A method for internal pressure creep test of molybdenum alloy ultra-high temperature heat pipe

Abstract

The present disclosure provides a kind of molybdenum alloy super high temperature heat pipe internal pressure creep test method, comprising the following steps: molybdenum alloy internal pressure creep sample and active metal getter material are placed in inner layer quartz glass tube;The inner layer quartz glass tube is evacuated and is fused and sealed, and the inner layer vacuum assembly is formed;The inner layer vacuum assembly is placed in the outer layer quartz glass tube arranged concentrically;The outer layer quartz glass tube is evacuated and is fused and sealed, to form vacuum layer between the inner layer vacuum assembly and the outer layer quartz glass tube, to obtain multilayer vacuum protection device;The multilayer vacuum protection device is placed in high temperature furnace and heated to predetermined temperature for creep test.

Description

Technical Field

[0001] This disclosure relates to the field of high-temperature performance testing technology for materials, and in particular to a method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe. Background Technology

[0002] Molybdenum alloys are one of the candidate materials for ultra-high temperature heat pipes in nuclear reactors due to their extremely high melting point, good thermal and electrical conductivity, small neutron absorption cross section, good strength at room temperature and high temperature, small coefficient of linear expansion and corrosion resistance.

[0003] Welding, as a key process in material forming, is widely used in the manufacture of various structures. In molybdenum alloy heat pipes, the connection between the heat pipe and the end plug needs to be sealed by welding. However, this welded joint is often the weakest point in the mechanical properties of the entire structure, and is prone to failure first. High-temperature creep performance is the primary indicator for evaluating the reliability of molybdenum alloy heat pipes. During service, the internal liquid metal working fluid (such as sodium, potassium, or lithium) generates extremely high saturated vapor pressure at high temperatures, causing the pipe body to be under coupled loads of high temperature and internal pressure for a long time. Under this environment, the material will undergo slow creep deformation, making the middle part of the base material and the weld area the areas with the highest risk of creep failure.

[0004] Currently, while various methods exist for testing the creep properties of materials, such as uniaxial tension, small punching, and nanoindentation, existing methods struggle to accurately reflect the creep behavior of molybdenum alloy heat pipes under real-world operating conditions. Therefore, to obtain accurate evaluation results, a creep testing method highly consistent with the actual service conditions of the heat pipe must be employed.

[0005] Molybdenum alloy internal pressure creep specimens can be prepared through circumferential welding of the tubing and end plugs, as well as high-pressure plugging welding. Molybdenum alloys oxidize in air above 500°C, and catastrophic rapid failure occurs at temperatures above 700°C. This material characteristic dictates that internal pressure creep tests must be conducted in a high-vacuum environment. However, conventional high-temperature equipment cannot simultaneously meet the required high temperature and high vacuum conditions, while specialized equipment that does meet these requirements is prohibitively expensive, constituting a major technical obstacle.

[0006] Therefore, providing a cost-effective test method that meets the internal pressure creep test conditions of molybdenum alloys is an important problem that needs to be solved to promote the rapid evaluation of the creep performance of molybdenum alloy heat pipes.

[0007] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure and may therefore contain information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this disclosure is to provide a method for testing the internal pressure creep of molybdenum alloy ultra-high temperature heat pipes, so as to solve the problem of the lack of low-cost, high-reliability high-temperature and high-vacuum testing methods in the prior art.

[0009] This disclosure provides the following technical solutions:

[0010] A method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe includes the following steps:

[0011] Step S100: Place the molybdenum alloy internal pressure creep sample and the active metal getter material together in the inner quartz glass tube;

[0012] Step S200: Vacuum the inner quartz glass tube and melt-seal it to form an inner vacuum assembly;

[0013] Step S300: Place the inner vacuum assembly into the concentrically arranged outer quartz glass tube;

[0014] Step S400: Vacuum the outer quartz glass tube and melt-seal it to form a vacuum layer between the inner vacuum assembly and the outer quartz glass tube, thereby obtaining a multi-layer vacuum protection device.

