A test device and method for analyzing the gas release characteristics of a material weld under vacuum conditions

Abstract

The application discloses a kind of test device and method for material weld venting characteristic analysis under vacuum condition, it is related to material analysis field, device includes mutually communicating vacuum pumping system, measuring system and with the standardization sample of measuring system connection;Vacuum pumping system contains air extraction chamber, vacuum pumping set, vacuum valve, air extraction chamber is equipped with first vacuum gauge tube and both sides symmetry is equipped with flow guide small hole;Measuring system contains first, second test chamber, two test chambers are equipped with second, third vacuum gauge tube and mass spectrometer respectively;Standardization sample includes weld test piece and no weld standard piece, two are respectively mounted in two test chamber opening place by sealing flange, wall thickness, material and test chamber are identical, except weld area, the effective venting surface area of base material is equal, the device is designed by symmetrical structure and standardization sample, guarantee test environment equivalence and sample comparability, can accurately quantify weld venting characteristic, provide reliable data support for vacuum cavity welding process optimization.

Description

Technical Field

[0001] This invention relates to the field of materials analysis, and in particular to an experimental apparatus and method for analyzing the outgassing characteristics of material welds under vacuum conditions. Background Technology

[0002] In the manufacturing of ultra-high vacuum equipment (such as particle accelerators, space simulation devices, and semiconductor processing equipment), large-sized vacuum cavities are difficult to machine as a single unit and are often produced by component welding, especially for cavities with complex spatial structures. The weld seams in these cavities, having undergone high-temperature thermal cycling and microstructural changes, often exhibit outgassing rates and compositions far exceeding those of the base material, making them a significant source of gas in the vacuum system. For thick vacuum cavities, weld seams are typically placed both inside and outside the weld joint. However, for smaller, more complex cavities where welding torches cannot enter the interior, or where strict dimensional precision is required for the internal cavity, welding must be performed externally. Therefore, in the development of high-vacuum cavities, accurately evaluating the outgassing characteristics of different welding methods (such as argon arc welding, electron beam welding, and laser welding) and joint types (such as butt joints and corner joints) during the material and process selection stage is crucial for optimizing vacuum cavity manufacturing processes and improving equipment performance.

[0003] Currently, vacuum outgassing rate measurement devices based on the orifice conduction method are general-purpose equipment for measuring the outgassing rate of materials. However, when applied to weld outgassing research, the following significant technical challenges exist:

[0004] (1) Poor sample comparability: Traditional methods lack standardized sample design. If workpieces with different shapes and weld positions are directly used as samples, it is difficult to define and calculate their effective venting area in a unified manner, which makes it impossible to make fair and accurate comparisons of the measured venting rate data and to truly reflect the quality of the welding process itself.

[0005] (2) The weld contribution cannot be separated: The measured outgassing rate is the combined effect of the weld and the base metal. Existing methods lack effective technical means to separate the outgassing in the weld area from the base metal background, making it difficult to accurately quantify the outgassing characteristics of the weld itself.

[0006] (3) Low testing efficiency: There are no special samples for weld research. Each test requires special design and installation of samples, which is cumbersome and makes it impossible to achieve high-throughput, standardized comparative testing of multiple welds.

[0007] Therefore, an experimental apparatus and method for analyzing the gas release characteristics of material welds under vacuum conditions are proposed to solve the above problems. Summary of the Invention

[0008] This invention overcomes the shortcomings of the prior art and provides a test device and method for analyzing the outgassing characteristics of material welds under vacuum conditions.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a test device for analyzing the gas release characteristics of material welds under vacuum conditions, comprising: a vacuum pumping system, a measuring system, and a standardized sample, wherein the vacuum pumping system is connected to the measuring system, and the standardized sample is connected to the measuring system;

[0010] The vacuum pumping system includes a pumping chamber, a vacuum pumping unit, and a vacuum valve. A first vacuum gauge tube is installed on the pumping chamber. The pumping chamber is connected to the vacuum pumping unit. Small flow guide holes are symmetrically arranged on both sides of the pumping chamber.

[0011] The measurement system includes a test chamber, a second vacuum gauge tube, a third vacuum gauge tube, and two mass spectrometers. The test chamber includes a first test chamber and a second test chamber. The second vacuum gauge tube is installed in the first test chamber, and the third vacuum gauge tube is installed in the second test chamber. The two mass spectrometers are respectively installed in the first test chamber and the second test chamber.

[0012] The standardized specimens include welded test pieces and weldless standard pieces. The welded test pieces and the weldless standard pieces are respectively disposed at the openings of the first test chamber and the second test chamber and connected by a sealing flange. The effective venting surfaces of the welded test pieces and the weldless standard pieces are exposed to the vacuum in the first and second test chambers.

[0013] The wall thickness and material of the welded test piece and the weldless standard piece are the same as those of the first and second test chambers. Except for the weld area, the effective venting surface area of ​​the base material of the welded test piece and the weldless standard piece are equal.

[0014] In a preferred embodiment of the present invention, both the welded test piece and the weldless standard piece are equipped with heating components of the same specifications on their outer sides. The heating components are programmed temperature rise desorption components, which can monitor the desorption peak temperature of different gases on the weld surface in real time and calculate the adsorption energy.

[0015] In a preferred embodiment of the present invention, the air extraction chamber, the first test chamber, and the second test chamber are all connected to the vacuum pump assembly via pipelines. The first test chamber and the second test chamber are each equipped with a vacuum valve, which is located in the pipeline connecting the flow guide orifice to the first and second test chambers.

