Visual simulation deep sea long-period in-situ electrochemical corrosion-aging test system

Abstract

The invention belongs to the technical field of high-pressure tests, and discloses a visual simulation deep-sea long-period in-situ electrochemical corrosion-aging test system which comprises an autoclave, a temperature control system, an online monitoring and data acquisition system and a pressure control system, the temperature control system comprises a high-low temperature all-in-one machine, a heat exchange jacket and a heat exchange hose; the heat exchange jacket exchanges heat for the outer wall of the kettle body so as to adjust the temperature in the kettle body; the pressure control system comprises an air compressor, a liquid pressurization system and a high-pressure pipeline, and liquid in the kettle body is pressurized through the liquid pressurization system; the online monitoring and data acquisition system comprises a visual assembly and an electrochemical measurement assembly which are mounted in the kettle cover, the visual assembly comprises a high-voltage camera and a high-voltage illuminating lamp, the electrochemical measurement assembly comprises a platinum electrode and a reference electrode, and the high-voltage camera is used for acquiring a corrosion picture; and the visual assembly transmits a signal to an external instrument communication box or an electrochemical workstation through the high-pressure watertight connector.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-voltage test, and particularly relates to a visual simulation deep-sea long-period in-situ electrochemical corrosion-aging test system. BACKGROUND

[0002] With the deepening of the exploration and development of marine resources, various types of deep-sea submersibles, underwater robots and seabed observation networks and other marine engineering equipment need to serve in hundreds or even thousands of meters deep sea extreme environment for a long time. The deep sea environment has the characteristics of high hydrostatic pressure and low temperature, which poses a severe challenge to the material properties, structural strength and sealing reliability of the core components of the equipment. In order to avoid high economic losses and safety risks caused by equipment failure, the equipment must be fully simulated in deep-sea environment before formal deployment through ground experimental devices to conduct comprehensive performance testing and reliability evaluation.

[0003] In order to achieve the above-mentioned goal, the existing technology usually uses a high-pressure experimental device to simulate the high-pressure condition of the deep sea. However, the existing deep-sea environment simulation experimental device has the following technical defects: it is difficult to effectively couple the high-pressure and low-temperature environment. Most of the existing high-pressure experimental devices can only simulate the high-pressure environment, ignoring the low-temperature condition commonly existing in the deep sea. The mechanical and corrosion behavior of materials in a single high-pressure environment is significantly different from that in a "high-pressure-low-temperature" coupled environment. This distortion of the simulated environment causes the experimental results to be unable to fully reflect the performance degradation law of the equipment in the real service environment, thereby affecting the accuracy of its life prediction and reliability evaluation.

[0004] The pressure control mode has limitations. At present, more simulation tests use gas as the pressure transmission medium. Due to the greater compressibility of gas, the pressure control system under this mode has the problems of slow response, poor stability, low precision and large noise during operation. These deficiencies limit the ability to accurately and smoothly control the pressure, causing interference to experiments that require precise pressure control. Lack of online monitoring capability of dynamic process. Traditional experimental devices are mostly "black box" equipment, and researchers can only take out the sample after the experiment for offline macroscopic and microscopic analysis. This "after-the-fact" detection method cannot capture the dynamic evolution information of key behaviors such as crack initiation and propagation, corrosion product film formation and shedding of materials during pressure bearing and corrosion process, resulting in the loss of important process data. Lack of quantitative characterization means of in-situ electrochemical performance. For the corrosion problem research of deep-sea equipment, it is crucial to obtain the corrosion rate, corrosion potential and other key electrochemical parameters of materials in the in-situ high-pressure environment. However, the existing high-pressure kettle device usually does not have the capability to integrate an electrochemical test system, and cannot perform online and in-situ quantitative analysis.

[0005] Therefore, there is an urgent need in this field to develop a new deep-sea environment simulation experimental system that can overcome the above-mentioned defects, achieve precise coupling and stable control of high-pressure and low-temperature environments, and integrate online visualization observation and in-situ electrochemical measurement functions, so as to significantly improve the accuracy, comprehensiveness and real-time performance of test data. Summary of the Invention

[0006] This invention provides a visualization simulation system for long-term in-situ electrochemical corrosion-aging testing in the deep sea. The purpose is to overcome the defects mentioned in the background technology. This new deep-sea environment simulation experimental system can achieve precise coupling and stable control of high pressure and low temperature environment, and integrate online visualization observation and in-situ electrochemical measurement functions, so as to significantly improve the accuracy, comprehensiveness and real-time performance of test data.

