum port and connection weld position are visually inspected to determine whether there are obvious cracks, pits or welding defects on the cavity surface, and the outer surface of the superconducting cavity 30 is preliminarily wiped and cleaned; First, the superconducting cavity 30 to be processed is placed in a clean room environment to reduce the impact of particles and microorganisms in the air on subsequent processing. By carefully visually inspecting the common interfaces, vacuum ports and connecting welds of the cavity, obvious structural defects (such as cracks, pits or poor welding) can be discovered in time. At the same time, the outer surface of the superconducting cavity 30 is initially wiped and cleaned to help remove loose dirt and floating dust on the surface.

[0037] Step S12, a leak test is performed on the superconducting cavity 30 that has passed the initial inspection. The superconducting cavity 30 is connected to the adjustable pressurization system through an airtight connecting pipe, and high-purity helium is gradually filled into the superconducting cavity 30 and maintained at a predetermined pressure range (e.g., 0.05MPa to 0.1MPa) for a preset time. A mass spectrometer leak detector is used to perform a gas probe scan around the cavity to determine whether there is a small leak in the cavity wall and the peripheral connection parts. If a leak point is found, its position information is recorded to facilitate plugging or repairing until there is no leak point. After the initial inspection, the superconducting cavity 30 is connected to the adjustable pressurization system and high-purity helium is gradually filled into the cavity, so that the predetermined pressure condition can be maintained stably for a certain period of time. After that, the gas probe around the cavity is scanned by a mass spectrometer leak detector. Once there is a small leak, the helium will leak out through the defect and be detected. This leak test can find tiny leaks that are difficult to detect. If there is a leak, the location information needs to be recorded for subsequent repair and re-inspection to ensure that the cavity maintains good airtightness and reliability during subsequent processing.

[0038] Step S13, after the leak detection is qualified, the surface condition of the inner surface of the superconducting cavity 30 is inspected, and the inner surface of the cavity is scanned and photographed in all directions by an industrial endoscope combined with a digital imaging analysis system, and the local protrusions, depressions, scratches or stains on the surface are marked and digitized through image processing software to identify abnormal surface data.

[0039] Step S14, after the surface condition inspection, the inner wall thickness of the superconducting cavity 30 is measured for the first time in a multi-point distribution by using an ultrasonic thickness gauge to obtain first thickness distribution data of the cavity wall; wherein the layout of the multi-point distribution of thickness measurement points is carried out according to several radial and axial regions, specifically including at least 4 thickness measurement points uniformly distributed in the circumferential direction of the cavity, and at least 3 thickness measurement points selected at different height positions in the axial direction; After obtaining the surface state data, the inner wall of the cavity is measured by multi-point distributed thickness measurement using an ultrasonic thickness gauge to obtain the first thickness distribution data. By evenly distributing at least 4 thickness measurement points in the radial direction and selecting at least 3 thickness measurement points at different heights in the axial direction, data mapping of the cavity wall thickness in multiple directions can be obtained. This data will become a reference for subsequent comparison, control and optimization of the polishing process.

[0040] Step S15, cleaning the surface of the superconducting cavity 30 after the first thickness measurement is completed, placing the superconducting cavity 30 in an ultrasonic cleaning machine, injecting ultrapure water filtered by 0.1 μm into the cleaning tank, controlling the cleaning water temperature between 20° C. and 30° C., and adjusting the position of the ultrasonic head according to the surface abnormality data to focus on cleaning the abnormal surface position.

[0041] The ultrasonic frequency is set in the range of 40kHz to 80kHz, and the tiny particles, light oil stains and dust remaining on the surface of the cavity wall are further removed by ultrasonic cleaning for 5 to 10 minutes; after cleaning, the surface is blown dry with high-purity nitrogen and visually inspected again to ensure that there is no obvious residue on the surface.

