A testing device and method for testing the erosion corrosion stability of superhydrophobic coatings

Abstract

This invention provides a testing device and method for testing the erosion corrosion stability of superhydrophobic coatings. The testing device includes a cyclic erosion unit and an in-situ optical observation unit. The cyclic erosion unit includes a storage tank and an erosion test chamber connected to the storage tank. The erosion test chamber contains a sample stage and a test medium. The sample stage is used to place and fix the superhydrophobic coating sample to be tested, and the superhydrophobic coating sample is completely immersed in the test medium to avoid interference from gas-liquid interface fluctuations on optical observation. The storage tank is used to provide a dynamic erosion environment to the erosion test chamber. The in-situ optical observation unit is placed outside the erosion test chamber. This invention overcomes the problem of offline detection distortion and can truly reflect the service status of the coating under dynamic erosion corrosion conditions. Through the full-domain acquisition and area ratio calculation of the silver mirror effect image, the distribution and expansion law of local failure areas of the coating are intuitively visualized, and the overall failure ratio of the coating is accurately quantified.

Description

Technical Field

[0001] This invention relates to the field of superhydrophobic coating surface performance testing technology, and more specifically, to a device and method for testing the erosion corrosion stability of superhydrophobic coatings. Background Technology

[0002] Superhydrophobic coatings, due to their excellent drag reduction, antifouling, and anti-corrosion properties, have broad application prospects in engineering scenarios such as ship hulls, offshore platform risers, oil and gas gathering and transportation pipelines, heat exchanger tube bundles, and hydroelectric turbine blades. The air layer trapped at the solid-liquid interface of a superhydrophobic coating is a key factor in achieving its superhydrophobic function, and the stability of this air layer directly determines the coating's service life. In the aforementioned application scenarios, superhydrophobic coatings are subjected to prolonged scouring and corrosion conditions resulting from the coupling of flowing water and corrosive media. Therefore, accurate detection of the existence, failure process, and stability of the air layer at the superhydrophobic coating interface under flowing conditions is a crucial step in the research and performance evaluation of superhydrophobic coatings.

[0003] Currently, the evaluation methods for the stability of superhydrophobic coatings mainly include contact angle measurement, roll-off angle testing, electrochemical impedance spectroscopy (EIS) testing, and weight loss method. However, these methods all have obvious drawbacks: contact angle, roll-off angle testing, and weight loss method are mostly offline static tests. Samples used in fluids need to be removed from the scouring environment and dried before testing. This process may cause the coating's Cassie-Baxter state to reversibly recover, and the air layer that was originally destroyed in the fluid will recover in the air, which cannot reflect the true service state under flowing water. Electrochemical impedance spectroscopy can achieve online monitoring, but the presence of the air layer makes it take a long time for the superhydrophobic coating to enter the stable state required for impedance measurement, and it cannot intuitively record the performance changes of the coating in the fluid.

[0004] In existing technologies, some patents evaluate the stability of superhydrophobic coatings, but all have significant limitations. For example, Chinese patent CN120741261A discloses a device and method for testing the stability of the liquid-gas interface of superhydrophobic materials. This method uses laser irradiation of the superhydrophobic material surface and measures the intensity of reflected light to characterize the stability of the underwater gas film. However, this device is only designed for hydrostatic environments and lacks a flowing water scouring module, making it unable to simulate the scouring and corrosion conditions in actual engineering projects. Furthermore, it uses single-point laser reflected light intensity measurement, which cannot achieve a comprehensive evaluation of the coating. Similarly, Chinese patent CN114279897A discloses a device for testing the stability of superhydrophobic states under water pressure. This device is also limited to hydrostatic environments and can only test the critical pressure for the transition of the wetting state, unable to monitor the dynamic evolution of coating stability in real time. Chinese patent CN119223798A discloses a superhydrophobic surface erosion resistance testing device and method, which only simulates the erosion conditions of superhydrophobic coatings underwater. However, the evaluation process still requires the sample to leave the liquid, which cannot avoid the reversible recovery of the Cassie-Baxter state of the coating in the air. Therefore, the test results cannot reflect the changes in coating performance under the flow state. Summary of the Invention

[0005] In view of this, the present invention aims to provide a test device and test method for the erosion corrosion stability of superhydrophobic coatings, so as to solve the problem that the superhydrophobic sample is taken out from the dynamic erosion environment during the test process of the prior art, resulting in inaccurate test results.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] On one hand, the present invention proposes a device for testing the erosion corrosion stability of superhydrophobic coatings, including a circulating erosion unit and an in-situ optical observation unit. The circulating erosion unit includes a liquid storage tank and an erosion test chamber connected to the liquid storage tank. The erosion test chamber has a sample stage and a test medium inside. The sample stage is used to place and fix the superhydrophobic coating sample to be tested, and the superhydrophobic coating sample is completely immersed in the test medium to avoid interference of gas-liquid interface fluctuations on optical observation. The liquid storage tank is used to provide a dynamic erosion environment to the erosion test chamber. The in-situ optical observation unit is placed outside the erosion test chamber.

