A method for evaluating the compatibility of automotive dissimilar metal couples based on deconvolution technology

Abstract

The application discloses a kind of based on the deconvolution technology's automobile dissimilar metal galvanic compatibility evaluation method, comprising the following steps: for dissimilar metal A material, through basic electrochemical parameters, including solution pH value, oxygen content, metal ion initial content etc. Information, the equilibrium potential of cathode reaction and anode reaction is calculated;Step defines the Tafel slope of oxygen and H+ reduction reaction, exchange current density and limiting diffusion current density parameter, and the cathode polarization curve of oxygen and H+ reduction is fitted.The application is suitable for corrosion protection technical field, relates to the galvanic corrosion compatibility evaluation method of dissimilar metal connecting structure in automobile, and the deconvolution technology is integrated into dissimilar metal galvanic compatibility evaluation, can significantly shorten experimental period, realizes the evaluation fast of dissimilar metal galvanic compatibility in automobile.

Description

Technical Field

[0001] The invention belongs to the technical field of corrosion protection and is a method for evaluating automobile dissimilar metal galvanic corrosion based on a deconvolution technology. Background Art

[0002] With advances in modern automotive manufacturing technology and the growing demand for lightweighting, dissimilar metals are increasingly used in vehicles. However, when dissimilar metals come into contact in humid, salty, or other corrosive environments, they can easily form galvanic cells, leading to increased galvanic corrosion. Galvanic corrosion not only compromises the structural integrity of automotive components but also shortens the service life of the materials, ultimately impacting the overall reliability and safety of the vehicle. Therefore, effectively assessing galvanic corrosion in dissimilar metals in vehicles to ensure optimal material selection and matching and ensure compatibility is a critical task in current automotive manufacturing.

[0003] Traditional methods for evaluating galvanic corrosion of dissimilar metals often rely on accelerated testing and electrochemical impedance spectroscopy. These methods often require long experimental tests, and the superposition of cathodic and anodic reaction information in the experimental data also limits the precise analysis of the corrosion reaction mechanism.

[0004] In recent years, advances in signal processing technology have led to the gradual introduction of deconvolution techniques into the field of electrochemical research. Deconvolution is a mathematical calculation method that separates signals to restore more details of the original signal. In electrochemical corrosion assessment, deconvolution can separate the cathodic and anodic reactions in polarization curves, allowing researchers to fit more accurate polarization curves. Compared to traditional methods, corrosion evaluation methods based on deconvolution technology can shorten experimental cycles and extract key reaction characteristics, enabling rapid and accurate assessment of galvanic corrosion of dissimilar metals.

[0005] Against this backdrop, the present invention proposes a method for evaluating automotive dissimilar metal galvanic corrosion based on deconvolution technology. This method uses deconvolution to separate the cathodic and anodic reactions of the materials from the overall polarization curve, accurately calculating the intersection of the dissimilar metal corrosion current density and potential, thereby enabling rapid assessment of the material's galvanic compatibility level. This method, which eliminates the need for long-term corrosion testing, provides a scientific basis for the selection and application of dissimilar metal materials in automobiles, helping to improve the accuracy of material matching and the effectiveness of corrosion protection. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology. To achieve this, the technical solution adopted by the present invention includes the following steps:

[0007] Step 1: For the dissimilar metal material A, calculate the equilibrium potential E of the cathode reaction and the anode reaction through basic electrochemical parameters, including solution pH, oxygen content, initial metal ion content and other information reversible ; The equilibrium potential of the reaction can be determined by the Nernst equation:

[0008]

[0009] Among them E ref is the reference equilibrium potential, n is the number of reaction electrons, is the Faraday constant, R is the gas constant, T is the temperature, C R is the activity of reducing substances / fugacity, C O is the activity / fugacity of the oxide. The activity / fugacity of the substance in the solution can be replaced by its concentration / gas phase partial pressure.

