Scanning electrochemical microscope in-situ stress corrosion testing device and method

Abstract

The invention discloses a scanning electrochemical microscope in-situ stress corrosion testing device and method, and belongs to the technical field of material stress corrosion testing, and the device comprises a base, a power transmission module, a clamping module, a corrosion module, a signal acquisition module and a scanning electrochemical microscope module. Slow strain rate stretching of a sample is achieved through a servo motor, a planetary gear speed reducer and a transmission mechanism, the clamping module is integrated with a force sensor to monitor loads in real time, the corrosion module provides a temperature-controllable corrosion environment, and the scanning electrochemical microscope module achieves electrochemical scanning of the surface of the sample. The device can synchronously obtain a load-deformation curve, corrosion morphology and microcell electrochemical information under stress-corrosion-temperature multi-field coupling, and provides an effective technical means for deeply researching a stress corrosion mechanism of a material. The method comprises the steps of sample installation, corrosion solution preparation, electrode arrangement, tensile test, electrochemical scanning and the like, and has the advantages of simplicity and convenience in operation, comprehensive data, high precision and the like.

Description

Technical Field

[0001] This invention relates to the field of material stress corrosion testing technology, and in particular to a scanning electrochemical microscope in-situ stress corrosion testing device and method. Background Technology

[0002] Stress corrosion testing is a crucial method for assessing the performance degradation of materials under the combined effects of tensile stress and corrosive environments. Its test results directly impact the safety assessment and lifespan prediction of engineering equipment. This method has wide applications in key industrial sectors such as aerospace and petrochemicals. Based on the loading method, existing stress corrosion testing techniques are mainly divided into three categories: constant load method, constant deformation method, and slow strain rate method. Among these, the constant load method and constant deformation method suffer from excessively long test cycles, while the slow strain rate method, by continuously damaging the passivation film on the material surface at a constant strain rate, significantly accelerates crack propagation and offers the advantage of high testing efficiency.

[0003] Current research on stress corrosion faces two major technical bottlenecks: First, existing studies largely focus on macroscopic crack propagation behavior, neglecting the multi-scale evolution mechanism of the entire stress corrosion process, particularly the unclear microscopic mechanism of crack initiation. Although micro-area electrochemical testing techniques such as scanning electrochemical microscopy (e.g., the in-situ stress corrosion micro-area testing device and method disclosed in CN116046537A) can obtain information on surface electrochemical activity, their inherent characteristic of requiring horizontal scanning of the probe makes them difficult to integrate with conventional vertical stress corrosion testing systems. Second, the sample sealing method affects testing accuracy. According to the GB / T 15970.7-2017 standard, the sample clamping area should avoid contact with corrosive media to prevent galvanic corrosion interference. While existing dynamic sealing technologies (e.g., the rubber ring combined with magnetohydrodynamic scheme used in CN112284898B) can effectively prevent leakage, the dynamic friction between the seal and the sample can interfere with load measurement, leading to distorted stress data.

[0004] In summary, existing stress corrosion testing systems suffer from key technical problems such as poor compatibility of in-situ observation and the impact of sealing structures on measurement accuracy. There is an urgent need to develop new testing devices to resolve these technical contradictions. Summary of the Invention

[0005] The purpose of this invention is to provide an in-situ stress corrosion testing device and method using scanning electrochemical microscopy (SEM) to address technical problems in existing technologies, such as poor compatibility between stress corrosion testing and SEM, the impact of sealing structures on measurement accuracy, and insufficient multi-field coupling testing capabilities. This device achieves in-situ integration of the stress corrosion testing device and the SEM through a miniaturized horizontal structure design. It employs a static sealing scheme combining silicone seals, clamps, and bellows, replacing traditional dynamic seals with two static seals to avoid frictional interference and ensure load measurement accuracy. Furthermore, this device provides a stress-corrosion-temperature multi-field coupling testing environment, enabling simultaneous and accurate measurement of load-deformation curves, corrosion morphology, and micro-area electrochemical information during stress corrosion, providing a reliable technical means for in-depth research on stress corrosion mechanisms.

