Test structure for hydrogen permeation test in high-pressure gas-phase hydrogen environment as well as mounting method and application of test structure

Abstract

The invention relates to the technical field of hydrogen energy conveying and material performance testing, in particular to a testing structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment and an installation method and application of the testing structure. The testing structure comprises a sample body and an insulation sealing assembly, and the sample body is of a double-step disc structure; the uppermost edge of the first sealing insulation assembly is flush with the upper end face of the cylindrical platform, the sample body is installed on the inner side of the first sealing insulation assembly in a matched mode, the second sealing insulation assembly is in a shape with an upward opening, and the first sealing insulation assembly is installed in the second sealing insulation assembly in a matched mode. The test surface of the sample body of the test structure and the gas main flow keep a consistent flow velocity field, and when the test structure is used for testing, the permeation behavior of the hydrogen flow on the material surface can be truly reflected; all the clamping and conducting structures are arranged outside the pipe wall of the test pipeline or at the left part of the sample body, so that flow field disturbance is prevented from being introduced into a main airflow path.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen energy delivery and material performance testing, and is a test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment, and an installation method and application thereof. Background Art

[0002] The efficient and safe transportation of hydrogen has become a technical challenge in the development of hydrogen energy. The hydrogen permeation characteristics of metal pipelines directly impact their service safety, particularly under high-pressure gas-phase flow conditions, where hydrogen-induced failures are likely to occur. Therefore, constructing a structure that can realistically simulate high-pressure gas-phase hydrogen environments and perform hydrogen permeation testing on in-service steels is crucial for understanding hydrogen embrittlement mechanisms and assessing the serviceability of materials.

[0003] Patent application publication number CN118688069A discloses a permeability testing device and method for non-metallic pipelines used for pure hydrogen transportation. The device uses a sealed chamber outside the non-metallic pipeline section to collect hydrogen gas that permeates through it. A gas chromatograph measures the hydrogen concentration within the sealed chamber, and the permeation level of the section is calculated based on time. Each section can be tested sequentially, or separate sealed chambers can be installed outside each section for simultaneous testing.

[0004] Patent application publication number CN115814702A discloses a propeller-type hydrogen permeation single-view window autoclave, comprising an autoclave body having a single view window; a hollow sample holder mounted on the single view window, one end of which is used to clamp the sample and extend through the single view window into the interior of the autoclave body, and the other end of which is connected to a hydrogen permeation testing device; and a stirring assembly comprising a propeller extending into the interior of the autoclave body and its drive. The propeller disturbs the hydrogen in the autoclave, simulating the flow of hydrogen in a pipeline, thereby testing the degree of hydrogen permeation into the material while the hydrogen is in motion.

[0005] At present, the samples commonly used in hydrogen permeation testing are mostly circular thin-sheet structures. Such samples need to be compressed and sealed by clamps on both sides (such as the attached document with publication number CN115814702A and the title of "A Propeller-Type Hydrogen Permeation Single-Window Autoclave"). Figure 5The sample fixture shown in the figure). When used for hydrogen permeation performance testing in a dynamic gas-phase environment, in order to achieve airtightness and electrical offset, thick fixtures or special mounting components are often set at the upper and lower ends of the sample. However, these fixture structures inevitably form geometric mutations and flow field disturbance areas on the sample surface, seriously affecting the flow uniformity and boundary layer stability of the high-pressure gas-phase hydrogen flow on the sample surface, and thus causing deviations in the hydrogen-bearing conditions of the sample. Especially in the high-pressure dynamic flow field that simulates the actual operating conditions of the pipeline, this type of structure is difficult to truly restore the hydrogen flow erosion and concentration gradient distribution that the material surface is subjected to, which limits its accuracy in characterizing hydrogen permeation behavior and deviates from engineering reality. Therefore, there is an urgent need for a new sample structure that can be easily loaded and unloaded with the test container and minimizes boundary disturbances to improve the authenticity and repeatability of dynamic gas-phase hydrogen permeation testing. Summary of the Invention

[0006] The present invention provides a test structure for hydrogen permeation testing in a high-pressure gaseous hydrogen environment, an installation method thereof, and an application thereof, which overcome the deficiencies of the above-mentioned prior art. The test structure can be repeatedly loaded and unloaded with a test container and can minimize boundary disturbances.