[0007] Therefore, the present invention adopts the following technical solution: A visualization simulation system for long-term in-situ electrochemical corrosion-aging testing in the deep sea includes an autoclave, a temperature control system, an online monitoring and data acquisition system, and a pressure control system. The autoclave consists of a vessel body and a lid. The lid is fixed to the top of the vessel body with bolts, and the inner cavity of the vessel body provides the experimental environment. The temperature control system includes a high and low temperature integrated unit, a heat exchange jacket, and a heat exchange hose. The heat exchange jacket is connected to the outer wall of the vessel and is connected to the high and low temperature integrated unit through the heat exchange hose. The heat exchange hose forms a loop and heat is exchanged with the outer wall of the vessel through the heat exchange jacket to adjust the temperature inside the vessel. The pressure control system includes an air compressor, a liquid pressurization system, and a high-pressure pipeline. The air compressor provides power to the liquid pressurization system, and the high-pressure pipeline is connected at one end to the liquid pressurization system and at the other end to the bottom of the vessel. The liquid pressurization system pressurizes the liquid inside the vessel. The online monitoring and data acquisition system includes a visualization component and an electrochemical measurement component installed inside the vessel lid. The visualization component includes a high-pressure camera and a high-pressure lamp, while the electrochemical measurement component includes a platinum electrode and a reference electrode. The high-pressure camera is used to acquire corrosion images. The visualization component transmits signals to an external instrument communication box or electrochemical workstation via a high-pressure watertight connector.

[0008] Furthermore, the liquid pressurization system is equipped with a large-area piston and a small-area piston. The power of the air compressor is used to drive the large-area piston, which in turn drives the small-area piston, which in turn pressurizes the liquid.

[0009] Furthermore, the vessel body is provided with a sample support system, which includes a horizontal upper connecting plate and a lower connecting plate, with a vertical first connecting rod connecting between the four corners of the upper and lower connecting plates; a vertical second connecting rod is connected to the vessel lid at the middle of the upper connecting plate. The upper connecting plate is provided with holes, and the high-voltage camera and high-voltage lighting lamp are fixed vertically downward on the holes and directly opposite the lower connecting plate.

[0010] Furthermore, the platinum electrode and the reference electrode are fixed below the upper connecting plate.

[0011] Furthermore, the high-pressure pipeline includes a water pump, the water pump outlet of which is connected in sequence to an inlet valve and a booster valve via a pipeline; a second safety valve is connected to the pipeline between the water pump and the inlet valve, and a drain valve is connected to the pipeline between the inlet valve and the booster valve.

[0012] Furthermore, a first safety valve and a pressure gauge transmitter are connected to the vessel lid.

[0013] The beneficial effects of this invention are as follows: 1. A pneumatic-driven liquid pressurization system was adopted, and its working principle is as follows: Power source: Compressed air generated by an air compressor serves as the power source. Pressurization conversion: Compressed air is injected into the liquid pressurization system, pushing a large-area piston; this piston then pushes a connected small-area piston, pressurizing the liquid (experimental medium) on the other side to an extremely high pressure. Finally, the high-pressure, incompressible liquid is injected into the already filled reactor through a high-pressure pipeline, thereby increasing the pressure inside the reactor.

[0014] The advantage of this method is that liquid, rather than gas, enters the vessel directly. Utilizing the near-incompressibility of liquids, it fundamentally avoids the pressure fluctuations and control lag issues associated with gaseous media. Injecting a small amount of liquid can induce a significant and stable pressure change, resulting in pressure control stability and accuracy (e.g., reaching ±0.1 MPa levels) far exceeding that of gas pressurization systems, enabling a true replication of the deep-sea environment. Pressure transmission is rapid, the pressurization process is smooth and efficient, and there is no lag effect characteristic of gas pressurization.

[0015] The simulation of the "high pressure-low temperature" coupled environment has been improved from "can be achieved" to "can be achieved accurately and stably," solving the key pain points of existing technologies.