[0042] In this embodiment, it is specifically described that step S2 specifically includes: Step S21, transport the pre-treated superconducting cavity 30 to the chemical buffer treatment device, fix it vertically in the fixture, and adjust the verticality and coaxiality of the superconducting cavity 30 by fine-tuning the support structure during fixation; (for example, use a laser collimator or an optical level to review and position the upper and lower flange surfaces of the cavity) to ensure that the inner wall stress and acid flow conditions of the superconducting cavity 30 reach the optimal state during the subsequent polishing process.

[0043] Step S22, after the position of the superconducting cavity 30 is fixed, the parameters of the liquid injection system are set, the buffered chemical polishing solution is configured according to a predetermined ratio and stored in a solution storage tank, and the buffered chemical polishing solution is gradually injected into the superconducting cavity 30 at a preset flow rate through an adjustable speed metering pump.

[0044] The solution is pre-configured and placed in a high-purity solution storage tank; the solution is gradually injected into the superconducting cavity 30 at a set flow rate (such as 5L / min or higher) using an adjustable speed high-precision metering pump, and during the injection process, the inlet temperature (below 20°C) and injection rate of the solution are dynamically monitored and adjusted by a temperature sensor and a flow meter to ensure the uniformity and controllability of the solution injection.

[0045] Step S23, while the buffered chemical polishing solution is injected, the external cooling water circulation system is started for cooling, the cooling water that has been subjected to temperature reduction treatment is injected into the cooling water tank, and after being pressurized by the water circulation pump group 70, the outer surface of the superconducting cavity 30 is continuously sprayed from top to bottom through the spray device 10; wherein, the nozzle of the spray device 10 can select a porous annular structure to ensure that the cooling water forms a uniform water film around the cavity, and a water circulation path is formed between the annular coolant channel 22 of the fixture and the bottom cooling water collection plate 40, so that the cooling water maintains a stable temperature distribution and flow distribution in multiple cycles.

[0046] Step S24, while the cooling process is in progress, the temperature distribution of the superconducting cavity 30 is monitored in real time through the multi-point temperature sensors and the online data acquisition system arranged outside the superconducting cavity 30, and the temperature monitoring data is fed back to the control module; when the temperature monitoring data shows that the temperature inside the superconducting cavity 30 has a local upward trend, the control module automatically fine-tunes the cooling water spraying amount or the polishing solution injection rate to maintain the temperature balance of the inner and outer surfaces and avoid uneven corrosion caused by excessive temperature gradient.

[0047] Step S25, after the first buffer chemical polishing reaches the preset polishing time, the operation of the liquid injection system and the external cooling water circulation system is stopped.

[0048] Under the above-mentioned solution injection and cooling linkage control conditions, the first buffer chemical polishing process is maintained to reach the predetermined polishing time or polishing parameters (such as timely termination according to the real-time monitored solution acid consumption rate or inner wall roughness change trend), thereby achieving uniform corrosion and polishing of the cavity surface under relatively constant and balanced temperature and chemical conditions.

[0049] In this embodiment, it is specifically described that step S3 specifically includes: In step S31, the buffered chemical polishing solution inside the superconducting cavity 30 is discharged in a direction through a drainage pipeline, the drainage pipeline is connected to a solution collection container, and the solution recovery rate is monitored by a flow meter during the discharge process; ensuring that the solution is recovered completely and without leakage, and the recovered solution can be further analyzed or processed to improve resource utilization.

[0050] Step S32, after the polishing solution is discharged, the interior of the superconducting cavity 30 is cleaned multiple times by the spray device 10 of the ultrasonic cleaning machine; The ultrapure water used for cleaning can be filtered through a 0.1μm grade filter, and the cleaning water temperature can be controlled between 20℃ and 30℃. The cleaning time and the amount of cleaning water are adjusted in time according to the detection results of the residual solution in the cavity to ensure that no harmful components and tiny particles remain on the surface of the cavity wall.