[0007] One of the technical solutions of the present invention is achieved through the following measures: a test structure for hydrogen permeation testing in a high-pressure gaseous hydrogen environment, including a sample body and an insulating sealing assembly, the sample body is a two-step disc structure, the sample body includes a cylindrical platform and an annular extension located below the cylindrical platform, the upper end of the extension is connected to the lower end of the cylindrical platform as a whole; the insulating sealing assembly includes a first sealing insulating assembly and a second sealing insulating assembly, the first sealing insulating assembly is a two-step annular structure, the uppermost edge of the first sealing insulating assembly is flush with the upper end surface of the cylindrical platform, the sample body is mounted on the inner side of the first sealing insulating assembly, the second sealing insulating assembly is U-shaped with the opening facing upward, and the first sealing insulating assembly is mounted in the second sealing insulating assembly.

[0008] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The extension of the sample body is fitted in the second step at the bottom of the first sealed insulating component, the second step of the first sealed insulating component is fitted in the second sealed insulating component, and the bottom end surface of the extension is fitted with the upper end surface of the second sealed insulating component.

[0009] The uppermost edge of the second sealing and insulating component is flush with the uppermost end surface of the second step of the first sealing and insulating component.

[0010] The above-mentioned test structure also includes a sample side pressing flange for connecting to the fixed flange of the test pipe, and the outer side surface of the second sealing insulation component is in contact with the inner wall surface of the sample side pressing flange.

[0011] The above-mentioned test structure also includes a transition tube, and a connecting portion is provided at the upper end of the transition tube. The connecting portion passes through the second sealing insulation component from the middle of the sample side clamping flange and extends into the sample cavity of the cylindrical platform. At least one seal is provided between the outside of the transition tube and the inside of the sample side clamping flange. An auxiliary electrode hole, a reference electrode hole and a drainage hole are provided on the tube wall of the transition tube, and the inner cavity of the transition tube is an electrolytic cell.

[0012] The above-mentioned test structure also includes a test pipe, on which a mounting hole is radially arranged, and the mounting hole is stepped. The outer edge of the first step of the first sealing insulation component is fitted with the first step of the mounting hole, and the upper edge of the first sealing insulation component and the upper end face of the cylindrical platform are flush with the inner wall of the test pipe. The upper side edge of the second sealing insulation component and the upper end face of the second step of the first sealing insulation component are fitted with the second step of the mounting hole. A fixed flange is fixed at the test pipe corresponding to the mounting hole, and the fixed flange is fixedly connected to the sample side compression flange. The inner wall of the fixed flange is fitted with the outer wall of the second sealing insulation component.

[0013] The second technical solution of the present invention is achieved by the following measures: a method for installing a test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment, comprising: First, embed the first sealing and insulating assembly into the installation hole of the test pipe; Next, the sample body is completely embedded in the first sealing and insulating assembly, with the upper end surface of the cylindrical platform of the sample body flush with the inner surface of the inner wall of the test pipe; Subsequently, the second sealed insulating component is installed below the first sealed insulating component, the second step of the first sealed insulating component is enclosed in the second sealed insulating component, and the bottom surface of the extended portion of the sample body is in contact with the bottom surface of the second sealed insulating component; Next, the transition pipe is inserted into the compression flange on the sample side, passes through the second sealing and insulating assembly, and extends into the sample cavity of the cylindrical platform of the sample body; Finally, align the fixed flange of the test pipe with the compression flange on the specimen side and install it, and clamp the specimen body firmly.

[0014] The third technical solution of the present invention is achieved through the following measures: application of the test structure described in one of the technical solutions in a hydrogen permeation test under a high-pressure gas-phase hydrogen environment.

[0015] The following are further optimizations and / or improvements to the third technical solution of the above invention: The methods of the above application include: The sample cavity serves as the working electrode, and the auxiliary electrode and the reference electrode are inserted into the electrolytic cell of the transition tube. The auxiliary electrode, the reference electrode and the sample cavity form a stable electrochemical circuit interface. The auxiliary electrode and the reference electrode are connected to the constant potential instrument through a quick-connect cable to perform continuous testing of the hydrogen permeation current.