[0015] Step S500: Place the multi-layer vacuum protection device in a high-temperature furnace and heat it to a predetermined temperature for a creep test.

[0016] In the method described, before placing the sample and getter material in the inner quartz glass tube, a spacer is used to fix the sample and getter material so that they do not come into direct contact with the inner wall of the inner quartz glass tube.

[0017] In the method described, the insulating element is a high-purity quartz glass cap.

[0018] In the method described, the selection of the active metal getter material is based on the following criteria: at a predetermined temperature in the test, the Gibbs free energy of the active metal material reacting with oxygen to form oxides is lower than that of the molybdenum alloy reacting with oxygen to form oxides.

[0019] In the method described, the active metal material is selected from one of foil, wire, and powder.

[0020] In the method described, when the active metal air-absorbing material is in the form of powder, the types and shapes of the materials can be combined.

[0021] The method described herein, wherein the method for evacuating and fusion-sealing the inner and outer quartz glass tubes includes: evacuating to a vacuum level below 10. -4 After Pa, the tube body is baked and then melt-sealed.

[0022] The method further includes a step of verifying the sealing performance of the molybdenum alloy internal pressure creep sample before step S100. The verification includes placing the sample in an environment filled with test gas and detecting its leakage rate with a leak detector to confirm that the sample meets the high vacuum test requirements.

[0023] In the method described in step S500, after the creep test is completed, the deformation of the sample needs to be measured and analyzed. Specifically, this includes measuring the change in outer diameter at multiple positions along the axial and circumferential directions of the sample, and calculating the axial strain and circumferential strain.

[0024] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0025] This disclosure provides a method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe. By encapsulating the sample and an active metal getter within a multi-layered vacuum protection device, a harsh testing environment of ultra-high temperature and high vacuum can be achieved using a conventional high-temperature furnace. Furthermore, the built-in active metal getter can continuously adsorb trace amounts of oxygen at high temperatures, ensuring that the vacuum level of the test chamber at high temperatures is even better than at room temperature. The multi-layered vacuum quartz glass structure can effectively delay the crystallization failure of the inner quartz tube at high temperatures.

[0026] The description provided is merely an overview of the technical solution disclosed herein. In order to make the technical means of this disclosure clearer and more understandable, to the point that those skilled in the art can implement it according to the contents of the specification, and in order to make the described and other objects, features and advantages of this disclosure more obvious and understandable, specific embodiments of this disclosure are illustrated below. Attached Figure Description

[0027] Various other advantages and benefits of this disclosure will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0028] Figure 1 This is a schematic diagram of a method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe provided in this disclosure;

[0029] Figure 2 This is a schematic diagram of a multilayer vacuum protection device obtained under one embodiment of the present disclosure;

[0030] Figure 3 This is a schematic diagram of the state of a molybdenum alloy internal pressure creep specimen before packaging, obtained in one embodiment of this disclosure.

[0031] Figure 4 A schematic diagram of the overall experimental apparatus with a double-layer vacuum protection structure obtained according to one embodiment of the present disclosure;

[0032] Figure 5 This is a schematic diagram of the inner vacuum quartz glass tube encapsulation assembly obtained after a creep test according to one embodiment of the present disclosure;

[0033] Figure 6 This is a schematic diagram of the specimen morphology after a high-temperature internal pressure creep test obtained under one embodiment of the present disclosure;

[0034] Figure 7 This is a schematic diagram illustrating a method for measuring the outer diameter and length of a specimen after a high-temperature internal pressure creep test, according to one embodiment of this disclosure.

