Optimal selection method for anti-corrosion coating of structural part in marine atmospheric environment

Abstract

The invention provides an optimal selection method for an anticorrosive coating of a structural member in a marine atmospheric environment, which comprises the following steps: S1, selecting a research object, and taking samples which are exposed for 4 years in the marine atmospheric environment and contain different coatings as test articles; s2, measuring parameters of the test article in the corrosion simulation process; s3, performing assignment calculation, importing the parameters measured in the step S2 into a finite element model, and performing marine atmospheric corrosion simulation on the coating test article; s4, performing result analysis, obtaining a simulation result of the coating test article, and performing life prediction; and S5, outputting a result. According to the method, the corrosion behavior of the structural member containing the coating can be predicted, the corrosion high-risk area can be accurately identified, the corrosion sensitive range can be defined, a guiding direction is provided for an anti-corrosion maintenance strategy of metal equipment and implementation of the anti-corrosion maintenance strategy, and the method is a key method for evaluating the service life of the metal structural member.

Description

Technical Field

[0001] The invention belongs to the technical field of corrosion simulation, and in particular relates to a method for optimizing anti-corrosion coatings of structural parts in a marine atmospheric environment. Background Art

[0002] Traditionally, corrosion research is mainly conducted with the help of simulation experiments, but this approach has two major drawbacks: one is the high cost, and the other is the long experimental cycle; especially when conducting marine atmospheric corrosion experiments, it may take up to several years, which is a huge waste of time and manpower and financial costs for the selection of excellent products, and also hinders the determination of product research and development directions. Furthermore, when it is necessary to screen out the best anti-corrosion coating, if an experimental approach is adopted, it means that multiple coating combinations must be tested one by one, which will undoubtedly greatly increase costs. In addition, in the process of corrosion experiments on structural parts, the substances produced by corrosion will be displaced due to the influence of gravity, making it extremely difficult to accurately determine the corrosion risk area, and the accuracy of the experimental results is thus reduced. Summary of the invention

[0003] In view of the problems faced by the screening of anti-corrosion coatings in marine atmospheric environments, such as high cost, long time consumption, wide testing range, and difficulty in predicting corrosion hotspot areas, the present invention proposes a new optimization method specifically for the selection of anti-corrosion coatings for structural parts in marine atmospheric environments. Compared with traditional corrosion experiments, this method not only significantly reduces costs, but also can efficiently evaluate the protective performance of various coatings in a short time. This not only provides an important basis for the formulation of corrosion protection strategies for structural parts, but also allows the laws of material corrosion to be more clearly presented. The present invention can predict the corrosion behavior of coated structural parts, accurately identify high-risk corrosion areas, and define the corrosion sensitive range. This not only provides guidance for the anti-corrosion maintenance strategy and its implementation of metal equipment, but is also a key method for evaluating the service life of metal structural parts.

[0004] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0005] A method for optimizing anti-corrosion coating of structural parts in a marine atmosphere environment comprises the following steps:

[0006] S1. Select the research objects and use samples with different coatings exposed to the natural environment for 4 years as test products to prepare for the next parameter measurement;

[0007] S2. Measure the parameters required for the test product during the corrosion simulation process, such as electrochemical data and water permeability data;

[0008] S3, assigning calculations, importing the parameters measured in step S2 into the finite element model, and performing marine atmospheric corrosion and water permeability simulation on the coating test product;

[0009] S4. Result analysis: obtain the simulation results of the coating test product, make life predictions, and compare the advantages and disadvantages of different types of coatings;

[0010] S5. Output the optimal result.

[0011] Further, in step S1, the selected samples are:

[0012] The samples are coating samples exposed to marine atmosphere for 4 years. Four samples are taken as an example, and the test samples are numbered C1, C2, C3 and C4 respectively. Preferably, the sample size is 120mm×50mm×3mm, and the coatings applied to the samples are different.