[0016] The present invention has the following beneficial effects: (1) The test structure has a flat embedded structure, and the test surface (i.e., the rightmost end surface of the cylindrical platform of the test structure) maintains the same velocity field as the main flow of gas. When using this test structure for testing, it can truly reflect the penetration behavior of hydrogen flow on the material surface; (2) All clamping and conducting structures (i.e., flange structure and transition pipe, etc.) are arranged on the outside of the test pipe wall or on the left side of the sample body. Compared with the traditional clamping sample that introduces flow field disturbance in the main airflow path, the present invention can avoid introducing flow field disturbance in the main airflow path; (3) The flange and sealing structure are highly versatile and adaptable to a variety of sample materials and test systems; (4) The installation process is standardized and simple, supporting highly repeatable assembly and rapid replacement of multiple specifications. It is the basic process unit for high-pressure dynamic hydrogen permeation testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Attachment Figure 1 The figure shows the front view of the test specimen body of the present invention installed in the test pipe.

[0018] Attachment Figure 2 Shown attached Figure 1 BB cross-sectional view.

[0019] Attachment Figure 3 Shown attached Figure 1 Axonometric drawing of .

[0020] Attachment Figure 4 The figure shows the streamline diagram of the hydrogen permeation simulation test using a sample fixture to clamp a thin-film structure sample (inlet flow rate 10 m / s).

[0021] Attachment Figure 5 The figure shows a streamline diagram of a hydrogen permeation simulation test using the test structure of the present invention (inlet flow rate 10 m / s).

[0022] Attachment Figure 6 The figure shows the streamline diagram of the hydrogen permeation simulation test using a sample fixture to clamp a thin-film structure sample (inlet flow rate 5 m / s).

[0023] Attachment Figure 7 The figure shows a streamline diagram of a hydrogen permeation simulation test using the test structure of the present invention (inlet flow rate 5 m / s).

[0024] The codes in the attached drawings are: 1 for mounting hole, 2 for cylindrical platform, 3 for extension part, 4 for first sealing and insulating component, 5 for second sealing and insulating component, 6 for fixing flange, 7 for sample side pressing flange, 8 for transition pipe, 9 for connection part, 10 for sample cavity, 11 for auxiliary electrode hole, 12 for reference electrode hole, 13 for drainage hole, 14 for test pipe, a for first step, b for second step. Figure 2 In the figure, the arrows indicate the direction of hydrogen flow. DETAILED DESCRIPTION

[0025] The present invention is not limited to the following embodiments, and specific implementation methods can be determined based on the technical solutions of the present invention and actual conditions.

[0026] In the present invention, it should be noted that the terms "first", "second", etc. are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the modules or elements referred to must have a specific order and operation, and therefore cannot be understood as a limitation on the present invention, such as the first sealed insulating component.

[0027] For the convenience of description, the relative position relationship of each component is described based on the Figure 2 The positional relationships of front, back, top, bottom, left, and right are described in the layout of the manual. Figure 2 The layout direction is determined by the

[0028] The present invention will be further described below in conjunction with the embodiments: Example 1: Figures 1 to 3 As shown, a test structure for hydrogen permeation testing in a high-pressure gaseous hydrogen environment includes a sample body and an insulating sealing assembly. The sample body is a two-step disc structure, and the sample body includes a cylindrical platform 2 and an annular extension 3 located below the cylindrical platform 2, and the upper end of the extension 3 is connected to the lower end of the cylindrical platform 2 as a whole; the insulating sealing assembly includes a first sealing insulating assembly 4 and a second sealing insulating assembly 5. The first sealing insulating assembly 4 is a two-step annular structure, and the uppermost edge of the first sealing insulating assembly 4 is flush with the upper end surface of the cylindrical platform 2. The sample body is mounted on the inner side of the first sealing insulating assembly 4, and the second sealing insulating assembly 5 is U-shaped with an opening facing upward. The first sealing insulating assembly 4 is mounted in the second sealing insulating assembly 5.

[0029] The sample body supports a variety of material options: including metal materials such as low-alloy steel, stainless steel, nickel-based alloys with different strength levels, as well as non-metallic materials such as ceramics and polymer composite materials.

[0030] Other existing hydrogen-suppressing coatings such as physical vapor deposition (PVD), chemical plating or spraying may also be constructed on the surface of the sample body (i.e., the upper end surface of the cylindrical platform 2) to study the interface behavior under various hydrogen permeation environments.

[0031] To enhance versatility, the outer diameter and step height of the specimen body support standardized serial design (such as φ35 mm, φ30 mm, etc.), and can be quickly replaced with the flange structure stroke and pipeline size.