[0006] To achieve the above objectives, in one aspect, the present invention provides a scanning electrochemical microscope in-situ stress corrosion testing device, comprising: a base; a power transmission module disposed on the base, including a servo motor, a planetary gear reducer, and a transmission mechanism, for performing slow strain rate tensile testing on the sample; a clamping module, including a first clamping module and a second clamping module, respectively used to clamp both ends of the sample, wherein the first clamping module integrates a force sensor to monitor the tensile load in real time; a corrosion module, including a heating pool and a corrosion medium pool; a signal acquisition module, including a force sensor, a grating displacement acquisition module, and a temperature sensor; and a scanning electrochemical microscope module, including a reference electrode, a probe, a counter electrode, and a dual potentiostat, for performing electrochemical scanning on the sample surface and monitoring electrochemical information during the stress corrosion process in real time.

[0007] Furthermore, the transmission mechanism includes a multi-stage worm gear transmission assembly and a ball screw assembly.

[0008] Furthermore, the multi-stage worm gear transmission assembly includes worm one and worm wheel one, worm two and worm wheel two, and worm three and worm wheel three, which are used to achieve multi-stage deceleration and torque increase.

[0009] Furthermore, the ball screw assembly includes ball screw one and ball screw two, which are respectively connected to the clamping module through ball screw pair nuts to achieve bidirectional synchronous tensile testing of the sample.

[0010] Furthermore, the grating displacement acquisition module includes a scale and a grating reading head, used to measure the relative displacement between the first clamping module and the second clamping module.

[0011] Furthermore, the corrosion module also includes a sealing assembly comprising multiple bellows, silicone seals, and clamps to ensure the sealing and stability of the sample in the corrosive medium.

[0012] Furthermore, the probe in the scanning electrochemical microscope module is located above the sample, and the reference electrode and the counter electrode are located on both sides of the sample, forming a four-electrode system together with the sample.

[0013] Furthermore, the heating pool is equipped with heating rods and temperature sensors to precisely control the temperature of the corrosive medium.

[0014] As can be seen from the above technical solution, the testing device of this invention adopts a miniaturized horizontal structure, integrating power transmission, clamping, corrosion, signal acquisition, and scanning electrochemical microscopy modules. A static sealing scheme avoids the frictional interference of traditional dynamic seals, ensuring the accuracy of load measurement. This device can realize multi-field coupled testing of stress-corrosion-temperature, simultaneously acquiring load-deformation curves, corrosion morphology, and micro-area electrochemical information. It solves the problems of poor compatibility between scanning electrochemical microscopy and stress corrosion testing, and the influence of sealing structure on measurement accuracy in existing technologies. It provides an effective technical means for in-depth research on the stress corrosion mechanism of materials.

[0015] In another aspect, the present invention also provides a scanning electrochemical microscope in-situ stress corrosion testing method, based on the scanning electrochemical microscope in-situ stress corrosion testing device described in any of the above claims, the testing method comprising the following steps:

[0016] The sample is installed in the clamping module, and the seal between the sample and the corrosive medium pool is ensured.

[0017] A corrosive solution is injected into the corrosive medium pool, and the temperature of the corrosive medium is adjusted to a preset value by heating the pool.

[0018] Arrange the reference electrode, counter electrode, and probe together with the sample to form a four-electrode system, and adjust the distance between the probe and the sample.

[0019] The servo motor is started, and the sample is stretched at a slow strain rate through the power transmission module. At the same time, the load, displacement and temperature data are collected in real time using the signal acquisition module.

[0020] During the tensile process, the sample surface is electrochemically scanned using a scanning electrochemical microscope module to obtain corrosion morphology and electrochemical information.

[0021] Furthermore, during the tensile process, the sample displacement is monitored in real time by a grating displacement acquisition module, and the tensile load data is converted into an engineering stress-strain curve.

