CN117214076A - Comprehensive analysis device and monitoring method for corrosion state of marine structure - Google Patents

Abstract

The application discloses a comprehensive analysis device and a monitoring method for corrosion states of marine structures, which can realize real-time monitoring of the stripping degree of a coating of a structure to be monitored and the performance of a sacrificial anode by the comprehensive analysis device for the corrosion states of the marine structures, and acquire the actual corrosion rate of a metal structure under the protection of the sacrificial anode after the coating is stripped. The comprehensive analysis device and the monitoring method for the corrosion state of the marine structure can realize the state monitoring of two common corrosion protection means of a coating and a sacrificial anode at the same time; meanwhile, the close connection between the monitoring equipment and the structure to be monitored in the ocean is realized, and the problem that the reliability of monitoring data is lacking because the traditional monitoring equipment is independent of the structure to be monitored and cannot be subjected to the actual cathodic protection effect of the structure to be monitored is solved; and further, the reliability of monitoring data is ensured, and the method has important value for corrosion and protection of marine engineering equipment.

Description

A comprehensive analysis device and monitoring method for corrosion status of marine structures

Technical field

The invention relates to the technical field of key supporting equipment for marine engineering, and in particular to a comprehensive analysis device and monitoring method for the corrosion status of marine structures.

Background technique

Corrosion is an important factor causing the loss of marine metal structures. In marine engineering, coatings and sacrificial anodes are usually used as means of corrosion protection. However, since most coatings and sacrificial anodes are located in underwater areas, it is difficult to effectively monitor the coating status and the working performance of the sacrificial anode. Therefore, reliable monitoring equipment needs to be developed.

Existing marine engineering corrosion protection monitoring equipment usually only monitors the performance of coatings and sacrificial anodes. However, in actual engineering, the two are often used jointly, and there is an interference effect that affects each other. In addition, existing monitoring equipment is usually independent of the structure to be monitored, without establishing a coupling relationship with the structure, and the monitoring data lacks reliability.

Contents of the invention

The present invention provides a comprehensive analysis device and monitoring method for the corrosion status of marine structures to overcome the above technical problems.

In order to achieve the above objects, the technical solution of the present invention is:

A comprehensive analysis device for the corrosion status of marine structures, including a device shell, an array electrode probe assembly, a device base plate, a welding fixing plate and an analysis terminal; the welding fixing plate is fixedly connected to the position to be measured of the structure to be monitored, and the device base plate Fixed installation with welded fixing plate;

The device housing is a cavity structure with one end open, and the open end of the device housing is fixedly connected to the device bottom plate to form a sealed cavity structure;

A component mounting hole structure is provided at the top of the sealed cavity structure, and the array electrode probe assembly is fixedly connected to the sealed cavity structure through the component mounting hole structure;

The top part of the array electrode probe assembly is provided with an anti-corrosion coating, and the array electrode probe assembly is used to monitor the coating status of the structure to be monitored;

There is a mounting circuit board inside the sealed cavity structure, the array electrode probe assembly is connected to the mounting circuit board through wires, and there is an underwater cable joint on the side wall of the sealed cavity structure. One end of the underwater cable connector is connected to the installation circuit board, and the other end of the underwater cable connector is connected to the analysis terminal through an underwater cable;

The analysis terminal is used to evaluate the damage level of the anti-corrosion coating based on the damage points monitored by the array electrode probe assembly.

Further, the array electrode probe assembly includes a probe shell, a first epoxy resin filling layer, an anti-corrosion coating, a coating status monitoring electrode device, and a plurality of electrodes; the plurality of electrodes include a sacrificial anode performance monitoring electrode and a working electrode. , reference electrode and counter electrode;

The coating status monitoring electrode device is arranged at the center of the probe housing; and the top of the coating status monitoring electrode device is provided with an anti-corrosion coating;

The sacrificial anode performance monitoring electrode and the working electrode are arranged inside the probe housing and oppositely arranged at both ends of the coating status monitoring electrode device;

The reference electrode and counter electrode are arranged on both sides of the working electrode;

A first epoxy resin filling layer is formed between the probe shell, the coating status monitoring electrode device and the plurality of electrodes, and the coating status monitoring electrode device and the coating status monitoring electrode device are connected to each other by filling epoxy resin in the first epoxy resin filling layer. A plurality of electrodes are fixedly arranged inside the probe housing.

Further, the coating status monitoring electrode device includes several coating status monitoring electrodes, a fixed mold and a second epoxy resin filling layer;

The coating status monitoring electrode is an integrated structure formed by connecting a first structural member and a second structural member; the fixed molds are each provided with a number of fixed hole structures, and the coating status monitoring electrode is connected to the fixed structure through the second structural member. The mold is fixedly connected; and the bottom end of the second structural member is connected to the installation circuit board through wires;

A second epoxy resin filling layer is formed between the coating status monitoring electrodes, and the distance between adjacent coating status monitoring electrodes does not exceed a preset threshold.