[0016] In a preferred embodiment of the present invention, the weld of the test piece with weld can be processed on the inner or outer wall of the joint, and the weld structure can be formed by different welding methods or different joint forms.

[0017] In a preferred embodiment of the present invention, the flow guide holes are symmetrically installed on both sides of the air extraction chamber and have identical structures.

[0018] In a preferred embodiment of the present invention, the mass spectrometer has a mass resolution capable of identifying mass resolutions as low as [missing information]. The mass spectrometer can capture trace amounts of gas and has a rapid scanning function, enabling it to capture the dynamic changes in weld gas release.

[0019] Another technical solution adopted in this invention is a method for analyzing the gas release characteristics of material welds under vacuum conditions, based on the above-mentioned experimental apparatus, comprising the following steps:

[0020] S1. Preparation of standard parts: Using the same base material as the weld to be tested, a weld-free standard part is fabricated.

[0021] S2. Prepare test pieces: Process a series of test pieces with welds that have the same geometric dimensions as the standard pieces in step S1. On the effective venting surface of each test piece, different target welding processes or joint forms are used to process the welds.

[0022] S3. Installation and Measurement: Seal and install the seamless standard part in the second test chamber, and seal and install any test part with a weld in the first test chamber.

[0023] Start the vacuum pumping system, open the vacuum valve to pump the vacuum to the preset limit pressure, close the vacuum valve, set the pretreatment conditions to pretreat the two samples, and after the pretreatment is completed and the pressure stabilizes, record the pressure values ​​P1, P2, and P3 of the first vacuum gauge tube, the second vacuum gauge tube, and the third vacuum gauge tube, as well as the detection data of the two mass spectrometers at different time intervals.

[0024] S4. Calculate the outgassing rate: Calculate the total outgassing rate of the weld according to the formula Q=C×(P2–P3), where C is the known conductance value of the flow conductance orifice, P2 is the stable pressure of the first test chamber, and P3 is the stable pressure of the second test chamber.

[0025] The normalized area venting rate is calculated using the formula q_weld=Q / A_weld, where A_weld is the pre-calibrated measured surface area of ​​the weld region.

[0026] In a preferred embodiment of the present invention, in step S2, all the test pieces prepared are consistent with the standard pieces in terms of effective venting surface area, surface condition, geometric dimensions and wall thickness of the base material, except for the difference in the position, form and processing technology of the weld area.

[0027] Before installation, the prepared test pieces need to be tested for weld air tightness using a helium mass spectrometer to ensure that the weld quality meets the vacuum requirements of the test chamber.

[0028] In a preferred embodiment of the present invention, the pretreatment conditions in step S3 include baking temperature and baking time, and the heating conditions of the two test chambers are completely consistent during the pretreatment process to ensure that the venting environment of the background sample and the control sample are equivalent.

[0029] In a preferred embodiment of the present invention, in step S3, the outgassing components are analyzed by the mass spectrometer to obtain the desorption peak temperatures of different gases on the weld surface, and a correlation model between adsorption energy and outgassing rate is established.

[0030] If the heating component is a programmed temperature rise desorption component, the desorption peak temperature of different gases on the weld surface is recorded synchronously. Combined with the outgassing rate data in step S4, a correlation model between adsorption energy and outgassing rate is established.

[0031] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0032] (1) The device of the present invention adopts an integrated design of standardized sample + symmetrical test system, which clearly defines that the wall thickness, material and geometric dimensions of the test piece with weld and the standard piece without weld are completely consistent, and the effective venting surface area and surface condition of the base material except for the weld area are kept equal, eliminating the key error of uncontrollable effective venting area caused by the difference in sample shape and size in traditional test; at the same time, flow guide holes with identical structures are symmetrically set on both sides of the extraction chamber, and the specifications and measurement components of the first and second test chambers are completely consistent, ensuring that the test environment of the two types of samples is completely equivalent, so that the venting data of welds with different welding processes and different joint forms have a fair basis for comparison, and truly reflect the advantages and disadvantages of the welding process itself.

[0033] The device employs a symmetrical dual-chamber layout, adapting to both weld-free standard parts (providing pure base material venting background) and welded test parts (providing comprehensive venting of base material + weld). Stable pressures P2 and P3 are precisely collected from both types of test chambers via second and third vacuum gauges. Combined with flow conductance orifices with known conductance values ​​between the extraction chamber and the test chamber, a quantitative structural foundation is established for weld venting = comprehensive venting - base material venting. This overcomes the technical bottleneck of existing technologies that cannot isolate base material background interference, providing an indispensable device guarantee for subsequent precise quantification of the venting characteristics of the weld itself.

[0034] Standardized samples are detachably and sealed via a sealing flange, eliminating the need for separate installation structures for different weld types and enabling immediate testing upon installation. Simultaneously, the symmetrical integrated design of the device allows the same system to continuously adapt to multiple sets of welded test pieces with different welding processes and joint types, without requiring reconstruction of test pipelines or adjustment of core components. This significantly simplifies the testing process and solves the cumbersome problem of traditional methods requiring specialized sample design and installation for each test, meeting the needs of large-scale, multi-variable welding process screening.

