Automobile dissimilar metal galvanic couple compatibility evaluation method based on deconvolution technology

Abstract

The invention discloses an automobile dissimilar metal galvanic couple compatibility evaluation method based on a deconvolution technology, and the method comprises the following steps: calculating the equilibrium potential of a cathode reaction and an anode reaction according to a dissimilar metal A material through basic electrochemical parameters including the pH value of a solution, the oxygen content, the initial content of metal ions and other information; defining Tafel slope, exchange current density and limit diffusion current density parameters of oxygen and H < + > reduction reaction, and fitting a cathodic polarization curve of oxygen and H < + > reduction. The invention is suitable for the technical field of corrosion protection, and relates to a galvanic corrosion compatibility evaluation method for a dissimilar metal connection structure in an automobile, which integrates a deconvolution technology into dissimilar metal galvanic compatibility evaluation, can significantly shorten the experimental period, and realizes rapid evaluation of the dissimilar metal galvanic compatibility in the automobile.

Description

Technical Field

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

[0002] With the advancement of modern automobile manufacturing technology and the increasing demand for lightweighting, dissimilar metals are increasingly used in automobiles. However, when dissimilar metals come into contact with each other in a humid, salty or other corrosive environment, they are prone to form galvanic cells, which leads to increased galvanic corrosion. Galvanic corrosion not only affects the structural integrity of automotive parts, but also shortens the service life of materials, thereby affecting the overall reliability and safety of the vehicle. Therefore, it is an important task in current automobile manufacturing to effectively evaluate the galvanic corrosion of dissimilar metals in automobiles in order to reasonably select and match materials and ensure material compatibility.

[0003] Traditional evaluation methods for galvanic corrosion of dissimilar metals mostly use accelerated experimental testing and electrochemical impedance spectroscopy. These methods often require long-term experimental testing, and the superposition of cathode and anode reaction information in the experimental data also limits the accurate analysis of the corrosion reaction mechanism.

[0004] In recent years, the development of signal processing technology has led to the gradual introduction of deconvolution technology into the field of electrochemical research. Deconvolution technology is a mathematical operation method that restores more details of the original signal through signal separation. In electrochemical corrosion assessment, deconvolution technology can separate the cathode reaction and the anode reaction in the polarization curve, allowing researchers to fit a more accurate polarization curve. Compared with traditional methods, the corrosion evaluation method based on deconvolution technology can shorten the experimental cycle and extract key reaction characteristics, thereby achieving rapid and accurate assessment of galvanic corrosion of dissimilar metals.

[0005] In this context, the present invention proposes a method for evaluating automotive dissimilar metal galvanic corrosion based on deconvolution technology. This method uses deconvolution technology to separate the cathodic reaction and anodic reaction of the material from the total polarization curve, and accurately calculates the intersection of the dissimilar metal corrosion current density and potential, thereby realizing a rapid evaluation of the material galvanic compatibility level. This method does not need to rely on long-term corrosion experimental testing, provides a scientific basis for the selection and application of dissimilar metal materials in automobiles, and helps to improve the accuracy of material matching and the effect 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. In order to achieve the evaluation of the compatibility of dissimilar metal couples in automobiles, the technical solution adopted by the present invention includes the following steps:

[0007] Step 1: For heterogeneous 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] Where 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 / fugacity of the reducing substance, C O is the activity / fugacity of the oxide. The activity / fugacity of a substance in a 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 of the oxygen and H+ reduction reaction, fit the cathode polarization curve of oxygen and H+ reduction, and the total cathode current is:

[0011]

[0012] where i 0 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 oxidation 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. At this time, 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 totala +∑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: 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 given.

[0022] Preferably, in step 1, for 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 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.

[0025] Preferably, in step 4, 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 accurate 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.

[0027] Preferably, in step 6, the anode curve of the anode and the cathode curve of the cathode are used, and the current corresponding to the intersection of the two is the galvanic corrosion current density; and the corrosion rate is converted according to the galvanic corrosion current density*acceleration factor, and the compatibility level is evaluated. The acceleration factor value is adjusted according to different types of dissimilar metal combinations and environmental conditions, so that the comprehensive application of corrosion current and acceleration factor can be achieved. 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;

[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;

[0032] Figure 5 The compatibility evaluation results of nickel alloy and carbon steel in Example 2 of the present invention are as follows; DETAILED DESCRIPTION

[0033] The following is a further description of the specific implementation of the automotive dissimilar metal couple compatibility evaluation method based on deconvolution technology of the present invention in conjunction with the embodiments. The automotive dissimilar metal couple compatibility evaluation method based on deconvolution technology of the present invention is not limited to the description of the following embodiments.

