Corrosion coupon testing system and method based on voltage matrix imaging

Abstract

The invention discloses a corrosion coupon testing system and method based on voltage matrix imaging, and belongs to the technical field of corrosion monitoring. The system comprises a hanging piece, a shell, a plurality of signal acquisition electrodes, a plurality of current feed-in / feed-out electrodes, an environment sensor and a plurality of watertight sockets with different functions, the shell is of a hollow structure with an opening in one side; the hanging piece is arranged on the opening side of the shell and connected with the shell in a sealed mode. The signal acquisition electrodes are fixedly arranged on the inner side wall of the hanging piece in an array mode. The environment sensor is fixedly arranged on the inner side wall of the hanging piece and is adjacent to the signal acquisition electrode; the watertight socket is fixedly arranged on one outer side wall of the shell; and the signal acquisition electrode, the current feed-in / feed-out electrode and the environment sensor are respectively connected with the corresponding watertight sockets through cables. By combining the coupon with voltage matrix imaging, the local corrosion monitoring capability is improved, and the requirements for uniform thinning of the coupon and real-time monitoring of local corrosion are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of corrosion monitoring, and particularly relates to a corrosion coupon test system and method based on voltage matrix imaging. Background Art

[0002] Corrosion test stations mainly study the corrosion behavior and laws of materials in different environments, and provide basic data for the design and corrosion control of major projects. As the most common and traditional corrosion monitoring method in corrosion test stations, the coupon method has the advantages of simple operation, reliable data, and being unrestricted by the medium environment, and is widely used. In this monitoring method, the coupon is taken out after being exposed to the corrosion medium for a specific time period, and weight loss measurement and more detailed morphology observation are carried out. By calculating the weight loss of the test piece before and after the test, the average corrosion rate of the test material under actual conditions within a specific time period can be calculated; the corrosion type of the material in the environment can be determined by observing the surface state of the test piece. However, the ordinary coupon experiment has a long cycle, and the single experiment time ranges from several months to several years. Only through weight loss testing, the corrosion details on the time scale such as diurnal variation and seasonal variation during the long-term corrosion process cannot be reflected, nor can the dynamic details of the surface morphology of the coupon sample on the spatial scale be reflected.

[0003] The voltage matrix imaging technology (Potential Matrix Mapping, abbreviated as PMM, also known as electric field fingerprint, field fingerprint) is a non-invasive corrosion monitoring technology. By arranging an electrode matrix on the surface of the object to be measured, and based on the tiny voltage changes generated on the surface of the object to be measured, high-precision monitoring of internal defects, cracks, corrosion and their expansion conditions of the metal structure can be achieved. It can be used to monitor the overall and local corrosion, erosion and cracks of metal structures, pipeline systems and containers, and has been successfully applied in many fields. If the advantages of high sensitivity and long service life of this method are combined with the corrosion coupon, the corrosion condition of the coupon can be monitored in real time, and the detection ability of corrosion details on the time and space scales can be improved on the basis of the advantages of the coupon method itself. Therefore, it is particularly important to develop a corrosion coupon preparation and test method based on voltage matrix imaging technology. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the above related technologies to some extent.

[0005] For this reason, the purpose of the present invention is to provide a corrosion coupon test system and method based on voltage matrix imaging. By combining the traditional corrosion coupon preparation with the voltage matrix imaging technology, the online monitoring of the coupon corrosion process is carried out, the monitoring ability of the corrosion coupon for local corrosion is improved, and the real-time monitoring requirements of the corrosion test site for the uniform thinning and local corrosion of the coupon are met.

[0006] To solve the above technical problems, the present invention is implemented as follows: An embodiment of the present invention provides a corrosion coupon test system based on voltage matrix imaging. The system includes: a coupon 3, a housing, a plurality of signal acquisition electrodes 4, a plurality of current feeding / feeding-out electrodes 5, an environmental sensor, and a plurality of watertight sockets with different functions; The housing is a hollow structure with an opening on one side; the coupon 3 is arranged on the opening side of the housing and is sealingly connected to the housing; The signal acquisition electrodes 4 are fixedly arranged in an array on the inner side wall of the coupon 3; The environmental sensor is fixedly arranged on the inner side wall of the coupon 3 and is adjacent to the signal acquisition electrodes 4; The watertight sockets are fixedly arranged on an outer side wall of the housing; the signal acquisition electrodes 4, the current feeding / feeding-out electrodes 5, and the environmental sensor are respectively connected to the corresponding watertight sockets through corresponding cables.