[0032] Example 2: Figure 1 As shown, as an optimization of the above embodiment, the extension portion 3 of the sample body is fitted and installed in the second step b at the bottom of the first sealing insulation component 4, and the second step b of the first sealing insulation component 4 is fitted and installed in the second sealing insulation component 5, and the bottom end surface of the extension portion 3 is in contact with the upper end surface of the second sealing insulation component 5.

[0033] The first step a and the second step b are counted from top to bottom.

[0034] The first sealing and insulating component 4 is an integrally formed two-step annular structure, the outer side surface of the upper step (i.e., the first step a) and the upper end surface of the second step b are both in contact with the mounting hole 1 on the wall of the test pipe 14, forming external insulation and sealing; its inner side is in close contact with the outer wall of the test sample body, used for external circular positioning of the test sample body and isolation of the gas and flange area, realizing axial primary sealing and electrical insulation.

[0035] Example 3: Figure 1 As shown, as an optimization of the above embodiment, the uppermost edge of the second sealing and insulating component 5 is flush with the uppermost end surface of the second step b of the first sealing and insulating component 4 .

[0036] The bottom end surface of the extension portion 3 is fitted with the bottom surface inside the second sealing and insulating component 5, and the outer wall of the lower part of the second sealing and insulating component 5 is fitted with the inner wall surface of the fixing flange 6; the inner side surface of the second sealing and insulating component 5 is fitted with the outer wall of the second step b of the first sealing and insulating component 4, and the outer side surface of the upper part of the second sealing and insulating component 5 is tightly matched with the inner surface of the second step b of the mounting hole 1, forming a complete multi-faceted contact sealing and electrical insulation structure.

[0037] Example 4: Figure 1 As shown, as an optimization of the above embodiment, the test structure also includes a sample side clamping flange 7 for connecting to the fixed flange 6 of the test pipe 14, and the bottom surface of the second sealing insulation component 5 is in contact with the upper end surface of the sample side clamping flange 7.

[0038] Flange structures and sealing and insulating components can also be standardized and customized to meet different system requirements. Flange connection methods can be designed according to GB / T, ASME standards or for specific working conditions. Sealing and insulating components support a variety of configurations, including rubber rings, metal sealing rings, and composite gaskets, to meet the needs of high-temperature, high-pressure, corrosive, or dynamic hydrogen flow environments.

[0039] Example 5: Figure 1 As shown, as an optimization of the above embodiment, the test structure also includes a transition tube 8, and a connecting portion 9 is provided at the upper end of the transition tube 8. The connecting portion 9 passes through the second sealing insulation component 5 from the middle of the sample side clamping flange 7 and extends into the sample cavity 10 of the cylindrical platform 2. At least one sealing member is provided between the outer side of the transition tube 8 and the inner side of the sample side clamping flange 7. An auxiliary electrode hole 11, a reference electrode hole 12 and a drainage hole 13 are provided on the tube wall of the transition tube 8. The inner cavity of the transition tube 8 is an electrolytic cell.

[0040] The auxiliary electrode hole 11 and the reference electrode hole 12 support various structures, including center through-hole type and eccentric blind hole type. The connection form can be thread locking, welding fixation or quick plug-in type to adapt to various types of electrochemical instruments.

[0041] After the experiment is finished, the electrolyte is discharged through the drain hole 13. During the experiment, the drain hole 13 can be blocked with a structure such as a wire plug.

[0042] The transition pipe 8 is a slender cylindrical metal pipe or a high-strength insulating material pipe.

[0043] Example 6: Figures 1 to 3 As shown, as an optimization of the above embodiment, the test structure also includes a test pipe 14, and a mounting hole 1 is radially arranged on the test pipe 14, and the mounting hole 1 is stepped. The outer edge of the first step a of the first sealing insulation component 4 is fitted with the first step a of the mounting hole 1, and the uppermost edge of the first sealing insulation component 4 and the uppermost end face of the cylindrical platform 2 are flush with the inner wall of the test pipe 14, and the upper side edge of the second sealing insulation component 5 and the upper end face of the second step b of the first sealing insulation component 4 are fitted with the second step b of the mounting hole 1. A fixing flange 6 is fixed at the test pipe 14 corresponding to the mounting hole 1, and the fixing flange 6 is fixedly connected to the sample side clamping flange 7, and the inner wall of the fixing flange 6 is fitted with the outer wall of the second sealing insulation component 5.

