A device and method for in-situ micro-area measurement of galvanic corrosion of dissimilar metals

Abstract

The application provides a kind of in-situ synchronous measurement device and method of dissimilar metal galvanic corrosion micro area, the device includes: environment simulation unit, sample clamping mechanism, electrochemical signal acquisition unit and real-time observation unit;Sample clamping mechanism is set in environment simulation unit, realizes the coplanar clamping of two or more dissimilar metal samples;Electrochemical signal acquisition unit, realize the real-time measurement and monitoring of the electrochemical parameters of sample;Real-time observation unit, realize time synchronization with electrochemical signal acquisition unit, high-resolution dynamic image acquisition of space same visual field.This application realizes real contact interface, and has micro area electrochemical quantitative analysis and topography visualization ability.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology of material corrosion, and more specifically, to a device and method for in-situ synchronous measurement of micro-area corrosion of dissimilar metal galvanic couplings. Background Technology

[0002] Galvanic corrosion is an accelerated corrosion phenomenon caused by the difference in electrode potential between dissimilar metals in an electrolyte environment. It is widely present in engineering structures such as ships, offshore platforms, aerospace equipment, and energy equipment, seriously threatening service safety and lifespan. Currently, domestic and international standards generally adopt the "spacing" connection method: two metal samples are installed on insulating supports at a certain distance, forming a galvanic couple through an external circuit, and the total current or open-circuit potential is measured. This method can only obtain the macroscopic average electrochemical response, but cannot reflect the local potential gradient, current distribution, and corrosion morphology evolution at the micrometer scale at the direct contact interface between the two metals. This results in a crude understanding of the mechanism and a lack of microscopic basis for protective design.

[0003] In recent years, although several improved galvanic corrosion testing devices have been proposed to simulate complex working conditions such as friction and wear, high temperature and high pressure, and flow erosion, such as the multi-condition galvanic corrosion testing device disclosed in Chinese patent CN113029931A, which ensures sealing through mutual compression between the sample, waterproof tape, rubber plug, and sample fixing hole, and achieves convenient loading and unloading, their detection methods are still limited to overall current / potential recording or offline morphology analysis, lacking in-situ, synchronous, and micro-area resolution capabilities. Especially in dynamic water environments, the perturbation of the interfacial double layer, uneven ion transport, and local micro-cell effects are significantly enhanced, making it even more difficult for traditional methods to capture the generation and expansion process of transient corrosion hotspots.

[0004] Furthermore, existing in-situ observation techniques (such as SVET and LEIS) are mostly used in single-working-electrode systems, making it difficult to adapt to the real-world engineering configuration of close coplanar contact between dissimilar metals. Factors such as contact pressure, interfacial gap, and oxide film integrity all affect the micro-region electrochemical behavior, while conventional fixtures are prone to introducing insulation contamination or wire interference, leading to measurement distortion. Currently, no publicly available technology can simultaneously satisfy the following four requirements: controllable dynamic water environment simulation, interference-free coplanar clamping, micron-level spatial resolution in-situ scanning, and high-resolution real-time imaging of corrosion morphology, achieving dynamic coupling characterization of interfacial electrochemistry and morphology.

[0005] Therefore, there is a need for a novel galvanic corrosion measurement device and method that is designed for real contact interfaces and has both micro-area electrochemical quantitative analysis and morphology visualization capabilities, in order to overcome current technical bottlenecks and support refined corrosion assessment and reliability design of dissimilar metal structures. Summary of the Invention

[0006] The purpose of this invention is to provide an in-situ synchronous measurement device and method for micro-area corrosion of dissimilar metals, which can simultaneously meet the following requirements: controllable dynamic water environment simulation, interference-free coplanar clamping, micron-level spatial resolution in-situ scanning and high-resolution real-time imaging of corrosion morphology, achieving the goal of facing real contact interfaces and possessing both micro-area electrochemical quantitative analysis and morphology visualization capabilities.