[0013] Furthermore, the specific steps of step S2 include:

[0014] 201: Collect electrochemical data of coating test products: Use a three-electrode system to conduct electrochemical tests on different coating test products, obtain electrochemical data by testing AC impedance spectroscopy and potentiodynamic polarization curves, fit the obtained electrochemical data and draw Nyquist and Tafel curves, and calculate the corrosion voltage, corrosion current density, corrosion rate, coating resistance and charge transfer resistance of the coating test products;

[0015] 202: Collect water permeability data of coating test products: Use the weighing method to measure the weight of dry coating and water-saturated coating, and calculate the water permeability of coating by formula. Based on Fick's law, the diffusion coefficient D of coating can be calculated by the following formula:

[0016]

[0017] Among them, dlnC c (t) / dt 1 / 2 is the slope, D is the diffusion coefficient (m 2 ·s -1 ), C ∞ is the water-saturated coating capacitance (F), C d is the coating capacitance of the dry coating (F), and L is the coating thickness in μm.

[0018] Furthermore, between steps S2 and S3, the method further includes step S2': simplifying the training model, specifically:

[0019] The parameters obtained in step S2 are used for parameter training to establish a training model so that the corrosion situation in the real environment can be restored as much as possible. In this step, the obtained training model is simplified, wherein the main area used for simplification is the meshing module in the finite element model. After the training model is imported, the model is firstly meshed extremely finely, and the areas where meshing fails in the observation area are observed. According to the error instructions prompted by the system and the symmetry of the three-dimensional model, the thin domain and the tip part in the obtained three-dimensional model are removed, thereby obtaining a simplified three-dimensional model, which is used to vividly simulate the corrosion situation of the sample under the action of an external field.

[0020] Furthermore, in step S3, the method for performing the value assignment calculation is specifically as follows:

[0021] 301. Import the simplified 3D model into the finite element model and make some initial definitions of the model boundaries to facilitate subsequent selection;

[0022] 302. Import the parameters (electrochemistry and water permeability) measured in step S2, and import the remaining required parameters;

[0023] 303. Select the physical fields of marine atmospheric corrosion and water permeability, input the required parameters, use secondary current distribution for marine atmospheric corrosion and diffusion coefficient D for water permeability;

[0024] 304. Study the selection of transient state with initialization and solve the simulation.

[0025] Furthermore, in step S4, the method of result analysis is specifically as follows:

[0026] By observing the simulation results of marine atmospheric corrosion and water permeability obtained in step S3, the corrosion rates and corrosion hot spots of different coating test pieces are observed, and which coating has better protection performance for the sample is determined based on the size of the corrosion rate and the corrosion life prediction.

[0027] Furthermore, the results obtained in step S4 are compared, so that the best result is output in step S5.

[0028] Advantages of the preferred method provided by the present invention:

[0029] (1) The present invention proposes a preferred strategy for anti-corrosion coatings of structural parts in a marine atmospheric environment. Its core purpose is to improve the corrosion resistance of structural parts and to deeply explore the high-corrosion risk areas and their inherent corrosion mechanisms that structural parts may encounter during use.

[0030] (2) The present invention introduces a method for selecting an anti-corrosion coating for a structural part in a marine atmosphere environment. This method abandons the old model of completely relying on experimental means to determine corrosion protection measures, and instead relies mainly on corrosion simulation technology. This significantly reduces costs and shortens time costs, greatly improving research and development benefits. In addition, this method has broad potential application prospects and is expected to be extended to corrosion protection research of other types of structural parts in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are an important part of the present invention and are intended to help to better understand the present invention. The exemplary embodiments and their descriptions provided below are only used to illustrate the principles of the present invention and are not intended to set any unnecessary limitations on the present invention. In the accompanying drawings:

[0032] Figure 1 The present invention is a flow chart of an embodiment of a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment.

[0033] Figure 2 This is the electrochemical impedance spectrum of C1, C2, C3 and C4 coating test samples in an embodiment of a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment of the present invention.

[0034] Figure 3 This is a polarization curve diagram of C1, C2, C3, and C4 coating test products in an embodiment of a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment of the present invention.

[0035] Figure 4 Cl is the position monitoring point of the water seepage process of the C1, C2, C3, and C4 coating test products in an embodiment of the preferred method for anti-corrosion coating of structural parts in marine atmospheric environment of the present invention. - Concentration change simulation curve.

[0036] Figure 5 Cl is the water seepage process of C1, C2, C3 and C4 coating test products in an embodiment of the preferred method for anti-corrosion coating of structural parts in marine atmospheric environment of the present invention. - Concentration change simulation diagram.