[0044] The upper end surface of the cylindrical platform 2 of the sample body is flush with the inner surface of the inner wall of the test pipe 14, so that the upper end surface of the cylindrical platform 2 of the sample body and the inner wall of the pipe form a smooth continuous structure without causing sudden changes in the flow field.

[0045] The stepped mounting hole 1 can form a chimeric structure with the sample body and the first sealing and insulating component 4 , thereby improving the structural stability and sealing performance of the sample body and the test pipe 14 .

[0046] Example 7: Figure 1 As shown, a method for installing a test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment includes: First, the first sealing and insulating assembly 4 is embedded into the mounting hole 1 of the test pipe 14; Next, the sample body is completely embedded in the first sealed insulating assembly 4, with the upper end surface of the cylindrical platform 2 of the sample body flush with the inner surface of the inner wall of the test pipe 14; this forms a continuous airflow adherent structure, avoids flow field interference, establishes a stable adherent flow, and forms a real boundary layer structure; Then, the second sealed insulating component 5 is installed below the first sealed insulating component 4. The second step b of the first sealed insulating component 4 is enclosed in the second sealed insulating component 5. The bottom surface of the extension portion 3 of the sample body is in contact with the bottom surface of the second sealed insulating component 5. Next, the transition tube 8 is inserted into the sample-side compression flange 7, passes through the second sealing and insulating assembly 5, and extends into the sample cavity 10 of the cylindrical platform 2 of the sample body. The outer wall of the transition tube 8 forms an interference fit with the through hole of the sample-side compression flange 7; Finally, align the fixing flange 6 of the test pipe 14 with the sample-side pressing flange 7 and install them to firmly clamp the sample body.

[0047] An installation groove is pre-opened on the outside of the transition pipe 8 or the inside of the sample-side compression flange 7, and the sealing member is installed in the installation groove.

[0048] Example 8: Application of the test structure described in the above embodiment in hydrogen permeation testing under high-pressure gas-phase hydrogen environment.

[0049] Example 9: As an optimization of Example 8, the application method includes: The sample cavity 10 serves as the working electrode, and the auxiliary electrode and the reference electrode are inserted into the electrolytic cell of the transition tube 8. The auxiliary electrode, the reference electrode and the sample cavity 10 form a stable electrochemical circuit interface. The auxiliary electrode and the reference electrode are connected to the constant potential instrument through a quick-connect cable to perform continuous testing of the hydrogen permeation current.

[0050] Example 10: Processing and assembly of metal material sample body In this example, a 4mm-thick 316L stainless steel disc with an initial outer diameter of 35mm was used as the raw material for the sample body. This disc was then machined to a surface roughness of Ra ≤ 0.8μm. Subsequently, a two-stage disc structure was fabricated using CNC equipment: the upper stage (i.e., cylindrical platform 2) was constructed as a 20mm-diameter, 2.8mm-high, 0.8mm-thick platform, serving as the gas flow field contact surface. The lower stage (extension 3) was machined into an annular platform structure with a diameter of 35mm and a thickness of 1.2mm, serving as the positioning, mounting, and sealing area. Simultaneously, a shallow circular cavity (i.e., sample cavity 10) was hollowed out in the center of the sample body. This cavity served as the working electrode. The right bottom surface of this shallow circular cavity served as the hydrogen permeation reaction surface, and the inner wall provided the current collection channel.

[0051] A stepped mounting hole 1 is preset on the wall of the test pipe 14 for mounting the sample body and the matching sealing assembly (including the first sealing insulation assembly 4 and the second sealing insulation assembly 5): the upper end of the mounting hole 1 (i.e., the first step a) has a diameter of 22 mm and a depth of 0.8 mm, which is flush with the upper step of the sample body and the uppermost edge of the first sealing insulation assembly 4; the diameter of the second step b of the mounting hole 1 is 39 mm, which fits the outer edge of the second sealing insulation assembly 5.