[0022] As can be seen from the above technical solution, the testing method of the present invention includes steps such as sample installation, preparation of corrosive solution, electrode arrangement, tensile testing and electrochemical scanning, and has the advantages of simple operation, comprehensive data and high accuracy. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is an overall structural diagram of the in-situ stress corrosion testing device for scanning electrochemical microscopy of the present invention;

[0025] Figure 2 This is a schematic diagram of the main structure of the device of the present invention;

[0026] Figure 3 This is a schematic diagram of the power transmission module in the device of the present invention;

[0027] Figure 4 This is a schematic diagram of the structure of the first clamping module in the device of the present invention;

[0028] Figure 5 This is a schematic diagram of the structure of the second clamping module in the device of the present invention;

[0029] Figure 6 This is a schematic diagram of the grating displacement acquisition module in the device of the present invention;

[0030] Figure 7 This is a schematic diagram of the corrosion module in the device of the present invention;

[0031] Figure 8 This is an integrated schematic diagram of the scanning electrochemical microscope module in the device of the present invention.

[0032] Figure 9 For the present invention in 10 -4 ~10 -6 Stress-strain curves for tensile engineering within a strain rate range of / s.

[0033] Figure 10 The stress-strain curves of the present invention under slow strain rate tensile engineering in air and 3.5% NaCl solution are shown.

[0034] Figure 11 The surface current distribution of the sample in different stages of stress corrosion in 3.5% NaCl solution, measured by scanning electrochemical microscopy according to this invention. Figure 1 ;

[0035] Figure 12 The surface current distribution of the sample in different stages of stress corrosion in 3.5% NaCl solution, measured by scanning electrochemical microscopy according to this invention. Figure 2 ;

[0036] Figure 13 The surface current distribution of the sample in different stages of stress corrosion in 3.5% NaCl solution, measured by scanning electrochemical microscopy according to this invention. Figure 3 ;

[0037] Figure 14 The surface current distribution of the sample in different stages of stress corrosion in 3.5% NaCl solution, measured by scanning electrochemical microscopy according to this invention. Figure 4 ;

[0038] Figure 15 The surface current distribution of the sample in different stages of stress corrosion in 3.5% NaCl solution, measured by scanning electrochemical microscopy according to this invention. Figure 5 .

[0039] In the diagram: 1. Base; 2. Optical axis support plate one; 3. Worm gear three; 4. Worm wheel three; 5. Optical axis; 6. Worm gear two; 7. Worm wheel two; 8. Optical axis support plate two; 9. Worm wheel one; 10. Worm gear one; 11. Optical axis support plate three; 12. Reducer fixing bracket; 13. Planetary gear reducer; 14. Support plate one; 15. Servo motor; 16. Ball screw pair nut one; 17. Displacement support seat three; 18. Ball screw one; 19. Displacement support 20. Ball screw pair nut two; 21. Ball screw pair nut seat one; 22. Force sensor; 23. Force sensor mounting plate; 24. Support plate two; 25. Ball screw pair nut three; 26. Ball screw two; 27. Corrosive medium pool; 28. Heating pool; 29. ​​Ball screw pair nut four; 30. Ball screw pair nut seat two; 31. Angular contact ball bearing one; 32. Angular contact ball bearing two; 33. Angular contact ball bearing three; 34. Angular contact... 35. Deep groove ball bearing 1; 36. Deep groove ball bearing 2; 37. Angular contact ball bearing 5; 38. Fixture 1; 39. Fixture cover 1; 40. Locking nut 2; 41. Locking nut 1; 42. Locking nut 3; 43. Fixture 2; 44. Fixture cover 2; 45. Scale; 46. Grating reading head; 47. Displacement support 1; 48. Limit switch 1; 49. Limit switch 2; 50. Clamp 4; 51. Silicone seal 3; 52. Bellows II; 53. Clamp III; 54. Circulating water connector I; 55. Heating rod; 56. Temperature sensor; 57. Clamp I; 58. Bellows I; 59. Silicone seal I; 60. Clamp II; 61. Silicone seal II; 62. Cylindrical hole I; 63. Circulating water connector II; 64. Sample; 65. Cylindrical hole II; 66. Silicone seal IV; 67. Reference electrode; 68. Probe; 69. Counter electrode; 70. Dual potentiostat. Detailed Implementation

[0040] 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.