[0007] To achieve the above objectives, this invention provides an in-situ synchronous measurement device and method for micro-area corrosion of dissimilar metals. The technical solution of this invention is implemented as follows:

[0008] A device for in-situ synchronous measurement of micro-area corrosion of dissimilar metal galvanic electrodes, comprising:

[0009] The environmental simulation unit includes: an electrolytic cell, an inlet pipe, and an outlet pipe, wherein the inlet pipe and the outlet pipe are connected to the electrolytic cell;

[0010] The sample clamping mechanism is set inside the electrolytic cell to achieve coplanar clamping of two or more dissimilar metal samples.

[0011] An electrochemical signal acquisition unit is located on one side of the working surface of the sample to realize real-time measurement and monitoring of the electrochemical parameters of the sample.

[0012] A real-time observation unit is set up near the sample to achieve dynamic image acquisition that is synchronized in time and in the same field of view as the electrochemical signal acquisition unit.

[0013] Furthermore, the environmental simulation unit also includes an overflow port, a flow meter, and a valve. The overflow port is located on the side wall of the electrolytic cell, and the flow meter and valve are both located on the inlet pipe and / or outlet pipe to control the liquid in the electrolytic cell.

[0014] Furthermore, the sample clamping mechanism includes a stage and bolts, with the sample clamped on the stage and secured by the bolts; the bolts are insulated screw-in bolts.

[0015] Furthermore, the bolt has a tapered pressure head at its front end, which allows for controllable screwing depth and provides an axial preload feedback structure.

[0016] Furthermore, the electrochemical signal acquisition unit includes an SVET probe, which performs two-dimensional step scanning within a vertical distance of 50~200μm from the sample contact interface; the sample is connected to the electrochemical workstation test cable via a wire to detect the potential distribution and changes.

[0017] Furthermore, the device also includes an external data acquisition and processing unit for synchronously receiving and correlating analysis of electrochemical signals and morphology video streams.

[0018] A method for in-situ synchronous measurement of micro-areas of dissimilar metal galvanic corrosion, using the aforementioned device, includes the following steps:

[0019] S1, Sample preparation and pretreatment;

[0020] S2, sample coplanar clamping and electrical connection sealing;

[0021] S3, dynamic water environment construction and electrolyte injection;

[0022] S4, start the electrochemical signal acquisition unit for real-time measurement and monitoring, and simultaneously start the real-time observation unit to record the evolution of the interface morphology;

[0023] S5, collect the vibration potential difference ΔE(x,y) at each measuring point and plot the current density distribution;

[0024] S6. Analyze the hot spots of current density and the locations of pit initiation / expansion in the morphology images to establish the mapping relationship between electrochemical activity and morphological damage.

[0025] Furthermore, the dissimilar metal samples have uniform dimensions and their surfaces are polished smooth.

[0026] Furthermore, when plotting the current density distribution diagram, the formula is used. The current density J is converted, where σ is the electrolyte conductivity and A is the probe amplitude.

[0027] Furthermore, the electrolyte conductivity σ is measured in real time by a conductivity sensor; the probe amplitude A is 10~30 μm.

[0028] Compared with existing technologies, the in-situ synchronous measurement device and method for micro-area corrosion of dissimilar metals described in this invention have the following advantages:

[0029] 1. High spatial resolution. Enables in-situ current density mapping at the micrometer level, locating corrosion hotspots on the anodic side (such as the current concentration area at the Q235 steel interface), with an accuracy of ±5μm spatial overlap (SVET and morphology field of view). This fills the gap in "simultaneous electrochemical and morphological characterization of micro-areas at direct contact interfaces".

[0030] 2. Guaranteed Interface Authenticity. Utilizing insulated, screw-in clamping bolts, it achieves coplanar, tight, and stable physical contact between dissimilar metals without localized stress concentration or electrical interference, ensuring controllable fluctuations in contact pressure and resistance. This solves the measurement distortion problems caused by stress corrosion, interface gaps, and insulation contamination introduced by conventional fixtures.

[0031] 3. Environmental Compatibility. The flow rate of the environmental simulation unit is continuously adjustable, including overflow stabilization design, supporting various real-world marine / industrial service scenarios such as still and dynamic water environments. It breaks through the limitations of traditional static immersion, achieving in-situ observation of the coupled "flow-electrochemical-morphology" three fields.