[0007] In addition, the corrosion coupon test system based on voltage matrix imaging according to the present invention may further have the following additional technical features: In some embodiments, epoxy resins are provided on the outer peripheries of the signal acquisition electrodes 4, the current feeding / feeding-out electrodes 5, and the environmental sensor. The epoxy resins surround all of the signal acquisition electrodes 4, the current feeding / feeding-out electrodes 5, and the environmental sensor and a part of the cables.

[0008] In some embodiments, the watertight sockets include a signal acquisition watertight socket 101, a power supply feeding watertight socket 102, and an environmental watertight socket; The signal acquisition watertight socket 101 is simultaneously connected to all the signal acquisition electrodes 4; The power supply feeding watertight socket 102 is simultaneously connected to all the current feeding / feeding-out electrodes 5; The environmental watertight socket is connected to the environmental sensor.

[0009] In some embodiments, the environmental sensor is a patch type temperature sensor 6.

[0010] In some embodiments, the coupon 3 and the housing are sealingly connected by a sealant.

[0011] In some embodiments, the watertight sockets and the housing are sealingly connected by a sealant.

[0012] In some embodiments, the system further includes a temperature control device and / or a salt spray chamber; The temperature control device is configured to be able to heat and control the temperature of the space where the coupon is located; The salt spray chamber is configured to be able to adjust the salt concentration in the space where the coupon is located, thereby adjusting the corrosion rate of the coupon.

[0013] An embodiment of the present invention further provides a method for testing a corroded coupon based on voltage matrix imaging, which is implemented by using the corroded coupon testing system based on voltage matrix imaging described in any one of the above; the steps of the method include: S1. Expose the coupon of the corroded coupon testing system based on voltage matrix imaging to the corrosion environment, and connect each watertight socket to an external PMM data acquisition device and a constant current source through cables; S2. Start the PMM data acquisition device and the constant current source, and collect the initial voltage data and initial environment data at each signal acquisition electrode of the coupon when no corrosion occurs; S3. Collect the voltage signals and environment data at each signal acquisition electrode on the coupon at the current acquisition time point or time period through the PMM data acquisition device; S4. Process and analyze the collected data to obtain the corresponding corrosion depth of the coupon; S5. Repeat steps S3 and S4 until the end condition is met; S6. Draw a three-dimensional corrosion image of the coupon according to the obtained corrosion depth of the coupon.

[0014] In addition, according to the method for testing a corroded coupon based on voltage matrix imaging of the present invention, the following additional technical features may also be provided: In some embodiments, the end condition in step S5 is to reach a preset coupon exposure time or a preset coupon corrosion intensity.

[0015] In some embodiments, the steps of the method further include: S7. Evaluate the coupon corrosion behavior according to the three-dimensional corrosion image.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: In the embodiment of the present invention, the provided corroded coupon testing system and method based on voltage matrix imaging can be used in combination with a PMM device after preparing a conventional corroded coupon, realizing real-time monitoring of the corrosion situation of the coupon, providing real-time data during the corrosion process, improving the accumulation method of basic corrosion data of metal materials in a seawater corrosion test site, quickly expanding the data scale, and providing more convenient conditions for the application of corrosion big data; In the embodiments of the present invention, the provided corrosion coupon test system and method based on voltage matrix imaging can realize real-time monitoring of the corrosion situation of the coupons by collecting voltage responses, provide more detailed corrosion information in terms of time and space dimensions, improve the accumulation method of basic corrosion data of metal materials in the corrosion test field, can quickly expand the scale of corrosion data, and provide richer conditions for the application of corrosion big data; In the embodiments of the present invention, the provided corrosion coupon test system and method based on voltage matrix imaging are applicable to various metal materials, have the advantages of small excitation, high precision, good reliability, etc., and still belong to a non-destructive corrosion monitoring technology; the combination of voltage matrix imaging technology and the coupon method reduces the manual detection cost of the traditional coupon method, expands the application scenarios of the existing voltage matrix corrosion monitoring technology, and improves the practicability of the monitoring system.