[0037] Figure 6 This is a 10-year distribution diagram of corrosion prediction of a C1 coating test sample in an embodiment of a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment of the present invention.

[0038] Figure 7 This is a 10-year distribution diagram of corrosion prediction of a C2 coating test sample in an embodiment of a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment of the present invention.

[0039] Figure 8This is a 10-year distribution diagram of corrosion prediction for a C3 coating test sample in an embodiment of the present invention in a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment.

[0040] Fig. 9 This is a 10-year distribution diagram of corrosion prediction for a C4 coating test sample in an embodiment of a preferred method for anti-corrosion coating of structural parts in a marine atmospheric environment of the present invention. DETAILED DESCRIPTION

[0041] The present invention is described in detail below through specific embodiments. It is pointed out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above invention content.

[0042] Example 1

[0043] See also Figure 1 , the specific implementation steps are as follows:

[0044] S100, C1 and C2 coating samples exposed to the marine atmosphere for four years were selected to observe the corrosion hot spots of the samples in preparation for the next step of measuring parameters.

[0045] The test products mainly use metals with different coatings as electrodes. The sample size is 120mm×50mm×3mm, among which the C1 coating is primer+M paint, and the C2 coating is primer+M paint+Type I paint.

[0046] S200, measuring the test product parameters required during corrosion simulation:

[0047] S201. Measurement of electrochemical experimental parameters: Measure the corrosion voltage, corrosion current density, corrosion rate, coating resistance and charge transfer resistance of different coating samples required for corrosion simulation.

[0048] Specifically: Collect electrochemical data of coating samples. Use three-electrode system to conduct electrochemical test on C1 and C2 coating samples, see Figure 2-3 , obtain electrochemical data by testing AC impedance spectroscopy and potentiodynamic polarization curves, fit the obtained electrochemical data and draw Nyquist and Tafel curves to calculate the required parameters.

[0049] S202. Measurement of water permeability experimental parameters: measuring the water permeability parameters of the C1 and C2 test coating samples required for corrosion simulation.

[0050] Specifically: Collect the water permeability data of the coating sample. Use the weighing method to measure the weight of the dry coating and the water-saturated coating, and calculate the water permeability of the coating through the formula. Based on Fick's law, the diffusion coefficient D of the coating can be calculated by the following formula:

[0051]

[0052] Among them, dlnC c (t) / dt 1 / 2 is the slope, D is the diffusion coefficient (m 2 ·s -1 ), C ∞ is the water-saturated coating capacitance (F), C d is the coating capacitance of the dry coating (F), and L is the coating thickness in μm.

[0053] The electrochemical workstation was used to monitor the chloride ion concentration in real time during the coating seepage process. The obtained data were collated and the Cl concentration at different monitoring points during the coating seepage process was plotted. - Concentration change simulation curve (see Figure 4 ).

[0054] S200', the simplified model method is different from the previous method of directly simplifying the three-dimensional model into a two-dimensional model. Instead, it simplifies the complex three-dimensional model into a simpler three-dimensional model through the meshing function in the finite element model, making the simulation more accurate and intuitive.

[0055] Specifically: import the parameter-trained model into the finite element model, use the meshing module in the finite element model, first perform free tetrahedral meshing on the geometry, select the size to be extremely fine, observe where the meshing fails, and according to the prompts, find the assembly relationship, thin domains and tip parts in the model. According to the symmetry of the three-dimensional model, remove the tip and thin domain in the model, and change the three-dimensional model as little as possible to make the simulation more accurate.

[0056] S300, assigning values ​​and calculating, importing all the data measured in step S200 into the finite element model, performing model simulation and curve drawing on the marine atmospheric corrosion and water permeability of the component, and performing life prediction based on the results;

[0057] S301, import the electrochemical parameters measured by the electrochemical experiment into the three-dimensional model obtained in step S200'. Select the physical field. The physical field of marine atmospheric corrosion is the secondary current distribution. Use this physical field to solve the potential Φ on the component electrode domain formed by different materials. s (Unit: V):

[0058]

[0059]

[0060] Ф1=phi1,Ф s =phis

[0061] Among them, i s (Unit: A / m 2 ) is the electrode current density vector, σ s (Unit: S / m) is the conductivity, phil is the electrolyte potential, phis is the potential, Q1, Q s are all constants.

