Metal contact corrosion evaluation method and system based on Tafel polarization curve

Abstract

The invention relates to a metal contact corrosion evaluation method and system based on a Tafel polarization curve, and the method comprises the steps: installing a to-be-evaluated sample in an electrochemical testing device, and simulating the corrosion condition of a working environment; carrying out linear polarization scanning on the to-be-evaluated sample by adopting an electrochemical workstation, recording changes of electrode potential and current density, and generating a Tafel polarization curve; a strong polarization interval is selected according to the measured Tafel polarization curve data, and Tafel curves of the anode and the cathode are obtained through mathematical fitting; and calculating the corrosion potential and the corrosion current density based on the Tafel curves of the anode and the cathode obtained by fitting. Compared with the prior art, through accurate mathematical fitting and calculation, the accuracy and reliability of corrosion parameters are ensured, and the corrosion tendency and corrosion rate of the metal material can be accurately evaluated. And an effective technical means is provided for evaluating the corrosion performance of the metal material.

Description

Technical Field

[0001] The invention relates to the field of corrosion assessment of electrical equipment, and in particular to a corrosion assessment method for plum blossom contacts inside a switch cabinet. Background Art

[0002] The corrosion of metal materials is a ubiquitous natural phenomenon that widely affects equipment and structures in all walks of life. Corrosion not only leads to the decline of metal material performance, but may even lead to structural failure, causing huge losses to production and life. In order to effectively prevent corrosion and increase the service life of metal materials, surface treatment technologies such as electroplating, coating, and anodizing are used. These technologies form a protective layer on the metal surface to isolate the corrosive medium, thereby slowing down the corrosion process. However, how to accurately evaluate the effects of these surface treatment technologies has become an important research topic.

[0003] Tafel polarization curve is a commonly used electrochemical analysis method. By measuring the relationship between electrode potential and current density, the corrosion behavior of metal materials can be intuitively reflected. This method can not only provide key parameters such as corrosion potential and corrosion current density, but also reveal the corrosion mechanism of metal materials under different environmental conditions. Using Tafel polarization curves for corrosion research can better understand the electrochemical reaction process of metal materials and provide a theoretical basis for optimizing surface treatment processes.

[0004] Chinese patent document number CN116417073A discloses an analysis method and system for the electrochemical oxidation performance of hydrogen in alloy catalysts; and Chinese patent document number CN110568051B discloses a method for testing the reaction kinetic parameters of porous electrodes in liquid flow batteries. The two patents use Tafel polarization curves to evaluate the electrochemical oxidation performance of hydrogen in alloy catalysts, and calculate the electrode kinetic parameters on porous electrodes to evaluate the electrode performance parameters, proving that this method can effectively evaluate the electrochemical performance parameters of batteries and electrodes. According to the effectiveness of the Tafel polarization curve in the field of metal electrodynamics, when using it in corrosion research, how to accurately extract the corrosion potential and corrosion current density from the polarization curve is still a difficult problem. Traditional extrapolation methods usually rely on manually determining the starting and ending points of the Tafel region, or calculating through empirical formulas, which has large human errors, resulting in poor repeatability of the results; and traditional extrapolation methods usually have strong assumptions and reliance on the shape and characteristics of the curve, and it is difficult to deal with experimental data that do not meet ideal conditions, which may lead to large errors in the calculation results. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a method and system for evaluating the corrosion of metal contacts after different surface treatments based on Tafel polarization curves.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] As a first aspect of the present invention, a method for evaluating metal contact corrosion based on Tafel polarization curve is provided, the steps comprising:

[0008] The sample to be evaluated is installed in an electrochemical test device and the corrosion conditions of the working environment are simulated;

[0009] An electrochemical workstation was used to perform linear polarization scanning on the sample to be evaluated, and the changes in electrode potential and current density were recorded to generate Tafel polarization curves.

[0010] The strong polarization interval is selected according to the measured Tafel polarization curve data, and the Tafel curves of the anode and cathode are obtained by mathematical fitting;

[0011] The corrosion potential E was calculated based on the fitted Tafel curves of the anode and cathode. corr and corrosion current density I corr .

[0012] As a preferred technical solution, the Tafel curves of the anode and cathode obtained by mathematical fitting are as follows:

[0013] According to the measured Tafel polarization potential-current density curve data, find the potential value E corresponding to the minimum current density min ;

[0014] Select the strong polarization interval based on the potential value E corresponding to the minimum current density min And the strong polarization interval obtains the corresponding cathode fitting interval and anode fitting interval;

[0015] The least square method is used in the fitting interval to fit the relationship between the potential and the logarithmic current density using the Tafel formula:

[0016] η=a+blgi

[0017] Where η is the overpotential, i is the current density, a and b are the Tafel constants, which are the intercept and slope of the Tafel curve, respectively;

[0018] The slope b of the Tafel curves of the anode and cathode is obtained by linear fitting a and b c and the corresponding intercept b a and a c .