[0017] The corrosion coupon test method based on voltage matrix imaging of the present invention is implemented by using the corrosion coupon test system based on voltage matrix imaging, and thus has at least all the features and advantages of the corrosion coupon test method based on voltage matrix imaging, which will not be elaborated here. The additional aspects and advantages of the present invention will be partly given in the following description, partly become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0018] Figure 1 Schematic diagram of the corrosion coupon structure based on voltage matrix imaging technology disclosed in an embodiment of the present invention; Figure 2 Schematic diagram of the electrode layout scheme of the corrosion coupon based on voltage matrix imaging technology disclosed in an embodiment of the present invention; Figure 3 Schematic diagram of the PMM corrosion coupon assembly disclosed in an embodiment of the present invention; Figure 4 Schematic diagram of the PMM corrosion coupon finished product disclosed in an embodiment of the present invention; Figure 5 Flow chart of the preparation of the PMM corrosion coupon disclosed in an embodiment of the present invention; Figure 6 Flow chart of the test of the PMM corrosion coupon disclosed in an embodiment of the present invention; Figure 7 Graph of the change of FC value during the monitoring of the Q235 corrosion coupon based on PMM technology disclosed in an embodiment of the present invention; Figure 8 Graph of the change of FC value during the monitoring of the B10 corrosion coupon based on PMM technology disclosed in an embodiment of the present invention.

[0019] Description of the reference numerals: 101 - Signal acquisition watertight socket, 102 - Power supply feed watertight socket, 103 - Temperature watertight socket, 201 - Outer shell top plate, 202 - Outer shell panel, 203 - Outer shell side plate, 3 - Hanging piece, 4 - Signal acquisition electrode, 5 - Current feed-in / feed-out electrode, 6 - Temperature sensor, 7 - Signal acquisition cable, 8 - Power supply feed cable, 9 - Epoxy resin, 10 - Sealant. Detailed implementation manners

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Next, in conjunction with the accompanying drawings, the embodiments of the present invention will be described in detail through specific embodiments and their application scenarios.

[0022] In some embodiments of the present invention, a corrosion coupon test system and method based on voltage matrix imaging are provided. Please refer to Figure 5 As shown, the steps of the corrosion coupon preparation method based on voltage matrix imaging include: Step 1, Coupon pretreatment: Select a coupon 3 with common specifications and materials in the corrosion test station. Select one side as the exposed surface of the corrosion coupon, and the other side as the electrode connection surface of the test system. Determine the positions of the electrodes on the electrode connection surface, and polish the electrode positions to a metallic luster to ensure reliable electrical connection between the electrodes and the coupon 3. The electrodes of the corrosion coupon test system based on voltage matrix imaging include current feed-in / feed-out electrodes 5 provided at both ends of the coupon 3, and a plurality of signal acquisition electrodes 4 arranged in a matrix in the middle of the coupon 3. The matrix of the signal acquisition electrodes 4 needs to be arranged within the effective detection area formed by the current feed-in / feed-out electrodes 5. The signal acquisition electrode 4 is a voltage signal acquisition probe. A temperature sensor 6 is also provided on the electrode connection surface of the coupon 3, and the temperature sensor 6 is also arranged within the effective detection area formed by the current feed-in / feed-out electrodes 5.

[0023] In the above implementation manner, there may be two current feed-in / feed-out electrodes 5, which are respectively arranged at the upper and lower ends of the array formed by the signal acquisition electrodes 4. The temperature sensor 6 is arranged between a certain current feed-in / feed-out electrode 5 and the array formed by the signal acquisition electrodes 4. The temperature sensor 6 is a patch-type RTD temperature acquisition sensor.

[0024] Step 2, Electrode installation: Weld the two current feed-in / feed-out electrodes 5 and the signal acquisition electrode matrix at the pre-determined positions respectively by stud welding. After welding, gently tap the welding studs with a wrench to ensure reliable welding quality.

[0025] Step 3. Shell processing: Make a shell according to the size of a conventional corrosion coupon. The shell must surround and seal the corrosion coupon, and an opening should be reserved on one side of the shell opposite to the coupon to provide installation space for the feed electrode, the signal acquisition electrode matrix, and the connectors of the sensors.

[0026] Preferably, the connector is a watertight socket. The shell material is preferably titanium alloy, which can not only avoid its own corrosion but also shield external noise signals. Considering the cost performance, for corrosion coupons with a short test period, the shell material can also be aluminum alloy.