[0010] Step 2: Define the Tafel slope, exchange current density, and limiting diffusion current density parameters for the oxygen and H+ reduction reactions, and fit the cathode polarization curves for oxygen and H+ reduction. The total cathode current is:

[0011]

[0012] Where i0 is the exchange current density, η c is the cathode overpotential, i c is the cathode current density. For cathode reactions with concentration polarization, specify i L is the limiting current density, and the total cathode current is:

[0013]

[0014] Step 3: Define the Tafel slope, exchange current density, passivation current density, and passivation potential parameters of the oxidative dissolution reaction of metal A, and fit the polarization curve during the dissolution process of metal A;

[0015]

[0016] where η a is the anode overpotential, i a is the anode current density. If the anode has passivation behavior, from the passivation potential Ep to the passivation completion potential Ecp. Set the parameter S, S is 1 before the applied potential reaches Ep and 0 after reaching Ecp, indicating the proportion of active metal surface; specify i f is the anodic current when there is a passivation film. The total anodic current is:

[0017] i totala =i a S+i f (1-S) (5)

[0018] Step 4: Combine the polarization curves of the cathode segment and the anode segment to obtain i total , forming a complete fitting polarization curve, and optimizing the input parameters to achieve the best polarization curve fitting result.

[0019] i total =∑i total +∑i totalc (6)

[0020] Step 5: Repeat steps 1 to 5 for dissimilar metal B, store the polarization curve results of metal A / B after parameter optimization into the database, and achieve the following: ① For metal A / B materials, the one with low self-corrosion potential is the anode, and the one with high self-corrosion potential is the cathode; ② Obtain the intersection of the polarization curves of metal A / B materials and make a reasonable judgment on the intersection data.

[0021] Step 6: Based on the intersection data of the metal A / B polarization curves, the acceleration factor, and the compatibility level evaluation criteria, the galvanic corrosion rate of the dissimilar metal connection structure in the automobile is calculated and a compatibility judgment is made.

[0022] Preferably, in step 1, for the heterogeneous metal materials, the equilibrium potential E of the cathode reaction and the anode reaction is calculated based on the solution pH value, oxygen content, initial metal ion content and other information. reversible , used to obtain the overpotential η of each reaction = |E ext -E reversible |.

[0023] Preferably, in step 2, deconvolution technology is used to separate various cathode reactions such as oxygen and hydrogen ion reduction reactions; at the same time, the influence of concentration polarization is taken into account, and when there is a limiting current density, the calculation of the total cathode current is adjusted using formula (3), so as to more accurately reflect the characteristics of the cathode reaction.

[0024] Preferably, in step 3, the parameters S and i f To dynamically adjust the anode passivation behavior, the parameter i f The active reaction and passivation reaction stages are distinguished, and the parameter S ensures a gradual change in the surface passivation coverage from the passivation potential to the passivation completion potential, so that the dissolution and passivation behavior of the metal can be analyzed in detail.

[0025] Preferably, in step four, the cathode and anode polarization curves extracted by deconvolution are combined to form an overall polarization curve; and a parameter optimization method is introduced to optimize the combined polarization curve by repeatedly adjusting the input parameters and the eigenvalues ​​obtained by deconvolution, so that it better fits the actual polarization behavior of the metal.

[0026] Preferably, in step 5, the precise polarization curve obtained by deconvolution is used, and the cathode and anode intersection data are automatically extracted, thereby reducing human error. At the same time, the optimized parameters and curve intersections of multiple metals are stored in a database, providing data support for galvanic corrosion compatibility analysis.

[0027] Preferably, in step 6, the anodic curve for the anode and the cathodic curve for the cathode are used, and the current corresponding to the intersection of the two is the galvanic corrosion current density. The corrosion rate is converted based on the galvanic corrosion current density * the acceleration factor, and the compatibility level is evaluated. By adjusting the acceleration factor value according to different types of dissimilar metal combinations and environmental conditions, the corrosion current and acceleration factor can be combined. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a model architecture diagram of the present invention;

[0029] Figure 2 The polarization curve fitting results of bare steel plate and magnesium-aluminum alloy after parameter optimization in Example 1 of the present invention are shown;

[0030] Figure 3 This is the compatibility evaluation result of the bare steel plate and the magnesium-aluminum alloy in Example 1 of the present invention;

[0031] Figure 4 The polarization curve fitting results of nickel alloy and carbon steel after parameter optimization in Example 2 of the present invention are shown;

[0032] Figure 5 This is the compatibility evaluation result of nickel alloy and carbon steel in Example 2 of the present invention; DETAILED DESCRIPTION

[0033] The following examples further illustrate a specific embodiment of the present invention's method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology. The present invention's method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology is not limited to the following examples.