[0008] Optionally, the scouring test chamber is made of transparent material, and the in-situ optical observation unit is placed on the outer side of the sidewall and / or the outer side of the top, with the sample stage connected to the inner bottom of the scouring test chamber.

[0009] Optionally, the circulating flushing unit and the operating condition controller are connected, and the unit also includes a circulating water circuit module and an operating condition control module. The operating condition control module includes a temperature sensor, a pressure sensor, a temperature control component, a variable frequency centrifugal pump, a solenoid valve, and an electromagnetic flow meter. The temperature sensor, pressure sensor, and temperature control component are all connected inside the storage tank. The outlet of the storage tank is connected to the flushing test chamber through a first pipeline. The variable frequency centrifugal pump, solenoid valve, and electromagnetic flow meter are connected in series on the first pipeline.

[0010] Optionally, the circulating water circuit module includes a pulse damper and a pre-filter. The pulse damper and the pre-filter are connected in series on the first pipeline and are arranged along the flow direction of the test medium from the storage tank to the flushing test chamber. The pulse damper is located at the downstream end of the variable frequency centrifugal pump.

[0011] Optionally, the angle between the sample stage and the direction of the test medium flowing into the scouring test chamber can be adjusted, and the angle is 0~90°.

[0012] Optionally, the in-situ optical observation unit includes an imaging acquisition module, an illumination module, and a synchronization trigger control module. The imaging acquisition module is installed on the top and / or outside the sidewall of the scour test chamber, and the illumination module is installed on the outside of the two sidewalls of the scour test chamber. Both the imaging acquisition module and the illumination module are connected to the synchronization trigger control module, which is used to precisely control the timing synchronization of the imaging acquisition module and the illumination module.

[0013] Optionally, the circulating flushing unit and the in-situ optical observation unit are respectively connected to the data analysis and processing unit. The data analysis and processing unit is used to receive the original image of the silver mirror effect acquired by the in-situ optical observation unit and perform processing and quantization calculations.

[0014] Optionally, the data analysis and processing unit includes an image preprocessing module, a region segmentation module, a quantization calculation module, and a result output module. The image preprocessing module is used to process the original image of the silver mirror effect acquired by the in-situ optical observation unit; the region segmentation module is used to distinguish between the effective region of the silver mirror effect with high gray values ​​and the ineffective region with low gray values; and the quantization calculation module is used to calculate the core evaluation index.

[0015] Optionally, the high grayscale value silver mirror effect effective region corresponds to the Cassie-Baxter wetting region where the interfacial air layer exists, and the low grayscale value failure region corresponds to the Wenzel wetting region where the air layer is lost.

[0016] The present invention also proposes a testing method using the above-mentioned testing apparatus, the testing method comprising the following steps:

[0017] Step 1: Place the superhydrophobic coating sample into the scouring test chamber, so that the superhydrophobic coating sample is completely immersed in the test medium;

[0018] Step 2: Activate the lighting module, adjust the light intensity to a stable state, acquire the initial silver mirror image under static, erosion-free conditions, and establish an effective area benchmark with η=100%.

[0019] Step 3: Adjust the circulating flushing unit to simulate the preset flushing and corrosion conditions;

[0020] Step 4: Acquire the original image of the silver mirror effect of the superhydrophobic coating sample through the in-situ optical observation unit;

[0021] Step 5: Eliminate artifact interference in the original image of the silver mirror effect, perform grayscale analysis, and divide the image into a high grayscale effective region of the silver mirror effect and a low grayscale ineffective region based on the grayscale threshold.

[0022] Step 6: Calculate the core evaluation index and count the percentage of the pixel area of ​​the effective region of the silver mirror effect to the total image area, which is the effective area ratio η of the silver mirror effect.