[0052] The specimen body assembly process is carried out in the following order: First, insert the first sealing and insulating assembly 4 into the mounting hole 1 of the test pipe 14. This assembly, injection-molded from PPS engineering plastic, is 2mm thick and has a two-step, ring-shaped structure. The upper step (i.e., first step a) has an outer diameter of 22mm, its outer edge closely fitting the upper end of the mounting hole 1, and a height of 0.8mm. The lower step (i.e., second step b) has an outer diameter of 37mm and a height of 3.2mm. The outer side and bottom surfaces of the lower step of the first sealing and insulating assembly 4 form close contact with the inner surface of the second sealing and insulating assembly 5. The first sealing and insulating assembly 4 simultaneously performs external circular positioning of the test specimen, gas isolation, and primary electrical insulation.

[0053] Next, the processed 316L sample body is completely embedded in the first sealing insulation component 4, ensuring that its uppermost end surface is flush with the inner wall surface of the test pipe 14 to form a continuous airflow wall structure to avoid flow field interference.

[0054] Subsequently, the second sealing insulation component 5 is installed under the first sealing insulation component 4. The second sealing insulation component 5 is made of PEEK material, with a thickness of 2 mm, and is a hollow cylindrical structure with a through hole. The bottom surface of the extension part 3 of the sample body is tightly fitted with the bottom surface of the second sealing insulation component 5. A through hole with a diameter of 10 mm is opened in the center of the second sealing insulation component 5 for the insertion and connection of the transition pipe 8.

[0055] After the sample body and the sealing assembly are positioned, the sample side clamping flange 7 is placed against the outer surface of the second sealing insulation assembly 5. The sample side clamping flange 7 is made of stainless steel as a whole, with a thickness of 6.mm. The inner hole size is slightly larger than the outer diameter of the transition pipe 8, and there are six symmetrical bolt holes around it. Then align the fixed flange 6 of the test pipe 14 and install it. Insert the M4 specification high-strength stainless steel bolts into the screw holes in sequence, and apply a uniform axial compression force in a diagonal order. The tightening torque is 8N·m. During the flange clamping process, the sample body is firmly clamped, the sealing assembly is fitted on three sides, the end of the transition pipe 8 is stably positioned, and the overall assembly is completed.

[0056] After the sample body is compressed, the transition tube 8 is inserted into the through-hole of the sample-side compression flange 7, passed through the second sealing and insulating assembly 5, and extended into the sample cavity 10 of the sample body. The transition tube 8 is made of acrylic, and the outer wall of the connecting end forms an interference fit with the through-hole of the sample-side compression flange 7. A seal (a PTFE or PFA gasket) is installed between the outer side of the transition tube 8 and the inner side of the sample-side compression flange 7. Using a conical compression or O-ring design, axial pressure is applied to achieve a two-point radial seal, ensuring no leakage of hydrogen or electrolyte.

[0057] Finally, the auxiliary and reference electrodes of the electrolytic cell are inserted into the cell through transition tube 8, forming a stable electrochemical circuit interface with the sample cavity 10. Externally, they are connected to a potentiostat via a quick-connect cable to continuously measure the hydrogen permeation current. The system is leak-tested with 10 MPa nitrogen or helium. No gas escape is considered sealed and ready for formal high-pressure hydrogen permeation testing. After the experiment, the electrolyte is drained through drain hole 13.

[0058] According to the working principle of the electrochemical three-electrode system, the auxiliary electrode and the reference electrode are placed in the electrolytic cell.

[0059] Example 11: Preparation and assembly of non-metallic material specimen body This example, based on Example 10, replaced the sample body material with an alumina ceramic disc (Al2O3, purity ≥99.5%, thickness 4.0 mm). Considering the high brittleness and prone to edge chipping of ceramic materials, the sample was processed using a combination of ultrasonic grinding and precision lapping to create a stepped structure with an upper step diameter of 20 mm and a thickness of 0.8 mm, and a lower step diameter of 35 mm and a thickness of 1.2 mm. The sample cavity 10 was formed by laser machining and had a depth of 3.2 mm.

[0060] A conductive layer of silver paste is applied to the inner wall of the sample cavity 10 and dried at 120°C for one hour to form a stable conductive interface, replacing the electrode path in the metal body. The remaining sealing components, flange, and transition tube 8 are identical to those in Example 10, but the tightening torque is controlled to ≤5 N·m during compression to prevent ceramic fracture. The electrodes are contacted with the sample cavity 10 using flexible probes or liquid contact.