[0051] Step S33, after the ultrapure water cleaning is completed, the inner wall of the superconducting cavity 30 is purged, and then the inner wall thickness of the superconducting cavity 30 is measured for the second time in a multi-point distribution by using an ultrasonic thickness gauge to obtain second cavity wall thickness distribution data; A short purge with high-purity nitrogen or clean air is performed to accelerate the removal of the water film on the inner surface of the cavity and stabilize the surface conditions. Then, a high-precision thickness gauge is used to measure the thickness of the inner wall of the cavity for the second time. Similar to the first thickness measurement, the thickness measurement process can be carried out by arranging several fixed measuring points along the axial and circumferential directions of the cavity to collect data, and the obtained thickness measurement data is recorded in the cavity surface status file to compare and analyze the thickness change trend of the cavity wall before and after polishing and after flipping.

[0052] Step S34, after completing the second thickness measurement, the superconducting cavity 30 is flipped 180° as a whole by the flipping tool and fixed in the tooling fixture, and the state information of the superconducting cavity 30 after flipping is recorded; the state information of the superconducting cavity 30 includes the flipping angle, the centering degree of the re-fixed position, and the stress sensing data during the flipping process.

[0053] The flipping tooling may include a precision rotating shaft and an anti-vibration buffer component, and utilize sensors and locking mechanisms to ensure that the cavity does not sway, shake or vibrate during the flipping process, and after the flipping is completed, the cavity is stably fixed in a vertical manner in the tooling fixture again; the state information of the superconducting cavity 30 after flipping (including the flipping angle, the degree of centering of the re-fixed position, and the stress sensing data during the flipping process) can be recorded and archived by the online monitoring system, thereby ensuring that the superconducting cavity 30 is always in a controllable and uniform working state in the subsequent processing links.

[0054] In this embodiment, it is specifically described that step S5 specifically includes: Step S51, using an ultrasonic thickness gauge to perform a third multi-point distribution thickness measurement on the inner wall thickness of the dried superconducting cavity 30 to obtain third thickness distribution data of the cavity wall, and obtaining a processing quality index of chemical polishing by comparing the difference between the first thickness distribution data of the first thickness measurement, the second thickness distribution data of the second thickness measurement, and the third thickness distribution data and analyzing the thickness fluctuation.

[0055] The third thickness measurement can be performed on the inner wall of the cavity using the same thickness gauge as the first two thickness measurements, ensuring that the position of each measuring point corresponds to the first two measurements, thereby obtaining comparability of the first thickness distribution data, the second thickness distribution data, and the third thickness distribution data; by comparing the above three sets of thickness distribution data, the thickness change trend of the cavity wall before and after surface treatment and the degree of improvement in uniformity can be quantitatively evaluated, providing a data basis for subsequent performance verification and quality improvement.

[0056] Step S52, placing the superconducting cavity 30 that has completed the third thickness measurement into a vacuum furnace for medium-temperature annealing; the temperature range of the medium-temperature annealing is set between 200°C and 600°C and maintained at a constant temperature for 2 to 6 hours. During the annealing process, the cavity temperature distribution is monitored in real time by an integrated infrared thermometer and a thermocouple, and the operating parameters of the vacuum furnace are regulated by the cavity temperature distribution data.

[0057] After the third thickness measurement, the superconducting cavity 30 is placed in a vacuum furnace for medium-temperature annealing to further eliminate the hydrogen elements introduced during the chemical polishing process and other stresses and defects that may affect the performance. The temperature range of medium-temperature annealing is 200°C to 600°C, and the constant temperature time is maintained for 2 to 6 hours to ensure that the cavity wall material structure reaches an ideal state. During the annealing process, the temperature distribution of the cavity is monitored and data feedback is performed in real time through the integrated infrared thermometer and thermocouple. The vacuum furnace operating parameters are dynamically adjusted according to the monitoring data to make the cavity temperature distribution uniform, so as to improve the electrical performance and structural stability of the cavity.

[0058] Step S53, after annealing is completed, the superconducting cavity 30 is transferred from the vacuum furnace to the measuring workbench, and the electrical performance parameters of the superconducting cavity 30 are tested. In combination with the obtained processing quality index, the superconducting cavity 30 is divided into quality grades, and the superconducting cavity 30 of each quality grade is classified and stored to complete the overall surface buffer chemical polishing process.