[0023] Compared with existing technologies, the superhydrophobic coating erosion corrosion stability testing device and method described in this invention have the following advantages:

[0024] (1) It overcomes the problem of distortion in offline testing. The test process does not require removing the superhydrophobic sample from the dynamic scouring environment, completely avoiding the reversible recovery of coating performance caused by the drying process. It truly reflects the service status of the coating under dynamic scouring corrosion conditions. The consistency between the test results and the actual service status is significantly better than that of offline testing technology.

[0025] (2) Full-domain quantitative evaluation was achieved. Through the full-domain acquisition of silver mirror effect images and the calculation of area ratio, the distribution and expansion law of local failure areas of the coating were visualized intuitively, and the overall failure ratio of the coating was accurately quantified.

[0026] (3) The working conditions simulation is in line with the actual engineering situation. The device can be adapted to various complex working conditions such as single-phase clean water, Cl⁻ corrosive media, and acidic media. It is highly matched with the service environment of actual engineering scenarios such as ships, pipelines, and heat exchangers. The test results can directly guide the engineering application of superhydrophobic coatings.

[0027] (4) The test device has a simple structure and is easy to maintain. All electronic components are located outside the scouring test chamber module, so there will be no corrosion loss. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0029] Figure 1 This is a schematic diagram of the structure of the testing device described in this invention;

[0030] Figure 2 This is a flowchart illustrating the workflow of the testing device described in this invention.

[0031] Figure 3 The curve showing the effective area ratio η of the superhydrophobic coating silver mirror effect in Embodiment 1 of the present invention is a time-varying curve.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Circulating flushing unit; 11. Liquid storage tank; 12. Temperature sensor; 13. Pressure sensor; 14. Temperature control component; 15. Variable frequency centrifugal pump; 16. Pulse damper; 17. Pre-filter; 18. Solenoid valve; 19. Electromagnetic flow meter; 111. Flushing test chamber; 2. In-situ optical observation unit; 21. Imaging acquisition module; 22. Illumination module; 23. Synchronous trigger control module; 3. Data analysis and processing unit; 4. Superhydrophobic coating sample; 5. First pipeline; 6. Second pipeline. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments. First, it should be noted that the data in the following experimental examples were obtained by the inventors through numerous experiments. Due to space limitations, only a portion of these data is shown in the specification, and those skilled in the art can understand and implement the present invention based on this data. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the contents of this invention, those skilled in the art can make various modifications or alterations to the invention, and these modifications or alterations also fall within the scope of protection of this application.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0036] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] like Figures 1-2 As shown, the present invention discloses a superhydrophobic coating erosion corrosion stability testing device, comprising a circulating erosion unit 1 and an in-situ optical observation unit 2. The circulating erosion unit 1 includes a liquid storage tank 11 and an erosion test chamber 111 connected to the liquid storage tank 11. The erosion test chamber 111 has a sample stage and a test medium inside. The sample stage is used to place and fix the superhydrophobic coating sample 4 to be tested, and the superhydrophobic coating sample 4 is completely immersed in the test medium to avoid interference from gas-liquid interface fluctuations on optical observation. The liquid storage tank 11 is used to provide a dynamic erosion environment to the erosion test chamber 111. The in-situ optical observation unit 2 is placed outside the erosion test chamber 111. The circulating erosion unit 1 and the in-situ optical observation unit 2 are respectively connected to a data analysis and processing unit 3. The data analysis and processing unit 3 is used to receive the original image of the silver mirror effect collected by the in-situ optical observation unit 2, and to process and quantify it to realize the quantitative evaluation of the erosion corrosion stability of the superhydrophobic coating.

[0039] The cyclic scouring unit 1 is used to simulate the scouring and corrosion conditions during the actual service of the superhydrophobic coating. This invention overcomes the problem of distortion in offline testing. The entire testing process does not require removing the superhydrophobic coating sample 4 from the dynamic scouring environment, completely avoiding the reversible recovery of coating performance caused by the drying process. It can truly reflect the service state of the coating under scouring and corrosion conditions, and the consistency between the test results and the actual service state is significantly better than that of offline testing technology.

[0040] Optionally, the erosion test chamber 111 is made of transparent material, and the in-situ optical observation unit 2 is placed on the outer side of the sidewalls and / or the outer side of the top. The sample stage is connected to the inner bottom of the erosion test chamber 111. The transparent erosion test chamber 111 facilitates the in-situ excitation and acquisition of the silver mirror effect image of the superhydrophobic coating sample 4 by the in-situ optical observation unit 2. Specifically, the erosion test chamber 111 is made of transparent glass or transparent plastic.