[0035] (2) The method of the present invention clearly requires that the geometric dimensions, wall thickness, effective venting surface area of ​​the base material, and surface condition of the test piece with weld and the standard piece without weld be completely consistent, with only the position, form and processing technology of the weld area being different. This locks in the uniformity of non-weld variables from the source of sample preparation. At the same time, by pre-calibrating the surface area A_weld of the weld area and using the normalization calculation method q_weld=Q / A_weld, the influence of different weld area differences on the test results is eliminated, so that the venting characteristics of welds with different welding processes and different joint forms can be directly compared, solving the difficulty of fair data comparison in traditional methods.

[0036] Meanwhile, a seamless standard part was innovatively introduced as the venting benchmark for the base material. By installing it and the test part with welds separately in a symmetrical test chamber, and using the equivalent test environment of the same vacuum system, the pressure difference (P2-P3) directly corresponds to the additional venting contribution of the weld. Combined with the flow conductance orifice with a known flow conductance value C, the total venting rate of the weld was accurately calculated using the formula Q=C×(P2–P3). This successfully separated the venting of the weld from the base material venting, achieving precise quantification of the venting characteristics of the weld itself and solving the technical difficulty of distinguishing between the venting of the weld and the base material in the existing technology.

[0037] In addition, the batch preparation + modular testing process design allows for the one-time processing of a series of welded test pieces with the same specifications as standard parts. Multiple sets of tests with different variables can be completed continuously on the same set of testing equipment without the need to reconstruct the testing system or adjust the core parameters. At the same time, the standardized process of sample installation, vacuum evacuation and data acquisition avoids the cumbersome operation of traditional methods that require special sample design and installation schemes for each test, greatly shortening the testing cycle and meeting the actual needs of rapid optimization of welding processes in the development of high vacuum chambers. Attached Figure Description

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0039] Figure 1 This is a schematic diagram of the test apparatus structure according to a preferred embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the structure of a weldless standard part according to a preferred embodiment of the present invention;

[0041] Figure 3 These are schematic diagrams of the structure of a welded test specimen and a weldless test specimen according to preferred embodiments of the present invention;

[0042] Figure 4 This is a flowchart illustrating the method of using the test apparatus according to a preferred embodiment of the present invention.

[0043] In the diagram: 1. First vacuum gauge tube; 2. Evacuation chamber; 3. Flow guide orifice; 4. First test chamber; 5. Second vacuum gauge tube; 6. Mass spectrometer; 7. Sealing flange; 8. Heating assembly; 9. Test piece with weld; 10. Vacuum pump assembly; 11. Weldless standard piece; 12. Third vacuum gauge tube; 13. Second test chamber; 14. Vacuum valve. Detailed Implementation

[0044] 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, and 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.

[0045] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or it can be fixed through another intermediate component. When a component is said to be "connected to" another component, it can be directly connected to the other component or it may be fixed through another intermediate component. When a component is said to be "set on" another component, it can be set directly on the other component or it may be set through another intermediate component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] like Figures 1 to 3 As shown, an experimental apparatus and method for analyzing the outgassing characteristics of material welds under vacuum conditions includes: a vacuum pumping system, a measuring system, and a standardized sample. The vacuum pumping system is connected to the measuring system, and the standardized sample is connected to the measuring system.

[0048] Specifically, the vacuum pumping system includes a pumping chamber 2, a vacuum pumping unit 10, and a vacuum valve 14. A first vacuum gauge tube 1 is installed on the pumping chamber 2. The pumping chamber 2 is connected to the vacuum pumping unit 10. Flow guiding holes 3 are symmetrically arranged on both sides of the pumping chamber 2. The flow guiding holes 3 are symmetrically installed along both sides of the pumping chamber 2 and have the same structure. The symmetrical installation of the flow guiding holes 3 along both sides of the pumping chamber 2 and having the same structure ensures that the gas flow conductance values ​​between the two test chambers and the pumping chamber 2 are completely consistent, avoiding pressure measurement deviations caused by differences in flow conductance. At the same time, the symmetrical structure keeps the gas flow state and pumping efficiency of the two test chambers consistent, further ensuring the equivalence of the test environment between the background sample and the test sample, and improving the accuracy of weld gas release separation calculation.

[0049] The measurement system includes a test chamber, a second vacuum gauge tube 5, a third vacuum gauge tube 12, and two mass spectrometers 6. The mass spectrometers 6 have a mass resolution capable of identifying mass levels as low as [missing information]. The mass spectrometer can accurately capture trace gases released from welds, solving the problem that traditional detection equipment cannot identify trace outgassing components. It provides key evidence for analyzing the source of weld outgassing. With a rapid scanning function, the mass spectrometer can capture the dynamic changes of weld outgassing. The rapid scanning function can track the dynamic changes of weld outgassing components and concentrations in real time, such as the component differences between the pretreatment stage and the stable testing stage. It breaks through the limitation of traditional equipment that can only obtain steady-state data, and helps to explore the dynamic laws of weld outgassing in depth.

[0050] The testing chamber includes a first testing chamber 4 and a second testing chamber 13. A second vacuum gauge tube 5 is installed in the first testing chamber 4, and a third vacuum gauge tube 12 is installed in the second testing chamber 13. Two mass spectrometers 6 are installed in the first testing chamber 4 and the second testing chamber 13, respectively. The dual testing chambers are adapted to the weldless standard part 11 and the welded test part 9, respectively, and are equipped with dedicated vacuum gauge tubes to accurately collect the pressure of each chamber. This constructs a quantitative structural basis for weld venting = comprehensive venting - base material venting, breaking the technical bottleneck of existing technology that cannot remove the background interference of the base material. This provides an indispensable device guarantee for the subsequent accurate quantification of the venting characteristics of the weld itself.