[0041] This invention aims to overcome the shortcomings of existing technologies by providing a scanning electrochemical microscope (SEM) in-situ stress corrosion testing device and method. The device can construct a multi-field coupled testing environment of stress, corrosion, and temperature: a double static seal is achieved between the sample and the cylindrical orifice of the corrosion medium pool via silicone seals, clamps, and a bellows. The expandable nature of the bellows replaces the single dynamic seal commonly used in existing technologies with two static seals, thus ensuring the accuracy of load measurements. Simultaneously, the device adopts a miniaturized horizontal structure, facilitating in-situ integration with a scanning electrochemical microscope, and can simultaneously and accurately acquire the material's load-deformation curves, corrosion morphology, and micro-area electrochemical information during stress corrosion.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Reference Figures 1 to 8 As shown, this embodiment provides an in-situ stress corrosion testing device using a scanning electrochemical microscope, including a base 1, a power transmission module, a clamping module, a corrosion module, a signal acquisition module, and a scanning electrochemical microscope module. The power transmission module, clamping module, corrosion module, and signal acquisition module are all mounted on the base 1.

[0044] In this embodiment, the power transmission module is powered by a servo motor 15. After being reduced in speed and torque by a planetary gear reducer 13, a secondary worm gear, and a primary worm gear, the rotational motion is converted into linear motion via ball screws 18 and 26. This process drives ball screw nut 16, nut 20, nut 3, and nut 4 to perform linear motion, thereby achieving slow strain rate tensile testing of the sample 64. The secondary worm gear includes worm 10 and worm wheel 9, and the primary worm gear includes worm 6, worm 3, worm wheel 7, and worm wheel 4.

[0045] In this embodiment, the clamping module consists of a first clamping module and a second clamping module, which are installed opposite each other between the support plate 14 and the support plate 24, and are suspended above the base by the ball screw nut seat 21 and the ball screw nut seat 30.

[0046] In this embodiment, the corrosion module includes a heating pool 28 and a corrosion medium pool 27. The corrosion medium pool 27 is placed in the heating pool 28, and the heating pool 28 is fixed on the base 1.

[0047] In this embodiment, the signal acquisition module includes a force sensor 22, a grating displacement acquisition module, and a temperature sensor 56. The force sensor 22 is installed in the first clamping module and is used to acquire tensile load data; the grating displacement acquisition module is fixed on one side of the first clamping module and the second clamping module and is used to measure the relative displacement of the two clamping modules; the temperature sensor 56 is installed in the corrosive medium pool 27 and is used to detect the current temperature of the corrosive medium.

[0048] In this embodiment, the scanning electrochemical microscope module includes a reference electrode 67, a probe 68, a counter electrode 69, and a dual potentiostat 70. The probe 68 is located above the sample 64, while the reference electrode 67 and the counter electrode 69 are distributed on both sides of the sample 64.

[0049] The scanning electrochemical microscope in-situ stress corrosion testing device in this embodiment integrates multiple modules to achieve real-time monitoring of multiple parameters of materials during the stress corrosion process. It can accurately measure information such as load-deformation curves, corrosion morphology, and micro-area electrochemistry during stress corrosion, providing a valuable tool for studying the stress corrosion behavior of materials.

[0050] like Figure 3 As shown, in a specific embodiment, the power transmission module mainly includes a base 1, a servo motor 15, a planetary gear reducer 13, a reducer fixing bracket 12, a worm gear 10, a worm gear 2 6, a worm gear 3 3, a worm wheel 1 9, a worm wheel 2 7, a worm wheel 3 4, an optical axis support plate 1 2, an optical axis support plate 2 8, an optical axis support plate 3 11, an optical axis 5, an angular contact ball bearing 1 31, an angular contact ball bearing 2 32, an angular contact ball bearing 3 33, an angular contact ball bearing 4 34, an angular contact ball bearing 5 37, a deep groove ball bearing 1 35, a deep groove ball bearing 2 36, a support plate 1 14, a support plate 2 24, a ball screw 1 18, a ball screw 2 26, a ball screw auxiliary nut 1 16, a ball screw auxiliary nut 2 20, a ball screw auxiliary nut 3 25, a ball screw auxiliary nut 4 29, and other components. Worm 10 and worm wheel 19, worm 2 6 and worm wheel 2 7, worm 3 and worm wheel 3 4 form a multi-stage worm gear transmission assembly. Ball screw 18 and ball screw 26 form a ball screw assembly. The multi-stage worm gear transmission assembly and the ball screw assembly together form a transmission mechanism.