[0019] As a preferred technical solution, the method calculates the corrosion current density I according to the Tafel curves of the anode and cathode obtained by fitting. corr:

[0020]

[0021] The intersection of the anode and cathode Tafel curves is the corrosion potential E corr .

[0022] As a preferred technical solution, the samples to be evaluated include a variety of metal contacts that have been surface treated based on different coating materials, and the corrosion potential E of each sample to be evaluated is calculated respectively. corr and the corrosion current density i corr , and conduct comparative evaluation on their corrosion resistance.

[0023] As a preferred technical solution, the surface treatment of the metal contact includes silver plating, gold plating and silver plating followed by gold plating.

[0024] As a preferred technical solution, the electrochemical testing device adopts a standard three-electrode system, including a working electrode, a reference electrode and an auxiliary electrode. The working electrode is the sample to be evaluated, and the corrosion conditions of the marine environment are simulated by the electrolyte.

[0025] As a preferred technical solution, the reference electrode is a saturated calomel electrode.

[0026] As a preferred technical solution, the auxiliary electrode is a platinum sheet.

[0027] As a preferred technical solution, during the testing of the sample to be evaluated, the temperature and concentration conditions of the electrodes and the electrolyte of the electrochemical testing device are kept constant.

[0028] As a second aspect of the present invention, a metal contact corrosion assessment system based on Tafel polarization curve is provided, wherein the system implements the corrosion assessment method as described above, comprising:

[0029] Electrochemical testing device, used to measure the changes in electrode potential and current density of the sample to be evaluated under the corrosion conditions of the working environment, and generate Tafel polarization curve;

[0030] Corrosion assessment module: Based on the measured Tafel polarization curve data, the strong polarization interval is selected, and the Tafel curves of the anode and cathode are obtained by mathematical fitting, and the corrosion potential E is further calculated. corr and the corrosion current density i corr .

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention proposes a method for calculating corrosion potential and corrosion current based on Tafel polarization curve. Through precise mathematical fitting and calculation, the accuracy and reliability of corrosion parameters are ensured, and the corrosion tendency and corrosion rate of metal materials can be more accurately evaluated. This provides an effective technical means for evaluating the corrosion performance of metal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of the method for evaluating metal contact corrosion based on Tafel polarization curves of the present invention;

[0034] Figure 2 Schematic diagram of the three-electrode test system of the present invention

[0035] Figure 3 Polarization curve test results of samples with different coating materials;

[0036] The numbers in the figure are as follows: 1. ammeter, 2. voltmeter, 3. auxiliary electrode, 4. reference electrode, 5. working electrode. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] Polarization is an obstacle to the corrosion process. Since it can reduce corrosion current and reduce corrosion rate, the analysis and discussion of polarization law is of great significance to metal corrosion research and surface treatment effect evaluation. Potential-current intensity or potential-current density diagrams are often used to describe the change of electrode potential. For an electrochemical reaction, such as formula 1, where O x is an oxidized substance, Re is a reduced substance, the equation to the right is the cathode reaction, and the equation to the left is the anode reaction.

[0040]

[0041] Assume that the standard activation energies of the anodic reaction and the cathodic reaction at the zero point of the potential coordinate are W a 0 and W c o , then the reaction rates of the two poles are:

[0042]

[0043] Among them, k a and k c is a constant, CRe and C ox are the concentrations of reduced and oxidized substances, respectively. When the electrode potential changes from 0 to E, the relationship between the activation energy of the bipolar reaction and the standard activation energy in this state satisfies equations (4) and (5).

[0044] W a =W a 0 -(1-a)nFΔE (4)

[0045] W c =W c o +anFΔE (5)

[0046] Among them, a is a constant less than 1, n is the number of electrons lost by the electrode reaction, and F is the Faraday constant. The rates of the anode reaction and the cathode reaction are related to their respective current densities, and the relationship is:

[0047]

[0048] Substituting equations (4) and (5) into equations (2) and (3), respectively, and combining equations (6) and (7), we can obtain the relationship between the anode current density and cathode current density when the electrode potential is E and the anode current density and cathode current density when the electrode potential is 0:

[0049]

[0050] Rearranging equations (8) and (9) yields the relationship between the electrode potential and the anode and cathode current densities as shown in equations (10) and (11), which indicates that there is a semi-logarithmic relationship between the electrode potential and the anode current density and the cathode current density.