[0061] Example 12: Preparation and Application of Metal-Based Coating Samples Based on Example 10, the sample body still utilizes a 316L stainless steel disc, and retains the same design of the sample body and sample cavity 10. The difference is that the uppermost end surface of the cylindrical platform 2 of the sample body (which contacts hydrogen) undergoes surface pretreatment (sandblasting and ultrasonic cleaning), followed by a TiN coating deposited using physical vapor deposition (PVD) with a thickness of approximately 500 nm. This TiN coating is used to suppress the hydrogen permeation rate.

[0062] The specimen body installation, sealing assembly, transition tube 8 structure, and operating procedures are identical to those of Example 10. This configuration (TiN-coated specimen body) is suitable for studying the performance stability and film failure behavior of hydrogen suppression coatings under high-pressure flowing gas. The interior of the specimen cavity 10 is uncoated, leaving exposed metal areas to form permeation pathways between the inner and outer interfaces.

[0063] This invention provides an embedded stepped hydrogen permeation test specimen (specimen body) and its mounting assembly (including sealing components), featuring a standardized structure, repeatable assembly and disassembly, and minimized flow field disturbance. These components enable realistic simulation testing of hydrogen permeation properties of materials under high-pressure gas phase conditions. The specimen body is suitable for installation on the inner wall of a gas circulation system pipeline, offering excellent airflow conformity, structural sealing, and electrode conductivity, effectively ensuring test accuracy and system compatibility.

[0064] Flow field disturbance comparison experiment: (1) In actual hydrogen transportation projects, the hydrogen flow rate in the pipeline can usually reach more than 10m / s, which is in a high-speed shear flow state. The sample structure used in traditional hydrogen permeation testing is usually a thin sheet clamped in the middle, fixed and insulated by a clamp-shaped structure fixture (such as the attached document with publication number CN115814702A and the subject name "A Propeller-Type Hydrogen Permeation Single-Window Autoclave"). Figure 5 However, this type of fixture forms a significant protrusion in the flow field, which easily causes vortexes, separation, and backflow in the upstream and downstream regions, seriously disrupting the hydrogen flow state on the sample surface. Simulation results show that under an inlet flow rate of 10m / s, this type of structure forms stable vortices at the upper and lower ends of the sample, causing boundary layer shedding, resulting in extremely uneven distribution of hydrogen concentration and flow rate on the sample surface, making it difficult to truly reflect the dynamic hydrogen permeation behavior under pipeline operation (see Figure 4), and the sample body of the invention is flush with the wall of the test pipe 14, which can significantly reduce local flow interference and maintain a smooth and uniform surface flow state under the condition of an inlet flow rate of 10m / s (see Figure 5 ), which is more conducive to establishing a stable hydrogen concentration gradient.

[0065] (2) In conventional laboratory hydrogen permeation tests, the flow rate of gaseous hydrogen is usually maintained at around 5 m / s due to the limitations of the equipment's flow control capabilities. Although this flow rate is lower than the actual operating conditions of engineering pipelines, it can still reflect some of the permeation characteristics of the material under a dynamic airflow environment. Simulation results show that under this flow rate condition, the traditional clamping sheet structure (such as the publication number CN115814702A, the subject name of which is "A propeller-type hydrogen permeation single-window autoclave") forms protrusions on both sides of the sample in its clamping structure, causing disturbances in the local flow field, resulting in obvious backflow and vortexes, destroying the continuity of the hydrogen boundary layer on the sample surface, and thus affecting the stability of the hydrogen concentration distribution (see Figure 6 The sample body of the present invention is flush with the wall of the test pipe 14, which can significantly reduce local flow interference and maintain a smooth and uniform surface flow state under the condition of an inlet flow rate of 5m / s (see Figure 7 ), which is more conducive to establishing a stable hydrogen concentration gradient.

[0066] Comparing the two samples under different gas flow rates, the present invention's sample body is flush with the inner wall of the pipeline, with a continuous transition between the sample area boundaries and the absence of sudden flow disturbances. Under the same flow rate conditions, the present invention's sample body significantly reduces near-wall backflow and secondary flow, maintaining a uniform, stable high-shear flow of hydrogen on the sample body surface, which is beneficial for simulating the hydrogen permeation environment under actual pipeline service conditions. This optimized design ensures flow consistency and repeatability across the sample test surface (the uppermost surface of the cylindrical platform 2 of the sample body), providing a key structural foundation for high-pressure gas-phase dynamic hydrogen permeation testing.