[0041] The circulating flushing unit 1 is connected to the operating condition controller 110, and also includes a circulating water circuit module and an operating condition control module. The operating condition control module includes a temperature sensor 12, a pressure sensor 13, a temperature control component 14, a variable frequency centrifugal pump 15, a solenoid valve 18, and an electromagnetic flow meter 19. The temperature sensor 12, pressure sensor 13, and temperature control component 14 are all connected to the inside of the liquid storage tank 11. The liquid outlet of the liquid storage tank 11 is connected to the flushing test chamber 111 through the first pipeline 5. The variable frequency centrifugal pump 15, the solenoid valve 18, and the electromagnetic flow meter 19 are connected in series on the first pipeline 5.

[0042] The operating condition control module is used to adjust the conditions of the test medium flowing from the outlet of the storage tank 11 to the flushing test chamber 111, so that the test medium can better simulate and conform to the actual flushing conditions, thereby improving the test accuracy.

[0043] The temperature sensor 12 and the pressure sensor 13 are used to monitor the temperature and pressure of the test medium in the storage tank 11 in real time, and transmit the monitored signals to the operating condition controller 110 to adjust the temperature control component 14, the variable frequency centrifugal pump 15, and the solenoid valve 18, thereby adjusting the temperature and pressure to preset conditions. The electromagnetic flow meter 19 is used to monitor the flow rate of the test medium flowing into the flushing test chamber 111. Under the control of the operating condition controller 110, the temperature sensor 12 and the temperature control component 14 achieve precise control of the test medium temperature, and the pressure sensor 13, the variable frequency centrifugal pump 15, the solenoid valve 18, and the electromagnetic flow meter 19 achieve precise control of the test medium flow rate.

[0044] Specifically, the variable frequency centrifugal pump 15 can directly regulate the flow rate by changing the delivery flow rate of the test medium, and the solenoid valve 18 can indirectly regulate the flow rate by changing its opening degree. Optionally, the solenoid valve 18 is a three-way valve, with its first and second openings both connected to the first pipeline 5, and its third opening connected to the liquid storage tank 11 via the second pipeline 6. The flow rate of the test medium is controlled by adjusting the opening angle of the three-way valve, thereby changing the flow rate of the test medium.

[0045] The circulating water circuit module includes a pulse damper 16 and a pre-filter 17. The pulse damper 16 and the pre-filter 17 are connected in series on the first pipeline 5, along the flow direction of the test medium from the storage tank 11 to the flushing test chamber 111. The pulse damper 16 is located downstream of the variable frequency centrifugal pump 15 and is used to eliminate the inherent pressure pulsation of the test medium output by the variable frequency centrifugal pump 15, so that the flow field entering the flushing test chamber 111 is stabilized into a laminar flow state. The pre-filter 17 can prevent solid impurities in the test medium from scratching the superhydrophobic coating and contaminating the optical window.

[0046] The angle between the sample stage and the direction of the test medium flowing into the scouring test chamber 111 is adjustable, and the angle is 0~90°. Since the angle of the sample stage is adjustable, the angle between the superhydrophobic coating sample 4 and the test medium can be changed to simulate the service state of the coating under different scouring angles.

[0047] In existing technologies, the erosion corrosion stability test of superhydrophobic coatings based on the silver mirror effect largely relies on ambient light as the excitation source. The intensity, angle, and distribution of ambient light are uncontrollable, leading to unstable brightness and uneven distribution of the silver mirror effect, resulting in poor repeatability of test results. Especially under flowing erosion conditions, the turbulence of the water flow continuously alters the scattering distribution of ambient light within the water body, causing instability in the silver mirror images acquired under natural light, making effective quantitative evaluation impossible. To address this issue, the in-situ optical observation unit 2 of this invention includes an imaging acquisition module 21, an illumination module 22, and a synchronization trigger control module 23. The imaging acquisition module 21 is installed on the top and / or outside the sidewall of the erosion test chamber 111, and the illumination module 22 is installed on the outside of both sidewalls of the erosion test chamber 111. Both the imaging acquisition module 21 and the illumination module 22 are connected to the synchronization trigger control module 23, which is used to precisely control the timing synchronization of the imaging acquisition module 21 and the illumination module 22.