[0035] Figure 8 A schematic diagram of the circumferential strain, length, and weld width strain of a specimen after a high-temperature internal pressure creep test according to an embodiment of this disclosure;

[0036] Figure 9 The image shows a comparison of the metal composition of a creep specimen before and after internal pressure creep and at the weld seam, as provided in one embodiment of this disclosure. Detailed Implementation

[0037] The following will be combined with the appendix Figures 1 to 9 The embodiments described herein are provided in detail and are intended to explain, rather than limit, this disclosure. While specific embodiments of this disclosure are shown in the accompanying drawings, it should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0038] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions of preferred embodiments of this disclosure are for the purpose of implementing the general principles of the specification and are not intended to limit the scope of this disclosure. The scope of protection of this disclosure is determined by the appended claims.

[0039] To facilitate understanding of the embodiments of this disclosure, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of this disclosure.

[0040] A method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe includes the following steps:

[0041] Step S100: Place the molybdenum alloy internal pressure creep sample and the active metal getter material together in the inner quartz glass tube;

[0042] Step S200: Vacuum the inner quartz glass tube and melt-seal it to form an inner vacuum assembly;

[0043] Step S300: Place the inner vacuum assembly into the concentrically arranged outer quartz glass tube;

[0044] Step S400: Vacuum the outer quartz glass tube and melt-seal it to form a vacuum layer between the inner vacuum assembly and the outer quartz glass tube, thereby obtaining a multi-layer vacuum protection device.

[0045] Step S500: Place the multi-layer vacuum protection device in a high-temperature furnace and heat it to a predetermined temperature for a creep test.

[0046] In this embodiment, by encapsulating the sample and an active metal getter within a multi-layered vacuum protection device, a harsh testing environment of ultra-high temperature and high vacuum can be achieved using a conventional high-temperature furnace. Furthermore, the built-in active metal getter material can continuously adsorb trace amounts of oxygen at high temperatures, ensuring that the vacuum level of the test chamber at high temperatures is even better than at room temperature. The multi-layered vacuum quartz glass structure can effectively delay the crystallization failure of the inner quartz tube at high temperatures.

[0047] In a preferred embodiment of the method, before placing the sample and getter material in the inner quartz glass tube, a spacer is used to fix the sample and getter material so that they do not come into direct contact with the inner wall of the inner quartz glass tube.

[0048] In a preferred embodiment of the method, the insulating element is a high-purity quartz glass cap.

[0049] In a preferred embodiment of the method, the selection of the active metal getter material is based on the following criteria: at a predetermined test temperature, the Gibbs free energy of the active metal material reacting with oxygen to form an oxide is lower than that of the molybdenum alloy reacting with oxygen to form an oxide.

[0050] Specifically, the Gibbs free energy of the selected reactive metal getter material reacting with oxygen to form oxides at the predetermined test temperature is lower than that of the molybdenum alloy reacting with oxygen to form oxides. This means that this type of material has a stronger thermodynamic affinity for oxygen and can preferentially react with trace amounts of residual oxygen in the first vacuum chamber at high temperatures to form stable oxides. Since this reaction continues at high temperatures, the getter material can continuously consume the trace amounts of oxygen desorbed from the material surface or chamber wall, thereby maintaining or even further reducing the oxygen partial pressure in the chamber in dynamic equilibrium. Furthermore, the outer vacuum structure effectively isolates external oxygen infiltration, ensuring that the actual vacuum level of the first vacuum chamber containing the sample at high temperatures does not deteriorate due to material outgassing or tube wall permeation. On the contrary, due to the continuous action of the getter, it is superior to the initial vacuum level during room temperature sealing, providing a long-term stable oxidation-free testing environment for the molybdenum alloy sample.

[0051] In a preferred embodiment of the method, the reactive metal material is selected from foil, wire, and powder.

[0052] In a preferred embodiment of the method, when the active metal air-absorbing material is in the form of powder, the types and shapes of the material can be combined.

[0053] In a preferred embodiment of the method, the method of evacuating and fusion-sealing the inner and outer quartz glass tubes includes: evacuating to a vacuum level below 10. -4 After Pa, the tube body is baked and then melt-sealed.