[0016] 2. Constructing a "High-Pressure-Low-Temperature" Coupled Environment Simulation System: Traditional autoclaves typically only achieve pressure control and cannot simultaneously simulate the low-temperature conditions commonly found in deep-sea environments. This leads to a severe disconnect between the experimental environment and real-world conditions, limiting the reference value of the test data. The improvement of this invention lies in the systematic integration of a liquid pressurization system and a high-low temperature integrated unit. The former provides stable high pressure, while the latter forms a closed-loop temperature control circuit through heat exchange hoses and the heat exchange jacket of the autoclave body. For the first time, precise coupling and independent control of the two key environmental factors—high pressure and low temperature—are achieved within a single device. This allows for the realistic reproduction of extreme deep-sea environments, fundamentally improving the accuracy and reliability of experimental results.

[0017] 3. Achieving Online Visual Monitoring: Traditional high-pressure experiments are like "black box operations," unable to observe the dynamic changes of materials during the experiment. Static, offline analysis is only possible after the experiment, missing a significant amount of crucial process information. The improvement of this invention lies in the high-pressure camera and high-power high-pressure lighting integrated inside the reactor lid. High-definition video signals are exported in real time via a watertight connector, transforming the experimental process from "invisible" to "fully visible." This enables in-situ, real-time, and uninterrupted visual recording and analysis of the entire process of corrosion initiation and crack propagation in the test sample, providing the most intuitive visual evidence for revealing failure mechanisms.

[0018] 4. Achieving In-situ Quantitative Data Acquisition: Conventional visualization observations can only provide qualitative or semi-quantitative information on morphological changes, and cannot accurately quantify the corrosion rate, passivation behavior, etc., of materials. The improvement of this invention lies in the pre-installation of a complete three-electrode system consisting of a platinum electrode, a reference electrode, and a test sample inside the autoclave. A dedicated watertight connector transmits the weak electrochemical signal losslessly, enabling simultaneous and quantitative in-situ measurement of electrochemical performance under high pressure, temperature control, and visualization. Key data such as polarization curves and AC impedance can be acquired in real time, allowing research to move from "observing phenomena" to "measuring data." Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the experimental system of the present invention; Figure 2 This is a schematic diagram of the high-pressure reactor of the present invention; Figure 3 yes Figure 2 Sectional view of BB; Figure 4 yes Figure 3 Sectional view of CC; Figure 5 This is a front view of the sample holder system of the present invention; Figure 6 This is a side view of the sample holder system of the present invention; Figure 7 yes Figure 5 Sectional view of AA; Figure 8 This is a schematic diagram of the sample holder structure; Figure 9 These are the pressure and temperature variation curves over time during the experimental period in the embodiment; Figure 10 This is a sample surface morphology image taken 1 hour after the experiment in the example; Figure 11 This is a corrosion morphology image of the sample surface 7 hours after the experiment in the example; Figure 12The curves showing the change of open circuit potential (OCP) of the material over time under different pressures in the embodiments are shown. Figure 13 These are the Tafel curves of the material under different pressures; 1-High and low temperature integrated unit, 2-Heat exchange hose, 3-Reservoir lifting platform, 4-Wire harness drag chain, 5-Instrument communication box, 6-High pressure vessel, 7-Liquid pressurization system, 8-Air compressor, 9-Pressure inlet water pipe; 10-Bench frame, 11-Exhaust valve, 12-M42 double-ended bolt, 13-M42 nut, 14-First safety valve, 15-Pressure gauge transmitter, 16-Temperature sensor, 17-Inlet and outlet pipes, 18-Reservoir cover, 19-Reservoir body, 20-Oil outlet, 21-Insulation jacket, 22-Heat exchange jacket, 23-Oil inlet, 24-Sample holder, 25-Water pump, 26-Pressure booster valve, 27-Drain valve, 28-Water inlet valve, 29-Second safety valve; 31-First watertight connector, 32-High-voltage camera, 33-Upper connecting plate, 34-First connecting rod, 35-Platinum electrode, 36-Lower connecting plate, 37-Reference electrode, 38-High-voltage lighting lamp, 39-Second watertight connector, 40-Second connecting rod, 41-Test sample, 43-Test rubber socket, 44-Electrochemical test cable, 45-Lighting lamp cable, 46-Camera cable. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments: This invention provides a visualization simulation system for long-term in-situ electrochemical corrosion-aging testing in the deep sea. The system includes a high-pressure autoclave, a temperature control system, an online monitoring and data acquisition system, and a pressure control system. The experimental method of the visualization simulation deep-sea long-term in-situ electrochemical corrosion-aging test system of this invention is as follows, specifically including the following steps: Step 1: Perform an integrity check on the sample holder 24 to ensure that all connecting rods and plates are free from deformation and damage. Place the test sample 41 into the dedicated sample holder 24, ensuring it is firmly positioned without shaking; up to four samples can be installed. Check the surface condition of the platinum electrode 35 and the reference electrode 37, ensuring they are clean and free from contamination, and then securely install them to the dedicated electrode connector inside the vessel lid 18. Install the high-pressure camera 32 and high-pressure lighting lamp 38 onto the flange face below the vessel lid 18. Precisely connect the internal cables to the inner ports of the first watertight connector (for lighting and imaging) and the second watertight connector (for electrochemical measurements), ensuring the pins are fully inserted and making good contact.

