Detection system and method for corrosion resistance of metal external anti-corrosion coating

Abstract

The invention provides a system and a method for detecting the corrosion resistance of a metal external anticorrosive coating, and relates to the technical field of coating corrosion detection, the system comprises: a measurement host device, which comprises a measurement cell and an electrode system, the measurement cell is used for forming a closed test environment, and the electrode system is used for detecting the corrosion resistance of the metal external anticorrosive coating; the electrode system can collect electrochemical signals of the coating of the tested equipment and form an electrochemical test loop; the hinge mechanism comprises a hinge base and a hinge connecting rod, the hinge base can be fixed on the surface of the measured equipment, and the hinge connecting rod is used for connecting the hinge base and the measurement host device; the control device is used for supplying power and controlling the detection process, and the measurement host device and the hinge mechanism are both connected with the control device. According to the method, the performance or aging condition of the coating is evaluated by testing an average value of phase angle attenuation rates under 3-5 characteristic frequencies in an interval of 5mHz-30mHz. The evaluation method makes up the limitation of the existing coating performance detection method, and has important popularization value.

Description

Technical Field

[0001] This invention relates to the field of coating corrosion detection technology, and in particular to a detection system and method for the corrosion resistance of metal external anti-corrosion coatings. Background Technology

[0002] Various industrial and civilian metal equipment and facilities, such as those made of carbon steel, stainless steel, and aluminum alloys, often require anti-corrosion coatings to mitigate corrosion damage to the substrate. Coating protection is widely used due to its ease of application, low cost, and excellent protective effect.

[0003] However, during the service life of coatings, the metal substrate is often damaged by the penetration of corrosive media, leading to coating failure. This process is often very slow in actual service. The handling of coatings during the routine maintenance of some metal equipment, facilities, and devices is often perplexing. Because the condition of the coatings in service, including performance parameters and remaining lifespan, is unavailable, extreme measures are often taken, such as recoating the visibly damaged coatings or recoating all coatings, resulting in inadequate protection or unnecessary waste.

[0004] The key to this problem lies in the inability to effectively obtain the critical performance of the coating during its service life, especially the inability to obtain key performance parameters for coating failure and remaining life through non-destructive monitoring and testing methods. Some traditional coating performance testing methods, such as adhesion testing, pull-out testing, and DC spark testing, limit their application scope due to their destructive nature on the coating in service.

[0005] In recent years, some non-destructive electrochemical monitoring and detection methods have been applied to the online service performance evaluation of coatings. A Chinese invention patent, CN101634623A, entitled "A Method and System for Rapid Evaluation of the Corrosion Resistance of In-Service Coatings," effectively reflects the impedance changes of the coating during service by utilizing the phase angle of the coating / metal system at a specific frequency over service time. Based on this, an electrochemical method for rapidly evaluating the performance of in-service coatings was established. Furthermore, a software system for rapid evaluation and management of in-service coating performance suitable for industrial applications was designed and developed. This system is used to quickly evaluate the corrosion resistance and lifespan prediction of in-service coatings, offering advantages such as fast and convenient measurement, reliable data, simple instruments, and no need for impedance data analysis.

[0006] However, using the phase angle change at a single electrochemical impedance characteristic frequency as a criterion for evaluating the corrosion resistance of a coating often results in significant errors. Although the phase angle at a characteristic frequency of 10 mHz is representative, there are significant differences between different types of coatings and under different service environments.

[0007] The Chinese invention patent, CN108827868A, entitled "A Coating Failure Monitoring Probe and a Rapid On-Site Coating Failure Monitoring Method," proposes using four indicators—impedance value, phase angle, characteristic frequency, and specific capacitance—along with an aging coefficient to evaluate the aging condition of coatings. It also develops a dedicated probe device for on-site coating monitoring. However, this method is complex, and data analysis requires specialized personnel for fitting.