Further, it also includes a welded fixing plate for fixing the bottom plate of the installation device;

The welding fixed plate is fixedly connected to the structure to be monitored, the welding fixed plate is connected to the device bottom plate through bolts, and an insulating gasket is provided between the device bottom plate and the bolts.

Further, the installation circuit board is provided with a multiplexer, a first zero-resistance ammeter a, a second zero-resistance ammeter b, a third zero-resistance ammeter c, a signal generator and a voltmeter;

One end of the multiplexer is connected to each coating status monitoring electrode, and the other end of the multiplexer is connected to one end of the first zero-resistance ammeter a. The first zero-resistance ammeter a The other end of a is connected to the device shell;

One end of the second zero-resistance ammeter b is connected to the sacrificial anode performance monitoring electrode, and the other end of the second zero-resistance ammeter b is connected to the device housing;

One end of the voltmeter is connected to the reference electrode, one end of the third zero-resistance ammeter c is connected to the counter electrode, and the other end of the voltmeter, the other end of the third zero-resistance ammeter c and the working electrode Connect to one end of the signal generator;

The reference electrode, counter electrode and working electrode constitute a three-electrode system, and the other end of the signal generator is grounded.

A monitoring method for a comprehensive analysis device for corrosion status of marine structures, including the following steps:

Step S1: Collect the galvanic currents i ₁ -i ₂₅ flowing through each coating status monitoring electrode through the first zero-resistance ammeter a based on the multiplexer;

The cathodic protection current i _protect flowing through the sacrificial anode performance monitoring electrode is collected through the second zero resistance ammeter b;

Step S2: Based on the three-electrode system, use a signal generator to apply a potentiodynamic scanning signal, and use the third zero resistance ammeter c and voltmeter to measure the self-corrosion current i _corr of the working electrode using the linear polarization method;

Step S3: The obtained galvanic current i ₁ -i ₂₅ flowing through each coating status monitoring electrode, the cathodic protection current i _protect of the sacrificial anode performance monitoring electrode, and the self-corrosion current i _corr of the working electrode are passed through the underwater cable Transmit to analysis terminal;

Step S4: Calculate the self-corrosion rate CR of the working electrode according to the self-corrosion current i _corr of the working electrode. The calculation formula is:

In the formula: M is the molar mass of the metal to be measured, F is Faraday’s constant, and ρ _m is the density of the metal to be measured;

According to the Bulter-Volmer equation, the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode and the cathode current i _cprotect of the sacrificial anode performance monitoring electrode are determined; the calculation formula is:

i _cprotect =i _protect +i _aprotect (2)

In the formula: ΔE represents the potential difference between the electrode and its self-corrosion potential under the protection of coating and sacrificial anode; b _a and b _c respectively represent the anode and cathode Tafel slopes of metal structural materials in the working environment;

And by simplifying formulas (2) to (4), we can get formula (5)

b _a ln (i _aprotect ) + b _c ln (i _protect +i _aprotect ) = (b _a + b _c ) ln (i _corr ) (5)

Step S5: Simplify formula (4) into a function of the anode dissolution current i _aprotect of the sacrificial anode performance monitoring electrode. The calculation formula is:

Perform a first-order Taylor expansion on formula (5) and ignore the infinitesimal term to obtain formula (7):

(b _a +b _c )i _protect +bc(i _protect +i _aprotect )＝(b _a +b _c )i _corr (7)

From formula (7), the approximate value i _aprotect ^* of the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode can be obtained as

Step S6: Use the approximate value b _aprotect ^* as the initial value, set the number of iterations according to the magnitude of the cathodic protection current i _protect flowing through the sacrificial anode performance monitoring electrode × 10 ^-3 , and perform iterative calculations according to formula (6);

If the difference between the anodic dissolution current i _aprotect of the current sacrificial anode performance monitoring electrode and the anodic dissolution current i aprotect of the sacrificial anode performance monitoring electrode obtained in the last iteration is less than or equal to the preset threshold, then the anodic dissolution current of the current sacrificial anode performance monitoring electrode i _aprotect i _aprotect is the target current;

If the difference between the anodic dissolution current i _aprotect of the current sacrificial anode performance monitoring electrode and the anodic dissolution current i _aprotect ° of the sacrificial anode performance monitoring electrode obtained in the last iteration is greater than the preset threshold, continue the iteration;

Step S7: Calculate the actual corrosion rate of the sacrificial anode performance monitoring electrode based on the obtained anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode;

Step S8: Set the critical current for coating peeling according to the cathodic protection current _iprotect of the sacrificial anode performance monitoring electrode;

And the critical current of coating peeling=1/10*i _protect

Based on the analysis terminal, count the galvanic currents i ₁ -i ₂₅ flowing through each coating status monitoring electrode, and record the current number n that exceeds the critical current for coating peeling;

Step S9: Add n current values exceeding the critical current of coating peeling to obtain a weighted current _id , and estimate the coating peeling ratio α based on the weighted current _id ;

The estimation formula for the coating peeling ratio α is:

The coating peeling grade is evaluated based on the coating peeling ratio α.