[0062] The model is meshed, and the simplified model is meshed with free tetrahedron. To improve convergence, the mesh size is extremely fine. The control equation of the modeling is transient with initialization, and the step size is set and calculated.

[0063] S302, simultaneously importing the chloride ion concentration data measured by electrochemistry into the water permeability model in the finite element model, and calculating the Cl - The concentration change is simulated and Cl - Concentration change simulation diagram (see Figure 5 );Cl during water seepage of C1 and C2 coating samples - The concentration change curves were compared.

[0064] S400, Result Analysis,First, compare the simulation results of marine atmospheric corrosion, compare the corrosion rate in different areas and the corrosion hotspot areas. Secondly, compare the corrosion rate and water permeability of C1 and C2 coating test products under the same years.

[0065] S500, output result comparison, electrochemical test on the structural parts, and verify the accuracy of the simulation by comparing the simulation results with the electrochemical experiment. Figure 6 and 7 ), and then identify the corrosion hot spots to optimize the protection methods under different coatings.

[0066] Specifically: First, observe the corrosion results of the samples, and analyze the simulation model of the surface corrosion of the C1 and C2 coating samples after the same corrosion years. Secondly, observe the corrosion data output in the finite element model, and output corrosion data such as corrosion potential, corrosion current density, corrosion rate, coating resistance, charge transfer resistance, and water permeability. Compare the data of the electrochemical test with the simulation experiment to observe whether the simulation is correct. If not, check the input parameters of the model and repeat steps S100-S500 until the error is as small as possible. If correct, you can change the coating, re-enter the parameters, and compare the protective effects of the C1 and C2 coating test products, so as to guide the optimization of the protection method.

[0067] Example 2

[0068] See also Figure 1, the specific implementation steps are as follows:

[0069] S100, C1 and C3 coating samples that have been exposed to Qingdao marine atmosphere for four years were selected to observe the corrosion hot spots of the samples in preparation for the next step of measuring parameters.

[0070] The test products mainly use metals with different coatings as electrodes. The sample size is 120mm×50mm×3mm, among which the C1 coating is primer+M paint, and the C3 coating is primer+M paint+Type II paint.

[0071] S200, measuring the test product parameters required during corrosion simulation:

[0072] S201. Measurement of electrochemical experimental parameters: Measure the corrosion voltage, corrosion current density, corrosion rate, coating resistance and charge transfer resistance of different coating samples required for corrosion simulation.

[0073] Specifically: Collect electrochemical data of coating samples. Use three-electrode system to conduct electrochemical test on C1 and C3 coating samples, see Figure 2-3 , obtain electrochemical data by testing AC impedance spectroscopy and potentiodynamic polarization curves, fit the obtained electrochemical data and draw Nyquist and Tafel curves to calculate the required parameters.

[0074] S202. Water permeability experimental parameter measurement: measuring the water permeability parameters of the C1 and C3 coating samples required for corrosion simulation.

[0075] Specifically: Collect the water permeability data of the coating sample. Use the weighing method to measure the weight of the dry coating and the water-saturated coating, and calculate the water permeability of the coating through the formula. Based on Fick's law, the diffusion coefficient D of the coating can be calculated by the following formula:

[0076]

[0077] Among them, dlnC c (t) / dt 1 / 2 is the slope, D is the diffusion coefficient (m 2 ·s -1 ), C ∞ is the water-saturated coating capacitance (F), C d is the coating capacitance of the dry coating (F), and L is the coating thickness in μm.

[0078] The electrochemical workstation was used to monitor the chloride ion concentration in real time during the coating seepage process. The obtained data were collated and the Cl concentration at different monitoring points during the coating seepage process was plotted. - Concentration change simulation curve (see Figure 4 ).

[0079] S200', the simplified model method is different from the previous method of directly simplifying the three-dimensional model into a two-dimensional model. Instead, it simplifies the complex three-dimensional model into a simpler three-dimensional model through the meshing function in the finite element model, making the simulation more accurate and intuitive.