[0051] The evacuation chamber 2, the first test chamber 4, and the second test chamber 13 are all connected to the vacuum pump group 10 via pipelines. Vacuum valves 14 are installed on both the first test chamber 4 and the second test chamber 13. These vacuum valves 14 are located in the pipeline connecting the flow guide orifice 3 to the first and second test chambers 13. By installing vacuum valves 14 in the pipeline connecting the flow guide orifice 3 to the test chambers, the valves can be opened at the beginning of the test to achieve rapid vacuuming of the evacuation chamber 2 and the two test chambers, significantly shortening the time to reach the required vacuum level. During the testing phase, closing the valves ensures that the gas released from the sample enters the evacuation chamber 2 only through the flow guide orifice 3 with a known flow conductance value, avoiding pressure measurement distortion caused by gas leakage or diversion, and ensuring the accuracy of the outgassing rate calculation. The evacuation chamber 2 and the two test chambers are connected to the same vacuum pump group 10 via pipelines, eliminating the need for separate evacuation equipment, simplifying the device structure, reducing equipment costs, and facilitating unified control of vacuum pumping parameters, thus ensuring the stability of the entire system's vacuum environment.

[0052] The standardized test specimens include welded test specimens 9 and weldless standard specimens 11. The weld of the welded test specimen 9 can be machined on the inner or outer wall of the joint. The weld structure is formed by different welding methods or different joint forms. The weld can be machined on the inner or outer wall of the joint, which can accurately simulate actual welding conditions such as double welds inside and outside of thick cavities and external welds of small / complex cavities. It solves the problem that traditional devices cannot specifically test specimens with different weld positions, making the test results more in line with actual engineering needs.

[0053] It is compatible with weld structures of different welding methods (argon arc welding, electron beam welding, etc.) and different joint forms (butt joints, corner joints, etc.), and can complete the comparison of multivariable weld venting characteristics without changing the core components of the device, providing more comprehensive data support for welding process screening.

[0054] The welded test piece 9 and the weldless standard piece 11 are respectively placed at the openings of the first test chamber 4 and the second test chamber 13, and are connected by a sealing flange 7. The effective venting surfaces of the welded test piece and the weldless standard piece 11 are exposed to the vacuum of the first and second test chambers 13.

[0055] Both the welded test piece 9 and the weldless standard piece 11 are equipped with heating components 8 of the same specifications on their outer sides. The heating components 8 are temperature-programmed desorption components, which can monitor the desorption peak temperature of different gases on the weld surface in real time and calculate the adsorption energy. Using a temperature-programmed desorption component as the heating component 8 can not only provide a stable heating environment for the sample, but also monitor the desorption peak temperature of different gases on the weld surface in real time and calculate the adsorption energy. This breaks through the limitation of traditional heating components 8, which can only provide constant temperature conditions. The heating components 8 of the same specifications are equipped on the outer sides of the two types of samples to ensure that the heating conditions of the two are completely consistent during the pretreatment and testing process, avoid the introduction of additional errors due to heating differences, and further ensure the accuracy of the calculation of the separation of base material venting and weld venting.

[0056] The wall thickness and material of the welded test piece 9 and the weldless standard piece 11 are the same as those of the first and second test chambers 13. Except for the welded area, the effective venting surface area of ​​the base material of the welded test piece 9 and the weldless standard piece 11 are equal.

[0057] The welded test piece 9 and the weldless standard piece 11 have completely identical geometric dimensions, wall thickness, and material. Except for the weld area, the effective venting surface area and surface condition of the base material are the same, eliminating the key error caused by the difference in sample shape and size in traditional testing, which makes the effective venting area uncontrollable.

[0058] like Figure 4 As shown, a method for analyzing the outgassing characteristics of material welds under vacuum conditions includes the following steps:

[0059] S1. Preparation of standard parts: Using the same base material as the weld to be tested, process a weld-free standard part 11;

[0060] S2. Prepare test pieces: Process a series of test pieces 9 with welded seams that have the same geometric dimensions as the standard parts in step S1. On the effective venting surface of each test piece, different target welding processes or joint forms are used to process the weld seams.

[0061] S3. Installation and Measurement: Seal and install the seamless standard part 11 in the second test chamber 13, and seal and install any one of the welded test parts 9 in the first test chamber 4.

[0062] Start the vacuum pumping system, open the vacuum valve 14 to pump the vacuum to the preset limit pressure, then close the vacuum valve 14, set the pretreatment conditions to pretreat the two samples, and after the pretreatment is completed and the pressure stabilizes, record the pressure values ​​P1, P2, and P3 of the first vacuum gauge tube 1, the second vacuum gauge tube 5, and the third vacuum gauge tube 12 at different time intervals, as well as the detection data of the two mass spectrometers 6.

[0063] S4. Calculate the outgassing rate: Calculate the total outgassing rate of the weld according to the formula Q=C×(P2–P3), where C is the known conductance value of the flow conduction orifice 3, P2 is the stable pressure of the first test chamber 4, and P3 is the stable pressure of the second test chamber 13.