Further, step S7 also includes obtaining the maximum corrosion rate allowed by the structure to be monitored based on the given corrosion margin and service life of the structure to be monitored, and comparing the maximum corrosion rate allowed by the structure to be monitored with the sacrificial anode performance monitoring electrode. Determine the actual corrosion rate;

If the maximum corrosion rate allowed by the structure to be monitored is greater than the actual corrosion rate of the sacrificial anode performance monitoring electrode, it is determined that the sacrificial anode of the structure to be monitored has a protective effect;

If the maximum allowable corrosion rate of the structure to be monitored is less than the actual corrosion rate of the sacrificial anode performance monitoring electrode, it is determined that the sacrificial anode protection of the structure to be monitored is insufficient.

Further, the actual corrosion rate of the sacrificial anode performance monitoring electrode is calculated as described in step S7, and the calculation formula is:

In the formula: M represents the molar mass of the metal to be measured; F represents the Faraday constant; ρ _m represents the density of the metal to be measured; i _aprotect represents the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode after iteration.

Beneficial effects: The present invention discloses a comprehensive analysis device for the corrosion status of marine structures and a monitoring method. Through the comprehensive analysis device for the corrosion status of marine structures, two types of corrosion protection can be achieved: coating peeling degree and sacrificial anode performance monitoring of the structure to be monitored. It uses a monitoring method to obtain the actual corrosion rate of the metal structure under the protection of the sacrificial anode after the coating peeling failure, and at the same time realizes the close connection between the monitoring equipment and the structure to be monitored in the ocean, solving the problem of traditional monitoring equipment being independent of the structure to be monitored. The monitoring structure cannot be protected by the actual cathodic protection of the structure to be monitored, resulting in the lack of reliability of the monitoring data; thus ensuring the reliability of the monitoring data is of great value to the corrosion and protection of marine engineering equipment.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a schematic diagram of the comprehensive analysis device for the corrosion state of marine structures according to the present invention;

Figure 2 is a schematic diagram of the array electrode probe of the comprehensive analysis device for corrosion status of marine structures according to the present invention;

Figure 3 is a structural diagram of the coating state electrode of the comprehensive analysis device for corrosion state of marine structures according to the present invention;

Figure 4 is a schematic diagram of the monitoring circuit of the comprehensive analysis device for corrosion status of marine structures according to the present invention;

Figure 5 is a flow chart of the monitoring method of the comprehensive analysis device for corrosion status of marine structures according to the present invention.

In the picture: 1. Device shell; 2. Array electrode probe assembly; 21. Probe shell; 22. First epoxy resin filling layer; 23. Anti-corrosion coating; 24. Coating status monitoring electrode device; 241. Coating Condition monitoring electrode; 2411, first structural member; 2412, second structural member; 242, fixed mold; 2421, fixed hole structure; 243, second epoxy resin filling layer; 25, sacrificial anode performance monitoring electrode; 26, work Electrode; 27. Reference electrode; 28. Counter electrode; 3. Device bottom plate; 4. Sealed cavity structure; 41. Component mounting hole structure; 5. Underwater cable connector; 6. Welding fixing plate; 7. Bolts; 8. Insulating gasket; 9. Multiplexer; 10. The first zero resistance ammeter a; 11. The second zero resistance ammeter b; 12. The third zero resistance ammeter c; 13. Signal generator; 14 ,Voltmeter.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

This embodiment provides a comprehensive analysis device for the corrosion status of marine structures, as shown in Figure 1, including a device housing 1, an array electrode probe assembly 2, a device bottom plate 3, a welding fixing plate 6 and an analysis terminal; the welding fixation The plate 6 is fixedly connected to the position to be measured of the structure to be monitored, and the device base plate 3 and the welding fixing plate 6 are fixedly installed; and the device base plate 3, the welding fixing plate 6 and the structure to be monitored are made of the same materials; the welding fixation The plate 6 is welded and fixed to the structure to be monitored. The welding fixing plate 6 is partially provided with a number of connection holes. The device bottom plate 3 is provided with bolt penetration holes relative to the connection holes of the welding fixation plate 6. The welding fixation plate 6 6 is connected to the device bottom plate 3 through bolts 7, and an insulating gasket 8 is provided between the device bottom plate 3 and the bolt 7, so that the bolt 7 and the welding fixing plate 6 are electrically insulated.