[0051] The servo motor 15 is coaxially and fixedly connected to the planetary gear reducer 13, which is fixed to the base 1 by the reducer fixing bracket 12.

[0052] Angular contact ball bearings 31, 32, and 33 are respectively mounted on the optical shaft 5 and fixed in the bearing holes reserved in the optical shaft support plates 2, 8, and 11. Angular contact ball bearings 34 and 37 are installed in the bearing holes reserved in the support plate 14, and deep groove ball bearings 35 and 36 are installed in the bearing holes reserved in the support plate 24. The front ends of ball screws 18 and 26 are respectively installed in the inner holes of angular contact ball bearings 34 and 37, and their rear ends are respectively installed in the inner holes of deep groove ball bearings 35 and 36.

[0053] Worm gear 10 clamps the output shaft of planetary gear reducer 13 via a set screw connection. Worm wheel 9 clamps the optical shaft 5 via a set screw connection and meshes with worm gear 10. Worm wheels 7 and 4 clamp the front ends of ball screw 18 and ball screw 26 via set screw connections, respectively. Worm gears 6 and 3 clamp the optical shaft 5 via set screw connections and mesh with worm wheels 7 and 4, respectively.

[0054] Ball screw auxiliary nut seat 1 21 and ball screw auxiliary nut seat 2 30 are mounted opposite each other on ball screw 1 18 and ball screw 2 26, while ball screw auxiliary nuts 1 16, ball screw auxiliary nut 2 20, ball screw auxiliary nut 3 25 and ball screw auxiliary nut 4 29 are mounted opposite each other in the reserved nut holes of ball screw auxiliary nut seat 1 21 and ball screw auxiliary nut seat 2 30.

[0055] Through the above structural design, the power transmission module can effectively transmit the power of the servo motor 15 to the ball screw after multi-stage deceleration and torque amplification, thereby achieving slow strain rate tension of the sample 64.

[0056] like Figure 4 , Figure 5 As shown, in one specific embodiment, the first clamping module includes a clamp 38, a clamp cover 39, a ball screw nut seat 21, a locking nut 41, a locking nut 40, a force sensor 22, and a force sensor fixing plate 23; the second clamping module includes a clamp 43, a clamp cover 44, a ball screw nut seat 30, and a locking nut 42.

[0057] In the first clamping module, one end of the force sensor 22 is coaxially mounted in the hole in the middle of the force sensor fixing plate 23 and fixed to the force sensor fixing plate 23 by a locking nut 41. The force sensor fixing plate 23 is fixedly connected to the ball screw auxiliary nut seat 21 through threaded holes on both sides. A second locking nut 40 is installed on the other end of the force sensor 22 for further fixation. A clamp 38 is coaxially connected to the force sensor 22 by threads, and a clamp cover 39 is connected to the clamp 38 through threaded holes to clamp the sample 64.

[0058] In the second clamping module, clamp 2 43 is installed in the reserved hole in the middle of ball screw auxiliary nut seat 2 30 and locked and fixed by locking nut 3 42, and is used to clamp the other end of sample 64.

[0059] With this structural design, the first clamping module and the second clamping module can firmly clamp the sample 64, and the force sensor 22 can accurately measure the load data of the sample 64 during the tensile process.