[0034] Embodiment 1:

[0035] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand and implement the technical solution of the present invention. A method for evaluating the galvanic compatibility of automotive dissimilar metals based on deconvolution technology is used to evaluate the galvanic compatibility of automotive dissimilar metal materials bare steel plates and magnesium-aluminum alloys in an acidic environment, comprising the following steps:

[0036] Step 1: For the bare steel plate, the liquid film environment pH = 6.7, the temperature is 293.15K, the oxygen content in the acidic solution is considered to be approximately 0, and the 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 48mV / dec and the exchange current density as 8.84e-11A / cm 2 , the anode is in an 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 from 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 of 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 evaluation criteria, the galvanic corrosion of bare steel and magnesium-aluminum alloy materials in automobiles is evaluated and a compatibility judgment is given. The corrosion rate is calculated to be 2.7 mm / year based on the galvanic corrosion current density*acceleration factor, and according to the compatibility judgment table 1 provided in "GALVANIC COMPATIBILITY OF ELECTRICALLY CONDUCTIVE MATERIALS", it is incompatible at level 6.

[0042] Table 1

[0043] Embodiment 2:

[0044] A method for evaluating the galvanic compatibility of automotive dissimilar metals based on deconvolution technology is used to evaluate the galvanic compatibility of automotive dissimilar metal materials nickel alloy and carbon steel in a neutral oxygen-containing liquid film environment, including the following steps:

[0045] Step 1: For nickel alloy, the liquid membrane environment pH = 7, temperature 293.15K, 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;

[0046] 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):

[0047] 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 an activated reaction state without passivation behavior, and the polarization curve during the anode dissolution process is fitted;

[0048] 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.

[0049] Step 5: Repeat steps 1 to 5 for different metal carbon steels, and store the polarization curve results of nickel alloy and carbon steel after parameter optimization into the database, such as Figure 4 The positive and negative poles of nickel alloy and carbon steel are judged 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 / m 2 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;

[0050] Step 6: Based on the intersection data of the polarization curves of nickel alloy and carbon steel, the acceleration factor and the compatibility level evaluation criteria, the galvanic corrosion of nickel alloy and carbon steel in automobiles is evaluated and a compatibility judgment is given. The corrosion rate is calculated to be 1.8e-4mm / year based on the galvanic corrosion current density*acceleration factor, and according to the compatibility judgment table 1 provided in "GALVANIC COMPATIBILITY OF ELECTRICALLYCONDUCTIVE MATERIALS", it is compatible.

[0051] 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, and accurately analyze the corrosion mechanism of the material interface. This technology not only shortens the experimental time, but also improves the prediction accuracy of corrosion rate and reaction activity, making it an important advantage in practical applications such as rapid evaluation of automotive material compatibility, material selection and optimization.

Claims

1. A method for evaluating the galvanic compatibility of dissimilar metals in automobiles based on deconvolution technology can analyze the experimental data of polarization curves, achieve high-precision electrochemical data reduction, and combine with the existing material corrosion database to quickly evaluate the galvanic compatibility of dissimilar metals in automobiles. It includes the following steps: Step 1: For heterogeneous 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 each reaction can be determined by the Nernst equation: Where 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 / fugacity of the reducing substance, C O is the activity / fugacity of the oxide. The activity / fugacity of a substance in a solution can be 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, fit the cathode polarization curve of oxygen and H+ reduction, and the total cathode current 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, and the total cathode current is: Step 3: define the Tafel slope, exchange current density, passivation current density, and passivation potential parameters of the oxidation 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. At this time, 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 metal A / B after parameter optimization into the database, and achieve: ① judge the anode and cathode of 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 curve of metal A / B materials, and judge the rationality of the intersection data. 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 given.

2. 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 the steps 1 to 5, the deconvolution technology 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. Deconvolution is a mathematical operation usually used to recover or restore the original information of a signal. It is the inverse process of convolution. In the present invention, deconvolution is used to infer the electrochemical behavior of the cathode and anode from the results of the polarization curve in order to perform a more accurate compatibility assessment.

3. 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 1, for heterogeneous metal materials, the equilibrium potential E of the cathode reaction and the anode reaction is calculated by using basic electrochemical parameters, including solution pH, oxygen content, initial metal ion content, etc. reversible , used to obtain the overpotential η of each reaction = |E ext -E reversible |.

4. 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 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. When there is a limiting current density, equation (3) is used to adjust the calculation of the total cathode current, thereby more accurately reflecting the characteristics of the cathode reaction.

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 3, the parameters S and i are used. 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.

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 the step 4, the cathode and anode polarization curves extracted by deconvolution are combined to form an overall polarization curve; A parameter optimization method is introduced to achieve fitting of the polarization curve by repeatedly adjusting the input parameters and the eigenvalues ​​obtained by deconvolution, making it more consistent with the actual polarization behavior of the metal.

7. 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 5, the accurate polarization curve obtained by deconvolution is used, and the cathode and anode intersection data are automatically extracted, which reduces the human error. At the same time, the optimized parameters and curve intersections of multiple metals are stored in the database, providing data support for galvanic corrosion compatibility analysis.

8. 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 6, the anode curve of the anode and the cathode 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 the compatibility level is evaluated. The acceleration factor value is adjusted according to different types of dissimilar metal combinations and environmental conditions, and the comprehensive application of corrosion current and acceleration factor can be achieved.

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