The device housing 1 is a cavity structure with one end open, and the open end of the device housing 1 is fixedly connected to the device bottom plate 3 to form a sealed cavity structure 4;

A component mounting hole structure 41 is provided at the top of the sealed cavity structure 4, and the array electrode probe assembly 2 is fixedly connected to the sealed cavity structure 4 through the component mounting hole structure 41;

The top part of the array electrode probe assembly 2 is provided with an anti-corrosion coating 23. The array electrode probe assembly 2 is used to detect damage points at the location to be measured of the structure to be monitored;

There is a mounting circuit board inside the sealed cavity structure 4. The array electrode probe assembly 2 is connected to the mounting circuit board through wires, and an underwater cable connector 5 is left on the side wall of the sealed cavity structure 4. , one end of the underwater cable connector 5 is connected to the installation circuit board, and the other end of the underwater cable connector 5 is connected to the analysis terminal through an underwater cable;

The analysis terminal is used to evaluate the damage level of the anti-corrosion coating 23 based on the damage points detected by the array electrode probe assembly 2, and detect the corrosion rate of the sacrificial anode under conditions corresponding to the damage level based on the electrode probe assembly 2.

Since during the actual inspection process, the damage to the anti-corrosion coating on the surface of the marine structure can affect the corrosion rate of the sacrificial anode of the marine structure, traditional marine engineering corrosion protection monitoring equipment usually only monitors the performance of the coating and the sacrificial anode. , making the detection time-consuming and the detection results inaccurate; through the comprehensive analysis device for the corrosion status of marine structures, it is possible to implement two corrosion protection methods of monitoring the coating peeling degree and sacrificial anode performance monitoring of the structure to be monitored, and obtain the coating The actual corrosion rate of the metal structure under the protection of the sacrificial anode after layer peeling failure, while achieving a close connection between the monitoring equipment and the structure to be monitored in the ocean, solving the problem that the traditional monitoring equipment cannot be monitored due to being independent of the structure to be monitored. The lack of reliability of monitoring data caused by the actual cathodic protection of the structure; thus ensuring the reliability of monitoring data is of great value to the corrosion and protection of marine engineering equipment.

In a specific embodiment, as shown in Figure 2, the array electrode probe assembly 2 includes a probe housing 21, a first epoxy resin filling layer 22, an anti-corrosion coating 23, a coating status monitoring electrode device 24 and a plurality of electrodes; The plurality of electrodes include a sacrificial anode performance monitoring electrode 25, a working electrode 26, a reference electrode 27 and a counter electrode 28; the probe housing 21, the sacrificial anode performance monitoring electrode 25 and the working electrode 26 are made of the same material as the structure to be monitored. Identical; the anti-corrosion coating 23 is completely consistent with the coating used on the structure to be monitored;

The first epoxy resin filling layer 22 is used to fill epoxy resin between the probe housing 21, the coating status monitoring electrode device 24 and the plurality of electrodes to play the role of insulation and fixation;

The coating status monitoring electrode device 24 is arranged at the center of the probe housing 21, and the top plane of the coating status monitoring electrode device 24 coincides with the top plane of the probe housing 21; and the coating status monitoring The top of the electrode device 24 is provided with an anti-corrosion coating 29;

The sacrificial anode performance monitoring electrode 25 and the working electrode 26 are arranged inside the probe housing 21 and oppositely arranged at both ends of the coating status monitoring electrode device 24;

The reference electrode 27 and the counter electrode 28 are arranged on both sides of the working electrode 26, and the centers of the working electrode 26, the reference electrode 27 and the counter electrode 28 are located on the same plane;

A first epoxy resin filling layer 22 is formed between the probe housing 21, the coating status monitoring electrode device 24 and the plurality of electrodes. The coating status is changed by filling epoxy resin in the first epoxy resin filling layer 22. The monitoring electrode device 24 and a plurality of electrodes are fixedly arranged inside the probe housing 21 .

In a specific embodiment, as shown in Figure 3, the coating status monitoring electrode device 24 includes several coating status monitoring electrodes 241, a fixed mold 242 and a second epoxy resin filling layer 243;

The coating status monitoring electrode 241 is an integrated structure formed by connecting a first structural member 2411 and a second structural member 2412; the fixed mold 242 is evenly provided with a plurality of fixed hole structures 2421, and the coating status monitoring electrode 241 passes through The second structural member 2412 is fixedly connected to the fixed mold 242; and the bottom end of the second structural member 2412 is connected to the installation circuit board through wires;

A second epoxy resin filling layer 243 is formed between the coating status monitoring electrodes 241 , and the distance between adjacent coating status monitoring electrodes 241 does not exceed a preset threshold of 0.2 mm.

The structure of each coating status monitoring electrode 241 is: the first structural member 2411 is a rectangular structure with a cross-sectional area of 2mm×2mm and a length of 20mm, and the second structural member 2412 is a cylindrical structure with a diameter of 0.9mm and a height of 4mm. And the top of the coating status monitoring electrode 241 is the working surface, and the coating is coated; the second structural member 2412 of the coating status monitoring electrode 241 is inserted into the fixed mold 242 and fixed by the fixed mold 242 to ensure that the working surfaces of adjacent electrodes are not spaced apart. More than 0.2mm, try to avoid monitoring errors caused by differences in coating bonding strength due to different surface properties of the epoxy resin and the coating status monitoring electrode 241.