[0008] Therefore, there is an urgent need for a testing system and method for the corrosion resistance of metal external anti-corrosion coatings to solve the above-mentioned technical problems. Summary of the Invention

[0009] The purpose of this invention is to provide a testing system and method for the corrosion resistance of metal external anti-corrosion coatings, enabling more accurate, rapid, and non-destructive testing of coating performance. The numerous technical effects of the preferred solutions among the many technical solutions provided by this invention are detailed below.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] This invention provides a testing system for the corrosion resistance of metal external anti-corrosion coatings, comprising:

[0012] The measurement host device includes a measurement cell and an electrode system, wherein the measurement cell is used to form a closed test environment, and the electrode system is capable of acquiring electrochemical signals of the coating of the device under test and forming an electrochemical test circuit;

[0013] A hinge mechanism includes a hinge base and a hinge link, wherein the hinge base can be fixed to the surface of the device under test, and the hinge link is used to connect the hinge base and the measuring host device;

[0014] A control device is used to supply power and control the detection process. The measuring host device and the hinge mechanism are both connected to the control device.

[0015] Preferably, the electrode system includes a working electrode for connection to the coating substrate metal of the device under test.

[0016] Preferably, the electrode system further includes an auxiliary platinum electrode sheet and a reference platinum electrode sheet, wherein:

[0017] Both the auxiliary platinum electrode and the reference platinum electrode are fixed to the inner wall of the measuring cell;

[0018] The working electrode, the auxiliary platinum electrode, and the reference platinum electrode work together to form an electrochemical testing circuit.

[0019] Preferably, the measuring host device further includes:

[0020] A first test electrolyte buffer tank is used to deliver electrolyte into the measuring cell. The first test electrolyte buffer tank is connected to the measuring cell through a first pipeline, and a first pump body is installed on the first pipeline.

[0021] The second test electrolyte buffer tank is used to receive the electrolyte output from the measuring tank. The second test electrolyte buffer tank is connected to the measuring tank through a second pipeline, and a second pump body is installed on the second pipeline.

[0022] The first test electrolyte buffer tank and the second test electrolyte buffer tank are connected by a third pipeline. The third pipeline is used to return the electrolyte in the second test electrolyte buffer tank to the first test electrolyte buffer tank. A regulating valve is installed on the third pipeline. The first pump body, the second pump body, and the regulating valve are all electrically connected to the control device.

[0023] Preferably, the measuring cell includes:

[0024] A measuring electrolytic cell, the measuring electrolytic cell being capable of containing the electrolyte, the measuring electrolytic cell being provided with an inlet for connecting to the first pipeline and an outlet for connecting to the second pipeline;

[0025] A sealing rubber gasket is provided on the bottom periphery of the measuring electrolytic cell.

[0026] Preferably, the control device includes: a central control and power supply module, a hinge control module, an electrochemical measurement control module, and a data storage and remote transmission module, wherein:

[0027] The hinge control module is connected to the hinge mechanism;

[0028] The electrochemical measurement and control module is connected to the measurement host device;

[0029] The hinge control module, the electrochemical measurement control module, and the data storage and remote transmission module are all connected to the main control and power supply module, which is used to supply power and control the detection process.

[0030] The data storage and remote transmission module is used to store test data and remotely transmit the test data to a remote receiver.

[0031] Preferably, the central control system includes a microcomputer system for presetting and executing the detection cycle, timed power on / off, and detection operation program;

[0032] The power source includes lithium batteries or dry cell batteries.

[0033] A method for testing the corrosion resistance of a metal external anti-corrosion coating, using the aforementioned testing system for the corrosion resistance of metal external anti-corrosion coatings, includes the following steps:

[0034] S1: Install and debug the detection system hardware on the coating equipment, and fill the first test electrolyte buffer tank with electrolyte, which is composed of 3.5% sodium chloride and 0.1% sodium benzoate;

[0035] S2: Set the detection parameters through the control device, including the detection cycle and electrochemical impedance measurement parameters;

[0036] S3: Measure the initial impedance parameters, start the detection system, and the hinge mechanism drives the measurement host device to move and fasten it to the coating surface;

[0037] S4: The first pump pumps the electrolyte in the first test electrolyte buffer tank into the measuring tank, where electrochemical testing is performed; after the test, the second pump pumps the electrolyte in the measuring tank back to the second test electrolyte buffer tank.

[0038] S5: The hinge mechanism drives the measuring host device to move away from the coating surface;

[0039] S6: Data storage and remote transmission system stores test data and remotely transmits the data to a remote receiver;

[0040] S7: The detection system will shut down and go into hibernation. It will automatically power on and repeat steps S1-S6 at the next measurement time.