[0064] The normalized area venting rate is calculated using the formula q_weld=Q / A_weld, where A_weld is the pre-calibrated measured surface area of ​​the weld region.

[0065] In a preferred embodiment of the present invention, in step S2, all the test pieces prepared are consistent with the standard pieces in terms of effective venting surface area, surface condition, geometric dimensions and wall thickness of the base material, except for the difference in the position, form and processing technology of the weld area.

[0066] Before installation, the prepared test pieces need to be tested for weld air tightness using a helium mass spectrometer to ensure that the weld quality meets the vacuum requirements of the test chamber.

[0067] In a preferred embodiment of the present invention, the pretreatment conditions in step S3 include baking temperature and baking time, and the heating conditions of the two test chambers are completely consistent during the pretreatment process to ensure that the venting environment of the background sample and the control sample are equivalent.

[0068] In a preferred embodiment of the present invention, in step S3, the outgassing components are analyzed by mass spectrometer 6 to obtain the desorption peak temperature of different gases on the weld surface and to establish a correlation model between adsorption energy and outgassing rate.

[0069] If the heating component 8 is a programmed temperature rise desorption component, the desorption peak temperature of different gases on the weld surface is recorded synchronously. Combined with the outgassing rate data in step S4, a correlation model between adsorption energy and outgassing rate is established.

[0070] Example 1: Comparison of outgassing characteristics of butt joints welded by argon arc welding and electron beam welding

[0071] This embodiment is based on the aforementioned experimental apparatus and method for analyzing the outgassing characteristics of material welds under vacuum conditions. Its aim is to provide accurate data support for the selection of vacuum chamber welding processes by comparing the outgassing characteristics of butt joints prepared by argon arc welding and electron beam welding through standardized testing. The core structure of the experimental apparatus includes a vacuum pumping system, a measurement system, and standardized samples. The coordinated operation of these components ensures the accuracy and comparability of the test data.

[0072] I. Sample Preparation

[0073] 1. Base material selection: 304 stainless steel is selected as the base material. This material is completely consistent with the cavity material of a certain actual ultra-high vacuum cavity project, ensuring the engineering adaptability of the test results.

[0074] 2. Sample specification design: Three standardized hollow cylindrical samples with identical geometric dimensions were fabricated, with specific parameters of 40mm diameter and 5mm thickness, consistent with the wall thickness of the vacuum chamber in the actual project. The wall thickness and material of the three samples were completely matched with the first test chamber 4 and the second test chamber 13 of the test device. In addition, except for the weld area, the effective venting surface area and surface condition of the base material were kept consistent, eliminating the test error introduced by sample differences from the source.

[0075] 3. Group preparation:

[0076] Sample A (base sample, i.e., weld-free standard part 11): The end face is machined to a smooth plane without any weld structure, and is used to provide venting background data of pure base material.

[0077] Sample B (argon arc welded sample, i.e. test piece 9 with weld): An argon arc welded butt weld is machined at the center of the end face. The weld is machined on the outer wall of the joint to simulate the external welding conditions of a small and complex cavity in reality.

[0078] Sample C (electron beam welded sample, i.e. test piece 9 with weld): An electron beam welded butt weld is machined at the center of the end face. The weld machining position is consistent with that of sample B, ensuring that only the welding process is variable.

[0079] 4. Weld pretreatment: The surface area A_weld of the weld area of ​​samples B and C was pre-calibrated using laser interferometric thickness measurement technology and recorded. Then, samples A, B, and C were installed on a helium mass spectrometer leak detector to test the airtightness of the weld. It was confirmed that there was no leakage in the weld of samples B and C and that the quality met the vacuum requirements of the vacuum chamber, thus avoiding the distortion of test data due to weld leakage.

[0080] II. Testing Process

[0081] 1. Sample installation: Install sample A (seamless standard part 11) in the opening of the second test chamber 13 through the sealing flange 7, ensuring that its effective venting surface is exposed to the vacuum of the second test chamber 13; install sample B (argon arc welded sample) in the opening of the first test chamber 4 through the sealing flange 7 of the same specification, ensuring that the installation posture and exposure range of the two are completely consistent; at the same time, confirm that the programmed temperature rise and deheating components 8 assembled on the outside of the two samples are of the same specification and are in the ready-to-work state.

[0082] 2. Vacuum System Start-up and Pretreatment: Start the vacuum pump group 10, and open the vacuum valve 14 in the connecting pipeline between the first test chamber 4, the second test chamber 13, and the flow guide orifice 3, so that the pumping chamber 2, the first test chamber 4, and the second test chamber 13 are connected to the same vacuum pump group 10 through the pipeline, achieving rapid vacuuming. Monitor the pressure P1 of the pumping chamber 2 in real time through the first vacuum gauge tube 1 on the pumping chamber 2 until the system reaches the preset ultimate vacuum degree; then close all vacuum valves 14 to ensure that the gas released from the sample can only enter the pumping chamber 2 through the symmetrically arranged and identically structured flow guide orifices 3 on both sides of the pumping chamber 2.