[0051]

[0052] In the polarization process, when the overpotential is relatively large, there is a linear relationship between it and the logarithm of the polarization current density, namely the Tafel formula:

[0053] η=a+blgi (12)

[0054] Where η is the overpotential (η=EE corr ), i is the current density, a and b are Tafel constants, which are the intercept and slope of the Tafel curve respectively. Therefore, the corrosion potential and corrosion current can be calculated according to the Tafel polarization curve to evaluate the corrosion tendency and corrosion rate of metal contacts after different surface treatments.

[0055] Based on the measured Tafel polarization curve data, the corrosion potential E is accurately calculated using the mathematical fitting method. corr and corrosion current density Icorr , the calculation steps and corresponding calculation formula are as follows:

[0056] In the polarization curve, the Tafel region can be identified in the linear part of the anode and cathode (usually at higher potential offsets). The selection method is to find the potential value E corresponding to the minimum current density based on the potential-current density curve. min Select ±(0.06V-0.12V) as the strong polarization interval and select the fitting interval as the cathode interval (E min -0.12V, E min -0.06V and the anode interval (E min +0.06V, E min +0.12V) in these regions, the relationship between the potential and the logarithmic current density in this interval is fitted using the least squares method combined with formula (12). The Tafel slope b can be obtained by linear fitting. a (anode) and b c (cathode), and the corresponding intercept b a and a c .

[0057] According to the fitted Tafel straight lines of the anode and cathode, the corrosion current density I is calculated by formula (13): corr . Corrosion potential E corr is the intersection point of the anode and cathode Tafel curves and is calculated using formula (14).

[0058]

[0059] The schematic diagram of the three-electrode test system is as follows Figure 2 As shown, it includes an ammeter 1, a voltmeter 2, an auxiliary electrode 3, a reference electrode 4 and a working electrode 5, and these electrodes are placed in an electrolytic cell. The auxiliary electrode 3 is a Pt sheet, the reference electrode 4 is a saturated calomel electrode, and the working electrode 5 is a metal contact sample. The system forms two circuits: the first circuit is composed of a working electrode and a reference electrode, and the current is extremely small, mainly used to measure the electrode potential; the second circuit is composed of a working electrode and an auxiliary electrode, and is used to measure the current. The test conditions are: the electrochemical impedance spectroscopy test frequency range is 0.1 to 10000Hz. The corrosive medium is a mixed solution of 5% NaOH and NaHCO3, the scanning speed is 5mV / s, and different scanning intervals are determined according to the open circuit potential of each test.

[0060] The present invention adopts a mathematical fitting method to fit the anode and cathode parts of the Tafel polarization curve through precise linear regression, and can more accurately capture the slope and intercept of the linear region. The method uses the least square method to obtain the optimal fitting parameters and minimize the error, thereby improving the calculation accuracy of the corrosion potential and the corrosion current density. For polarization curves with complex shapes, the mathematical fitting method can reasonably select the fitting area, and can select ±(0.06V-0.12V) or expand or reduce the range to process nonlinear or irregular data. It is more flexible and adaptable when processing complex polarization behaviors.

[0061] Example 2

[0062] Corrosion performance evaluation of silver-plated copper surface

[0063] (1) Sample preparation:

[0064] Pure copper samples were selected and strictly cleaned and pretreated to ensure that there were no contaminants on the surface of the samples. On this basis, a layer of silver with a thickness of 8μm was plated on the copper surface through the electroplating process. The parameter settings and operation steps in the electroplating process strictly follow the standard electroplating process to ensure the uniformity and adhesion of the coating. After the sample preparation was completed, a preliminary appearance inspection and thickness measurement were carried out to ensure that the quality and thickness of the coating met the experimental requirements.

[0065] (2) Test equipment and conditions:

[0066] The prepared silver-plated copper sample was installed in an electrochemical test device, and a 3.5% NaCl solution was selected as the electrolyte to simulate the corrosion conditions in salt water to improve the practical application value of the experiment. During the experiment, the temperature, concentration and other conditions of all electrodes and electrolytes were kept constant to ensure the accuracy and repeatability of the test data.

[0067] (3) Electrochemical test:

[0068] The silver-plated copper sample was subjected to linear polarization scanning using an electrochemical workstation, with the scanning range set to -0.4V to 0.2V and the scanning rate set to 0.5mV / s. The entire test process was carried out under constant temperature conditions, and the changes in electrode potential and current density were recorded in real time to generate a Tafel polarization curve. By analyzing the polarization curve, the characteristics of the electrode reaction can be intuitively observed, and the corrosion potential and corrosion current density can be calculated.