[0032] 4. Multimodal data synergy. SVET current density scanning and high-definition long-focal-length macro video acquisition are strictly synchronized in time and spatially in the same field of view. It supports pixel-by-pixel correlation analysis of current density distribution maps and dynamic frames of corrosion morphology, and can realize closed-loop analysis of "where corrosion occurs (electrochemical activity) → how corrosion occurs (morphological evolution) → why corrosion occurs (mechanism mapping)".

[0033] 5. Reliability of quantitative analysis. The built-in temperature-compensated conductivity sensor measures the electrolyte conductivity σ in real time. The probe amplitude A is set to 10~30 μm. Combined with the formula, the absolute quantification of current density is achieved, providing data support for corrosion rate prediction and evaluation. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the external overall structure of the in-situ synchronous measurement device for micro-area corrosion of dissimilar metal galvanic couplings as described in Embodiment 1 of the present invention.

[0035] Figure 2 This is a schematic diagram of the internal structure of the in-situ synchronous measurement device for micro-area corrosion of dissimilar metal galvanic couplings as described in Embodiment 1 of the present invention.

[0036] Figure 3 This is a top view of the internal structure of the in-situ synchronous measurement device for micro-area corrosion of dissimilar metal galvanic plates as described in Embodiment 1 of the present invention.

[0037] Figure 4 This is a current density distribution diagram of TA2 and Q235 steel, two dissimilar metals described in Embodiment 2 of the present invention, after being immersed in natural seawater for 24 days.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Environmental simulation unit; 2. Sample clamping mechanism; 3. Electrochemical signal acquisition unit; 4. Real-time observation unit; 5. Sample 1; 6. Sample 2; 10. Overflow port; 11. Inlet pipe; 12. Outlet pipe; 13. Optical observation window; 14. Flow meter; 15. Valve 1; 16. Valve 2; 17. Electrolytic cell; 22. Support; 23. Stage; 24. Wire; 27. Bolt; 40. Camera; 41. Connecting rod; 42. Base. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are only some, not all, of the embodiments of this invention. The specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0041] This invention provides an in-situ synchronous measurement device for micro-area corrosion of dissimilar metals, comprising an environmental simulation unit 1, a sample clamping mechanism 2, an electrochemical signal acquisition unit 3, a real-time observation unit 4, and an external data acquisition and processing unit.

[0042] The environmental simulation unit 1 includes an electrolytic cell 17, an inlet pipe 11, an outlet pipe 12, an overflow port 10, a valve, and a flow meter 14. The inlet pipe 11 and the outlet pipe 12 are connected to the electrolytic cell 17, forming a fluid cavity that can switch between static and dynamic water environments. The overflow port 10 is located on the side wall of the electrolytic cell 17, and the flow meter 14 and the valve are both located on the inlet pipe 11 and / or the outlet pipe 12, used to control the liquid within the fluid cavity.

[0043] The sample clamping mechanism 2, located within the electrolytic cell 17, enables the coplanar clamping of two or more dissimilar metal samples. The sample clamping mechanism 2 includes a stage 23 for clamping the samples and bolts 27, ensuring complete coplanarity and tight physical contact between the surfaces of the two or more samples. Bolt 27 is an insulated, screw-in clamping bolt with a tapered indenter at its front end. The screw-in depth is controllable, and it features an axial preload feedback structure, ensuring uniform pressure and stable contact resistance on the contact surfaces of the two metal samples without introducing additional electrochemical noise.

[0044] An electrochemical signal acquisition unit 3, positioned above the sample and cooperating with the sample clamping mechanism 2, enables real-time measurement and monitoring of the sample's electrochemical parameters. The electrochemical signal acquisition unit 3 includes an SVET probe, which performs a two-dimensional step scan within a range of 50 μm to 200 μm normal to the sample contact interface. The sample is connected to the electrochemical workstation test cable via a wire 24, enabling the detection of potential distribution and changes, and real-time output of micro-area current density distribution data.

[0045] The real-time observation unit 4 includes a camera 40, which enables high-resolution dynamic image acquisition that is synchronized with the electrochemical signal acquisition unit 3 in time and has the same field of view in space. The real-time observation unit 4 has the ability to adjust the pitch angle by ±15°, the horizontal rotation by 360°, and the Z-axis height by 50mm, and is equipped with a laser crosshair positioner to ensure that the spatial overlap deviation between the center of the camera's field of view and the SVET scanning origin is ≤±5μm.