[0048] This invention achieves stable excitation and precise acquisition of the silver mirror effect through active illumination optical path design, enabling quantitative evaluation. Furthermore, it implements an alternating working mode of "background acquisition (illumination module 22 triggers illumination to turn off, imaging acquisition module 21 acquires ambient light image) - signal acquisition (illumination module 22 triggers illumination to turn on, imaging acquisition module 21 acquires reflected light image of superhydrophobic coated sample 4)" through time synchronization, ensuring complete consistency between background and signal acquisition conditions and facilitating the elimination of ambient light interference through background subtraction algorithms.

[0049] Specifically, the imaging acquisition module 21 uses a high-resolution high-speed camera such as CMOS or CCD, and has macro focusing capabilities. Its position can be adjusted according to the size of the superhydrophobic coating sample 4 and the scouring angle. The illumination module 22 uses a flat LED diffuser light source or similar source that can provide uniform diffused light into the test medium.

[0050] The data analysis and processing unit 3 includes an image preprocessing module, a region segmentation module, a quantization calculation module, and a result output module. The image preprocessing module is used to process the original image of the silver mirror effect acquired by the in-situ optical observation unit 2. The region segmentation module is used to distinguish between the effective region of the silver mirror effect with high gray values ​​(corresponding to the Cassie-Baxter wetting region where the interfacial air layer exists) and the failure region with low gray values ​​(corresponding to the Wenzel wetting region where the air layer is lost). The quantization calculation module is used to calculate core evaluation indicators, such as the effective area ratio of the silver mirror effect η, the micro-area failure size, and the failure propagation rate, and to generate in real time the evolution curve of the η value with erosion time and the heat map of the failure region distribution. The result output module is used to output the evaluation indicators calculated by the quantization calculation module.

[0051] Optionally, the image preprocessing module performs Gaussian noise reduction and background subtraction on the original image of the silver mirror effect to eliminate the instantaneous interference from the flow of the test medium and the artifact interference caused by bubbles and solid particles attached to the surface of the superhydrophobic coating sample 4. The region segmentation module can use an adaptive grayscale threshold segmentation algorithm (Otsu algorithm) or a machine learning semantic segmentation model (U-Net model) for accurate differentiation.

[0052] The side-viewing device of the present invention also includes a third pipeline, through which the flushing test chamber 111 is connected to the inlet end of the liquid storage tank 11, for returning the side-viewing medium that has completed the test to the flushing test chamber 111 for continued recycling.

[0053] The present invention also proposes a testing method using the above-mentioned testing apparatus, the testing method comprising the following steps:

[0054] Step 1: Place the superhydrophobic coating sample 4 into the scouring test chamber 111, so that the superhydrophobic coating sample 4 is completely immersed in the test medium;

[0055] Step 2: Activate the lighting module 22, adjust the light intensity to a stable state, acquire the initial silver mirror image under static, erosion-free conditions, and establish an effective area benchmark with η=100%.

[0056] Step 3: Adjust the circulating flushing unit 1 to simulate the preset flushing and corrosion conditions;

[0057] Step 4: Acquire the original image of the silver mirror effect of the superhydrophobic coating sample 4 through the in-situ optical observation unit 2;

[0058] Step 5: Eliminate artifact interference in the original image of the silver mirror effect, perform grayscale analysis, and divide the image into a high grayscale effective region of the silver mirror effect and a low grayscale ineffective region based on the grayscale threshold.

[0059] Step 6: Calculate the core evaluation index and count the percentage of the pixel area of ​​the effective region of the silver mirror effect to the total image area, which is the effective area ratio η of the silver mirror effect.

[0060] Optionally, in step four, the synchronization trigger control module 23 is used to control the timing synchronization of the imaging acquisition module 21 and the illumination module 22 to acquire a signal image and a background image containing the silver mirror effect.

[0061] An air layer refers to the continuous gaseous interface trapped within the micro-nano rough structure of a superhydrophobic coating surface, determining whether superhydrophobic functionality can be achieved. The air layer produces a silver mirror visual effect by inducing total internal reflection of light. When the superhydrophobic coating sample 4 is in the Cassie-Baxter wetted state, a stable air layer is trapped at the solid-liquid interface. When light is incident from the aqueous phase (optically denser medium, refractive index n1≈1.33) to the air layer (optically less dense medium, refractive index n2≈1.0), total internal reflection occurs when the angle of incidence is greater than the critical angle θc=arcsin(n2 / n1)≈48.8°, resulting in a macroscopically silvery-white mirror-like reflective effect. When the coating fails and enters the Wenzel wetted region, the air layer is lost, and the test medium penetrates the micro-nano structure. Without total internal reflection at the interface, light either passes directly through or is absorbed, appearing as a dark area, corresponding to a low grayscale value region in the image. The silver mirror effect has a strong one-to-one correlation with the state of the interfacial air layer, and is a direct optical characteristic characterizing the state of the air layer at the interface of superhydrophobic coatings. Therefore, this invention utilizes the corresponding high grayscale region in the image to reflect the state of the air layer.