[0041] Preferably, in step S2, the electrochemical impedance measurement parameters include impedance amplitude and characteristic frequency value, wherein the impedance amplitude is selected according to the coating thickness d, specifically including:

[0042] When d≤50μm, the impedance amplitude is ±15mV;

[0043] When 50μm<d≤150μm, the impedance amplitude is ±20mV;

[0044] When d > 150 μm, the impedance amplitude is ±30 mV.

[0045] Preferably, in the long-term electrochemical impedance spectroscopy test of the same coating, the average phase angle attenuation rate at 3-5 characteristic frequencies within the 5mHz-30mHz range is used. The method for evaluating coating performance or aging is as follows: The formula for calculating the phase angle attenuation rate η at a certain characteristic frequency is:

[0046]

[0047] Where θ0 is the initial phase angle at a certain characteristic frequency; θ i Let i be the phase angle at a certain characteristic frequency at time i.

[0048] Average phase angle attenuation rate The calculation formula is:

[0049]

[0050] Wherein, η1-η n The phase angle attenuation rate is selected at 3-5 characteristic frequencies, where n is the number of characteristic frequencies.

[0051] This invention provides a testing system and method for the corrosion resistance of metal external anti-corrosion coatings. The testing system includes a measuring host device, a hinge mechanism, and a control device. The measuring host device includes a measuring cell and an electrode system. The measuring cell forms a closed testing environment, and the electrode system can collect electrochemical signals from the coating of the device under test and form an electrochemical testing circuit. The hinge mechanism includes a hinge base and a hinge link. The hinge base can be fixed to the surface of the device under test, and the hinge link connects the hinge base to the measuring host device. The control device provides power and controls the testing process. The measuring host device and the hinge mechanism are both connected to the control device. This system can realize long-cycle timed automatic measurement and remote data transmission, overcoming the shortcomings of existing technologies that cannot perform long-cycle timed automatic measurement and remote data transmission. Furthermore, for the testing technology of obtaining coating performance through electrochemical impedance spectroscopy, the average phase angle attenuation rate at multiple characteristic frequencies is used. This new method accurately assesses coating performance or aging conditions, significantly improving the precision of coating testing. It solves the challenge of testing the performance of external metal anti-corrosion coatings, overcomes the limitations of existing coating performance testing methods, and has significant potential for widespread application. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of an embodiment of the detection system for the corrosion resistance of the metal external anti-corrosion coating of the present invention;

[0054] Figure 2 This is a schematic diagram of the measuring cell in the detection system for the corrosion resistance of the metal external anti-corrosion coating of the present invention.

[0055] Figure 3 The figure shows the change of phase angle with service time at different characteristic frequencies in Example 1.

[0056] Figure 4 This is a comparison chart of phase angle attenuation rate η at different characteristic frequencies in Example 1.

[0057] Figure 5 This is a graph showing the change of phase angle with service time at different characteristic frequencies in Example 2.

[0058] Figure 6 This is a comparison chart of phase angle attenuation rate η at different characteristic frequencies in Example 2.

[0059] In the diagram: 1. Measuring main unit; 11. Measuring cell; 111. Measuring electrolytic cell; 112. Sealing rubber gasket; 113. Inlet; 114. Outlet; 12. Electrode system; 121. Working electrode; 122. Auxiliary platinum electrode; 123. Reference platinum electrode; 124. Wire; 131. First test electrolyte buffer cell; 132. Second test electrolyte buffer cell; 141. First pipeline; 142. Second pipeline; 143. Third pipeline; 151. First pump body; 152. Second pump body; 16. Regulating valve;

[0060] 2. Hinge mechanism; 21. Hinge base; 22. Hinge link;

[0061] 3. Control device; 31. Main control and power supply module; 32. Hinge control module; 33. Electrochemical measurement control module; 34. Remote transmission module. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0063] In the description of this invention, it should be understood that the terms "center," "side," "length," "width," "height," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and "side," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0064] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0065] Figure 1 This is a structural schematic diagram of this embodiment, as shown below. Figure 1 As shown, this embodiment provides a testing system for the corrosion resistance of metal external anti-corrosion coatings, including a measuring host device 1, a hinge mechanism 2, and a control device 3.