[0046] An external data acquisition and processing unit is used to synchronously receive and correlate SVET current density signals and topographic video streams.

[0047] This invention also provides an in-situ synchronous measurement method for micro-area corrosion of dissimilar metals, using the above-mentioned device, and includes the following steps:

[0048] S1, Sample preparation and pretreatment. Dissimilar metal samples have consistent dimensions and their surfaces are polished smooth.

[0049] S2, Coplanar clamping and electrical connection sealing of the sample. The sample is placed in the clamping mechanism to form a coplanar direct contact interface; the wire 24 is led out from the non-working surface of the sample and completely sealed.

[0050] S3, Dynamic water environment construction and electrolyte injection. Connect flow meter 14 to the regulating valve and set the flow rate; inject electrolyte into electrolysis cell 17 to maintain a constant water level and steady flow. The electrolyte can be natural seawater, artificial seawater, or sodium chloride solution. An external circulation system allows the electrolyte to flow in through the inlet and out through the outlet, with the flow meter enabling precise flow rate control. During static testing, close the outlet valve and, once the liquid level is 5mm–10mm above the sample surface, close the inlet valve.

[0051] S4, start the electrochemical signal acquisition unit 3 for real-time measurement and monitoring, and simultaneously start the real-time observation unit 4 to record the evolution of interface morphology, ensuring complete coverage of the corrosion induction period and early development period.

[0052] S5. Collect the vibration potential difference ΔE(x,y) at each measuring point and plot the current density distribution. When plotting the current density distribution, use the formula J(x,y)=−σ·ΔE(x,y) / A to convert the current density J(x,y), where σ is the electrolyte conductivity and A is the probe amplitude. The electrolyte conductivity σ is measured in real time by a built-in temperature-compensated conductivity sensor; the probe amplitude A is 10~30μm.

[0053] Identify the maximum current density J on the anode side based on the current density distribution diagram. max The camera uses its spatial coordinates (x0, y0) to perform multiple digital zooms and focus lock on the area in question, enabling enhanced tracking and observation of key corrosion sites.

[0054] S6. Analyze the hot spots of current density and the locations of pit initiation / expansion in the morphology images to establish the mapping relationship between electrochemical activity and morphological damage.

[0055] Example 1

[0056] This embodiment provides a device for simultaneous in-situ, electrochemical morphology measurement of micro-area interfaces for direct contact corrosion of dissimilar metals, as shown in the attached figure. Figures 1-3As shown. Its core lies in achieving high-resolution coupled observation of electrochemical response and dynamic corrosion morphology under the same interface, at the same time, and in the same coordinate system through the synergistic integration of mechanical structure design and multi-physics fields.

[0057] The device consists of four core modules: environmental simulation unit 1, sample clamping mechanism 2, electrochemical signal acquisition unit 3, and real-time observation unit 4. The modules work together to achieve dynamic coupling characterization of electrochemical response and corrosion morphology under the same interface, the same time, and the same coordinate system.

[0058] The environmental simulation unit 1 provides a closed, visible, and adjustable flow electrolysis environment, including: an electrolysis cell 17, an inlet pipe 11, an outlet pipe 12, an overflow port 10, and a flow meter 14.

[0059] Electrolytic cell 17 serves as the system's support and environmental constraint base. Electrolytic cell 17 is a cubic container with a platform 23 at the bottom of its inner cavity. Its side walls have inlet and outlet ports, connected to inlet pipe 11 and outlet pipe 12, respectively. Overflow port 10 is located on the upper part of the side wall of electrolytic cell 17 to maintain a constant liquid level within the cell, preventing overflow due to fluctuations in inlet flow or temperature changes. Overflow port 10, along with inlet pipe 11 and outlet pipe 12, forms a pressure-stabilizing and flow-stabilizing loop, eliminating liquid level fluctuations and turbulent disturbances, ensuring the stability of SVET measurements and the clarity of optical imaging.