[0021] Step 2: Inspect the main sealing surfaces of the flanges of the vessel body 19 and the vessel cover 18 to ensure they are smooth and free of any scratches, dents, or residues that could affect the seal. Using the vessel lifting platform 103, smoothly and slowly raise the pre-assembled vessel cover 18 directly above the vessel body 19, ensuring precise alignment and preventing collisions with the sealing surfaces. Tighten the bolts using M42 stud bolts and M42 nuts. Using a calibrated digital torque wrench, strictly follow the principle of "diagonal cross, multi-stage gradual tightening" to ensure the final pre-tightening torque value specified in the equipment manual is reached, and that the torque on each bolt is consistent.

[0022] Step 3: Inspect the heat exchange hose 2 for aging or damage. After ensuring the connectors are clean, reliably connect it to the port of the high and low temperature integrated unit 1 and the oil inlet 23 and outlet 20 of the heat exchange jacket 22, ensuring no leakage risk. Connect the booster water inlet pipe 9 to the output end of the liquid booster system 7 and the booster valve 26 of the autoclave 6, ensuring the high-pressure connector is fully tightened. Securely connect the external connectors of the lighting cable 45 and the camera cable 46 to the instrument communication box 5. Connect the electrochemical test cable 44 to the test rubber socket 43 and confirm that all electrical connections are dry and well insulated.

[0023] Step 4: Confirm pressurization; drain valve 27 is closed. Open the inlet valve 28 in the pipeline system and the vent valve 11 on the top of the vessel lid 18. Start the water pump 25 to inject the experimental medium into the vessel body 19. Observe the outlet of the vent valve 11; when the flowing medium is continuous and free of bubbles, it indicates that the air inside the vessel has been purged. Close the water pump 25, inlet valve 28, and vent valve 11 in sequence.

[0024] Step 5: Start the high and low temperature integrated unit 1, set the target temperature, and monitor the temperature inside the vessel 19 until it stabilizes using the feedback signal from the temperature sensor 16. Reconfirm that the exhaust valve 11 and drain valve 27 are completely closed. Start the air compressor 8 and the liquid pressurization system 7. Gradually open the pressurization valve 26 at a slow speed to steadily increase the pressure inside the vessel. Monitor the pressure rise rate in real time using the reading from the pressure gauge transmitter 15. The entire pressurization process is protected against overpressure (40 MPa) by the first safety valve 14.

[0025] Once the temperature and pressure have reached and stabilized at the experimental settings, start the experiment timing. Continuously monitor the readings of the pressure gauge transmitter 15 and temperature sensor 16 to ensure the stability of the experimental conditions and record any abnormal fluctuations. Turn on the high-pressure illumination lamp 38 and use the high-pressure camera 32 to perform continuous or timed online in-situ observations of the test sample 41, and archive the data. Connect the external electrochemical workstation to the test rubber socket 43, start the preset electrochemical measurement program, and collect and save the data.

[0026] Step 6: After the experiment, first stop the electrochemical measurements, save all data, and then turn off the high and low temperature integrated unit 1. Disassembly can only proceed after double confirmation, using the pressure gauge transmitter 15 reading and other auxiliary methods, that the pressure has completely returned to zero. Slowly and gradually open the exhaust valve 11 and drain valve 27 to release pressure, controlling the rate of pressure drop to prevent a sudden pressure decrease.