[0034] Example 1:

[0035] The present invention is further described below with reference to specific embodiments to facilitate those skilled in the art to better understand and implement the technical solutions of the present invention. A method for evaluating the galvanic compatibility of automotive dissimilar metals based on deconvolution technology is employed to evaluate the galvanic compatibility of bare steel sheets and magnesium-aluminum alloys in an acidic environment. The method comprises the following steps:

[0036] Step 1: For bare steel plate, liquid film environment pH = 6.7, temperature 293.15K, oxygen content in acidic solution is considered to be approximately 0, initial metal ion content is 0.056mg / L, calculate the equilibrium potential E of the cathode / anode reaction reversible-0.1V / -0.44V respectively;

[0037] Step 2: Define the Tafel slope of the H+ reduction reaction as 98mV / dec and the exchange current density as 8.48e-8A / cm 2 Without considering the limiting diffusion current density parameter, the cathodic polarization curve of H+ reduction is fitted using formula (2):

[0038] Step 3: Define the Tafel slope of the anodic dissolution reaction as 48 mV / dec and the exchange current density as 8.84e-11 A / cm 2 , the anode is in the activated reaction state without passivation behavior, and the polarization curve during the anode dissolution process is fitted;

[0039] Step 4: Combine the polarization curves of the cathode segment and the anode segment to obtain i total , forming a complete fitting polarization curve, and optimizing the input parameters to achieve the best polarization curve fitting result.

[0040] Step 5: Repeat steps 1 to 5 for the dissimilar metal magnesium-aluminum alloy, and store the polarization curve results of the bare steel plate and magnesium-aluminum alloy after parameter optimization into the database, such as Figure 2 As shown. Judging by the material self-corrosion potential, the magnesium-aluminum alloy is the anode and the bare steel plate is the cathode; and the intersection of the polarization curves of the bare steel plate and the magnesium-aluminum alloy is obtained, and the self-corrosion current at the intersection is 1.3A / m 2 At the same time, the self-corrosion potential of the intersection is -0.63V, which is between the self-corrosion potentials of the two dissimilar metals, indicating that the intersection is reasonably obtained.

[0041] Step 6: Based on the intersection data of the polarization curves of bare steel and magnesium-aluminum alloy, the acceleration factor, and the compatibility level assessment criteria, the galvanic corrosion of bare steel and magnesium-aluminum alloy materials in the vehicle was evaluated and a compatibility judgment was made. The corrosion rate, calculated by multiplying the galvanic corrosion current density by the acceleration factor, was 2.7 mm / year. Based on the compatibility judgment table 1 provided in the "GALVANIC COMPATIBILITY OF ELECTRICALLY CONDUCTIVE MATERIALS," the corrosion rate was classified as Level 6 incompatibility.

[0042]

[0043]

[0044] Table 1

[0045] This deconvolution-based method for evaluating the galvanic compatibility of dissimilar metals in automobiles efficiently separates and analyzes electrochemical behavior details such as electrode potential and current density, accelerating the analysis of cathodic and anodic polarization curves. This method significantly shortens experimental cycles, facilitates rapid prediction of galvanic corrosion compatibility between dissimilar metals, and improves the accuracy and efficiency of evaluation, making it suitable for practical applications such as rapid evaluation and design.