[0060] A valve 15 is installed on the inlet pipe 11, and a valve 26 is installed on the outlet pipe 12. These valves are used to independently control the inflow and outflow of the electrolyte, enabling precise switching and stable maintenance of static and dynamic water environments. Opening valve 15 and closing valve 26 allows for the injection of electrolyte into the electrolytic cell and cessation of flow, creating a static water environment. Simultaneously opening both valves and adjusting them in conjunction with the flow meter 14 establishes a controllable dynamic water circulation environment. Individual adjustment of either valve allows for fine-tuning of the liquid level, flow field distribution, and pressure balance within the cell, ensuring the stability of SVET measurements and optical observations. The electrolyte flows through the main pathway, which consists of the inlet pipe 11, flow meter 14, valve 15, electrolytic cell 17, outlet pipe 12, and valve 26. The overflow port 10 connects to the return pipe to the storage tank. Preferably, all pipelines are made of polytetrafluoroethylene (PTFE) to prevent interference from metal ion precipitation.

[0061] An optical observation window 13 is also provided on the side wall of the electrolytic cell 17 to provide a distortion-free, high-transmittance lateral observation channel. Preferably, the optical observation window 13 is made of anti-reflective coated quartz glass to ensure distortion-free optical path. Specifically, the optical observation window 13 is located at the bottom of the side wall of the electrolytic cell 17 and is made of transparent, corrosion-resistant quartz glass to facilitate device installation and auxiliary positioning.

[0062] The top of the electrolytic cell 17 is equipped with an SVET probe access hole and a camera 40 mounting interface. The flow meter 14 is installed on the inlet pipe 11 or the outlet pipe 12 to accurately measure and regulate the electrolyte flow rate, thereby realizing quantitative switching and stable simulation of static and dynamic water environments.

[0063] The sample clamping mechanism 2 includes a bracket 22, a stage 23, a wire 24, and a bolt 27. The sample clamping mechanism 2 is located inside the electrolytic cell 17 and can simultaneously clamp two or more dissimilar metals to conduct multiple sets of comparative galvanic corrosion tests.

[0064] like Figure 2 As shown, the samples include sample 5 (sample one) and sample 6 (sample two). The samples are clamped on the stage 23 and secured by a pair of insulated, screw-in bolts 27. A copper wire 24 is led out from the non-working surface of the sample for electrochemical signal acquisition. Bolts 27 are made of insulating material, ensuring reliable fixation and clamping of the metal samples while avoiding the introduction of additional electrical contact interference and preventing the clamp itself from participating in the thermocouple circuit. Specifically, bolts 27 are insulated, screw-in clamping bolts made of polytetrafluoroethylene (PTFE) or ceramic. The front end of bolt 27 has a conical indenter, allowing for controllable screw-in depth and an axial preload feedback structure, ensuring uniform pressure and stable contact resistance on the contact surfaces of the two metal samples without introducing additional electrochemical noise.

[0065] Specifically, sample 5 is pure titanium TA2, and sample 6 is carbon structural steel Q235. Both samples 5 and 6 are cuboid specimens, embedded side-by-side in the positioning grooves on the stage 23, and simultaneously screwed in by bolts 27 to achieve coplanar clamping, preventing contact misalignment or edge lifting. The lead wire 24 extends from the non-working end of the sample, passes through the sealing plug, and connects to an external electrochemical workstation. The sealing plug has a double-layer structure: an inner layer of silicone rubber hot-pressed and an outer layer of epoxy resin potting, achieving an IP68 waterproof seal at the lead wire 24, completely blocking the creepage path of the solution along the lead wire 24. The measured contact resistance is <10mΩ, meeting the requirements for microvolt-level potential gradient measurement.

[0066] The electrochemical signal acquisition unit 3 includes an SVET probe and a displacement platform. The electrochemical signal acquisition unit 3 is positioned directly above the sample. The SVET probe is driven by a three-dimensional precision displacement platform (not shown), whose scanning plane is parallel to the sample surface. The SVET probe signal is preamplified and input to the SVET host, synchronously outputting a ΔE(x,y) data stream.