[0062] In step five, a Gaussian filter function is called to smooth the original image of the silver mirror effect, removing high-frequency noise caused by turbulence or solid particles in the test medium. Then, background subtraction is performed, and the signal image of the silver mirror effect obtained in step three is compared with the background image to eliminate the inhomogeneity of ambient light and the baseline drift caused by the reflection of the inner wall of the scouring test cavity 111, thus obtaining a pure original image of the silver mirror effect.

[0063] Accurate segmentation can be achieved using an adaptive grayscale threshold segmentation algorithm (Otsu algorithm) or a machine learning semantic segmentation model (U-Net model).

[0064] The Otsu algorithm, also known as the maximum inter-class variance method, adaptively determines the optimal segmentation threshold T and identifies pixels with gray values ​​≥ T as effective regions of the silver mirror effect, while pixels with gray values ​​< T are considered ineffective regions with low gray values. The U-Net model performs pixel-level classification and recognition of effective regions of the silver mirror effect in the image using the training dataset. Since the use of the Otsu algorithm to adaptively determine the optimal segmentation threshold T and the use of the U-Net model for classification and recognition are existing technologies, they will not be detailed here.

[0065] Example 1

[0066] This embodiment provides a test device for the erosion corrosion stability of superhydrophobic coatings based on the silver mirror effect, used to simulate the erosion corrosion conditions of superhydrophobic coatings in a marine environment. The parameters of each component in the test device are as follows:

[0067] The circulating flushing unit 1 includes a circulating water circuit module, a working condition control module, and a flushing test chamber 111. The circulating water circuit module includes: a storage tank 11 (volume 0.5m³). 3 ), pulse damper 16, pre-filter 17 (filtration accuracy 5μm), the side-view medium in the storage tank 11 is simulated seawater (Cl), -1 The concentration is 3.5 wt%. The operating condition control module includes: an operating condition controller 110 and a variable frequency centrifugal pump 15 (flow rate 10 m³ / h). 3 The system includes: a flow meter (0.1~15m / s, accuracy ±0.5%), an electromagnetic flow meter (0.1~15m / s, accuracy ±0.5%), a solenoid valve (18), a pressure sensor (0~2MPa, accuracy ±0.1%), a temperature sensor (12, accuracy ±0.1℃), and a temperature control assembly (14, temperature control range room temperature~90℃, temperature control accuracy ±0.5℃).

[0068] The scouring test chamber 111 is made of high-transparency quartz glass and has a volume of 0.05 m³. 3 The internal sample stage is made of TA2 titanium alloy, with an angle adjustment range of 0~90°, adjustment accuracy of ±0.1°, and repeatability of ≤±0.05°. It is used to fix carbon steel samples (50mm×50mm×5mm) with a superhydrophobic coating on the surface, and the samples are completely immersed in simulated seawater.

[0069] The in-situ optical observation unit 2 includes an imaging acquisition module 21, an illumination module 22, and a synchronous trigger control module 23. The imaging acquisition module 21 uses a CMOS area array camera (resolution 2048×1536, frame rate 60fps), mounted on the top outside of the scouring test chamber 111, with the lens vertically downwards facing the center of the sample. A polarizer is added in front of the camera lens to eliminate reflections from the chamber wall and improve image contrast. With this arrangement, the relative brightness of the silver mirror is 100%, the signal-to-noise ratio is >25:1, and clear images of the silver mirror across the entire area can be acquired. The illumination module 22 consists of two 100mm×100mm flat LED diffuser light sources, respectively mounted on the outer sidewalls of the left and right sides of the scouring test chamber 111, with the emitting surface facing inwards. The illumination uniformity is ≥95%, the light intensity fluctuation is ≤0.5% / h, the color temperature is 5500K, and the power is 30W, completely covering the surface of the carbon steel sample under test, achieving symmetrical and uniform illumination. The synchronous trigger control module 23 realizes the synchronous triggering of the light source and the camera, and adopts an alternating mode of "background acquisition (lighting module 22 off, imaging acquisition module 21 on) - signal acquisition (lighting module 22 on, imaging acquisition module 21 on)".