[0066] The measurement host device 1 includes a measurement cell 11 and an electrode system 12. The measurement cell 11 is used to form a closed test environment, and the electrode system 12 can collect electrochemical signals of the coating of the device under test and form an electrochemical test circuit.

[0067] Specifically, in this embodiment, the measuring cell 11 can be configured as a cavity with an open top and a sealed bottom. The measuring cell 11 is used to cooperate with the coating surface of the device under test to form a closed test environment. The electrode system 12 is integrated into the measuring cell 11 and can collect electrochemical signals such as impedance and phase angle of the coating of the device under test, and cooperate with the control device to form a complete electrochemical test circuit.

[0068] The hinge mechanism 2 includes a hinge base 21 and a hinge link 22. The hinge base 21 can be fixed to the surface of the device under test, and the hinge link 22 is used to connect the hinge base 21 and the measuring host device 1.

[0069] Optionally, in this embodiment, the hinge base 21 is made of corrosion-resistant stainless steel and is fixed to the surface of the device under test by a combination of expansion bolts and elastic washers. The hinge link 22 is a double-axis universal joint structure, with one end rotatably connected to the hinge base 21 and the other end detachably fixed to the measuring host device 1, enabling the measuring host device 1 to be adjusted horizontally and vertically.

[0070] The control device 3 includes a power supply and control mechanism for the detection process. The measuring host device 1 and the hinge mechanism 2 are both connected to the control device 3.

[0071] In this embodiment, the control device 3 includes at least a main control unit and a power supply module. The power supply module provides a stable DC power supply to the measuring host device 1 and the hinge mechanism 2. The main control unit controls the detection process through a preset program. Specifically, in this embodiment, the measuring host device 1 is electrically connected to the control device 3 through a shielded wire, and the hinge mechanism 2 is connected to the control device 3 through a drive signal line.

[0072] As an optional implementation, the electrode system 12 includes a working electrode 121 for connection to the coating substrate metal of the device under test.

[0073] Optionally, in this embodiment, the working electrode is made of copper core plated with nickel, with a diameter of 2-5mm and a length adapted to the coating thickness of the device under test. One end is connected to the coating base metal of the device under test by bolt crimping or welding, and the other end extends to the outside of the measuring cell 11 through a shielded wire and is electrically connected to the signal acquisition terminal of the control device 3. The connection part between the working electrode 121 and the coating base metal is wrapped with anti-corrosion insulating tape to avoid direct contact with the electrolyte.

[0074] As an optional implementation, the electrode system 12 also includes an auxiliary platinum electrode sheet 122 and a reference platinum electrode sheet 123.

[0075] The auxiliary platinum electrode 122 and the reference platinum electrode 123 are both fixed to the inner wall of the measuring cell 11; the working electrode 121, the auxiliary platinum electrode 122 and the reference platinum electrode 123 work together to form an electrochemical testing circuit.

[0076] Optionally, in this embodiment, both the auxiliary platinum electrode 122 and the reference platinum electrode 123 are fixed to the inner wall of the measuring cell 11 with high-temperature resistant insulating adhesive. During operation, the signal acquisition end of the working electrode 121, the current output end of the auxiliary platinum electrode 122, and the potential reference end of the reference platinum electrode 123 are all connected to the control device 3 through independent shielded wires 124. The three work together to form a three-electrode system electrochemical test circuit, which can stably acquire the impedance spectrum and phase angle signal of the coating.

[0077] As an optional implementation, the measurement host device 1 further includes a first test electrolyte buffer 131 and a second test electrolyte buffer 132.

[0078] The first test electrolyte buffer tank 131 is used to supply electrolyte to the measuring tank 11. The first test electrolyte buffer tank 131 is connected to the measuring tank 11 through a first pipeline 141, and a first pump body 151 is installed on the first pipeline 141. The second test electrolyte buffer tank 132 is used to receive the electrolyte output from the measuring tank 11. The second test electrolyte buffer tank 132 is connected to the measuring tank 11 through a second pipeline 142, and a second pump body 152 is installed on the second pipeline 142. The first test electrolyte buffer tank 131 and the second test electrolyte buffer tank 132 are connected through a third pipeline 143. The third pipeline 143 is used to return the electrolyte in the second test electrolyte buffer tank 132 to the first test electrolyte buffer tank 131. A regulating valve 16 is installed on the third pipeline 143. The first pump body 151, the second pump body 152, and the regulating valve 16 are all electrically connected to the control device 3.