[0059] After annealing is completed, the superconducting cavity 30 is transferred to the measuring workbench for testing of its electrical performance parameters (such as the quality factor Q value and the index of the acceleration gradient). According to the electrical performance test results and the processing quality index calculated above, the superconducting cavity 30 is divided into quality grades: for example, the standard thresholds of the acceleration gradient and the quality factor can be set to achieve multi-level classification of the cavity; the cavity with a higher processing quality index and the electrical performance parameters closer to or exceeding the design target can be classified as Class A quality; the cavity slightly lower than the target value but still within the qualified range can be classified as Class B quality; if the processing quality index and the electrical performance parameters have a large deviation and need to be subsequently optimized, the cavity is classified as Class C quality. Through this clear quality grade division and classification storage, the factory quality can be finely controlled and clear quality guidance can be provided for subsequent use or reprocessing.

[0060] In this embodiment, it is specifically described that the external cooling water circulation system includes a tooling support 20, a storage cavity 21 for accommodating the superconducting cavity 30 is provided in the middle of the tooling support 20, and a ring-shaped cooling liquid channel 22 is provided on the outside of the tooling support 20; a spray device 10 is provided above the tooling support 20, and a cooling water collection tray 40 is provided below the tooling support 20, so that the cooling water sprayed from the spray device 10 from top to bottom can flow into the cooling water collection tray 40 through the cooling liquid channel 22 for recovery. Among them, the spray device 10 is also provided with a spray protection cover 60.

[0061] In this embodiment, it is further explained that the spray device 10 is correspondingly provided with a water circulation pump group 70 and a cold water tank 80. The water circulation pump group 70 is respectively connected to the cold water tank 80 and the spray device 10, and is used to pump cooling water from the cold water tank 80 to the spray device 10; the cold water tank 80 is connected to the cooling water collection tray 40, which is used to realize the reflux of cooling water.

[0062] It should be noted that, combined with Figure 3 and Figure 4 As shown, the working principle of the external cooling water circulation system is as follows: when the system is running, the water circulation pump group 70 first extracts the cooling water that has been cooled from the cold water tank 80 and transports it to the spray device 10 located above the superconducting cavity 30. The spray device 10 evenly distributes the cooling water on the outer surface of the superconducting cavity 30 from top to bottom, forming a continuous and stable cooling water film. The cooling water flowing through the surface of the cavity then flows downward along the annular coolant channel 22 set on the tooling bracket 20, and finally flows into the cooling water collection tray 40. The cooling water in the collection tray returns to the cold water tank 80 through the reflux pipeline for cooling and recycling, thereby forming a closed-loop controllable circulation process.

[0063] This external cooling water circulation system can effectively stabilize the temperature gradient inside and outside the cavity during the polishing process, so that the solution corrosion reaction is balanced and not prone to local overheating. Through this uniform cooling, the risk of excessive corrosion in certain areas of the cavity wall can be reduced to a certain extent, and the overall uniformity and processing accuracy of polishing can be improved. In addition, this cooling water circulation system has high flexibility and adjustability. Through the precise control of the water temperature and spray volume in the cooling water tank, it can be adaptively adjusted according to different cavity structures or different polishing processes.