[0027] Please refer to Figure 1 As shown, in the above embodiment, the shell includes a shell top plate 201, two shell panels 202, and two shell side plates 203. The shell top plate 201 is arranged parallel to the coupon 3, the shell side plates 203 are arranged perpendicular to the shell top plate 201 and the coupon 3, and the two shell side plates 203 are respectively arranged at both ends of the shell top plate 201 and the coupon 3. The shell top plate 201, the coupon 3, the two shell panels 202, and the two shell side plates 203 form a sealed cuboid. The joints between the shell top plate 201, the shell panels 202, the shell side plates 203, and the coupon 3 are sealed with a sealant 10.

[0028] Step 4. Cable and connector preparation: Prepare a power feed cable 8 and a signal acquisition cable 7 according to the internal space of the PMM corrosion coupon shell. Connect one end of a signal acquisition cable 7 to a signal acquisition electrode 4 and the other end to the corresponding signal acquisition watertight socket 101. Each signal acquisition electrode 4 corresponds to a signal acquisition cable 7. Connect one end of the power feed cable 8 to a current feed-in / feed-out electrode 5 and the other end to the corresponding power feed watertight socket 102. Each current feed-in / feed-out electrode 5 corresponds to a power feed cable 8. The temperature sensor 6 is connected to the corresponding temperature watertight socket 103 through a sensor cable. Cable connections need to ensure reliable electrical connections at all wiring points.

[0029] Step 5. Signal conductivity test: After wiring, connect the connectors to a constant current source and a PMM device for signal acquisition experiments, and verify the signal conductivity by the ability of each device to receive corresponding signals. Among them, the constant current source is connected to the power feed watertight socket 102 to inject a constant current into the coupon through the current feed-in / feed-out electrode 5, thereby forming an electric field distribution. The PMM device is connected to the signal acquisition watertight socket 101 and the temperature watertight socket 103 to receive the collected corrosion signals and temperature signals. The PMM data acquisition device can use existing devices.

[0030] Step 6. Housing assembly and watertight treatment: Coat the periphery of the PMM corrosion coupon with epoxy resin 9 to ensure insulation between the coupon and the housing during housing assembly. Pour high-hardness epoxy resin 9 into the housing through the watertight socket interface until the electrodes are covered, and let it cure at room temperature while standing still.

[0031] Step 7. Fixing the watertight socket: Fix the watertight socket to the housing opening and seal it with sealant 10.

[0032] In some embodiments of the present invention, please refer to Figure 6 As shown, the steps of the corrosion coupon test method based on voltage matrix imaging include: Step 1. Connect the signal acquisition watertight socket 101, the power supply feeding watertight socket 102, and the temperature watertight socket 103 to the PMM data acquisition device and the constant current source respectively.

[0033] Step 2. Place the PMM corrosion coupon in the corrosion environment, start the constant current source and the PMM data acquisition device, and collect the initial voltage data of the coupon when no corrosion occurs.

[0034] Step 3. During the exposure of the PMM corrosion coupon in the corrosion environment, use the PMM data acquisition device and the constant current source to continuously collect data for a certain period of time at a fixed time period every day, and take the average value of the data as the voltage response at the interval time.

[0035] Step 4. Import the collected voltage response data into the PMM data analysis program, invert the corrosion depth of the coupon represented by the data, and use software to draw a three-dimensional graph to visually show the corrosion situation of the coupon.

[0036] Step 5. Repeat Step 3 to Step 4 until the exposure time of the PMM corrosion coupon ends.

[0037] Preferably, a temperature control device or a salt spray chamber can be used to accelerate the corrosion of the PMM corrosion coupon. Correspondingly, the number of data collections per day also needs to be increased.

[0038] Example 1: The present invention provides a method for preparing a corrosion coupon based on voltage matrix imaging technology. As Figure 1 shown, the PMM coupon includes: a coupon test plate, an electrode probe, a housing, a cable interface, and watertight treatment measures.

[0039] The method for preparing the coupon provided by the present invention includes the following steps: Step 1. Coupon pretreatment: Select the corrosion coupons commonly used in the corrosion test station. The coupon size is 200×100×3 mm, and the coupon material is Q235 low-carbon steel. Select one side as the exposed surface of the corrosion coupon, and the other side as the probe connection surface. Adopt a signal acquisition electrode matrix layout of 4 rows and 5 columns, with an adjacent electrode spacing of 20 mm; the feeding and feeding-out electrodes are located on both sides of the coupon, 15 mm from both ends, as shown in Figure 2 shown. Polish the probe position to a metallic luster to ensure reliable electrical connection between the probe and the coupon.