In a specific embodiment, as shown in Figure 4, the installation circuit board is provided with a multiplexer 9, a first zero-resistance ammeter a10, a second zero-resistance ammeter b11, a third zero-resistance ammeter c12, Signal generator 13 and voltmeter 14;

One end of the multiplexer 9 is connected to each coating status monitoring electrode 241, and the other end of the multiplexer 9 is connected to one end of the first zero resistance ammeter a10. The first zero resistance ammeter a10 The other end of the resistance ammeter a10 is connected to the device housing 1;

Specifically, the coating monitoring electrode 241 has a total of 25 wires (i.e., electrodes). The multiplexer 9 functions as a multi-channel switch. By controlling each wire in turn, it is connected to one end of the first zero-resistance ammeter a10. The other end of the first zero-resistance ammeter a10 is coupled with the remaining 24 wires, and then the other end of the first zero-resistance ammeter a10 coupled with the 24 wires is connected to the device shell 1, and then through the multi-channel The converter can measure the current flowing through each wire;

One end of the second zero-resistance ammeter b11 is connected to the sacrificial anode performance monitoring electrode 25, and the other end of the second zero-resistance ammeter b11 is connected to the device housing 1; one end of the voltmeter 14 is connected to the reference electrode. 27 is connected, one end of the third zero resistance ammeter c12 is connected to the counter electrode 28, and the other end of the voltmeter 14, the other end of the third zero resistance ammeter c12 and the working electrode 26 are connected to the signal generator One end of 13 is connected;

The reference electrode 27, the counter electrode 28 and the working electrode 26 constitute a three-electrode system. The functions of the reference electrode 27 and the counter electrode 28 are to form a three-electrode system for electrochemical testing with the working electrode 26, and the three-electrode system For a standard corrosion rate measurement method, the other end of the signal generator 13 is grounded.

A monitoring method of a comprehensive analysis device for corrosion status of marine structures, as shown in Figure 5, and the monitoring method specifically includes a monitoring method for evaluating coating status and sacrificial anode performance; including the following steps:

Step S1: Collect the galvanic currents i ₁ -i ₂₅ flowing through each coating status monitoring electrode through the first zero-resistance ammeter a based on the multiplexer;

The cathodic protection current i _protect flowing through the sacrificial anode performance monitoring electrode is collected through the second zero resistance ammeter b;

Step S2: Based on the three-electrode system, use a signal generator to apply a potentiodynamic scanning signal, and use the third zero resistance ammeter c and voltmeter to measure the self-corrosion current i _corr of the working electrode using the linear polarization method;

Step S3: The obtained galvanic current i ₁ -i ₂₅ flowing through each coating status monitoring electrode, the cathodic protection current i _protect of the sacrificial anode performance monitoring electrode, and the self-corrosion current i _corr of the working electrode are passed through the underwater cable Transmit to analysis terminal;

Step S4: Calculate the self-corrosion rate CR of the working electrode according to the self-corrosion current i _corr of the working electrode. The calculation formula is:

In the formula: M is the molar mass of the metal to be measured, F is Faraday’s constant, and ρ _m is the density of the metal to be measured;

According to the Bulter-Volmer equation, the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode and the cathode current i _cprotect of the sacrificial anode performance monitoring electrode are determined; the calculation formula is:

i _cprotect =i _protect +i _aprotect (2)

In the formula: ΔE represents the potential difference between the electrode and its self-corrosion potential under the protection of coating and sacrificial anode; b _a and b _c respectively represent the anode and cathode Tafel slopes of the metal structural material in the working environment; i _protect and i _aprotect are Two different meanings, i _protect is the current value flowing through the sacrificial anode performance monitoring electrode 25 measured by the second zero resistance ammeter b, which is usually called galvanic current. The galvanic current value is actually the difference between the metal anode current and the cathode current. Here I define the anode dissolution current of the sacrificial anode performance monitoring electrode as i _aprotect and define the anode of the sacrificial anode performance monitoring electrode. The dissolution current is i _cprotect ; metal corrosion is actually electrochemical corrosion, including anode reaction and cathode reaction, and the currents corresponding to the anode reaction and cathode reaction are called anode current and cathode current respectively;

And by simplifying formulas (2) to (4), we can get formula (5)

b _a ln (i _aprotect ) + b _c ln (i _protect +i _aprotect ) = (b _a + b _c ) ln (i _corr ) (5)

Step S5: Simplify formula (4) into a function of the anode dissolution current i _aprotect of the sacrificial anode performance monitoring electrode. The calculation formula is:

Perform a first-order Taylor expansion on formula (5) and ignore the infinitesimal term to obtain formula (7):

(b _a +b _c )i _aprotect +bc(i _protect +i _aprotect )＝(b _a +b _c )i _corr (7)

From formula (7), the approximate value i _aprotect ^* of the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode can be obtained as

Step S6: Take the approximate value i _aprotect ^* as the initial value, set the number of iterations according to the magnitude of the cathodic protection current i _protect flowing through the sacrificial anode performance monitoring electrode × 10 ^-3 , and perform iterative calculations according to formula (6);

If the difference between the anodic dissolution current i _aprotect of the current sacrificial anode performance monitoring electrode and the anodic dissolution current i aprotect of the sacrificial anode performance monitoring electrode obtained in the last iteration is less than or equal to the preset threshold, then the anodic dissolution current of the current sacrificial anode performance monitoring electrode i _aprotect i _aprotect is the target current;

If the difference between the anodic dissolution current i _aprotect of the current sacrificial anode performance monitoring electrode and the anodic dissolution current i _aprotect ° of the sacrificial anode performance monitoring electrode obtained in the last iteration is greater than the preset threshold, continue the iteration;

Step S7: Calculate the actual corrosion rate of the sacrificial anode performance monitoring electrode based on the obtained anode dissolution current iaprotect of the sacrificial anode performance monitoring electrode;

Specifically, step S7 also includes obtaining the maximum allowed corrosion rate of the structure to be monitored based on the corrosion allowance and service life given by the structure to be monitored, where the corrosion allowance and service life given by the structure to be monitored are The given corrosion allowance during the design process and the service life of the metal structure design are existing known technical means and are not the invention of this application, so they will not be described again here; and the maximum allowable limit of the structure to be monitored is The corrosion rate is determined with the actual corrosion rate of the sacrificial anode performance monitoring electrode;

If the maximum corrosion rate allowed by the structure to be monitored is greater than the actual corrosion rate of the sacrificial anode performance monitoring electrode, it is determined that the performance of the sacrificial anode of the structure to be monitored has a protective effect;

If the maximum allowable corrosion rate of the structure to be monitored is less than the actual corrosion rate of the sacrificial anode performance monitoring electrode, it is determined that the performance protection of the sacrificial anode of the structure to be monitored is insufficient and needs to be processed in a timely manner, and the corresponding processing means and methods are not the original ones. The invention points of the application will not be repeated here;

The above calculation obtains the actual corrosion rate of the sacrificial anode performance monitoring electrode, and the calculation formula is:

In the formula: M represents the molar mass of the metal to be measured; F represents the Faraday constant; ρ _m represents the density of the metal to be measured; i _aprotect represents the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode after iteration.

Step S8: Set the critical current for coating peeling according to the cathodic protection current _iprotect of the sacrificial anode performance monitoring electrode;

And the critical current of coating peeling=1/10*i _protect

Based on the analysis terminal, count the galvanic currents i ₁ -i ₂₅ flowing through each coating status monitoring electrode, and record the current number n that exceeds the critical current for coating peeling;

Step S9: Add n current values exceeding the critical current of coating peeling to obtain a weighted current _id , and estimate the coating peeling ratio α based on the weighted current _id ;

The estimation formula for the coating peeling ratio α is:

Based on the specification GB/T 30789.5-2015/ISO 4628-5:2003, Assessment of peeling grade for evaluation of aging of paint and varnish coatings, the coating peeling grade is evaluated in conjunction with the coating peeling ratio α. Among them, the evaluation of the peeling grade for the aging evaluation of the paint and varnish coatings is a well-known technology in the art and is not the invention of the present application, and will not be described again here.

In summary, it can be seen that the present invention integrates the monitoring method of coating peeling, sacrificial anode consumption and corrosion rate under exposure, and can effectively realize comprehensive analysis of the corrosion status of marine structures. At the same time, through the improved array electrode processing technology, the array electrode spacing is greatly shortened, and the error in using array electrodes to monitor the coating status caused by the poor performance of the epoxy resin and metal surfaces is reduced. And by coupling the coating status monitoring motor to the actual marine structure through the device shell, it is possible to monitor the coating status under the condition of external cathode (sacrificial anode) protection in the actual marine engineering environment, which is more in line with actual engineering conditions. A method for monitoring the consumption status of sacrificial anodes is proposed. By calculating the corrosion rate under the protection status of sacrificial anodes, the performance of sacrificial anodes can be accurately judged.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, but not to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features can be equivalently replaced; and these modifications or substitutions do not deviate from the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention. scope.