[0079] In this embodiment, the first test electrolyte buffer tank 131 is a container made of polytetrafluoroethylene (PTFE) and has a replenishment port with a sealed cap for storing and supplying electrolyte to the measuring cell 11. The first test electrolyte buffer tank 131 is connected to the inlet of the measuring cell 11 through a first PTFE pipeline 141. A miniature one-way peristaltic pump is installed on the first pipeline 141 as the first pump body 151, with a flow rate adjustment range of 0.5-5 mL / min.

[0080] The structure of the second test electrolyte buffer tank 132 is the same as that of the first test electrolyte buffer tank 131. It is used to receive the electrolyte output from the measuring tank. The second test electrolyte buffer tank 132 is connected to the outlet of the measuring tank 11 through a second pipeline 142 of the same specification as the first pipeline 141. The same type of miniature unidirectional peristaltic pump is installed on the second pipeline 142 as the second pump body 152.

[0081] The first test electrolyte buffer tank 131 and the second test electrolyte buffer tank 132 are connected by a third pipeline 143. The third pipeline 143 is used to return the electrolyte in the second test electrolyte buffer tank 132 to the first test electrolyte buffer tank 131 to achieve electrolyte recycling. An electromagnetic regulating valve 16 is installed on the third pipeline 143. The first pump body 151, the second pump body 152, and the regulating valve 16 are all electrically connected to the execution module of the control device 3 through a drive control line, and the control device 3 synchronously controls the start / stop and flow rate.

[0082] As an optional implementation method, such as Figure 2 As shown, the measuring cell 11 includes a measuring electrolytic cell 111 and a sealing rubber gasket 112.

[0083] The measuring electrolytic cell 111 is capable of holding electrolyte. The measuring electrolytic cell 111 is provided with an inlet 113 for connecting to the first pipeline 141 and an outlet 114 for connecting to the second pipeline 142. A sealing rubber gasket 112 is provided on the bottom periphery of the measuring electrolytic cell 111.

[0084] Specifically, in this embodiment, the measuring electrolytic cell 111 is a cylindrical cavity made of polytetrafluoroethylene (PTFE) for containing the electrolyte. The upper part of the side wall of the measuring electrolytic cell 111 has an inlet for connecting to the first pipeline 141, and the lower part of the side wall has an outlet for connecting to the second pipeline 142. Both the inlet and outlet have built-in silicone sealing rings to achieve a sealed connection with the pipelines, ensuring smooth electrolyte flow without leakage. The sealing rubber gasket, made of nitrile rubber or fluororubber, is used to tightly adhere to the coating surface of the device under test to prevent electrolyte leakage.

[0085] As an optional implementation, the control device 3 includes a central control and power supply module 31, a hinge control module 32, an electrochemical measurement control module 33, and a data storage and remote transmission module 34.

[0086] The hinge control module 32 is connected to the hinge mechanism 2; the electrochemical measurement control module 33 is connected to the measurement host device 1; the hinge control module 32, the electrochemical measurement control module 33, and the data storage and remote transmission module 34 are all connected to the main control and power supply module 31, which provides power and controls the detection process. The data storage and remote transmission module 34 stores the test data and remotely transmits it to a remote receiver.

[0087] Specifically, the central control system includes a microcomputer system for presetting and executing detection cycles, timed power on / off, and detection operation programs; the power supply includes lithium batteries or dry batteries, which provide power to the system wirelessly for greater convenience.