[0083] 3. Constant Temperature Baking and Data Acquisition: The pretreatment conditions were set to constant temperature baking at 100℃ for 24 hours (this condition is completely consistent with the baking conditions of the vacuum chamber in the actual project above). During the baking process, the heating conditions of the two test chambers were ensured to be completely equivalent. After baking, once the system pressure stabilized, the following data were recorded synchronously at time intervals of 1h, 2h, 4h, 8h, and 24h: the pressure P1 of the evacuation chamber 2 measured by the first vacuum gauge tube 1, the pressure P2 of the first test chamber 4 measured by the second vacuum gauge tube 5, the pressure P3 of the second test chamber 13 measured by the third vacuum gauge tube 12, and the detection data of the two mass spectrometers 6 installed in the two test chambers respectively; among them, the mass spectrometer 6, with its low temperature... Its trace gas identification capability captures minute amounts of gas released from the weld (such as...) CO isotopes (etc.), and tracked the dynamic changes in the venting components and concentrations at different time points through the rapid scanning function.

[0084] 4. Sample replacement test: Replace sample B with sample C (electron beam welding sample), and repeat steps 1-3 above to complete the outgassing characteristic test of the electron beam welded butt joint, ensuring that the system parameters and environmental conditions of the two sets of tests are completely consistent.

[0085] III. Data Processing and Analysis

[0086] 1. Calculation of outgassing rate: The total outgassing rate of the weld for samples B and C is calculated according to the formula Q=C×(P2–P3) (where C is the known conductivity value of the flow conduction orifice 3. Since the structure of the flow conduction orifice 3 on both sides of the extraction chamber 2 is exactly the same, the value of C is uniform; P2-P3 directly corresponds to the additional outgassing pressure contribution of the weld, realizing the accurate stripping of the base material outgassing); then the normalized area outgassing rate of the two groups of samples is calculated according to the formula q_weld=Q / A_weld to eliminate the influence of weld area difference.

[0087] 2. In-depth analysis: Combining the detection data from two mass spectrometers 6, the main components and proportions of the outgassing from the butt joints of argon arc welding and electron beam welding were analyzed; using the temperature-programmed desorption heating component 8 to record the desorption peak temperatures of different gases, the adsorption energy of the corresponding gases was calculated, and "adsorption energy-outgassing rate" correlation models were established for the two groups of samples to explore the influence of the two welding processes on the outgassing mechanism of the weld.

[0088] IV. Test Conclusion

[0089] Through the standardized testing in this embodiment, the normalized area outgassing rate, outgassing composition, and outgassing dynamics of the butt joints of argon arc welding and electron beam welding can be directly compared, clarifying the advantages and disadvantages of the two welding processes. The test results directly provide data support for the selection of welding processes for the above-mentioned actual vacuum cavity projects, and at the same time provide a comprehensive basis of "rate + composition + mechanism" for the subsequent selection of getter and optimization of baking process for the cavity.

[0090] Example 2: Comparison of the outgassing characteristics of the outer and inner weld seams in butt welding

[0091] This embodiment is based on the aforementioned experimental apparatus and method for analyzing the outgassing characteristics of material welds under vacuum conditions. It aims to accurately compare the outgassing rates, outgassing components, and dynamic outgassing patterns of the outer and inner welds under the same butt welding process, providing direct engineering data support for the design of "double welds" in thick vacuum cavities and the selection of "single outer welds" in small, complex cavities. The core collaborative structure of the experimental apparatus (symmetrical flow conduction design, dual test chamber layout, programmed temperature rise desorption components, etc.) ensures the accuracy of the test.

[0092] I. Sample Preparation

[0093] 1. Base Material and Specifications Determination: 6061 aluminum alloy was selected as the base material, as this material is suitable for the manufacturing requirements of vacuum cavities in a certain aerospace field. Three standardized hollow cylindrical specimens with identical geometric dimensions were machined, specifically with a diameter of 50 mm and a thickness of 8 mm, consistent with the wall thickness of key components of the aerospace vacuum cavity. The wall thickness and material of the three specimens matched those of the first test chamber 4 and the second test chamber 13 of the test apparatus. Furthermore, except for the weld seams, the effective venting surface area, surface roughness, and other surface conditions of the base materials were completely uniform, thus avoiding interference from individual sample differences on the test results from the outset.

[0094] 2. Grouping and Welding Processing:

[0095] Sample D (base sample, standard part 11 without welds): The end face is machined to be a flat and smooth plane without any weld structure, used to provide pure venting base data of 6061 aluminum alloy base material.

[0096] Sample E (external weld sample, test piece 9 with weld): A butt weld (i.e., external weld) is processed on the outer edge of the sample end face using tungsten inert gas welding process to simulate the actual working condition where small-sized complex cavities cannot be welded from the inside.

[0097] Sample F (inner weld sample, with weld test piece 9): Using the same tungsten inert gas welding process parameters as sample E, a butt weld (i.e., inner weld) is processed on the inner edge of the sample end face to simulate the inner weld condition of a thick vacuum cavity; ensure that sample E and F are completely identical except for the weld position, and the other welding process, weld length and other parameters are completely the same.

[0098] 3. Weld pretreatment: Laser interferometric thickness measurement technology was used to accurately calibrate the weld area A_weld of sample E (outer weld) and sample F (inner weld) respectively, and the specific values ​​were recorded. Then, samples D, E and F were installed one by one on a helium mass spectrometer leak detector to test the airtightness of the welds of samples E and F, confirming that there was no leakage in the welds and that the forming quality met the standards, thus meeting the ultra-high vacuum requirements of aerospace vacuum cavities and avoiding the distortion of test data due to weld defects.