[0067] The above technical features respectively constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the requirements of different situations.

Claims

1. A test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment, characterized in that: It includes a sample body and an insulating sealing component. The sample body is a two-step disc structure. The sample body includes a cylindrical platform and an annular extension located below the cylindrical platform. The upper end of the extension is connected to the lower end of the cylindrical platform as a whole; the insulating sealing component includes a first sealing insulating component and a second sealing insulating component. The first sealing insulating component is a two-step annular structure. The uppermost edge of the first sealing insulating component is flush with the upper end surface of the cylindrical platform. The sample body is mounted on the inner side of the first sealing insulating component. The second sealing insulating component is U-shaped with the opening facing upward. The first sealing insulating component is mounted in the second sealing insulating component.

2. The test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to claim 1, characterized in that: The extension of the sample body is fitted in the second step at the bottom of the first sealed insulating component, and the second step of the first sealed insulating component is fitted in the second sealed insulating component, with the bottom end surface of the extension fitting the upper end surface of the second sealed insulating component.

3. The test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to claim 1 or 2, characterized in that: The uppermost edge of the second sealing and insulating component is flush with the uppermost end surface of the second step of the first sealing and insulating component.

4. The test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to claim 1 or 2, characterized in that: It also includes a sample side pressing flange for connecting to the fixed flange of the test pipe, and the bottom surface of the second sealing insulation component is in contact with the upper end surface of the sample side pressing flange.

5. The test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to claim 3, characterized in that: It also includes a sample side pressing flange for connecting to the fixed flange of the test pipe, and the outer side surface of the second sealing insulation component is in contact with the inner wall surface of the sample side pressing flange.

6. The test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to claim 5, characterized in that: It also includes a transition tube, the upper end of which is provided with a connecting portion, which extends from the middle of the sample side clamping flange through the second sealing insulation component and into the sample cavity of the cylindrical platform. At least one sealing member is provided between the outer side of the transition tube and the inner side of the sample side clamping flange. An auxiliary electrode hole, a reference electrode hole and a drainage hole are provided on the tube wall of the transition tube, and the inner cavity of the transition tube is an electrolytic cell.

7. The test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to claim 6, characterized in that: It also includes a test pipe, on which a mounting hole is radially arranged, and the mounting hole is stepped. The outer edge of the first step of the first sealing insulation component is fitted with the first step of the mounting hole, and the upper edge of the first sealing insulation component and the upper end face of the cylindrical platform are flush with the inner wall of the test pipe. The upper side edge of the second sealing insulation component and the upper end face of the second step of the first sealing insulation component are fitted with the second step of the mounting hole. A fixed flange is fixed at the test pipe corresponding to the mounting hole, and the fixed flange is fixedly connected to the sample side clamping flange, and the inner wall of the fixed flange is fitted with the outer wall of the second sealing insulation component.

8. A method for installing a test structure for hydrogen permeation testing in a high-pressure gas-phase hydrogen environment according to any one of claims 1 to 7, characterized in that: include: First, embed the first sealing and insulating assembly into the installation hole of the test pipe; Next, the sample body is completely embedded in the first sealing and insulating assembly, with the upper end surface of the cylindrical platform of the sample body flush with the inner surface of the inner wall of the test pipe; Subsequently, the second sealed insulating component is installed below the first sealed insulating component, the second step of the first sealed insulating component is enclosed in the second sealed insulating component, and the bottom surface of the extended portion of the sample body is in contact with the bottom surface of the second sealed insulating component; Next, the transition pipe is inserted into the compression flange on the sample side, passes through the second sealing and insulating assembly, and extends into the sample cavity of the cylindrical platform of the sample body; Finally, align the fixed flange of the test pipe with the compression flange on the specimen side and install it, and clamp the specimen body firmly.

9. Use of the test structure according to any one of claims 1 to 7 in a hydrogen permeation test under a high-pressure gas-phase hydrogen environment.

10. The use according to claim 9, characterized in that The method of application includes: The sample cavity is used as the working electrode. The auxiliary electrode and reference electrode are inserted into the electrolytic cell of the transition tube. The auxiliary electrode, reference electrode and sample cavity form a stable electrochemical circuit interface. The auxiliary electrode and reference electrode are connected to the constant potential instrument through a quick-connect cable to perform continuous testing of the hydrogen permeation current.

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