[0054] In a preferred embodiment of the method, before step S100, a step of verifying the sealing performance of the molybdenum alloy internal pressure creep sample is further included. The verification includes placing the sample in an environment filled with a test gas and detecting its leakage rate using a leak detector to confirm that the sample meets the high vacuum test requirements.

[0055] In a preferred embodiment of the method, after the creep test in step S500 is completed, the deformation of the sample needs to be measured and analyzed. Specifically, this includes measuring the change in outer diameter at multiple positions along the axial and circumferential directions of the sample, and calculating the axial strain and circumferential strain.

[0056] In one embodiment, the method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe includes the following steps:

[0057] Step S100: Place the molybdenum alloy internal pressure creep sample and the active metal getter material together in the inner quartz glass tube;

[0058] Before proceeding to step S100, a molybdenum alloy heat pipe internal pressure creep test specimen needs to be prepared. This specimen is manufactured by circumferentially welding a molybdenum alloy tube to an upper and lower plug with vent holes, followed by laser plugging of the vent holes in an environment filled with high-pressure inert gas, thereby sealing the specimen with inert gas at a predetermined pressure. After preparation, the specimen undergoes rigorous leak testing to ensure it meets the requirements of high-vacuum experiments.

[0059] Specifically, the criteria for determining the qualification of the molybdenum alloy heat pipe internal pressure creep test sample are as follows: Place the molybdenum alloy heat pipe internal pressure creep test sample in a high-pressure container, evacuate it, fill it with high-pressure argon gas and maintain the pressure for 4 hours. After removal, place it in a sealed cavity connected to a helium mass spectrometer leak detector, evacuate it again, and perform helium mass spectrometry leak detection. Record the leak rate over five minutes; a leak rate <1×10⁻⁶ is acceptable. -8 If the sample is deemed acceptable, repeat the steps for preparing the molybdenum alloy heat pipe internal pressure creep sample until the helium mass spectrometry leak detection is satisfactory.

[0060] After the molybdenum alloy heat pipe internal pressure creep test specimen is prepared, the active metal getter material is fixed using a first quartz glass cap, and the molybdenum alloy heat pipe internal pressure creep test specimen is fixed using a second quartz glass cap. Subsequently, the fixed active metal getter material and the molybdenum alloy heat pipe internal pressure creep test specimen are sequentially placed into a clean and dry inner quartz glass tube. The caps ensure that the active metal getter material and the molybdenum alloy heat pipe internal pressure creep test specimen are positioned axially within the tube, and that their outer surfaces do not directly contact the inner wall of the inner quartz glass tube.

[0061] Step S200: Vacuum the inner quartz glass tube and melt-seal it to form an inner vacuum assembly;

[0062] Specifically, the open end of the inner quartz glass tube containing the active metal getter material and the molybdenum alloy heat pipe internal pressure creep sample is connected to a vacuum system. The inside of the tube is evacuated, and when the vacuum level reaches a predetermined high vacuum level, the tube is baked to remove the adsorbed gas. Finally, a high-temperature flame is used to melt and seal the open end of the tube, thereby forming a sealed inner vacuum assembly with a high vacuum state inside.

[0063] Step S300: Place the inner vacuum assembly into the concentrically arranged outer quartz glass tube;

[0064] Specifically, a third quartz glass cap is fitted over the inner vacuum assembly, and then the entire assembly is placed into a concentric, clean, and dry outer quartz glass tube of matching size.

[0065] Step S400: Vacuum the outer quartz glass tube and melt-seal it to form a vacuum layer between the inner vacuum assembly and the outer quartz glass tube, thereby obtaining a multi-layer vacuum protection device.

[0066] Specifically, the open end of the outer quartz glass tube is connected to a vacuum system. The process of vacuuming, baking, and fusion sealing is repeated to form another independent high-vacuum chamber in the interlayer space between the inner vacuum assembly and the outer quartz glass tube, ultimately obtaining a multi-layer vacuum protection device.

[0067] Step S500: Place the multi-layer vacuum protection device in a high-temperature furnace and heat it to a predetermined temperature for a creep test.