[0067] Preferably, the SVET probe tip is kept at a constant distance of 100 μm from the normal distance to the contact interface, with a step size of 25~100 μm, achieving a lateral resolution ≤100 μm and accurately locating the concentrated anolyte current area. The vibration frequency is set to 80 Hz to effectively suppress double-layer capacitance interference, resulting in a signal-to-noise ratio >40 dB. A conductivity sensor is integrated into the inlet pipe to acquire the σ value in real time; the probe amplitude A is set to 10~30 μm. Substituting into the formula... This completes the absolute quantization of current density.

[0068] The real-time observation unit 4 includes a camera 40, a connecting rod 41, and a base 42. The camera 40 is a high-definition macro camera, fixed above the side wall of the electrolytic cell 17 via the base 42. Preferably, the angle between the lens axis of the camera 40 and the normal to the contact interface is 15°, ensuring that the field of view covers the entire 2mm × 2mm SVET scanning area. Light sources are symmetrically arranged around the lens of the camera 40; the light sources are a ring-shaped LED array used to eliminate shadows and glare.

[0069] The device also includes an external data acquisition and processing unit for synchronously receiving and correlating the SVET current density signal with the topographic video stream. The image data is transmitted to the computer in real time, strictly synchronized with the SVET data stream.

[0070] Example 2

[0071] This embodiment provides an in-situ synchronous measurement method for micro-area corrosion of dissimilar metals. Taking the direct contact interface of TA2 / Q235 steel as the research object, and in a simulated electrolyte of natural seawater, it combines dynamic water environment with synchronous observation of micro-area electrochemical-morphological processes to achieve a complete quantitative characterization of the micro-area corrosion behavior of the interface. The specific steps are as follows:

[0072] S1, Sample preparation and pretreatment.

[0073] S11. Take TA2 titanium plate and Q235 steel plate respectively, cut them into 50mm×25mm×5mm samples, namely sample 5 and sample 6.

[0074] S12, use 400#~1500# silicon carbide sandpaper to polish step by step until the surface is smooth like a mirror, removing the oxide layer and scratches.

[0075] S13, ultrasonically cleaned in anhydrous ethanol for 10 minutes, then dried with cold air for later use;

[0076] Ensure that the sample surface is uniform, clean, and has good coplanarity, eliminating the interference of surface roughness and contamination on the interfacial electrical contact resistance and local current distribution, and providing a repeatable initial reference for micro-area measurement.

[0077] S2, the sample is coplanarly clamped and electrically connected and sealed.

[0078] S21. Place the TA2 and Q235 samples side by side in the groove of the stage 23. Apply uniform pressure through the insulated screw-in clamping bolt 27 to make the working surfaces of the two samples strictly coplanar and tightly fitted (contact pressure about 1MPa), forming a gapless direct contact interface, realizing the physical reproduction of the "bolt-tightening" direct contact in real engineering.

[0079] S22, a copper wire 24 is led out from the non-working surface of the sample, and the wire 24 exits from the side opening of the stage 23. The wire 24 passes through a sealing plug and the outlet is completely sealed with fast-curing epoxy putty; after the putty has completely cured, the stage 23 is installed onto the support. Sealing the outlet of the wire 24 can completely block lateral electrolyte leakage and parasitic current paths, ensuring that the SVET scan signal responds only to the target interface area, significantly improving the spatial fidelity and signal-to-noise ratio of micro-area current density measurement.

[0080] S23. A high-precision level is used to adjust the support, ensuring that the levelness deviation of the sample working surface is ≤0.02°. This ensures that the sample working surface is on the same horizontal reference plane, thereby guaranteeing that when the scanning vibration electrode (SVET) performs micro-area potential scanning at a distance of approximately 100 μm from the surface, the probe maintains a constant and uniform working distance from the entire sample surface (especially the interface between dissimilar metals).

[0081] S3, dynamic water environment construction and electrolyte injection.

[0082] S31 connects the flow meter 14 to the regulating valve and sets the flow rate to 0.3 m / s to simulate low-speed ocean current conditions.

[0083] S32, inject natural seawater into electrolytic cell 17, controlling the liquid level below the overflow port 10 and approximately 5mm~10mm above the sample, maintaining a constant water level and steady flow. Keep the metal sample immersed in natural seawater for 24 hours.