[0040] Step 2. Electrode installation: Weld two current feeding and feeding-out electrodes and the signal acquisition electrode matrix at the pre-determined positions respectively by stud welding. After welding, gently tap the welding studs with a wrench to ensure reliable welding quality.

[0041] Step 3. Housing processing: Manufacture the housing according to the size of the corrosion coupon. The housing includes front and rear panels, upper and lower side panels, and a top panel opposite to the coupon. Among them, the top panel of the housing opposite to the coupon needs to be opened to reserve the installation space for the feeding electrode, the signal acquisition electrode matrix, and the connector of the temperature sensor, as shown in Figure 3 shown. Select a 2-core watertight socket for the feeding electrode connector, a 32-core watertight socket for the signal acquisition electrode matrix connector, and a 4-core watertight socket for the temperature sensor. Select 6061 aluminum alloy as the housing material, which can resist the corrosion of the atmosphere, water, and some chemicals, especially showing excellent performance in resisting stress corrosion cracking tendency. In addition, the aluminum alloy material has a certain signal shielding effect, which can reduce the noise interference of the PMM corrosion coupon acquisition signal.

[0042] Step 4. Cable and connector preparation: Prepare the feeding cable and the signal cable according to the internal space of the PMM corrosion coupon housing. Select a 2×6 mm 2 power cord for the feeding cable, with a cable length of 15 cm; select 16 pairs of 2×0.5 mm 2 shielded twisted pair cables for the signal cable, with a cable length of 15 cm. Crimp a cold-pressed terminal at one end of the cable and connect it to the feeding electrode or the signal acquisition electrode through nuts and washers, and weld the other end to the corresponding connector of the watertight socket. Install an OMEGA-SP1 patch-type RTD temperature acquisition sensor on the probe side of the corrosion coupon, and weld the temperature sensor cable to the corresponding connector of the 4-core watertight socket. Ensure reliable electrical connection at all wiring points.

[0043] Step 5. Signal conductivity test: After wiring, connect the constant current source and the PMM device to conduct a signal acquisition experiment to verify the signal conductivity.

[0044] Step 6. Housing assembly and watertight treatment: Coat the periphery of the PMM corrosion coupon with epoxy resin to ensure insulation between the coupon and the housing during housing assembly. Assemble the housing and the corrosion coupon, and use Kraft 704 sealant to waterproof the joint of the housing. Pour high-hardness epoxy resin into the housing through the watertight socket interface until it covers the electrode, and let it cure at room temperature for 12 hours.

[0045] Step 7. Fix the watertight socket: Fix the watertight socket to the opening of the housing, and use Kraft 704 sealant to treat the joint between the housing and the watertight socket.

[0046] The prepared PMM corrosion coupon is as Figure 4 shown.

[0047] Example 2: The method for corrosion monitoring using the above PMM corrosion coupon includes the following steps: Step 1. Connect the signal wire interface of the electrode matrix, the power supply feeder interface, and the temperature sensor interface to the PMM data acquisition device and the constant current source respectively. The used PMM data acquisition device is the ENDI-PMM-800 corrosion monitoring device, and the used constant current source is the ITECH IT6723C DC power supply.

[0048] Step 2. Place the PMM corrosion coupon in a glass cylinder filled with 3.5% NaCl solution to simulate the corrosion environment in the seawater fully immersed area. Start the constant current source and the PMM data acquisition device, continuously collect data for 10 minutes, and take the average value of the data as the initial voltage data of the coupon when no corrosion occurs.

[0049] Step 3. During the continuous immersion of the PMM corrosion coupon in 3.5% NaCl solution, use the PMM data acquisition device and the constant current source to continuously collect data for 10 minutes at a fixed time period every day, and take the average value of the data as the voltage response every 24 hours.

[0050] Step 4. Import the collected voltage response data into the PMM data analysis program, invert the corrosion depth of the coupon represented by the data, and use the software to draw a three-dimensional graph to visually show the corrosion situation of the coupon. The used PMM data analysis program is independently developed.