[0068] Specifically, the aforementioned double-layer vacuum protection device is placed entirely within the homogenization zone of a conventional tube furnace. The furnace is heated to the predetermined test temperature and held at that temperature for the required time. During this process, the active metal getter material in the inner quartz tube continuously adsorbs trace amounts of oxygen within the chamber, maintaining a high vacuum level in the environment surrounding the sample. The outer vacuum interlayer effectively mitigates the potential infiltration of external gases, together providing a simulated ultra-high temperature and high vacuum environment for the molybdenum alloy internal pressure creep sample until the creep test is completed.

[0069] In one embodiment, a schematic diagram of the multi-layer vacuum protection device is shown below. Figure 2 The device is a disposable high-vacuum protection device, comprising: an inner quartz glass tube 1, a molybdenum alloy heat pipe internal pressure creep sample 2, an active metal gas-absorbing material 3, a first high-purity quartz glass cap 4, a second high-purity quartz glass cap 5, an outer quartz glass tube 6, and a third high-purity quartz glass cap 7.

[0070] In another embodiment, the inner quartz glass tube 1 is made of high-purity quartz glass with a SiO2 mass fraction higher than 99.99%. Its inner diameter is 0.3-1.0 mm larger than the outer diameter of the subsequently installed cap, and its length is such that at least 30 mm remains after accommodating all internal items. The inner quartz glass tube 1 serves as the core cavity, and after subsequent vacuuming and fusion sealing, it forms a sealed inner vacuum assembly that directly encapsulates the sample and the active metal getter material.

[0071] The molybdenum alloy heat pipe internal pressure creep specimen 2 is a tubular molybdenum alloy component to be tested. Its interior has been sealed with an inert gas (such as argon) at a predetermined pressure through circumferential welding and high-pressure plugging welding. The molybdenum alloy heat pipe internal pressure creep specimen 2 is the test body for the experiment, used to withstand internal pressure and undergo creep deformation at high temperature.

[0072] The active metal getter material 3 includes metals such as Ti, Zr, Nb, and Hf, which have Gibbs free energies lower than those of typical oxides formed by the reaction of molybdenum alloys with oxygen. These metals are used in high-temperature experiments to preferentially react with trace amounts of residual oxygen in the first-stage vacuum chamber, thereby maintaining or even increasing the vacuum level of the chamber at high temperatures, by utilizing their stronger affinity for oxygen.

[0073] The first high-purity quartz glass cap 4 and the second high-purity quartz glass cap 5 are also made of high-purity quartz glass. They are used to fix the active metal absorbent material 3 and the molybdenum alloy heat pipe pressure creep sample 2 in the inner quartz glass tube 1, respectively, to ensure that the two are in the central axis position of the tube body, avoid direct contact with the tube wall, and prevent the quartz tube from accelerating crystallization or cracking due to thermal expansion difference or local overheating.

[0074] The outer quartz glass tube 6 is made of the same material as the inner quartz glass tube 1, but its inner diameter is 0.3-1.0 mm larger than the outer diameter of the third high-purity quartz glass cap 7, and its length is at least 20 mm longer than the encapsulated inner vacuum tube assembly. The outer quartz glass tube 6 is concentrically nested outside the inner quartz glass tube 1. After vacuuming and sealing, an independent second-stage vacuum chamber is formed between the inner and outer tubes. This structure effectively insulates against heat and reduces the thermal shock and penetration of air or protective gas into the inner tube at high temperatures, significantly delaying the crystallization failure process of the inner quartz glass tube at high temperatures, thereby extending the effective test time of the entire device.

[0075] The third high-purity quartz glass cap 7 is fitted onto both ends of the inner quartz glass tube 1. It is used to support and position the sealed inner components inside the outer quartz glass tube 6, ensuring that the inner and outer tubes remain coaxial and form a uniform vacuum interlayer space.