[0060] like Figure 6 As shown, in one specific embodiment, the grating displacement acquisition module includes a scale 45, a grating reading head 46, a first displacement support 47, a second displacement support 19, and a third displacement support 17. The first displacement support 47 is fixedly connected to the ball screw nut seat 21 via a threaded hole at its bottom. The second displacement support 19 is fixed to the sides of the ball screw nut seat 21 and the first displacement support 47. The third displacement support 17 is fixed to the side of the second ball screw nut seat 30 and is assembled inside the second displacement support 19.

[0061] In addition, limit switch 48 and limit switch 49 are fixed in the square groove of support plate 24, respectively, and are tightened through the screw holes on the side of support plate 24.

[0062] With this structural design, the grating displacement acquisition module can accurately measure the relative displacement between the first clamping module and the second clamping module, thereby providing accurate deformation data for stress corrosion testing.

[0063] like Figure 7 As shown, in one specific embodiment, the corrosion module mainly includes a heating pool 28 and a corrosion medium pool 27. The heating pool 28 is fixed on the base 1, and a heating rod 55 is placed in the heating pool 28 to provide heat. The corrosion medium pool 27 is fixed in a pre-reserved square groove in the heating pool 28, and a temperature sensor 56 is installed in a threaded hole in the middle of the corrosion medium pool 27 to monitor the temperature of the corrosion medium in real time. In addition, circulating water connector 1 54 and circulating water connector 2 63 are respectively installed in threaded holes on both sides of the corrosion medium pool 27 for the inlet and outlet of circulating water to control and regulate the temperature of the corrosion medium.

[0064] The corrosion module also includes a sealing assembly comprising multiple bellows, silicone seals, and clamps. The sample 64 is horizontally and centrally positioned within cylindrical holes 62 and 65 at the upper end of the corrosive medium pool 27. One end of bellows 58 is installed on the outside of cylindrical hole 62 and secured with clamp 57. Silicone seals 59 and 61 are fixed vertically to one end of the sample 64, while the other end of bellows 58 is coaxially fixed to the outside of silicone seals 61 and 59, and secured with clamp 60 to ensure a tight seal. Similarly, one end of bellows 52 is installed on the outside of cylindrical hole 65 and secured with clamp 53. Silicone seal 3 51 and silicone seal 4 66 are fixedly fixed at the other end of the sample 64, one above the other. The other end of bellows 2 52 is coaxially fixed to the outside of silicone seal 3 51 and silicone seal 4 66, and the three are locked together by clamp 4 50 to ensure the sealing and stability of the sample 64 in the corrosive medium.

[0065] With this design, the corrosion module can effectively control the temperature and medium flow of the corrosion environment, while ensuring the stability and sealing of sample 64 during the corrosion process, providing reliable conditions for accurate stress corrosion testing.

[0066] like Figure 1 and Figure 8 As shown, the scanning electrochemical microscope module mainly includes a reference electrode 67, a probe 68, a counter electrode 69, and a dual potentiostat 70. The reference electrode 67 and counter electrode 69, along with the sample 64 and probe 68, are immersed in the corrosive medium, forming a four-electrode system for scanning electrochemical microscopy (SECM). Probe 68 serves as the first working electrode, its potential precisely controlled, used to scan and detect local electrochemical signals above the surface of sample 64. Sample 64 serves as the second working electrode, its potential also independently controllable or monitored, used to study its surface corrosion and other electrochemical behaviors. Counter electrode 69 provides a current loop for the two working electrodes (probe 68 and sample 64). Reference electrode 67 provides a stable reference for the potential measurement and control of the two working electrodes. The dual potentiostat 70 is used to control and measure the voltage and current between sample 64 and probe 68. Probe 68 can perform three-dimensional high-resolution electrochemical scanning of the surface of sample 64, thereby acquiring electrochemical information of the sample 64 surface during stress corrosion testing.

[0067] This invention also provides a scanning electrochemical microscope in-situ stress corrosion testing method, based on the scanning electrochemical microscope in-situ stress corrosion testing device described in the above embodiments. The testing method includes the following steps:

[0068] Step 1: Sample Installation

[0069] The test sample is placed horizontally and centered in the cylindrical hole at the top of the corrosive medium pool. Silicone sealant, clamps, and a bellows are used to seal both sides of the sample to the cylindrical hole of the corrosive medium pool. Then, both ends of the sample are placed on the clamps on either side and the clamps are tightened to complete the sample installation.