[0027] Step 7: After the vessel body 19 has completely cooled to room temperature, drain the medium from the vessel through the drain valve 27. Perform the sealing steps in reverse order, using a digital torque wrench to loosen the M42 nut evenly in a diagonal sequence. Use the vessel lifting platform 103 to safely lift the vessel lid 18. Carefully remove the entire visualization sample holder 24 system from the vessel lid 18 and retrieve the test sample 41.

[0028] Using appropriate solvents and tools, thoroughly clean the inner walls and sealing surfaces of the vessel body 19 and vessel lid 18, as well as all parts in contact with the medium. Inspect all parts, especially the sealing surfaces and electrodes, for corrosion or damage, and record the findings. Properly store all cleaned and dried parts, and complete the experimental record filing.

[0029] The high-voltage camera 32 and high-voltage lighting lamp 38 utilize high-strength, corrosion-resistant sealed housings: both are made of 316L stainless steel. 316L stainless steel is a high-strength, highly corrosion-resistant alloy material, capable of withstanding external pressures of 40 MPa without structural deformation or damage, while effectively resisting chemical corrosion from experimental media (such as seawater). The camera lens and the lamp holder of the lighting lamp both utilize composite glass. This composite material, specifically designed for high-pressure environments, possesses extremely high mechanical strength and pressure resistance, serving as a reliable pressure barrier to ensure high-quality transmission of image signals and light while withstanding immense pressure. Power supply and signal transmission are achieved through dedicated watertight connectors. These connectors are designed to ensure safe cable penetration and reliable connection even under significant pressure differences inside and outside the vessel lid 18, completely eliminating the risk of media leakage and ensuring the dryness and insulation of internal electronic components. The high-voltage lighting lamp 38 has a water pressure resistance of 40 MPa, and the high-voltage camera 32 has a water pressure resistance of 42 MPa.

[0030] To verify that the present invention can stably simulate the deep-sea environment and realize the visualization and electrochemical synchronous monitoring of the material corrosion process, the following verification experiments were conducted.

[0031] 1. Experimental Results and Data Analysis (1) Stability of the working environment During the experiment, the pressure and temperature inside the autoclave 6 were continuously monitored using the system of this invention, such as... Figure 9 As shown.

[0032] from Figure 9 As can be seen, after the system was started, the temperature rapidly dropped from room temperature (about 20°C) and stabilized at about 6°C; the pressure rapidly rose and remained stable at about 33 MPa for a long period. During a monitoring period of over 25,000 seconds (about 7 hours), neither the pressure nor the temperature fluctuated significantly, proving that the present invention can successfully achieve precise and stable control of the "high pressure-low temperature" coupled environment, providing a reliable experimental environment for subsequent in-situ monitoring.

[0033] (2) Online visual monitoring of corrosion process This invention overcomes the limitations of traditional "black box" equipment by successfully capturing the surface morphology evolution of materials during the corrosion process through a built-in high-pressure camera system, as shown in Figures Y and Z.

[0034] contrast Figure 10 and Figure 11 As can be clearly seen, as the experiment progressed, obvious corrosion products appeared on the originally relatively smooth sample surface, changing in color from grayish-brown to orange-yellow, and significant corrosion was observed. This directly demonstrates that the present invention possesses the ability to perform in-situ, real-time visual monitoring of the corrosion process.

[0035] (3) In-situ electrochemical characterization of corrosion behavior To quantitatively study the influence of high-pressure environments on material corrosion behavior, the open-circuit potential (OCP) and tafel curves were measured under normal pressure (0.1 MPa-6℃) and high pressure (30 MPa-6℃) using the in-situ electrochemical testing system of this invention. Figure 12 and Figure 13 As shown.

[0036] from Figure 12 The OCP curves show that, compared to the normal pressure environment, the material corrosion potential is generally lower under a high pressure of 30 MPa, indicating a greater tendency to corrode. From... Figure 13 Tafel curve analysis revealed that the corrosion current density (icorr) under high pressure was significantly higher than that under normal pressure, and the corrosion potential (Ecorr) was also more negative. This quantitatively demonstrates that high pressure promotes the corrosion rate of the material. These data prove that the present invention possesses the unique ability to perform in-situ, quantitative electrochemical characterization of materials under high pressure.