[0046] Example 2:

[0047] A deconvolution-based galvanic compatibility evaluation method for automotive dissimilar metals was used to evaluate the galvanic compatibility of nickel alloy and carbon steel in a neutral oxygen-containing liquid film environment. The method includes the following steps:

[0048] Step 1: For nickel alloy, the liquid film environment pH = 7, temperature 293.15K, the oxygen content in the solution is 2mg / L, and the initial metal ion content is 0.06mg / L. Calculate the equilibrium potential E of the cathode / anode reaction. reversible -0.2V / -0.41V respectively;

[0049] Step 2: Define the Tafel slope of the oxygen reduction reaction as 133mV / dec and the exchange current density as 3e-10A / cm 2 , considering the limiting diffusion current density of 3.5e-4A / cm 2 , the cathode polarization curve of oxygen reduction is fitted using formula (3):

[0050] Step 3: Define the Tafel slope of the anodic dissolution reaction as 80 mV / dec and the exchange current density as 2.1e-8 A / cm 2 , the anode is in the activated reaction state without passivation behavior, and the polarization curve during the anode dissolution process is fitted;

[0051] Step 4: Combine the polarization curves of the cathode segment and the anode segment to obtain i total , forming a complete fitting polarization curve, and optimizing the input parameters to achieve the best polarization curve fitting result.

[0052] Step 5: Repeat steps 1 to 5 for different metal carbon steels, and store the polarization curves of nickel alloy and carbon steel after parameter optimization into the database, such as Figure 4 The anode and cathode of nickel alloy and carbon steel are determined by the self-corrosion potential of the material. Carbon steel is the anode and nickel alloy is the cathode. The intersection of the polarization curves of nickel alloy and carbon steel is obtained. The self-corrosion current of the intersection 1 is 1e-4A / m 2 At the same time, the self-corrosion potential of the intersection is -0.53V, which is between the self-corrosion potentials of the two dissimilar metals, indicating that the intersection is reasonably obtained; the self-corrosion current of the intersection 2 is 0.1A / m2 At the same time, the self-corrosion potential of the intersection is -0.2V, which is higher than the self-corrosion potential of nickel alloy, indicating that the intersection is unreasonable and should be discarded;

[0053] Step 6: Based on the intersection data of the nickel alloy and carbon steel polarization curves, the acceleration factor, and the compatibility rating assessment criteria, the galvanic corrosion of nickel alloys and carbon steel in automobiles was evaluated and a compatibility judgment was made. The corrosion rate, calculated by multiplying the galvanic corrosion current density by the acceleration factor, was 1.8e-4mm / year. Based on the compatibility judgment table 1 provided in "GALVANIC COMPATIBILITY OF ELECTRICALLY CONDUCTIVE MATERIALS," the two materials were found to be compatible.

[0054] The automotive dissimilar metal couple compatibility assessment method, using deconvolution technology, can efficiently extract and separate the cathode and anode behaviors in complex electrochemical reactions, accurately analyzing the corrosion mechanisms at material interfaces. This technology not only shortens experimental time but also improves the accuracy of corrosion rate and reaction activity predictions, making it a significant advantage in practical applications such as rapid automotive material compatibility assessment, material selection, and optimization.