[0080] Specifically: import the parameter-trained model into the finite element model, use the meshing module in the finite element model, first perform free tetrahedral meshing on the geometry, select the size to be extremely fine, observe where the meshing fails, and according to the prompts, find the assembly relationship, thin domains and tip parts in the model. According to the symmetry of the three-dimensional model, remove the tip and thin domain in the model, and change the three-dimensional model as little as possible to make the simulation more accurate.

[0081] S300, assigning values ​​and calculating, importing all the data measured in step S200 into the finite element model, performing model simulation and curve drawing on the marine atmospheric corrosion and water permeability of the component, and performing life prediction based on the results;

[0082] S301, import the electrochemical parameters measured by the electrochemical experiment into the three-dimensional model obtained in step S200'. Select the physical field. The physical field of marine atmospheric corrosion is the secondary current distribution. Use this physical field to solve the potential Φ on the component electrode domain formed by different materials. s (Unit: V):

[0083]

[0084]

[0085] Ф1=phi1,Ф s =phis

[0086] where i s (Unit: A / m 2 ) is the electrode current density vector, σ s (Unit: S / m) is the conductivity, phil is the electrolyte potential, phis is the potential, Q1, Q s are all constants.

[0087] The model is meshed, and the simplified model is meshed with free tetrahedron. To improve convergence, the mesh size is extremely fine. The control equation of the modeling is transient with initialization, and the step size is set and calculated.

[0088] S302, simultaneously importing the chloride ion concentration data measured by electrochemistry into the water permeability model in the finite element model, and calculating the Cl - The concentration change is simulated and Cl - Concentration change simulation diagram (see Figure 5 ) ; Cl during water seepage of C1 and C3 coating samples - The concentration change curves were compared.

[0089] S400,Result Analysis,First, the simulation results of marine atmospheric corrosion are compared,and the corrosion rates and corrosion hot spots in different regions are compared.,Secondly, the corrosion rates and water permeability of C1 and C3 coating samples are compared under the same years.

[0090] S500, output result comparison, electrochemical test on the structural parts, and verify the accuracy of the simulation by comparing the simulation results with the electrochemical experiment. Figure 6 and 8 ), and then identify the corrosion hot spots to optimize the protection methods under different coatings.

[0091] Specifically: First, observe the corrosion results of the samples, and analyze the simulation model of the surface corrosion of the C1 and C3 coating samples after the same corrosion years. Secondly, observe the corrosion data output in the finite element model, and output corrosion data such as corrosion potential, corrosion current density, corrosion rate, coating resistance, charge transfer resistance, and water permeability. Compare the data of the electrochemical test with the simulation experiment to observe whether the simulation is correct. If not, check the input parameters of the model and repeat steps S100-S500 until the error is as small as possible. If correct, you can change the coating, re-enter the parameters, and compare the protective effects of the C1 and C3 coating samples, so as to guide the optimization of the protection method.

[0092] Example 3

[0093] See also Figure 1 , the specific implementation steps are as follows:

[0094] S100, C1 and C4 coating samples that have been exposed to Qingdao marine atmosphere for four years were selected to observe the corrosion hot spots of the samples in preparation for the next step of measuring parameters.

[0095] The test products mainly use metals with different coatings as electrodes. The sample size is 120mm×50mm×3mm, among which the C1 coating is primer+M paint, and the C4 coating is primer+M paint+Type III paint.

[0096] S200, measuring the test product parameters required during corrosion simulation:

[0097] S201. Measurement of electrochemical experimental parameters: Measure the corrosion voltage, corrosion current density, corrosion rate, coating resistance and charge transfer resistance of different coating samples required for corrosion simulation.

[0098] Specifically: Collect electrochemical data of coating samples. Use three-electrode system to conduct electrochemical test on C1 and C4 coating samples, see Figure 2-3 , obtain electrochemical data by testing AC impedance spectroscopy and potentiodynamic polarization curves, fit the obtained electrochemical data and draw Nyquist and Tafel curves to calculate the required parameters.

[0099] S202. Water permeability experimental parameter measurement: measuring the water permeability parameters of the C1 and C4 coating samples required for corrosion simulation.