[0076] In another embodiment, the assembly process of the multilayer vacuum protection device includes: fixing the processed active metal getter material 3 and the molybdenum alloy heat pipe internal pressure creep sample 2 with a first high-purity quartz glass cap 4 and a second high-purity quartz glass cap 5 respectively, and sequentially inserting them into a clean and dry inner quartz glass tube 1; connecting the open end of the inner quartz glass tube 1 to a vacuum sealing machine, and evacuating it to a high vacuum (e.g., below 10). -4 After vacuuming (Pa), the inner vacuum assembly is fused and sealed to form a sealed inner vacuum component. Then, a third high-purity quartz glass cap 7 is fitted onto both ends of this assembly, and the entire assembly is placed inside the outer quartz glass tube 6. The vacuuming and fusion sealing operations are repeated until the open end of the outer quartz glass tube 6 is sealed, ultimately producing a test device with two independent inner and outer high-vacuum chambers. Placing the entire device in a conventional tube furnace and heating it to a predetermined temperature (e.g., 1100-1200℃) and holding it at that temperature allows for the testing of the internal pressure creep performance of molybdenum alloy samples under high temperature and high vacuum conditions, using relatively simple equipment.

[0077] To better understand this disclosure, a more specific embodiment is provided to illustrate the technology of this disclosure.

[0078] The method for testing the internal pressure creep of the molybdenum alloy ultra-high temperature heat pipe includes the following steps:

[0079] Step S100: Place the molybdenum alloy internal pressure creep sample and the active metal getter material together in the inner quartz glass tube;

[0080] Before proceeding to this step, a qualified molybdenum alloy heat pipe internal pressure creep test sample must first be prepared.

[0081] Specifically, a molybdenum alloy heat pipe with an outer diameter of 19mm and a wall thickness of 0.9mm, along with matching upper and lower end plugs, was ground and assembled with an assembly gap of less than 0.1mm. A 0.5mm diameter vent hole was pre-drilled in the upper end plug. After ultrasonic cleaning with acetone and drying, the assembly was placed in a rotating protective fixture and preheated to 600℃ in an argon atmosphere (15L / min) for 1 minute. Subsequently, laser ring welding was performed using an IPGYSL-4000 fiber laser and a YASKAWAHP20 robot with the following parameters: power 4000W, defocusing amount 0, welding speed 2r / s, time 4s, supplemented by beam oscillation with an amplitude of 2mm and a frequency of 485Hz. After circumferential welding, the sample was placed in a high-pressure container. After evacuation and argon replacement, it was filled with argon gas at a predetermined pressure calculated based on the target creep conditions and held at that pressure for 15 minutes. Finally, high-pressure plugging welding was performed on the vent hole through the quartz glass window at the top of the container using a 3600W laser power and a welding time of 1 second, thus obtaining a molybdenum alloy heat pipe internal pressure creep sample sealed with high-pressure argon gas. See the schematic diagram of the molybdenum alloy internal pressure creep sample before encapsulation. Figure 3 The clearly visible weld (bright and defect-free) proves the success of the welding process, which is the physical basis for subsequent tests to simulate real internal pressure loads; at the same time, the overall condition of the molybdenum alloy heat pipe internal pressure creep specimen is intact, ensuring the reliability of the test's starting conditions.

[0082] Simultaneously, preparatory work for encapsulation is carried out. Inner and outer quartz glass tubes that can be nested are selected, cleaned with anhydrous ethanol, and then dried. A combination of Ti and Zr foils, composed of reactive metals, is selected as the gas-getting material. The Ti foil is placed inside the Zr foil, utilizing the different oxidation temperatures of the two to achieve multiple deoxygenation processes. The Ti and Zr foils are then polished with 800-grit sandpaper, ultrasonically cleaned with anhydrous ethanol, and dried.

[0083] After completing the above preparations, proceed with the S100 operation.