[0070] Step 2: Preparation of Corrosion Solution and Temperature Control

[0071] A corrosive solution is injected into a corrosive medium tank. The temperature of the heating tank is controlled by adjusting the output voltage of the heating rods inside the tank, thereby using heat transfer to bring the corrosive solution in the tank to the required experimental temperature.

[0072] Step 3: Electrode arrangement and probe positioning

[0073] The reference electrode and the counter electrode are placed on opposite sides of the sample immersed in the corrosive medium. The probe is placed above the sample, and the distance between the probe and the sample is adjusted to the working distance. The probe serves as the first working electrode, and the sample serves as the second working electrode. Together with the reference electrode and the counter electrode, they form a four-electrode system.

[0074] Step 4: Tensile testing and electrochemical scanning

[0075] The slow strain rate tensile testing software was activated, and the specimen was subjected to slow strain rate tensile deformation at a preset speed. Tensile-load-displacement curves were obtained and converted into engineering stress-engineering strain curves. Load was maintained at different deformation stages, and a scanning electrochemical microscope was used to control the probe to perform high-resolution three-dimensional scanning of the specimen's micro-area to obtain the corrosion morphology of the specimen surface. Simultaneously, a dual potentiostat was used to control and measure electrochemical information such as current, voltage, and specific ion concentrations on the specimen surface. The following explanation uses a 6061 aluminum alloy specimen as an example. Figure 9 Demonstrated the use of 10 in dry air -4 / s、10 -5 / s、10 -6 The engineering stress-strain curves obtained by slow strain rate tensile tests at a strain rate of / s indicate that the device of the present invention can be used to carry out slow strain rate tensile tests at different strain rates. Figure 10 The results showed that the concentrations were 10 in dry air and 3.5% NaCl solution, respectively. -5 The comparison results of the engineering stress-strain curves obtained by the slow strain rate tensile test at a strain rate of / s show that the engineering stress-strain curve measured in 3.5% NaCl solution is significantly lower than the test results in dry air at the same strain rate, indicating that the device of the present invention can be successfully used for slow strain rate stress corrosion test. Figures 11 to 15 It demonstrates the effect of 10 in a 3.5% NaCl solution. -5Slow strain rate stress corrosion experiments were conducted at a strain rate of / s. In-situ surface current scanning was performed on a 200*200μm area in the center of the sample using scanning electrochemical microscopy at different deformation stages. The results showed that the surface current increased from −4.5×10⁻⁶ to −4.5×10⁻⁶. −11 A gradually increases to -3.1 × 10 −10 A. Strain accelerated the dissolution of the oxide film on the surface of 6061 aluminum alloy in 3.5% NaCl solution, indicating that the device of the present invention can perform in-situ monitoring of the electrochemical information of the surface micro-regions during the stress corrosion process of materials.

[0076] Through the above steps, the testing method of the present invention can realize real-time monitoring of multiple parameters of materials during stress corrosion, providing comprehensive and accurate data support for studying the stress corrosion behavior of materials.

[0077] Compared with the prior art, the embodiments of the present invention disclose at least the following beneficial effects:

[0078] This invention employs a servo motor-planetary reducer-two-stage worm gear reduction mechanism to achieve a wide range of speed reduction and torque amplification, providing a stable and slow speed for tensile testing of the specimen. The tensile strain rate range meets the speed requirements of slow strain rate tensile tests. This invention can simulate the actual stress conditions and service environments of materials, and can adjust the required strain rate, medium temperature, and corrosive medium type to explore the stress corrosion behavior of different metallic materials under different environments, and study the effects of multiple synergistic effects. This invention can be equipped with in-situ observation equipment to explore the stress corrosion cracking process, performing characterization and analysis at multiple scales, especially at the microscale. It uses a scanning electrochemical microscope to perform real-time in-situ micro-area scanning tests on the gauge length of the specimen, recording the three-dimensional morphology, micro-area current, voltage, and ion concentration evolution of the specimen during stress corrosion. This invention can accurately acquire tensile load-displacement curves and corrosive medium temperature in real time using force sensors, grating displacement sensors, and temperature sensors, and upload the data to host computer software for display, recording, and analysis. The invention adopts a compact design, is small in size, and can be easily integrated with various in-situ observation technologies to conduct multi-scale research on stress corrosion.