[0100] Specifically: Collect the water permeability data of the coating sample. Use the weighing method to measure the weight of the dry coating and the water-saturated coating, and calculate the water permeability of the coating through the formula. Based on Fick's law, the diffusion coefficient D of the coating can be calculated by the following formula:

[0101]

[0102] Among them, dlnC c (t) / dt 1 / 2 is the slope, D is the diffusion coefficient (m 2 ·s -1 ), C ∞ is the water-saturated coating capacitance (F), C d is the coating capacitance of the dry coating (F), and L is the coating thickness in μm.

[0103] The electrochemical workstation was used to monitor the chloride ion concentration in real time during the coating seepage process. The obtained data were collated and the Cl concentration at different monitoring points during the coating seepage process was plotted. - Concentration change simulation curve (see Figure 4 ).

[0104] S200', the simplified model method is different from the previous method of directly simplifying the three-dimensional model into a two-dimensional model. Instead, it simplifies the complex three-dimensional model into a simpler three-dimensional model through the meshing function in the finite element model, making the simulation more accurate and intuitive.

[0105] Specifically: import the parameter-trained model into the finite element model, use the meshing module in the finite element model, first perform free tetrahedral meshing on the geometry, select the size to be extremely fine, observe where the meshing fails, and according to the prompts, find the assembly relationship, thin domains and tip parts in the model. According to the symmetry of the three-dimensional model, remove the tip and thin domain in the model, and change the three-dimensional model as little as possible to make the simulation more accurate.

[0106] S300, assigning values ​​and calculating, importing all the data measured in step S200 into the finite element model, performing model simulation and curve drawing on the marine atmospheric corrosion and water permeability of the component, and performing life prediction based on the results;

[0107] S301, import the electrochemical parameters measured by the electrochemical experiment into the three-dimensional model obtained in step S200'. Select the physical field. The physical field of marine atmospheric corrosion is the secondary current distribution. Use this physical field to solve the potential Φ on the component electrode domain formed by different materials. s (Unit: V):

[0108]

[0109]

[0110] Ф1=phi1,Ф s =phis

[0111] where i s (Unit: A / m 2 ) is the electrode current density vector, σ s (Unit: S / m) is the conductivity, phil is the electrolyte potential, phis is the potential, Q1, Q s are all constants.

[0112] The model is meshed, and the simplified model is meshed with free tetrahedron. To improve convergence, the mesh size is extremely fine. The control equation of the modeling is transient with initialization, and the step size is set and calculated.

[0113] S302, simultaneously importing the chloride ion concentration data measured by electrochemistry into the water permeability model in the finite element model, and calculating the Cl - The concentration change is simulated and Cl - Concentration change simulation diagram (see Figure 5 );Cl during water seepage of C1 and C4 coating samples - The concentration change curves were compared.

[0114] S400,Result Analysis,First, the simulation results of marine atmospheric corrosion are compared,and the corrosion rates and corrosion hot spots in different regions are compared.,Secondly, the corrosion rates and water permeability of C1 and C2 coating samples are compared under the same years.

[0115] S500, output result comparison, electrochemical test on the structural parts, and verify the accuracy of the simulation by comparing the simulation results with the electrochemical experiment. Figure 6 and 9), and then identify the corrosion hot spots to optimize the protection methods under different coatings.

[0116] Specifically: First, observe the corrosion results of the samples, and analyze the simulation model of the surface corrosion of the C1 and C4 coating samples after the same corrosion years. Secondly, observe the corrosion data output in the finite element model, and output corrosion data such as corrosion potential, corrosion current density, corrosion rate, coating resistance, charge transfer resistance, and water permeability. Compare the data of the electrochemical test with the simulation experiment to observe whether the simulation is correct. If not, check the input parameters of the model and repeat steps S100-S500 until the error is as small as possible. If correct, you can change the coating, re-enter the parameters, and compare the protective effects of the C1 and C4 coating samples, so as to guide the optimization of the protection method.

[0117] Example 4

[0118] See also Figure 1 , the specific implementation steps are as follows:

[0119] S100, C2, C3 and C4 coating samples that have been exposed to Qingdao marine atmosphere for four years were selected to observe the corrosion hot spots of the samples in preparation for the next step of measuring parameters.

[0120] The test products mainly use metals with different coatings as electrodes. The sample size is 120mm×50mm×3mm. The C2 coating is primer + M paint + type I paint, the C3 coating is primer + M paint + type II paint, and the C4 coating is primer + M paint + type III paint.