Claims (8)

1. A comprehensive analysis device for the corrosion state of marine structures, characterized by comprising a device shell (1), an array electrode probe assembly (2), a device bottom plate (3), a welding fixing plate (6) and an analysis terminal; The welding fixing plate (6) is fixedly connected to the position to be measured of the structure to be monitored, and the device bottom plate (3) is fixedly installed with the welding fixing plate (6); The device housing (1) is a cavity structure with one end open, and the open end of the device housing (1) is fixedly connected to the device bottom plate (3) to form a sealed cavity structure (4); A component mounting hole structure (41) is provided at the top of the sealed cavity structure (4), and the array electrode probe assembly (2) is fixedly connected to the sealed cavity structure (4) through the component mounting hole structure (41); The top part of the array electrode probe assembly (2) is provided with an anti-corrosion coating (23), and the array electrode probe assembly (2) is used to monitor the coating status of the location to be measured of the structure to be measured; There is a mounting circuit board inside the sealed cavity structure (4), the array electrode probe assembly (2) is connected to the mounting circuit board through wires, and there are holes left on the side walls of the sealed cavity structure (4). Underwater cable connector (5), one end of the underwater cable connector (5) is connected to the installation circuit board, and the other end of the underwater cable connector (5) is connected to the analysis unit through an underwater cable. terminal connection; The analysis terminal is used to evaluate the damage level of the anti-corrosion coating (23) based on the damage points monitored by the array electrode probe assembly (2). 2. A comprehensive analysis device for corrosion status of marine structures according to claim 1, characterized in that the array electrode probe assembly (2) includes a probe shell (21) and a first epoxy resin filling layer (22) , anti-corrosion coating (23), coating status monitoring electrode device (24) and multiple electrodes; the multiple electrodes include a sacrificial anode performance monitoring electrode (25), a working electrode (26), a reference electrode (27) and Counter electrode (28); The coating status monitoring electrode device (24) is arranged at the center of the probe housing (21); and the top of the coating status monitoring electrode device (24) is provided with an anti-corrosion coating (29); The sacrificial anode performance monitoring electrode (25) and the working electrode (26) are arranged inside the probe housing (21) and oppositely arranged at both ends of the coating status monitoring electrode device (24); The reference electrode (27) and counter electrode (28) are arranged on both sides of the working electrode (26); A first epoxy resin filling layer (22) is formed between the probe housing (21), the coating status monitoring electrode device (24) and the plurality of electrodes. The coating status monitoring electrode device (24) and the plurality of electrodes are fixed inside the probe housing (21) by filling the epoxy resin. 3. A comprehensive analysis device for corrosion status of marine structures according to claim 1, characterized in that the coating status monitoring electrode device (24) includes a plurality of coating status monitoring electrodes (241), a fixed mold (242) ) and the second epoxy resin filling layer (243); The coating status monitoring electrode (241) is an integrated structure formed by connecting a first structural member (2411) and a second structural member (2412); the fixed mold (242) is evenly provided with a number of fixed hole structures (2421) , the coating status monitoring electrode (241) is fixedly connected to the fixed mold (242) through the second structural member (2412); and the bottom end of the second structural member (2412) is connected to the installation circuit board through a wire; A second epoxy resin filling layer (243) is formed between the coating status monitoring electrodes (241), and the distance between adjacent coating status monitoring electrodes (241) does not exceed a preset threshold. 4. A comprehensive analysis device for corrosion status of marine structures according to claim 3, characterized in that the welding fixing plate (6) and the device bottom plate (3) are connected by bolts (7), and the device bottom plate There is an insulating gasket (8) between (3) and the bolt (7). 5. A comprehensive analysis device for corrosion status of marine structures according to claim 3, characterized in that the installation circuit board is provided with a multiplexer (9) and a first zero-resistance ammeter a (10) , the second zero-resistance ammeter b (11), the third zero-resistance ammeter c (12), the signal generator (13) and the voltmeter (14); One end of the multiplexer (9) is connected to each coating status monitoring electrode (241), and the other end of the multiplexer (9) is connected to the first zero-resistance ammeter a (10) One end of the first zero-resistance ammeter a (10) is connected to the device housing (1); One end of the second zero-resistance ammeter b (11) is connected to the sacrificial anode performance monitoring electrode (25), and the other end of the second zero-resistance ammeter b (11) is connected to the device housing (1); One end of the voltmeter (14) is connected to the reference electrode (27), one end of the third zero-resistance ammeter c (12) is connected to the counter electrode (28), and the other end of the voltmeter (14) One end, the other end of the third zero-resistance ammeter c (12) and the working electrode (26) are connected to one end of the signal generator (13); The reference electrode (27), counter electrode (28) and working electrode (26) constitute a three-electrode system, and the other end of the signal generator (13) is grounded. 