[0084] Dynamic water conditions accelerate interfacial mass transfer and reduce the thickness of the diffusion layer, more realistically reflecting the scouring effect of anodic dissolution products and the enhanced cathodic oxygen reduction kinetics during marine service, thus making the measured micro-area current density distribution correlated with actual operating conditions.

[0085] S4, simultaneous acquisition of micro-area electrochemistry and morphology.

[0086] S40. Set up the electrochemical signal acquisition unit and the real-time observation unit. Move the probe of the micro-area electrochemical workstation with the external scanning vibrating electrode to approximately 100 μm above the sample working surface. Connect the test leads of each metal sample to the corresponding terminals of the micro-area electrochemical workstation. Set the scanning vibrating electrode to a scanning rate of 100 μm / s, a scanning range of 1 mm × 40 mm, an amplitude of 30 μm, and a frequency of 80 Hz. Before testing, adjust the camera angle and focal length of the real-time observation unit to enable continuous in-situ observation of the microstructure of the anode sample surface.

[0087] S41, activate the scanning vibration electrode (SVET) system to perform in-situ measurement of the current density distribution on the sample surface. The probe is a Pt / Ir microelectrode, the scanning step size is 100 μm, and the scanning range covers the entire contact interface of TA2 / Q235 and a 20 mm area on each side.

[0088] S42, simultaneously activates the high-definition telephoto macro camera 40, and uses the multi-angle adjustable bracket 22 to face the center of the interface, turning on the LED ring cold light source.

[0089] S43 continuously outputs SVET vibration potential difference ΔE(x,y) data and corresponding interface morphology images. It achieves micron-level spatial resolution synchronous mapping of current density and morphology; it can intuitively identify the initiation location and evolution sequence of current concentration areas on the anode side of Q235 (such as edges and micro-defects) and initial pitting / dissolution grooves, and establish a direct causal relationship between local electrochemical activity and micro-morphological damage.

[0090] S5, collect the vibration potential difference ΔE(x,y) at each measuring point and plot the current density distribution.

[0091] Based on the vibration potential difference ΔE(x,y) of the original SVET voltage signal, according to the formula The local current density J is calculated, where σ is the electrolyte conductivity, ΔE is the potential gradient measured by the probe, and A is the probe amplitude. The electrolyte conductivity σ is measured in real time using a built-in temperature-compensated conductivity sensor; the probe amplitude A is set to 10~30μm.

[0092] Identify the maximum current density J on the anode side based on the current density distribution diagram. max The camera 40 uses 10× digital zoom and focus lock on the coordinate area to achieve enhanced tracking and observation of key corrosion sites.

[0093] S6. Analyze the hot spots of current density and the locations of pit initiation / expansion in the morphology images to establish a mapping relationship between electrochemical activity and morphological damage. Overlay the morphology images and current density contour maps to calibrate the location of the maximum current density at the anode and the average current density at the interface.

[0094] The traditional macroscopic "average current" is upgraded into a quantitative parameter set with spatial coordinates, supporting the quantitative assessment of interface corrosion inhomogeneity, the inversion of local corrosion rates, and the verification of mechanism models.

[0095] like Figure 4 The figure shows a micro-area current density distribution cloud map measured by scanning vibrating electrode technique (SVET) at the dissimilar metal interface of TA2 / Q235 steel. The spatial resolution is 100 μm, and the measurement environment is a simulated natural seawater dynamic water condition. In the figure, the horizontal axis X represents the horizontal scanning position, the vertical axis Y represents the vertical scanning position, and the color bars represent the current density J variation gradient. Among them: the red to yellow area represents the anodic dissolution region, where the current density is positive (J>0), that is, the metal undergoes an oxidation reaction; the blue to cyan area represents the cathodic reduction region, where the current density is negative (J<0), that is, the cathodic reaction, such as oxygen reduction, is dominant.

[0096] An arrow is marked at approximately 20mm from X, indicating the direct contact boundary between the TA2 titanium plate and the Q235 carbon steel.

[0097] The area on the left with X < 20mm is the Q235 steel region. The image shows a large area of ​​high positive current density (red-orange), with a maximum value approaching +16.4μA / cm². 2 This indicates that Q235 steel, acting as the anode under the action of a galvanometer, is dissolved more rapidly, resulting in significant localized corrosion.