[0070] The results output unit displays the η value, failure area distribution heat map, and stability grading evaluation results in real time on the screen, and also supports data storage and export.

[0071] The test method in Example 1 includes the following steps:

[0072] Step 1, Sample preparation: Fix the carbon steel sample coated with superhydrophobic coating on the sample stage, adjust the angle of the sample stage to 30° (simulating the scouring angle of the ship's hull), ensure that the sample is completely immersed in simulated seawater, and seal the scouring test chamber module 111.

[0073] Step 2, System Calibration: Start the illumination module 22, adjust the light intensity to a stable state, acquire the initial silver mirror image under static, erosion-free conditions, and establish an effective area benchmark with η=100%;

[0074] Step 3, Operating Condition Debugging: Start the variable frequency centrifugal pump 15, adjust the simulated seawater flow rate to 3m / s, and adjust the simulated seawater temperature to 25℃ using the temperature control component 14. Run stably for 10 minutes to bring the flushing condition to a stable state.

[0075] Step 4, Testing and Data Acquisition: The synchronous trigger control module 23 is activated to begin timing testing. The imaging acquisition module 21 acquires the original image of the silver mirror effect at a frequency of 1 time / min. During each acquisition, background acquisition is performed first, with the illumination module 22 turned off, and the imaging acquisition module 21 acquires the background state once. Then, signal acquisition is performed, with the illumination module 22 turned on, and the imaging acquisition module 21 acquires the sample state once. The obtained data is transmitted to the data analysis and processing unit 3 in real time.

[0076] Step 5: The data analysis and processing unit 3 uses an industrial computer equipped with OpenCV-based image processing software. The image preprocessing module performs Gaussian noise reduction, background subtraction, and morphological processing on the acquired original silver mirror image. The region segmentation module uses the Otsu adaptive grayscale threshold segmentation algorithm. The quantization calculation module calculates the effective area ratio η of the silver mirror effect in real time.

[0077] Step Six: Result Output: The test lasts for 24 hours, during which the η value and the distribution of the failure area are recorded every 2 hours. After the test, the η-erosion time evolution curve is output, as shown in the attached figure. Figure 3 As shown. From Figure 3 It can be seen that η decreases over time, indicating that as scouring continues, the air layer is gradually lost, the failure area expands, and the coating enters the failure stage.

[0078] The test results of Example 1 show that the test device and test method of the present invention can stably simulate the erosion and corrosion conditions in the marine environment, with the brightness fluctuation of the silver mirror image being <1%, which can effectively evaluate the stability of the superhydrophobic coating under marine erosion and corrosion conditions.

[0079] Example 2

[0080] This embodiment is basically the same as Embodiment 1, except that the test medium is a hydrochloric acid solution with pH=1.

[0081] Start the variable frequency centrifugal pump 15, adjust the flow rate of the simulated hydrochloric acid solution to 8 m / s, adjust the temperature of the hydrochloric acid solution to 70°C using the temperature control component 14, set the sample stage angle to 90° (simulating the scouring angle at the bend of the pipe), and arrange the imaging acquisition module 21 on the front panel of the scouring test chamber module 111.

[0082] The testing process in Example 2 was the same as in Example 1. The test results show that the testing device of this invention is adaptable to hydrochloric acid solution rinsing conditions, the illumination is unaffected by the hydrochloric acid solution, the imaging is stable, and it can effectively evaluate the stability of superhydrophobic coatings under high flow rate and hydrochloric acid solution corrosion conditions.

[0083] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various alterations and modifications 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 testing the erosion corrosion stability of superhydrophobic coatings, characterized in that, The system includes a circulating rinsing unit (1) and an in-situ optical observation unit (2). The circulating rinsing unit (1) includes a liquid storage tank (11) and a rinsing test chamber (111) connected to the liquid storage tank (11). The rinsing test chamber (111) has a sample stage and a test medium inside. The sample stage is used to place and fix the superhydrophobic coating sample (4) to be tested, and the superhydrophobic coating sample (4) is completely immersed in the test medium to avoid interference of gas-liquid interface fluctuations on optical observation. The liquid storage tank (11) is used to provide a dynamic rinsing environment to the rinsing test chamber (111). The in-situ optical observation unit (2) is placed outside the rinsing test chamber (111).