[0099] II. Testing Process

[0100] 1. Sample Installation: Sample D (seamless standard part 11) is detachably and sealed to the opening of the second test chamber 13 using the metal knife-edge sealing flange 7, ensuring that its effective venting surfaces (end face and outer peripheral surface) are fully exposed to the vacuum in the second test chamber 13. Sample E (external weld sample) is installed to the opening of the first test chamber 4 using a metal knife-edge sealing flange 7 of the same specification, ensuring that the installation posture, sealing method, and effective surface exposure range of both are completely consistent. Simultaneously, check the programmed temperature rise and deheating components 8 mounted on the outside of both samples to confirm that they are of the same specification, securely installed, and in standby mode.

[0101] 2. Vacuum System Commissioning and Pre-evacuation: Start the vacuum pump group 10 (mechanical pump in series with molecular pump), open the vacuum valve 14 in the connecting pipeline between the first test chamber 4, the second test chamber 13 and the flow guide orifice 3, so that the pumping chamber 2 and the two test chambers are connected to the same pump group through the pipeline, realizing rapid pre-evacuation of the system. Monitor the pressure P1 of the pumping chamber 2 in real time through the first vacuum gauge tube 1 on the pumping chamber 2 until the system reaches the required pressure. The preset ultimate vacuum level ensures that the basic requirements for ultra-high vacuum testing are met.

[0102] 3. Sealing Test and Pretreatment: Close all vacuum valves 14, ensuring that the two test chambers are connected to the extraction chamber 2 only through symmetrically installed, identically structured flow guide holes 3 on both sides of the extraction chamber 2. This ensures that the gas released from the sample can only enter the extraction chamber 2 through the holes with a known flow conductance value C, guaranteeing the accuracy of the outgassing rate calculation. The pretreatment conditions are set to a constant temperature baking at 120℃ for 36 hours (this condition is completely consistent with the actual on-orbit pre-baking process for aerospace vacuum chambers). During the baking process, the control system of the programmed temperature rise desorption component ensures that the heating temperature and heating rate of the first test chamber 4 and the second test chamber 13 are completely equivalent, avoiding errors introduced by environmental differences.

[0103] 4. Data Acquisition: After baking, turn off the heating component 8 and allow the system to cool naturally to room temperature and stabilize the pressure. Then, synchronously collect the following data at time intervals of 30 min, 1 h, 2 h, 6 h, 12 h, and 24 h: P1 (pressure in evacuation chamber 2) of the first vacuum gauge tube 1, P2 (pressure in the first test chamber 4, corresponding to the outer weld sample) of the second vacuum gauge tube 5, P3 (pressure in the second test chamber 13, corresponding to the background sample) of the third vacuum gauge tube 12, and the detection data from the two time-of-flight mass spectrometers 6. Among these, the mass spectrometer 6 utilizes low-pressure mass spectrometers with a pressure of only 10 min, 1 h, 2 h, 6 h, 12 h, and 24 h. Its trace gas detection capability captures gases released from welds. CO Trace components; through rapid scanning, the concentration changes of the venting components at different time points are recorded, capturing the dynamic process of venting.

[0104] 5. Repeat the test with a different sample: Remove sample E from test chamber 4 and replace it with sample F (inner weld sample). Repeat steps 1-4 above to ensure that the system parameters, vacuum environment and data acquisition intervals are completely consistent between the two tests, so as to ensure the comparability of test data between the outer weld and the inner weld.

[0105] III. Data Processing and Analysis

[0106] 1. Calculation of outgassing rate: According to the formula Q=C×(P2–P3), the total outgassing rate of the welds of specimen E (outer weld) and specimen F (inner weld) is calculated respectively (where C is the known conductivity value of the flow conduction orifice 3. Since the flow conduction on both sides of the extraction chamber 2 is symmetrical and consistent, the same C value is used for the two tests; P2-P3 accurately removes the contribution of the base material to outgassing and only reflects the outgassing of the weld itself); then, the pre-calibrated A_weld is substituted into the formula q_weld=Q / A_weld to calculate the normalized area outgassing rate of the two welds, eliminating the slight differences that may exist in the weld area and realizing a direct comparison of outgassing rates.

[0107] 2. Composition and Mechanism Analysis: Combining the detection data from two mass spectrometers, the types and proportions of outgassing components in the outer and inner welds were compared to determine whether different weld locations led to differences in outgassing components. Using the temperature-programmed desorption components to record the desorption peak temperatures of different gases, the adsorption energy of the corresponding gases on the surfaces of the two types of welds was calculated. Correlation models of "adsorption energy-outgassing rate" were established to explore the influence of weld location on the gas adsorption-desorption mechanism.

[0108] IV. Test Conclusion

[0109] Through the standardized testing in this embodiment, the difference in gas release characteristics between the outer and inner welds under the same welding process can be directly identified: if the normalized area gas release rate of the inner weld is lower, and trace harmful gases (such as...) are present... Less gas release provides a preferred option for the "double weld seam" design of thick vacuum cavities; if the external weld seam has better gas release characteristics, it verifies the feasibility of the "external welding" scheme for small-sized complex cavities. The test results directly address the actual manufacturing requirements of aerospace vacuum cavities, providing comprehensive data support in terms of "rate + composition + mechanism" for weld seam location selection and process optimization.

[0110] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These are all equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of these fall within the protection scope of the present invention.