[0098] The area on the right side with an X>20mm region is the TA2 titanium plate area. The overall color ranges from dark blue to light blue, and the current density is negative (-7.6μA / cm²). 2 Up to -1.6 μA / cm 2 This indicates that TA2, as the cathode, mainly undergoes the oxygen reduction reaction and is protected by the cathode.

[0099] In the region X = 15 mm ~ 22 mm, the current density rapidly transitions from positive to negative, forming a steep gradient. This region is the core driving area for galvanic corrosion, where electrons transfer from Q235 to TA2, forming a macroscopic galvanic cell circuit. The high current density is concentrated on the Q235 side near the interface, indicating that corrosion mainly occurs in the near-interface region of the anolyte metal.

[0100] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "tail end," "head end," and "center," are only used to explain the relative positional relationships and connection situations between components in a specific state. They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where both A and B are satisfied simultaneously.

[0101] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A device for in-situ synchronous measurement of micro-area corrosion of dissimilar metal galvanic electrodes, characterized in that, include: The environmental simulation unit (1) includes an electrolytic cell (17), an inlet pipe (11) and an outlet pipe (12), wherein the inlet pipe (11) and the outlet pipe (12) are connected to the electrolytic cell (17); The sample clamping mechanism (2) is set inside the electrolytic cell (17) to achieve coplanar clamping of two or more dissimilar metal samples; An electrochemical signal acquisition unit (3) is set on one side of the working surface of the sample to realize real-time measurement and monitoring of the electrochemical parameters of the sample; The real-time observation unit (4) is set near the sample to realize dynamic image acquisition that is synchronized with the electrochemical signal acquisition unit (3) in time and in the same field of view in space.

2. The apparatus according to claim 1, characterized in that, The environmental simulation unit (1) also includes an overflow port (10), a flow meter (14) and a valve. The overflow port (10) is located on the side wall of the electrolytic cell (17), and the flow meter (14) and valve are located on the inlet pipe (11) and / or outlet pipe (12) to control the liquid in the electrolytic cell (17).

3. The apparatus according to claim 1, characterized in that, The sample clamping mechanism (2) includes a stage (23) and a bolt (27). The sample is clamped on the stage (23) and fixed by the bolt (27). The bolt (27) is an insulated screw-in bolt.

4. The apparatus according to claim 3, characterized in that, The bolt (27) has a conical pressure head at the front end, and the screwing depth is controllable and has an axial preload feedback structure.

5. The apparatus according to claim 1, characterized in that, The electrochemical signal acquisition unit (3) includes an SVET probe, which performs two-dimensional step scanning within a vertical distance of 50~200μm from the sample contact interface; the sample is connected to the electrochemical workstation test cable via a wire (24) to detect the potential distribution and changes.

6. The apparatus according to claim 1, characterized in that, The device also includes an external data acquisition and processing unit for synchronously receiving and correlating analysis of electrochemical signals and morphology video streams.

7. A method for in-situ synchronous measurement of micro-area corrosion of dissimilar metal galvanic electrodes, characterized in that, The measurement using the apparatus according to any one of claims 1 to 6 includes the following steps: S1, Sample preparation and pretreatment; S2, sample coplanar clamping and electrical connection sealing; S3, dynamic water environment construction and electrolyte injection; S4, start the electrochemical signal acquisition unit (3) to perform real-time measurement and monitoring, and simultaneously start the real-time observation unit (4) to record the evolution of interface morphology; S5, collect the vibration potential difference ΔE at each measuring point and draw the current density distribution map; S6. Analyze the hot spots of current density and the locations of pit initiation / expansion in the morphology images to establish the mapping relationship between electrochemical activity and morphological damage.

8. The method according to claim 7, characterized in that, The dissimilar metal samples have uniform dimensions and their surfaces are polished smooth.

9. The method according to claim 7, characterized in that, When plotting the current density distribution diagram, the formula is used. The current density J is converted, where σ is the electrolyte conductivity and A is the probe amplitude.

10. The method according to claim 9, characterized in that, The electrolyte conductivity σ is measured in real time by a conductivity sensor; the probe amplitude A is 10~30μm.

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