6. A monitoring method based on the comprehensive analysis device for corrosion status of marine structures according to any one of claims 1 to 5, characterized in that it includes the following steps: Step S1: Collect the galvanic currents i ₁ -i ₂₅ flowing through each coating status monitoring electrode through the first zero-resistance ammeter a based on the multiplexer; The cathodic protection current i _protect flowing through the sacrificial anode performance monitoring electrode is collected through the second zero resistance ammeter b; Step S2: Based on the three-electrode system, use a signal generator to apply a potentiodynamic scanning signal, and use the third zero resistance ammeter c and voltmeter to measure the self-corrosion current i _corr of the working electrode using the linear polarization method; Step S3: The obtained galvanic current i ₁ -i ₂₅ flowing through each coating status monitoring electrode, the cathodic protection current i _protect of the sacrificial anode performance monitoring electrode, and the self-corrosion current i _corr of the working electrode are passed through the underwater cable Transmit to analysis terminal; Step S4: The analysis terminal calculates the self-corrosion rate CR of the working electrode based on the self-corrosion current i _corr of the working electrode. The calculation formula is: In the formula: M is the molar mass of the metal to be measured, F is Faraday’s constant, and ρ _m is the density of the metal to be measured; According to the Bulter-Volmer equation, the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode and the cathode current i _cprotect of the sacrificial anode performance monitoring electrode are determined; the calculation formula is: i _cprotect =i _protect +i _protect (2) In the formula: ΔE represents the potential difference between the electrode and its self-corrosion potential under the protection of coating and sacrificial anode; b _a and b _c respectively represent the anode and cathode Tafel slopes of metal structural materials in the working environment; And by simplifying formulas (2) to (4), we can get formula (5) b _a ln (i _aprotect ) + b _c ln (i _protect +i _aprotect ) = (b _a + b _c ) ln (i _corr ) (5) Step S5: Simplify formula (4) into a function of the anode dissolution current i _aprotect of the sacrificial anode performance monitoring electrode. The calculation formula is: Perform a first-order Taylor expansion on formula (5) and ignore the infinitesimal term to obtain formula (7): (b _a +b _c )i _protect +bc(i _protect +i _aprotect )＝(b _a +b _c )i _corr (7) From formula (7), the approximate value i _aprotect ^* of the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode can be obtained as Step S6: Take the approximate value i _aprotect ^* as the initial value, set the number of iterations according to the magnitude of the cathodic protection current i _protect flowing through the sacrificial anode performance monitoring electrode × 10 ^-3 , and perform iterative calculations according to formula (6); If the difference between the anodic dissolution current i _aprotect of the current sacrificial anode performance monitoring electrode and the anodic dissolution current i aprotect ^o of the sacrificial anode performance monitoring electrode obtained in the last iteration is less than or equal to the preset threshold, then the anodic dissolution current of the current sacrificial anode performance monitoring electrode i _aprotect i _aprotect is the target current; If the difference between the anodic dissolution current i _aprotect of the current sacrificial anode performance monitoring electrode and the anodic dissolution current i _aprotect ^o of the sacrificial anode performance monitoring electrode obtained in the last iteration is greater than the preset threshold, continue the iteration; Step S7: Calculate the actual corrosion rate of the sacrificial anode performance monitoring electrode based on the obtained anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode; Step S8: Set the critical current for coating peeling according to the cathodic protection current _iprotect of the sacrificial anode performance monitoring electrode; And the critical current of coating peeling=1/10*i _protect Based on the analysis terminal, count the galvanic currents i ₁ -i ₂₅ flowing through each coating status monitoring electrode, and record the current number n that exceeds the critical current for coating peeling; Step S9: Add n current values exceeding the critical current of coating peeling to obtain a weighted current _id , and estimate the coating peeling ratio α based on the weighted current _id ; The estimation formula for the coating peeling ratio α is: The coating peeling grade is evaluated based on the coating peeling ratio α. 7. A monitoring method for a comprehensive analysis device for corrosion status of marine structures according to claim 6, characterized in that step S7 also includes obtaining the allowable corrosion allowance of the structure to be monitored based on the given corrosion margin and service life of the structure to be monitored. Maximum corrosion rate, and determine the maximum corrosion rate allowed by the structure to be monitored and the actual corrosion rate of the sacrificial anode performance monitoring electrode; If the maximum corrosion rate allowed by the structure to be monitored is greater than the actual corrosion rate of the sacrificial anode performance monitoring electrode, it is determined that the sacrificial anode of the structure to be monitored has a protective effect; If the maximum allowable corrosion rate of the structure to be monitored is less than the actual corrosion rate of the sacrificial anode performance monitoring electrode, it is determined that the sacrificial anode protection of the structure to be monitored is insufficient. 8. A monitoring method for a comprehensive analysis device for corrosion status of marine structures according to claim 6, characterized in that the actual corrosion rate of the sacrificial anode performance monitoring electrode is calculated as described in step S7, and the calculation formula is: In the formula: M represents the molar mass of the metal to be measured; F represents the Faraday constant; ρ _m represents the density of the metal to be measured; i _aprotect represents the anodic dissolution current i _aprotect of the sacrificial anode performance monitoring electrode after iteration.