[0037] Comprehensive analysis shows that the visual simulation deep-sea long-term in-situ electrochemical corrosion-aging testing system proposed in this invention not only successfully solves the problem of stable coupling in a "high-pressure-low-temperature" environment, but also revolutionarily integrates two major monitoring methods: online visualization and in-situ electrochemistry. It can accurately correlate macroscopic surface corrosion phenomena with microscopic electrochemical reaction rates, thereby providing a comprehensive and in-depth understanding of the corrosion mechanism of materials under high-pressure conditions. This experiment fully verifies the overall feasibility, functional completeness, and technological advancement of the proposed solution.

Claims

1. A visualization-simulation deep-sea long-term in-situ electrochemical corrosion-aging testing system, characterized in that, Includes a high-pressure autoclave (6), a temperature control system, an online monitoring and data acquisition system, and a pressure control system; The autoclave (6) includes a body (19) and a lid (18). The lid (18) is fixed to the top of the body (19) by bolts. The inner cavity of the body (19) provides the experimental environment. The temperature control system includes a high and low temperature integrated machine (1), a heat exchange jacket and a heat exchange hose (2). The heat exchange jacket is connected to the outer wall of the vessel body (19). The heat exchange jacket is connected to the high and low temperature integrated machine (1) through the heat exchange hose (2). The heat exchange hose (2) forms a loop and heats the outer wall of the vessel body (19) through the heat exchange jacket to adjust the temperature inside the vessel body (19). The pressure control system includes an air compressor (8), a liquid pressurization system (7), and a high-pressure pipeline. The air compressor (8) is used to provide power to the liquid pressurization system (7). One end of the high-pressure pipeline is connected to the liquid pressurization system (7), and the other end is connected to the bottom of the vessel body (19). The liquid pressurization system (7) pressurizes the liquid inside the vessel body (19). The online monitoring and data acquisition system includes a visualization component and an electrochemical measurement component installed inside the vessel lid (18). The visualization component includes a high-pressure camera (32) and a high-pressure lighting lamp (38). The electrochemical measurement component includes a platinum electrode (35) and a reference electrode (37). The high-pressure camera (32) is used to acquire corrosion images. The visualization component transmits signals to an external instrument communication box (5) or electrochemical workstation via a high-pressure watertight connector.

2. The visualization simulation deep-sea long-term in-situ electrochemical corrosion-aging test system according to claim 1, characterized in that, The liquid pressurization system (7) is equipped with a large-area piston and a small-area piston. The power of the air compressor (8) is used to drive the large-area piston, which in turn drives the small-area piston, which in turn drives the liquid pressurization.

3. The visualization simulation deep-sea long-term in-situ electrochemical corrosion-aging test system according to claim 1, characterized in that, The vessel body (19) is equipped with a sample support system, which includes a horizontal upper connecting plate (33) and a lower connecting plate (36). A vertical first connecting rod (34) is connected between the four corners of the upper connecting plate (33) and the lower connecting plate (36). A vertical second connecting rod (40) is connected between the middle of the upper connecting plate (33) and the vessel cover (18). The upper connecting plate (33) has holes, and the high-voltage camera (32) and high-voltage lighting lamp (38) are fixed vertically downward on the holes and directly opposite the lower connecting plate (36).

4. The visualization simulation deep-sea long-term in-situ electrochemical corrosion-aging test system according to claim 3, characterized in that, The platinum electrode (35) and the reference electrode (37) are fixed below the upper connecting plate (33).

5. The visualization simulation deep-sea long-term in-situ electrochemical corrosion-aging test system according to claim 1, characterized in that, The high-pressure pipeline includes a water pump, the outlet of which is connected to the inlet valve and the booster valve in sequence via a pipeline; a second safety valve (29) is connected to the pipeline between the water pump and the inlet valve, and a drain valve is connected to the pipeline between the inlet valve and the booster valve.

6. The visualization simulation deep-sea long-term in-situ electrochemical corrosion-aging test system according to claim 1, characterized in that, The first safety valve (14) and the pressure gauge transmitter (15) are connected to the vessel cover (18).

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