[0084] The cleaned Ti and Zr composite foil was rolled into a cylindrical shape, and its two ends were fixed with a first high-purity quartz glass cap; the two ends of the molybdenum alloy heat pipe internal pressure creep sample were fixed with a second high-purity quartz glass cap. Subsequently, the fixed Ti and Zr composite foil and the sample were placed sequentially into a dry inner quartz glass tube.

[0085] Step S200: Vacuum the inner quartz glass tube and melt-seal it to form an inner vacuum assembly;

[0086] The open end of the inner quartz glass tube containing the molybdenum alloy heat pipe internal pressure creep sample and the Ti and Zr composite foil is fixed on the vacuum tube sealing machine. First, the mechanical pump is turned on to evacuate to 10. -1 After maintaining the pressure at 10 Pa for 5 minutes, start the molecular pump to increase the vacuum to 10. -4 Pa and maintain for 20 minutes. Then, the tube is moved to the baking furnace and baked at 250°C for 10 minutes to completely remove adsorbed water vapor and gas. Finally, the reserved exhaust port is melt-sealed using an oxyhydrogen flame torch. After sealing, it is slowly cooled in the furnace to form a sealed inner vacuum assembly with a high vacuum state inside.

[0087] Step S300: Place the inner vacuum assembly into the concentrically arranged outer quartz glass tube;

[0088] The inner vacuum assembly obtained in step S200 is fitted with a third high-purity quartz glass cap at both ends, and then the entire assembly is placed into the cleaned and dried outer quartz glass tube.

[0089] Step S400: Vacuum the outer quartz glass tube and melt-seal it to form a vacuum layer between the inner vacuum assembly and the outer quartz glass tube, thereby obtaining a multi-layer vacuum protection device.

[0090] Connect the open end of the outer quartz glass tube to the vacuum sealing machine. Repeat the vacuuming, baking, and fusion sealing process in step S200 (i.e., evacuate to high vacuum, bake at 250°C, and seal with an oxyhydrogen flame), thereby forming another independent high-vacuum chamber in the interlayer space between the inner vacuum assembly and the outer quartz glass tube. Finally, a double-layer vacuum protection device with an inner and outer dual high-vacuum protection structure is obtained. The overall experimental device with the double-layer vacuum protection structure is as follows: Figure 4 As shown in the figure, a clear double-layered nested vacuum structure can be seen. The outer vacuum interlayer effectively blocks the penetration of external ambient gases into the inner quartz glass tube, thereby significantly delaying the crystallization failure process of the inner quartz glass tube at high temperatures.

[0091] Step S500: Place the multi-layer vacuum protection device in a high-temperature furnace and heat it to a predetermined temperature for a creep test.

[0092] The multilayer vacuum quartz glass tube sample prepared above was placed entirely into the homogenization zone of a conventional tube furnace. Argon gas was introduced into the furnace as a protective atmosphere, and then the furnace was heated to 900℃ and held for 100 hours to complete the high-temperature internal pressure creep test of the molybdenum alloy heat pipe. After the high-temperature internal pressure creep test, the inner vacuum assembly was removed, as shown below. Figure 5 As shown, no crystallization was observed in either the inner or outer layers of quartz glass, demonstrating excellent protective effect. The morphology of the sample after the high-temperature internal pressure creep test is shown in [reference needed]. Figure 6 ,Depend on Figure 6 It can be seen that the creep specimen underwent typical creep bulging deformation after the high-temperature test, rather than oxidation, cracking or other abnormal failures.

[0093] The outer diameter of the specimen after the high-temperature internal pressure creep test was measured. The measurement method and results are as follows: Figure 7 As shown. The measurement method includes: starting from the weld termination point, selecting eight specific locations along the sample axis, and measuring the outer diameter at 45° intervals along the circumference of each location using a high-precision micrometer (1μm). Figure 7 It is evident that after being held at 900℃ for 100 hours, the creep specimen remained intact, maintaining its structural integrity and measurability. This further demonstrates that the method described in this disclosure successfully isolates oxygen, providing the necessary inert high-vacuum environment for the molybdenum alloy specimen, thus preventing it from undergoing high-temperature oxidation failure.