[0088] This embodiment also provides a method for testing the corrosion resistance of metal external anti-corrosion coatings, using the aforementioned testing system for the corrosion resistance of metal external anti-corrosion coatings, including the following steps:

[0089] S1: Install and debug the hardware of the testing system on the device under test, and fill the first test electrolyte buffer tank 131 with electrolyte, which consists of 3.5% sodium chloride and 0.1% sodium benzoate;

[0090] The specific operating steps are as follows: install and debug the testing system hardware in a flat and undamaged area of ​​the coating equipment, ensure that the hinge mechanism 2 is firmly fixed and the pipeline connection is sealed without leakage, fill the first test electrolyte buffer tank 131 with electrolyte, the electrolyte is composed of 3.5% sodium chloride and 0.1% sodium benzoate by mass fraction, and the electrolyte temperature is consistent with the ambient temperature (temperature difference ≤2℃);

[0091] S2: Set the detection parameters through the control device 3. The detection parameters include the detection cycle and electrochemical impedance measurement parameters.

[0092] In this embodiment, the control device 3 includes a visual interface through which detection parameters are set. Optionally, the detection cycle can be set to, for example, 15 days / time for a total of six months; or 30 days / time for a total of one year.

[0093] S3: Measure the initial impedance parameters, start the detection system, and the hinge mechanism drives the measurement host device to move and fasten it to the coating surface;

[0094] In actual testing, this embodiment sets the drive measurement host device 1 to move and tightly fits it to the coating surface through a sealing rubber gasket, with the fitting pressure controlled at 5-10N.

[0095] S4: The first pump body 151 pumps the electrolyte in the first test electrolyte buffer tank 131 into the measuring tank 11, and the measuring tank 11 performs electrochemical testing; after the test is completed, the second pump body pumps the electrolyte in the measuring tank 11 back to the second test electrolyte buffer tank 132.

[0096] Optionally, the first pump body pumps the electrolyte in the first test electrolyte buffer tank 131 into the measuring tank 11 at a preset flow rate, such as 2 mL / min. After the measuring tank 11 is confirmed to be full of electrolyte by the liquid level sensor, the first pump body 151 stops. The electrode system performs electrochemical testing. After the test is completed, the second pump body 152 starts and pumps the electrolyte in the measuring tank back to the second test electrolyte buffer tank 132 at the same flow rate.

[0097] S5: The hinge mechanism 2 drives the measuring host device 1 to move away from the coating surface to avoid interfering with the normal service of the coating.

[0098] S6: Data storage and remote transmission system stores test data and remotely transmits the data to a remote receiver;

[0099] S7: The detection system will shut down and go into hibernation. It will automatically power on and repeat steps S3-S6 at the next measurement time.

[0100] As an optional implementation, in step S2, the electrochemical impedance measurement parameters include impedance amplitude and characteristic frequency value. The impedance amplitude is selected according to the coating thickness d, specifically including:

[0101] When d≤50μm, the impedance amplitude is ±15mV;

[0102] When 50μm<d≤150μm, the impedance amplitude is ±20mV;

[0103] When d > 150 μm, the impedance amplitude is ±30 mV.

[0104] As an optional implementation, in the long-term electrochemical impedance spectroscopy test of the same coating, the average phase angle attenuation rate at 3-5 characteristic frequencies within the 5mHz-30mHz range is used. The method for evaluating coating performance or aging is as follows: The formula for calculating the phase angle attenuation rate η at a certain characteristic frequency is:

[0105]

[0106] Where θ0 is the initial phase angle at a certain characteristic frequency; θ i Let i be the phase angle at a certain characteristic frequency at time i.

[0107] Average phase angle attenuation rate The calculation formula is:

[0108]

[0109] Wherein, η1-η n The phase angle attenuation rate is selected at 3-5 characteristic frequencies, where n is the number of characteristic frequencies.

[0110] The following is a further detailed description with reference to two embodiments:

[0111] Example 1

[0112] S1: Install and debug the testing system hardware on the device under test, and fill the first test electrolyte buffer tank 131 with electrolyte, which consists of 3.5% sodium chloride and 0.1% sodium benzoate;

[0113] S2: Set the detection parameters via control device 3. The detection parameters include the detection cycle and electrochemical impedance measurement parameters.

[0114] In this embodiment, the detection cycle is set to half a month / time, for a total of half a year, the impedance amplitude is selected as ±15mV, the coating thickness d≤50μm, and the phase angles at the four characteristic frequencies are set as follows: 5mHz, 10mHz, 15mHz, and 20mHz.