[0051] Step 5. Repeat steps S3 - S4 until the immersion time of the PMM corrosion coupon ends.

[0052] Preferably, a temperature control device can be used to accelerate the corrosion of the PMM corrosion coupon, and correspondingly, the number of data collections per day should also be increased.

[0053] Preferably, a salt spray test chamber can be used to accelerate the corrosion of the PMM corrosion coupon, and correspondingly, the number of data collections per day should also be increased.

[0054] Example 3: Example 3 further uses the corrosion coupon preparation and testing methods based on voltage matrix imaging technology provided in Example 1 and Example 2 for corrosion monitoring.

[0055] The coupon specification used in the experiment is Q235 low-carbon steel with a size of 200 mm × 100 mm × 3 mm. The specimens are divided into an experimental group (PMM corrosion coupon) and a control group (traditional corrosion coupon). The working surface is gradually polished with sandpaper to 800 mesh, and the back and periphery of the control group coupons are waterproofed with epoxy resin and 704 glue. The exposed metal area on the working surface should be the same as that of the experimental group. All coupons are cleaned with alcohol and dried before the experiment.

[0056] To study the corrosion behavior of the two types of coupons in the water environment, 50 L of prepared 3.5% NaCl solution is filled in a glass cylinder to simulate the seawater immersion zone. The position of the sealed working surface of the control coupon is clamped with a clip, and the coupon is suspended in the solution, and the temperature is kept at 35 ± 2 °C to accelerate corrosion and shorten the experimental period.

[0057] The removed coupons are processed according to GB / T 16545-2015 "Corrosion of metals and alloys - Removal of corrosion products from corrosion specimens". The Q235 coupon is brushed with a 1000 ml solution prepared by adding 3.5 g of corrosion inhibitor hexamethylenetetramine to 500 ml of hydrochloric acid ( ρ = 1.19 g / ml) and distilled water to remove the surface rust layer, rinsed with deionized water, and weighed after natural drying for 24 h.

[0058] The monitoring time period for the experimental group is ten days. 419 data are collected from each of the two types of coupons for ten minutes every day, and the average value is taken. The voltage value when no corrosion occurs on the first day is used as the initial value to calculate FC. The black solid line represents the calculated FC value of the control group coupon as shown in Figure 7 .

[0059] Example 4: Example 4 further uses the corrosion coupon preparation and testing methods based on voltage matrix imaging technology provided in Example 1 and Example 2 for local corrosion monitoring.

[0060] In this example, the corrosion environment and the treatment of the control group and experimental group coupons are the same as those in Example 3.

[0061] The coupon used in the experiment was B10 cupronickel with a specification of 200 mm×100 mm×3 mm. To accelerate the initiation and development of local corrosion, prefabricated pitting defects were processed on the cupronickel coupons in the experimental group and the control group. The processing dimensions were a pitting depth of 2 mm and a radius of 1 mm. The morphology of the processed defects was scanned by the Chengdu Liyang ultra-depth-of-field 3D microscopy equipment to obtain the three-dimensional information of the morphology of the B10 coupon before and after corrosion.

[0062] The control group processed the removed coupons according to GB / T 16545-2015 "Corrosion of metals and alloys - Removal of corrosion products from corrosion specimens". The rust layer on the B10 coupon was removed with a 1000 ml solution prepared by adding 500 ml of hydrochloric acid ( ρ =1.19 g / ml) and distilled water, rinsed with deionized water, and weighed after natural drying for 24 h.

[0063] Since the main component of B10 is copper, an oxide film will be formed on the surface to protect the matrix. The longer the immersion time, the worse the protective effect of the loose oxide film on the surface of the matrix metal on the matrix, and the more obvious the pitting corrosion.

[0064] Taking the coupon surface as the reference plane under the same scale, it can be seen that there are machining marks around the prefabricated defect before immersion and the lower surface of the pitting is relatively uneven. After immersion for 10 d, the inner surface of the pitting tends to be flat, and the increased color span between the pitting and the reference plane indicates an increase in the pitting volume. The depth and width before and after corrosion were measured using a three-dimensional ultra-depth-of-field digital microscope, and the average value was taken after three measurements to eliminate random errors, indicating that pitting corrosion occurred.