[0121] S200, measuring the test product parameters required during corrosion simulation:

[0122] S201. Measurement of electrochemical experimental parameters: Measure the corrosion voltage, corrosion current density, corrosion rate, coating resistance and charge transfer resistance of different coating samples required for corrosion simulation.

[0123] Specifically: Collect electrochemical data of coating samples. Use three-electrode system to conduct electrochemical test on C2, C3 and C4 coating samples, see Figure 2-3 , obtain electrochemical data by testing AC impedance spectroscopy and potentiodynamic polarization curves, fit the obtained electrochemical data and draw Nyquist and Tafel curves to calculate the required parameters.

[0124] S202. Measurement of water permeability experimental parameters: measuring the water permeability parameters of C2, C3 and C4 coating samples required for corrosion simulation.

[0125] Specifically: Collect the water permeability data of the coating sample. Use the weighing method to measure the weight of the dry coating and the water-saturated coating, and calculate the water permeability of the coating through the formula. Based on Fick's law, the diffusion coefficient D of the coating can be calculated by the following formula:

[0126]

[0127] Among them, dlnC c (t) / dt 1 / 2 is the slope, D is the diffusion coefficient (m 2 ·s -1 ), C ∞ is the water-saturated coating capacitance (F), C d is the coating capacitance of the dry coating (F), and L is the coating thickness in μm.

[0128] The electrochemical workstation was used to monitor the chloride ion concentration in real time during the coating seepage process. The obtained data were collated and the Cl concentration at different monitoring points during the coating seepage process was plotted. - Concentration change simulation curve (see Figure 4 ).

[0129] S200', the simplified model method is different from the previous method of directly simplifying the three-dimensional model into a two-dimensional model. Instead, it simplifies the complex three-dimensional model into a simpler three-dimensional model through the meshing function in the finite element model, making the simulation more accurate and intuitive.

[0130] Specifically: import the parameter-trained model into the finite element model, use the meshing module in the finite element model, first perform free tetrahedral meshing on the geometry, select the size to be extremely fine, observe where the meshing fails, and according to the prompts, find the assembly relationship, thin domains and tip parts in the model. According to the symmetry of the three-dimensional model, remove the tip and thin domain in the model, and change the three-dimensional model as little as possible to make the simulation more accurate.

[0131] S300, assigning values ​​and calculating, importing all the data measured in step S200 into the finite element model, performing model simulation and curve drawing on the marine atmospheric corrosion and water permeability of the component, and performing life prediction based on the results;

[0132] S301, import the electrochemical parameters measured by the electrochemical experiment into the three-dimensional model obtained in step S200'. Select the physical field. The physical field of marine atmospheric corrosion is the secondary current distribution. Use this physical field to solve the potential Φ on the component electrode domain formed by different materials. s (Unit: V):

[0133]

[0134]

[0135] Ф1=phi1,Ф s =phis

[0136] where i s (Unit: A / m 2 ) is the electrode current density vector, σ s (Unit: S / m) is the conductivity, phil is the electrolyte potential, phis is the potential, Q1, Q s are all constants.

[0137] The model is meshed, and the simplified model is meshed with free tetrahedron. To improve convergence, the mesh size is extremely fine. The control equation of the modeling is transient with initialization, and the step size is set and calculated.

[0138] S302, simultaneously importing the chloride ion concentration data measured by electrochemistry into the water permeability model in the finite element model, and calculating the Cl - The concentration change is simulated and Cl - Concentration change simulation diagram (see Figure 5 ); Cl during water seepage of C2, C3 and C4 coating samples - The concentration change curves were compared.

[0139] S400,Result Analysis,First, the simulation results of marine atmospheric corrosion are compared,and the corrosion rates and corrosion hot spots in different regions are compared.,Secondly, the corrosion rates and water permeability of C1 and C2 coating samples are compared under the same years.

[0140] S500, output result comparison, electrochemical test on the structural parts, and verify the accuracy of the simulation by comparing the simulation results with the electrochemical experiment. Figure 7-9 ), and then identify the corrosion hot spots to optimize the protection methods under different coatings.