[0064] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface buffer chemical polishing process for the entire superconducting cavity, characterized in that: include: Step S1, pre-treating the superconducting cavity to be treated, wherein the pre-treatment includes leak detection and surface condition inspection, followed by first thickness measurement and surface cleaning by ultrasonic wave; Step S2, fixing the pretreated superconducting cavity in a fixture of the chemical buffer treatment device in a vertical manner, injecting a buffered chemical polishing solution into the superconducting cavity, and simultaneously starting an external cooling water circulation system, cooling the superconducting cavity from top to bottom through a spray device in the external cooling water circulation system, so that the temperature of the inner and outer surfaces of the superconducting cavity is balanced, thereby performing the first buffered chemical polishing; Step S3, draining and recovering the polishing solution used after the first buffered chemical polishing is completed from the superconducting cavity, cleaning the superconducting cavity with ultrapure water, then measuring the thickness of the superconducting cavity for the second time, and turning the superconducting cavity over; Step S4, fixing the flipped superconducting cavity in the fixture in a vertical manner again, injecting the buffered chemical polishing solution and operating the external cooling water circulation system again to perform a second buffered chemical polishing, then draining and recovering the polishing solution and washing the superconducting cavity with ultrapure water, and then drying it; Step S5, measuring the thickness of the dried superconducting cavity for the third time, placing it in a vacuum furnace for medium-temperature annealing, and performing quality inspection and classification on the superconducting cavity after annealing, thereby completing the overall surface buffer chemical polishing process.

2. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1 is characterized in that: The buffered chemical polishing solution is a mixed solution of phosphoric acid and nitric acid, and the ratio of the mixed solution is 85% phosphoric acid: 65% nitric acid: 40% phosphoric acid = 2:1:

1.

3. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1 is characterized in that: The step S1 specifically includes: Step S11, performing an initial integrity inspection on the superconducting cavity to be processed. During the initial inspection, the superconducting cavity is placed in a clean room environment, and visual inspection is performed on its universal interface, vacuum port and connection weld position to determine whether there are obvious cracks, pits or welding defects on the cavity surface, and the outer surface of the superconducting cavity is initially wiped and cleaned; Step S12, performing a leak test on the superconducting cavity that has passed the initial inspection, connecting the superconducting cavity to the adjustable pressurization system through an airtight connecting pipe, gradually filling the interior of the superconducting cavity with high-purity helium and maintaining it within a predetermined pressure range for a predetermined time, using a mass spectrometer leak detector to perform a gas probe scan around the cavity to determine whether there is a tiny leak in the cavity wall and the peripheral connection parts, and if a leak is found, its location information is recorded; Step S13, after the leak detection is qualified, the surface condition of the inner surface of the superconducting cavity is inspected, and the inner surface of the cavity is scanned and photographed in all directions by an industrial endoscope combined with a digital imaging analysis system, and the local protrusions, depressions, scratches or stains on the surface are marked and digitized through image processing software to identify abnormal surface data.

4. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 3 is characterized in that: After step S13, the following steps are also included: Step S14, after the surface condition inspection, use an ultrasonic thickness gauge to perform a first multi-point distribution thickness measurement on the inner wall thickness of the superconducting cavity to obtain first cavity wall thickness distribution data; wherein the multi-point distribution thickness measurement point layout is performed according to several radial and axial regions, specifically including at least 4 thickness measurement points uniformly distributed in the circumference of the cavity, and at least 3 thickness measurement points selected at different height positions in the axial direction; Step S15, cleaning the surface of the superconducting cavity after the first thickness measurement is completed, placing the superconducting cavity in an ultrasonic cleaning machine, injecting ultrapure water filtered by 0.1 μm into the cleaning tank, controlling the cleaning water temperature between 20°C and 30°C, and adjusting the position of the ultrasonic head according to the surface abnormality data to focus on cleaning the abnormal surface position.

5. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1, characterized in that: The step S2 specifically includes: Step S21, transporting the pre-treated superconducting cavity to a chemical buffer treatment device, fixing it vertically in a fixture, and adjusting the verticality and coaxiality of the superconducting cavity by fine-tuning the support structure during fixing; Step S22, after the position of the superconducting cavity is fixed, the parameters of the liquid injection system are set, the buffered chemical polishing solution is configured according to a predetermined ratio and stored in a solution storage tank, and the buffered chemical polishing solution is gradually injected into the superconducting cavity at a preset flow rate through an adjustable speed metering pump.

6. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 5, characterized in that: After step S23, the following steps are also included: Step S23, while the buffered chemical polishing solution is injected, the external cooling water circulation system is started for cooling, the cooling water that has been subjected to temperature reduction treatment is injected into the cooling water tank, and after being pressurized by the water circulation pump group, the water is continuously sprayed from top to bottom on the outer surface of the superconducting cavity through the spray device; Step S24, while the cooling process is in progress, the temperature distribution of the superconducting cavity is monitored in real time through the multi-point temperature sensors and the online data acquisition system arranged outside the superconducting cavity, and the temperature monitoring data is fed back to the control module; when the temperature monitoring data shows that the temperature inside the superconducting cavity has a local upward trend, the control module automatically fine-tunes the cooling water spraying amount or the polishing solution injection rate; Step S25, after the first buffer chemical polishing reaches the preset polishing time, the operation of the liquid injection system and the external cooling water circulation system is stopped.

7. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1, characterized in that: The step S3 specifically includes: Step S31, directingly discharging the buffered chemical polishing solution in the superconducting cavity through a drainage pipeline, wherein the drainage pipeline is connected to a solution collection container, and during the discharging process, the solution recovery rate is monitored by a flow meter; Step S32, after the polishing solution is discharged, the interior of the superconducting cavity is cleaned multiple times by a spray device of an ultrasonic cleaning machine; Step S33, after the ultrapure water cleaning is completed, the inner wall of the superconducting cavity is purged, and then the thickness of the inner wall of the superconducting cavity is measured for the second time in a multi-point distribution by using an ultrasonic thickness gauge to obtain second thickness distribution data of the cavity wall; Step S34, after completing the second thickness measurement, the superconducting cavity is flipped 180° as a whole by the flipping tool and fixed in the tooling fixture, and the state information of the superconducting cavity after flipping is recorded; the superconducting cavity state information includes the flipping angle, the centering degree of the re-fixed position and the stress sensing data during the flipping process.

8. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1, characterized in that: The step S5 specifically includes: Step S51, using an ultrasonic thickness gauge to perform a third multi-point distribution thickness measurement on the inner wall thickness of the dried superconducting cavity to obtain third thickness distribution data of the cavity wall, and obtaining a processing quality index of chemical polishing by comparing the difference between the first thickness distribution data of the first thickness measurement, the second thickness distribution data of the second thickness measurement, and the third thickness distribution data and analyzing the thickness fluctuation; Step S52, placing the superconducting cavity that has completed the third thickness measurement into a vacuum furnace for medium-temperature annealing; the temperature range of the medium-temperature annealing is set between 200° C. and 600° C. and maintained at a constant temperature for 2 to 6 hours, and during the annealing process, the cavity temperature distribution is monitored in real time by an integrated infrared thermometer and a thermocouple, and the operating parameters of the vacuum furnace are regulated by the cavity temperature distribution data; Step S53, after annealing is completed, the superconducting cavity is transferred from the vacuum furnace to the measuring workbench, the electrical performance parameters of the superconducting cavity are tested, and the superconducting cavity is divided into quality grades based on the obtained processing quality index, and the superconducting cavities of each quality grade are classified and stored to complete the overall surface buffer chemical polishing process.

9. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1, characterized in that: The external cooling water circulation system comprises a tooling support, a receiving cavity for accommodating a superconducting cavity is arranged in the middle of the tooling support, and a ring-shaped cooling liquid channel is arranged on the outside of the tooling support; A spray device is arranged above the tooling bracket, and a cooling water collecting tray is arranged below the tooling bracket, so that the cooling water sprayed from top to bottom by the spray device can flow into the cooling water collecting tray through the coolant channel for recovery.

10. The surface buffer chemical polishing process for the entire superconducting cavity according to claim 1, characterized in that: The spray device is correspondingly provided with a water circulation pump group and a cold water tank. The water circulation pump group is respectively connected to the cold water tank and the spray device for pumping cooling water from the cold water tank to the spray device; the cold water tank is connected to the cooling water collecting tray for realizing the reflux of cooling water.

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