Claims

1. An experimental apparatus for analyzing the outgassing characteristics of material welds under vacuum conditions, characterized in that, include: The system includes a vacuum pumping system, a measuring system, and a standardized sample, wherein the vacuum pumping system is connected to the measuring system, and the standardized sample is connected to the measuring system. The vacuum pumping system includes a pumping chamber, a vacuum pumping unit, and a vacuum valve. A first vacuum gauge tube is installed on the pumping chamber. The pumping chamber is connected to the vacuum pumping unit. Small flow guide holes are symmetrically arranged on both sides of the pumping chamber. The measurement system includes a test chamber, a second vacuum gauge tube, a third vacuum gauge tube, and two mass spectrometers. The test chamber includes a first test chamber and a second test chamber. The second vacuum gauge tube is installed in the first test chamber, and the third vacuum gauge tube is installed in the second test chamber. The two mass spectrometers are respectively installed in the first test chamber and the second test chamber. The standardized specimens include welded test pieces and weldless standard pieces. The welded test pieces and the weldless standard pieces are respectively disposed at the openings of the first test chamber and the second test chamber and connected by a sealing flange. The effective venting surfaces of the welded test pieces and the weldless standard pieces are exposed to the vacuum in the first and second test chambers. The wall thickness and material of the welded test piece and the weldless standard piece are the same as those of the first and second test chambers. Except for the weld area, the effective venting surface area of ​​the base material of the welded test piece and the weldless standard piece are equal. Both the welded test piece and the weldless standard piece are equipped with heating components of the same specifications on their outer sides. The heating components are programmed temperature rise desorption components, which can monitor the desorption peak temperature of different gases on the weld surface in real time and calculate the adsorption energy. The extraction chamber, the first test chamber, and the second test chamber are all connected to the vacuum pump assembly via pipelines. Both the first test chamber and the second test chamber are equipped with vacuum valves, which are located in the pipelines connecting the flow guide orifice to the first and second test chambers.

2. The experimental apparatus for analyzing the outgassing characteristics of material welds under vacuum conditions according to claim 1, characterized in that: The weld seam of the test piece with weld seam is processed on the inner or outer wall of the joint, and the weld seam structure is formed by different welding methods or different joint forms.

3. The experimental apparatus for analyzing the outgassing characteristics of material welds under vacuum conditions according to claim 1, characterized in that: The flow guide holes are symmetrically installed on both sides of the extraction chamber and have identical structures.

4. The experimental apparatus for analyzing the outgassing characteristics of material welds under vacuum conditions according to claim 1, characterized in that: The mass spectrometer has a mass resolution capable of identifying values ​​as low as 10. -9 The mass spectrometer, capable of capturing trace amounts of gas (Pa) and featuring rapid scanning capabilities, is able to capture the dynamic changes in weld venting.

5. A method for analyzing the outgassing characteristics of material welds under vacuum conditions, characterized in that: The test apparatus according to any one of claims 1-4 includes the following steps: S1. Preparation of standard parts: Using the same base material as the weld to be tested, a weld-free standard part is fabricated. S2. Prepare test pieces: Process a series of test pieces with welds that have the same geometric dimensions as the standard pieces in step S1. On the effective venting surface of each test piece, different target welding processes or joint forms are used to process the welds. S3. Installation and Measurement: Seal and install the seamless standard part in the second test chamber, and seal and install any test part with a weld in the first test chamber. Start the vacuum pumping system, open the vacuum valve to pump the vacuum to the preset limit pressure, close the vacuum valve, set the pretreatment conditions to pretreat the two samples, and after the pretreatment is completed and the pressure stabilizes, record the pressure values ​​P1, P2, and P3 of the first vacuum gauge tube, the second vacuum gauge tube, and the third vacuum gauge tube, as well as the detection data of the two mass spectrometers at different time intervals. S4. Calculate the outgassing rate: Calculate the total outgassing rate of the weld according to the formula Q=C×(P2–P3), where C is the known conductance value of the flow conductance orifice, P2 is the stable pressure of the first test chamber, and P3 is the stable pressure of the second test chamber. The normalized area venting rate is calculated using the formula q_weld=Q / A_weld, where A_weld is the pre-calibrated measured surface area of ​​the weld region.

6. The method for analyzing the outgassing characteristics of material welds under vacuum conditions according to claim 5, characterized in that: In step S2, all the test pieces prepared are consistent with the standard pieces in terms of effective venting surface area, surface condition, geometric dimensions and wall thickness, except for the location, form and processing technology of the weld area. Before installation, the prepared test pieces need to be tested for weld air tightness using a helium mass spectrometer to ensure that the weld quality meets the vacuum requirements of the test chamber.

7. The method for analyzing the outgassing characteristics of material welds under vacuum conditions according to claim 5, characterized in that: The pretreatment conditions in step S3 include baking temperature and baking time, and the heating conditions of the two test chambers are completely consistent during the pretreatment process to ensure that the venting environment of the background sample and the control sample are equivalent.

8. A method for analyzing the outgassing characteristics of material welds under vacuum conditions according to claim 5, characterized in that: In step S3, the outgassing components are analyzed by the mass spectrometer to obtain the desorption peak temperature of different gases on the weld surface and to establish a correlation model between adsorption energy and outgassing rate. If the heating component is a programmed temperature rise desorption component, the desorption peak temperature of different gases on the weld surface is recorded synchronously. Combined with the outgassing rate data in step S4, a correlation model between adsorption energy and outgassing rate is established.

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