[0115] S3: Measure the initial impedance parameters, start the detection system, and the hinge system will automatically move and move the main measuring device to the coating surface.

[0116] S4: The first pump body 151 pumps the electrolyte in the first test electrolyte buffer tank 131 into the measuring tank 11, and the measuring tank 11 performs electrochemical testing; after the test is completed, the second pump body pumps the electrolyte in the measuring tank 11 back to the second test electrolyte buffer tank 132.

[0117] S5: The hinge mechanism 2 drives the measuring host device 1 to move away from the coating surface to avoid interfering with the normal service of the coating.

[0118] S6: Data storage and remote transmission system stores test data and remotely transmits the data to a remote receiver;

[0119] S7: The detection system will shut down and go into hibernation. After half a month, it will automatically power on and repeat the tests S1-S6 above.

[0120] The changes in phase angle with service time at different characteristic frequencies and the phase angle attenuation rate η obtained from the test are shown in the figure. Figure 3 , Figure 4 As shown.

[0121] Example 2

[0122] S1: Install and debug the testing system hardware on the device under test, and fill the first test electrolyte buffer tank 131 with electrolyte, which consists of 3.5% sodium chloride and 0.1% sodium benzoate;

[0123] S2: Set the detection parameters via control device 3. The detection parameters include the detection cycle and electrochemical impedance measurement parameters.

[0124] In this embodiment, the detection cycle is set to 1 month / time, for a total of 1 year, the impedance amplitude is selected as ±30mV, the coating thickness d>150μm, and the phase angles at 3 characteristic frequencies are set as follows: 10mHz, 20mHz, and 30mHz.

[0125] S3: Measure the initial impedance parameters, start the detection system, and the hinge system will automatically move and move the main measuring device to the coating surface.

[0126] S4: The first pump body 151 pumps the electrolyte in the first test electrolyte buffer tank 131 into the measuring tank 11, and the measuring tank 11 performs electrochemical testing; after the test is completed, the second pump body pumps the electrolyte in the measuring tank 11 back to the second test electrolyte buffer tank 132.

[0127] S5: The hinge mechanism 2 drives the measuring host device 1 to move away from the coating surface to avoid interfering with the normal service of the coating.

[0128] S6: Data storage and remote transmission system stores test data and remotely transmits the data to a remote receiver;

[0129] S7: The detection system will shut down and go into hibernation. After one month, it will automatically power on and repeat the tests S1-S6 above.

[0130] The changes in phase angle with service time at different characteristic frequencies and the phase angle attenuation rate η obtained from the test are shown in the figure. Figure 5 , Figure 6 As shown.

[0131] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A testing system for the corrosion resistance of metal external anti-corrosion coatings, characterized in that, include: The measurement host device includes a measurement cell and an electrode system, wherein the measurement cell is used to form a closed test environment, and the electrode system is capable of acquiring electrochemical signals of the coating of the device under test and forming an electrochemical test circuit; A hinge mechanism includes a hinge base and a hinge link, wherein the hinge base can be fixed to the surface of the device under test, and the hinge link is used to connect the hinge base and the measuring host device; A control device is used to supply power and control the detection process. The measuring host device and the hinge mechanism are both connected to the control device.

2. The testing system for the corrosion resistance of a metal external anti-corrosion coating according to claim 1, characterized in that, The electrode system includes a working electrode for connecting to the coated substrate metal of the device under test.

3. The testing system for the corrosion resistance of a metal external anti-corrosion coating according to claim 2, characterized in that, The electrode system further includes an auxiliary platinum electrode sheet and a reference platinum electrode sheet, wherein: Both the auxiliary platinum electrode and the reference platinum electrode are fixed to the inner wall of the measuring cell; The working electrode, the auxiliary platinum electrode, and the reference platinum electrode work together to form an electrochemical testing circuit.