Claims

1. A method for evaluating the galvanic compatibility of dissimilar metals in automobiles based on deconvolution technology analyzes polarization curve experimental data to achieve high-precision electrochemical data restoration. This method is then combined with an existing material corrosion database to rapidly evaluate the galvanic compatibility of dissimilar metals in automobiles. The method includes the following steps: Step 1: For the dissimilar metal material A, calculate the equilibrium potential E of the cathode reaction and the anode reaction based on basic electrochemical parameters, including solution pH, oxygen content, and initial metal ion content information. reversible ; The equilibrium potential of each reaction can be determined by the Nernst equation: Among them E ref is the reference equilibrium potential, n is the number of reaction electrons, F is the Faraday constant, R is the gas constant, T is the temperature, C R is the activity of reducing substances / fugacity, C O is the activity / fugacity of the oxide, the activity / fugacity of the substance in the solution is replaced by its concentration / gas phase partial pressure, Step 2: Define the Tafel slope, exchange current density, and limiting diffusion current density parameters of the oxygen and H+ reduction reaction, and fit the cathode polarization curve of oxygen and H+ reduction. The cathode current density is: Where i0 is the exchange current density, η c is the cathode overpotential, i c is the cathode current density. For cathode reactions with concentration polarization, specify i L is the limiting current density, The total cathode current is: Step 3: Define the Tafel slope, exchange current density, passivation current density, and passivation potential parameters of the oxidative dissolution reaction of metal A, and fit the polarization curve during the dissolution process of metal A; where η a is the anode overpotential, i a is the anode current density. If the anode has passivation behavior, from the passivation potential Ep to the passivation completion potential Ecp, set the parameter S. S is 1 before the applied potential reaches Ep and 0 after reaching Ecp, indicating the proportion of active metal surface. Specify i f is the anodic current when there is a passivation film. The total anodic current is: i totala =i a S+i f (1-S) (5) Step 4: Combine the polarization curves of the cathode segment and the anode segment to obtain i total , forming a complete fitting polarization curve, and optimizing the input parameters to achieve the best polarization curve fitting result, i total =∑i totala +∑i totalc (6) Step 5: Repeat steps 1 to 5 for dissimilar metal B, store the polarization curve results of metals A and B after parameter optimization into the database, and achieve: ① judge the anode and cathode of metals A and B, the one with low self-corrosion potential is the anode, and the one with high self-corrosion potential is the cathode; ② obtain the intersection of the polarization curves of metals A and B, and make a reasonable judgment on the intersection data. Step 6: Based on the intersection data of the polarization curves of metals A and B, the acceleration factor and the compatibility level evaluation criteria, the galvanic corrosion rate of the dissimilar metal connection structure in the car is calculated and a compatibility judgment is given. In steps 1 to 5, the deconvolution technique of the polarization curve is used to separate the cathode reaction and the anode reaction from the total polarization curve, so as to achieve more accurate analysis and model calculation of the electrode process. Among them: Deconvolution is a mathematical operation used to recover or restore the original information of the signal. It is the inverse process of convolution. Deconvolution is used to infer the electrochemical behavior of the anode and cathode from the results of the polarization curve in order to perform a more accurate compatibility assessment.

2. The method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology according to claim 1, characterized in that In step 2, the deconvolution technique is used to separate the two cathode reactions, oxygen and hydrogen ion reduction reactions. At the same time, the influence of concentration polarization is taken into account. When there is a limiting current density, the calculation of the total cathode current is adjusted using formula (3) to more accurately reflect the characteristics of the cathode reaction.

3. The method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology according to claim 1, characterized in that In the step 3, the parameters S and i f To dynamically adjust the anode passivation behavior, the parameter i f The active reaction and passivation reaction stages are distinguished, and the parameter S ensures the gradual change of the surface passivation coverage from the passivation potential to the passivation completion potential, so that the dissolution and passivation behavior of the metal can be analyzed in detail.

4. The method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology according to claim 1, characterized in that In the fourth step, the cathode and anode polarization curves extracted by deconvolution are combined to form an overall polarization curve; A parameter optimization method is introduced to repeatedly adjust the input parameters and the eigenvalues ​​obtained by deconvolution to achieve fitting of the polarization curve, making it more consistent with the actual polarization behavior of the metal.

5. The method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology as claimed in claim 1, characterized in that In step five, the precise polarization curve obtained by deconvolution is used, and the cathode and anode intersection data are automatically extracted, thereby reducing human errors. At the same time, the optimized parameters and curve intersections of multiple metals are stored in a database, providing data support for galvanic corrosion compatibility analysis.

6. The method for evaluating the compatibility of dissimilar metal couples in automobiles based on deconvolution technology as claimed in claim 1, characterized in that In step six, the anodic curve of the anode and the cathodic curve of the cathode are used, and the current corresponding to the intersection of the two is the galvanic corrosion current density; the corrosion rate is converted according to the galvanic corrosion current density * acceleration factor, and a compatibility level assessment is performed. The acceleration factor value is adjusted according to different types of dissimilar metal combinations and environmental conditions to achieve a comprehensive application of corrosion current and acceleration factor.

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