[0079] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0080] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A scanning electrochemical microscope in-situ stress corrosion testing device, characterized in that, include: Base (1); The power transmission module, set on the base (1), includes a servo motor (15), a planetary gear reducer (13) and a transmission mechanism, for achieving slow strain rate tension of the specimen (64); The clamping module includes a first clamping module and a second clamping module, which are used to clamp the two ends of the specimen (64) respectively. The first clamping module integrates a force sensor (22) to monitor the tensile load in real time. The corrosion module includes a heating tank (28) and a corrosive medium tank (27). The signal acquisition module includes a force sensor (22), a grating displacement acquisition module, and a temperature sensor (56). The scanning electrochemical microscope module includes a reference electrode (67), a probe (68), a counter electrode (69), and a dual potentiostat (70) for electrochemical scanning of the sample (64) surface and real-time monitoring of electrochemical information during stress corrosion.

2. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 1, characterized in that, The transmission mechanism includes a multi-stage worm gear transmission assembly and a ball screw assembly.

3. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 2, characterized in that, The multi-stage worm gear transmission assembly includes worm one (10) and worm wheel one (9), worm two (6) and worm wheel two (7), and worm three (3) and worm wheel three (4), which are used to achieve multi-stage deceleration and torque increase.

4. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 2, characterized in that, The ball screw assembly includes ball screw one (18) and ball screw two (26), which are connected to the clamping module through ball screw pair nuts to achieve bidirectional synchronous tensile testing of the sample (64).

5. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 1, characterized in that, The grating displacement acquisition module includes a scale (45) and a grating reading head (46) for measuring the relative displacement between the first clamping module and the second clamping module.

6. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 1, characterized in that, The corrosion module also includes a sealing assembly comprising multiple bellows, silicone seals and clamps, for ensuring the sealing and stability of the sample (64) in the corrosive medium.

7. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 1, characterized in that, The probe (68) in the scanning electrochemical microscope module is located above the sample (64), and the reference electrode (67) and the counter electrode (69) are located on both sides of the sample (64), together forming a four-electrode system with the sample (64).

8. The scanning electrochemical microscope in-situ stress corrosion testing device according to claim 1, characterized in that, The heating pool (28) is equipped with a heating rod (55) and a temperature sensor (56) for precise control of the temperature of the corrosive medium.

9. A scanning electrochemical microscope in-situ stress corrosion testing method, based on the scanning electrochemical microscope in-situ stress corrosion testing device according to any one of claims 1 to 8, characterized in that, Includes the following steps: The sample (64) is installed in the clamping module, and the seal between the sample (64) and the corrosive medium pool (27) is ensured. A corrosive solution is injected into the corrosive medium pool (27), and the temperature of the corrosive medium is adjusted to a preset value by heating the pool (28); Arrange a reference electrode (67), a counter electrode (69), and a probe (68) to form a four-electrode system together with the sample (64), and adjust the distance between the probe (68) and the sample (64); Start the servo motor (15) and stretch the specimen (64) at a slow strain rate through the power transmission module. At the same time, use the signal acquisition module to collect load, displacement and temperature data in real time. During the stretching process, the surface of the sample (64) was electrochemically scanned using a scanning electrochemical microscope module to obtain corrosion morphology and electrochemical information.

10. The in-situ stress corrosion testing method using scanning electrochemical microscopy according to claim 9, characterized in that, During the tensile process, the displacement of the specimen (64) is monitored in real time by the grating displacement acquisition module, and the tensile load data is converted into an engineering stress-strain curve.

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