2. The testing apparatus according to claim 1, characterized in that, The scouring test chamber (111) is made of transparent material, and the in-situ optical observation unit (2) is placed on the outer side of the sidewall and / or the outer side of the top. The sample stage is connected to the inner bottom of the scouring test chamber (111).

3. The testing apparatus according to claim 1, characterized in that, The circulating flushing unit (1) is connected to the operating condition controller (110), and also includes a circulating water circuit module and an operating condition control module. The operating condition control module includes a temperature sensor (12), a pressure sensor (13), a temperature control component (14), a variable frequency centrifugal pump (15), a solenoid valve (18), and an electromagnetic flow meter (19). The temperature sensor (12), pressure sensor (13), and temperature control component (14) are all connected to the inside of the storage tank (11). The outlet of the storage tank (11) is connected to the flushing test chamber (111) through the first pipeline (5). The variable frequency centrifugal pump (15), solenoid valve (18), and electromagnetic flow meter (19) are connected in series on the first pipeline (5).

4. The testing apparatus according to claim 3, characterized in that, The circulating water circuit module includes a pulse damper (16) and a pre-filter (17). The pulse damper (16) and the pre-filter (17) are connected in series on the first pipeline (5) and along the flow direction of the test medium from the storage tank (11) to the flushing test chamber (111). The pulse damper (16) is located at the downstream end of the variable frequency centrifugal pump (15).

5. The testing apparatus according to claim 1, characterized in that, The angle between the sample stage and the direction of the test medium flowing into the scouring test chamber (111) can be adjusted, and the angle is 0~90°.

6. The testing apparatus according to claim 1, characterized in that, The in-situ optical observation unit (2) includes an imaging acquisition module (21), an illumination module (22), and a synchronization trigger control module (23). The imaging acquisition module (21) is installed on the top and / or outside the side wall of the scour test chamber (111). The illumination module (22) is installed on the outside of the two side walls of the scour test chamber (111). The imaging acquisition module (21) and the illumination module (22) are both connected to the synchronization trigger control module (23). The synchronization trigger control module (23) is used to precisely control the timing synchronization of the imaging acquisition module (21) and the illumination module (22).

7. The testing apparatus according to claim 1, characterized in that, The circulating flushing unit (1) and the in-situ optical observation unit (2) are respectively connected to the data analysis and processing unit (3). The data analysis and processing unit (3) is used to receive the original image of the silver mirror effect collected by the in-situ optical observation unit (2) and perform processing and quantification calculation.

8. The testing apparatus according to claim 7, characterized in that, The data analysis and processing unit (3) includes an image preprocessing module, a region segmentation module, a quantization calculation module, and a result output module. The image preprocessing module is used to process the original image of the silver mirror effect acquired by the in-situ optical observation unit (2). The region segmentation module is used to distinguish between the effective region of the silver mirror effect with high gray values ​​and the ineffective region with low gray values. The quantization calculation module is used to calculate the core evaluation index.

9. The testing apparatus according to claim 8, characterized in that, The high grayscale value silver mirror effect effective area corresponds to the Cassie-Baxter wetting area where the interfacial air layer exists, and the low grayscale value failure area corresponds to the Wenzel wetting area where the air layer is lost.

10. A testing method, characterized in that, Using the testing apparatus according to any one of claims 1 to 9, the testing method includes the following steps: Step 1: Place the superhydrophobic coating sample (4) into the scouring test chamber (111) so that the superhydrophobic coating sample (4) is completely immersed in the test medium; Step 2: Start the lighting module (22), adjust the light intensity to a stable state, acquire the initial silver mirror image under static, erosion-free conditions, and establish an effective area benchmark of η=100%; Step 3: Adjust the circulating flushing unit (1) to simulate the preset flushing corrosion conditions; Step 4: Acquire the original image of the silver mirror effect of the superhydrophobic coating sample (4) through the in-situ optical observation unit (2); Step 5: Eliminate artifact interference in the original image of the silver mirror effect, perform grayscale analysis, and divide the image into a high grayscale effective region of the silver mirror effect and a low grayscale ineffective region based on the grayscale threshold. Step 6: Calculate the core evaluation index and count the percentage of the pixel area of ​​the effective region of the silver mirror effect to the total image area, which is the effective area ratio η of the silver mirror effect.

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