[0065] In this embodiment, the monitoring period of the experimental group is the same as that of Embodiment 1, and the results are as Figure 8 . There are peaks in the distribution of the FC value. The position and parameter size of pitting corrosion can be accurately identified using the peaks in the distribution of the FC value, and they are consistent with the actual pitting corrosion morphology parameters.

[0066] For the parts not detailed in the present invention, reference can be made to the prior art or the well-known technology in the art. This embodiment does not limit this and will not be described in detail here.

[0067] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and all of them fall within the protection scope of the present invention.

Claims

1. A corrosion coupon testing system based on voltage matrix imaging, characterized in that: The system comprises: a hanging piece (3), a shell, a plurality of signal collection electrodes (4), a plurality of current feeding / feeding-out electrodes (5), an environmental sensor and a plurality of watertight sockets with different functions; The shell is a hollow structure with one side open; the hanging piece (3) is arranged on the open side of the shell and is sealedly connected to the shell; The signal collection electrodes (4) are fixedly arranged in an array on the inner side wall of the hanging piece (3); The environmental sensor is fixedly mounted on the inner wall of the hanging piece (3) and is arranged adjacent to the signal collection electrode (4); The watertight socket is fixedly mounted on an outer side wall of the housing; the signal collection electrode (4), the current feed-in / feed-out electrode (5) and the environmental sensor are respectively connected to the corresponding watertight sockets via corresponding cables.

2. The corrosion coupon testing system based on voltage matrix imaging according to claim 1 is characterized in that: The peripheries of the signal collection electrode (4), the current feed-in / feed-out electrode (5) and the environmental sensor are all provided with epoxy resin, and the epoxy resin surrounds the entirety of the signal collection electrode (4), the current feed-in / feed-out electrode (5) and the environmental sensor, as well as a portion of the cable.

3. The corrosion coupon testing system based on voltage matrix imaging according to claim 1 is characterized in that: The watertight socket comprises a signal collection watertight socket (101), a power supply feeding watertight socket (102) and an environmental watertight socket; The signal collection watertight socket (101) is simultaneously connected to all the signal collection electrodes (4); The power supply watertight socket (102) is simultaneously connected to all the current feeding / feeding electrodes (5); The environmental watertight socket is connected to the environmental sensor.

4. The corrosion coupon testing system based on voltage matrix imaging according to claim 1 is characterized in that: The environmental sensor is a patch-type temperature sensor (6).

5. The corrosion coupon testing system based on voltage matrix imaging according to claim 1 is characterized in that: The hanging piece (3) and the shell are sealed and connected by means of a sealant.

6. The corrosion coupon testing system based on voltage matrix imaging according to claim 1 is characterized in that: The watertight socket and the housing are sealed and connected via sealant.

7. The corrosion coupon testing system based on voltage matrix imaging according to claim 1 is characterized in that: The system also includes a temperature control device and / or a salt spray chamber; The temperature control device is configured to heat and control the temperature of the space where the coupon is located; The salt spray box is configured to be able to adjust the salt concentration in the space where the coupon is located, thereby adjusting the corrosion rate of the coupon.

8. A corrosion coupon testing method based on voltage matrix imaging, characterized in that: The method is implemented by using the corrosion coupon testing system based on voltage matrix imaging as described in any one of claims 1 to 7; the steps of the method include: S1. Expose the coupon of the corrosion coupon test system based on voltage matrix imaging to a corrosion environment, and connect each watertight socket to an external PMM data acquisition device and a constant current source through a cable; S2, starting the PMM data acquisition device and the constant current source to collect initial voltage data and initial environmental data at each signal acquisition electrode of the coupon when no corrosion occurs; S3, collecting voltage signals and environmental data of each signal collection electrode on the hanging sheet at the current collection time point or time period through the PMM data collection device; S4, processing and analyzing the collected data to obtain the corresponding corrosion depth of the coupon; S5, repeat steps S3 and S4 until the end condition is met; S6. Draw a three-dimensional corrosion image of the hanging piece according to the obtained corrosion depth of the hanging piece.

9. The corrosion coupon testing method based on voltage matrix imaging according to claim 8 is characterized in that: The end condition in step S5 is that a preset coupon exposure time is reached or a preset coupon corrosion intensity is reached.

10. The corrosion coupon testing method based on voltage matrix imaging according to claim 8, characterized in that: The method further comprises the steps of: S7. Evaluate the corrosion behavior of the coupon based on the three-dimensional corrosion image.

Images