[0141] Specifically: First, observe the corrosion results of the samples, and analyze the simulation model of the surface corrosion of the C2, C3 and C4 coating samples after the same corrosion years. Secondly, observe the corrosion data output in the finite element model, and output corrosion data such as corrosion potential, corrosion current density, corrosion rate, coating resistance, charge transfer resistance, and water permeability. Compare the data of the electrochemical test with the simulation experiment to observe whether the simulation is correct. If not, check the input parameters of the model and repeat steps S100-S500 until the error is as small as possible. If correct, you can change the coating, re-enter the parameters, and compare the protective effects of the C2, C3 and C4 coating samples, so as to guide the optimization of the protection method.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing the anti-corrosion coating of structural parts in a marine atmosphere environment, characterized in that: The method comprises the following steps: S1. Select the research object and use samples with different coatings exposed to the marine atmosphere for 4 years as test products; S2. measuring the parameters of the test product during the corrosion simulation process; S3, assigning calculations, importing the parameters measured in step S2 into the finite element model, and performing marine atmospheric corrosion simulation on the coating test product; S4. Result analysis: obtaining simulation results of coating test products and performing life prediction; S5. Output the results.

2. The method for optimizing the anti-corrosion coating of a structural part in a marine atmosphere environment according to claim 1, characterized in that: In step S1, the selected samples are: The samples are samples of different coatings exposed to the marine atmosphere for 4 years as test products; the sample size is 120mm×50mm×3mm.

3. The method for optimizing the anti-corrosion coating of a structural part in a marine atmosphere environment according to claim 1, characterized in that: The specific steps of step S2 include: 201: Collect electrochemical data of coating test products: Use a three-electrode system to conduct electrochemical tests on different coating test products, obtain electrochemical data by testing AC impedance spectroscopy and potentiodynamic polarization curves, fit the obtained electrochemical data and draw Nyquist and Tafel curves, and calculate the corrosion voltage, corrosion current density, corrosion rate, coating resistance and charge transfer resistance of the coating test products; 202: Collect water permeability data of coating test products: Use the weighing method to measure the weight of dry coating and water-saturated coating, and calculate the water permeability of coating by formula. Based on Fick's law, the diffusion coefficient D of coating can be calculated by the following formula: Among them, dlnC c (t) / dt 1 / 2 is the slope; D is the diffusion coefficient, unit is m 2 ·s -1 ; C ∞ is the water-saturated coating capacitance, in F; C d is the coating capacitance of the dry coating in F; L is the coating thickness in μm.

4. The method for optimizing the anti-corrosion coating of a structural part in a marine atmosphere environment according to claim 1, characterized in that: Between step S2 and step S3, step S2' is also included: simplifying the training model, specifically: The training model established through parameter training is simplified. The main area used for simplification is the mesh division module in the finite element model. After the training model is imported, the model is firstly meshed extremely finely, and the areas where mesh drawing fails in the observation area are observed. According to the error instructions prompted by the system and the symmetry of the three-dimensional model, the thin domains and tip parts in the obtained three-dimensional model are removed to obtain a simplified three-dimensional model.

5. The method for optimizing the anti-corrosion coating of a structural part in a marine atmosphere environment according to claim 1, characterized in that: In step S3, the method for performing the assignment calculation is specifically as follows:

301. Import the simplified three-dimensional model into the finite element model and initially define the boundary of the model; 302. Import the parameters measured in step S2 and import the remaining required parameters; 303. Select the physical fields of marine atmospheric corrosion and water permeability, input the required parameters, use secondary current distribution for marine atmospheric corrosion and diffusion coefficient D for water permeability; 304. Study the selection of transient state with initialization and solve the simulation.

6. The method for optimizing the anti-corrosion coating of a structural component in a marine atmosphere environment according to claim 1, characterized in that: In step S4, the method of result analysis is specifically as follows: By observing the simulation results of marine atmospheric corrosion and water permeability obtained in step S3, the corrosion rate and corrosion hotspot area of ​​the coating test product are observed, and the protective performance of the coating on the substrate is judged based on the size of the corrosion rate and the corrosion life prediction.

7. The method for optimizing the anti-corrosion coating of a structural component in a marine atmosphere environment according to claim 1, characterized in that: The results obtained in step S4 are compared, and the optimal result is output in step S5.

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