[0094] The strain of the specimen after the high-temperature internal pressure creep test was further calculated, and the calculation results are shown in [reference]. Figure 8 This indicates that under internal pressure and high temperature load, the creep specimen undergoes bulging deformation, with the deformation being greatest near the middle and the axial strain being minimal.

[0095] Metallographic comparison of the creep specimen before and after internal pressure creep and at the weld seam Figure 9 As shown, by Figure 9 It can be seen that the sample pipe after the high temperature internal pressure creep test underwent significant recrystallization, and the weld area clearly showed typical creep failure characteristics such as gap expansion and grain boundary cracks.

[0096] In summary, the molybdenum alloy ultra-high temperature heat pipe internal pressure creep testing device described in this disclosure effectively isolates the oxidizing atmosphere through the built-in active metal getter material and multi-layer vacuum structure, preventing the sample from oxidizing and deteriorating at ultra-high temperatures. Furthermore, the built-in active metal getter material can continuously adsorb trace amounts of oxygen at high temperatures, and the multi-layer nested structure can effectively delay the crystallization failure of the quartz tube at high temperatures, extending the test time and providing a reliable experimental basis for reproducing the failure behavior analysis of molybdenum alloy heat pipes under service conditions.

[0097] Although the embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this disclosure is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the teachings of this specification and without departing from the scope of protection of the claims of this disclosure, and all of these are within the scope of protection of this disclosure.

Claims

1. A method for testing the internal pressure creep of a molybdenum alloy ultra-high temperature heat pipe, characterized in that, Includes the following steps: Step S100: Place the molybdenum alloy internal pressure creep sample and the active metal getter material together in the inner quartz glass tube; Step S200: Vacuum the inner quartz glass tube and melt-seal it to form an inner vacuum assembly; Step S300: Place the inner vacuum assembly into the concentrically arranged outer quartz glass tube; Step S400: Vacuum the outer quartz glass tube and melt-seal it to form a vacuum layer between the inner vacuum assembly and the outer quartz glass tube, thereby obtaining a multi-layer vacuum protection device. Step S500: Place the multi-layer vacuum protection device in a high-temperature furnace and heat it to a predetermined temperature for a creep test.

2. The method according to claim 1, characterized in that, Preferably, before placing the sample and getter material into the inner quartz glass tube, a spacer is used to fix the sample and getter material so that they do not come into direct contact with the inner wall of the inner quartz glass tube.

3. The method according to claim 2, characterized in that, The isolation element is a high-purity quartz glass cap.

4. The method according to claim 1, characterized in that, The selection criteria for the active metal getter material are as follows: at the predetermined temperature of the test, the Gibbs free energy of the oxide formed by the reaction of the active metal material with oxygen is lower than that of the oxide formed by the reaction of molybdenum alloy with oxygen.

5. The method according to claim 1, characterized in that, The active metallic material is selected from one of foil, wire, or powder.

6. The method according to claim 1, characterized in that, When the active metal air-absorbing material is in the form of powder, the types and shapes of the materials can be combined.

7. The method according to claim 1, characterized in that, The method for evacuating and fusion-sealing the inner and outer quartz glass tubes includes: evacuating to a vacuum level below 10. -4 After Pa, the tube body is baked and then melt-sealed.

8. The method according to claim 1, characterized in that, Before step S100, the method further includes a step of verifying the sealing performance of the molybdenum alloy internal pressure creep sample. The verification includes placing the sample in an environment filled with test gas and detecting its leakage rate using a leak detector to confirm that the sample meets the high vacuum test requirements.

9. The method according to claim 1, characterized in that, After the creep test described in step S500 is completed, the deformation of the specimen needs to be measured and analyzed. Specifically, this includes measuring the change in outer diameter at multiple positions along the axial and circumferential directions of the specimen, and calculating the axial strain and circumferential strain.

Images