4. A testing system for the corrosion resistance of a metal external anti-corrosion coating according to any one of claims 1-3, characterized in that, The measurement host device also includes: A first test electrolyte buffer tank is used to deliver electrolyte into the measuring cell. The first test electrolyte buffer tank is connected to the measuring cell through a first pipeline, and a first pump body is installed on the first pipeline. The second test electrolyte buffer tank is used to receive the electrolyte output from the measuring tank. The second test electrolyte buffer tank is connected to the measuring tank through a second pipeline, and a second pump body is installed on the second pipeline. The first test electrolyte buffer tank and the second test electrolyte buffer tank are connected by a third pipeline. The third pipeline is used to return the electrolyte in the second test electrolyte buffer tank to the first test electrolyte buffer tank. A regulating valve is installed on the third pipeline. The first pump body, the second pump body, and the regulating valve are all electrically connected to the control device.

5. The testing system for the corrosion resistance of a metal external anti-corrosion coating according to claim 4, characterized in that, The measuring cell includes: A measuring electrolytic cell, the measuring electrolytic cell being capable of containing the electrolyte, the measuring electrolytic cell being provided with an inlet for connecting to the first pipeline and an outlet for connecting to the second pipeline; A sealing rubber gasket is provided on the bottom periphery of the measuring electrolytic cell.

6. A testing system for the corrosion resistance of a metal external anti-corrosion coating according to any one of claims 1-3, characterized in that, The control device includes: a central control and power supply module, a hinge control module, an electrochemical measurement control module, and a data storage and remote transmission module, wherein: The hinge control module is connected to the hinge mechanism; The electrochemical measurement and control module is connected to the measurement host device; The hinge control module, the electrochemical measurement control module, and the data storage and remote transmission module are all connected to the main control and power supply module, which is used to supply power and control the detection process. The data storage and remote transmission module is used to store test data and remotely transmit the test data to a remote receiver.

7. The testing system for the corrosion resistance of a metal external anti-corrosion coating according to claim 6, characterized in that: The central control system includes a microcomputer system, which is used to preset and execute the detection cycle, timed power on / off, and detection operation program; The power source includes lithium batteries or dry cell batteries.

8. A method for testing the corrosion resistance of a metal external anti-corrosion coating, characterized in that, The testing system for the corrosion resistance of metal external anti-corrosion coatings according to any one of claims 1-7 includes the following steps: S1: Install and debug the detection system hardware on the coating equipment, and fill the first test electrolyte buffer tank with electrolyte, which is composed of 3.5% sodium chloride and 0.1% sodium benzoate; S2: Set the detection parameters through the control device, including the detection cycle and electrochemical impedance measurement parameters; S3: Measure the initial impedance parameters, start the detection system, and the hinge mechanism drives the measurement host device to move and fasten it to the coating surface; S4: The first pump pumps the electrolyte in the first test electrolyte buffer tank into the measuring tank, where electrochemical testing is performed; after the test, the second pump pumps the electrolyte in the measuring tank back to the second test electrolyte buffer tank. S5: The hinge mechanism drives the measuring host device to move away from the coating surface; S6: Data storage and remote transmission system stores test data and remotely transmits the data to a remote receiver; S7: The detection system will shut down and go into hibernation. It will automatically power on and repeat steps S1-S6 at the next measurement time.

9. The method for testing the corrosion resistance of a metal external anti-corrosion coating according to claim 8, characterized in that, In step S2, the electrochemical impedance measurement parameters include impedance amplitude and characteristic frequency value. The impedance amplitude is selected according to the coating thickness d, specifically including: When d≤50μm, the impedance amplitude is ±15mV; When 50μm<d≤150μm, the impedance amplitude is ±20mV; When d > 150 μm, the impedance amplitude is ±30 mV.

10. The method for testing the corrosion resistance of a metal external anti-corrosion coating according to claim 8, characterized in that: In long-term electrochemical impedance spectroscopy (EIS) tests of the same coating, the average phase angle attenuation rate at 3-5 characteristic frequencies within the 5-30 mHz range was used. The method for evaluating coating performance or aging is as follows: The formula for calculating the phase angle attenuation rate η at a certain characteristic frequency is: Where θ0 is the initial phase angle at a certain characteristic frequency; θ i Let i be the phase angle at a certain characteristic frequency at time i. Average phase angle attenuation rate The calculation formula is: Wherein, η1-η n The phase angle attenuation rate is selected at 3-5 characteristic frequencies, where n is the number of characteristic frequencies.

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