[0069] (4) Data processing and analysis:

[0070] Based on the measured Tafel polarization curve data, the corrosion potential E is accurately calculated using the mathematical fitting method. corr and corrosion current density I corrFor the silver-plated copper sample, the fitting results show that its corrosion potential is -0.266 V and the corrosion current density is 7.39×10 -5 A / cm2. By comparing with the untreated pure copper sample, it can be found that the corrosion potential of the silver-plated sample is significantly increased and the corrosion current density is significantly reduced, which indicates that the silver-plated treatment effectively enhances the corrosion resistance of copper.

[0071] (5) Result analysis:

[0072] The experimental results show that silver plating significantly improves the corrosion resistance of copper. Its corrosion potential is about 0.063V higher than that of the untreated sample, while the corrosion current density is reduced by more than an order of magnitude. This result confirms the protective effect of the silver plating on the copper substrate. By forming a dense and stable protective layer, it effectively blocks the contact between the corrosive medium and the copper, thereby slowing down the corrosion process. This result has important reference value for metal surface treatment in the fields of electronics, electrical engineering and machinery.

[0073] Table 1 Polarization curve fitting data of silver-plated material samples

[0074] Material Coating thickness(μm) <![CDATA[Corrosion potential E corr (V)]]> <![CDATA[Corrosion current I corr (A)]]> Copper / -0.329 <![CDATA[2.84×10 -4 ]]> Silver-plated copper 8 -0.266 <![CDATA[7.39×10 -5 ]]>

[0075] Example 3

[0076] Corrosion performance evaluation of gold-plated copper surface

[0077] (1) Sample preparation:

[0078] Pure copper samples were selected and strictly cleaned and pretreated to remove surface impurities and oxides. Then a gold layer with a thickness of 0.208μm was plated on the copper surface by electroplating. At the same time, a comparison group was set up. The copper surface was plated with silver and then gold by electroplating, and the thickness of the coating was 8.208μm. The gold plating process used a high-purity gold plating solution, and controlled the electroplating parameters such as current density, temperature and time to ensure that the coating was uniform and defect-free. The gold-plated samples were examined under a microscope after electroplating to confirm that the integrity and thickness of the coating met the experimental design requirements.

[0079] (2) Test equipment and conditions:

[0080] The gold-plated copper sample was installed in an electrochemical test device using a standard three-electrode system, including a working electrode (gold-plated copper sample), a reference electrode (saturated calomel electrode) and an auxiliary electrode (platinum sheet). The electrolyte was also selected as a 3.5% NaCl solution to simulate the corrosion conditions of the marine environment. During the experiment, the concentration and temperature of the electrolyte were kept stable to ensure the accuracy and reliability of the test results.

[0081] (3) Electrochemical test:

[0082] The electrochemical workstation was used for linear polarization scanning, with the scanning range set to -0.4V to 0.2V and the scanning rate set to 0.5mV / s. The entire test process was carried out under constant temperature conditions, and the changes in electrode potential and current density were recorded to generate Tafel polarization curves. By analyzing the polarization curves, the corrosion potential and corrosion current density were determined.

[0083] (4) Data processing and analysis:

[0084] According to the measured Tafel polarization curve data, the corrosion potential E is calculated by mathematical fitting method. corr and corrosion current density I corr For the gold-plated copper sample, the fitting results show that its corrosion potential is -0.242 V and the corrosion current density is 1.82×10 -5 A / cm 2 For the silver-plated and gold-plated copper sample, the fitting results show that its corrosion potential is -0.185 V and the corrosion current density is 1.35×10 -5 A / cm 2 Compared with the untreated pure copper samples, the corrosion potential of the samples after gold plating and silver plating was significantly increased, and the corrosion current density was significantly reduced, indicating that this treatment method greatly enhanced the corrosion resistance of copper.

[0085] (5) Result analysis:

[0086] like Figure 3 As shown in the figure, the corrosion potential of the copper sample after gold plating is about 0.087V higher than that of the untreated sample, while the corrosion current density is reduced by more than an order of magnitude. The gold plating has excellent chemical inertness and stability, and can form a dense and uniform protective layer on the copper surface, effectively blocking the erosion of corrosive media. Compared with the silver plating, the copper sample treated with gold plating shows better corrosion resistance, which further verifies the potential of gold plating in anti-corrosion applications.

[0087] Table 2 Polarization curve fitting data of samples with different coating materials

[0088] Material Coating thickness(μm) <![CDATA[Corrosion potential E corr (V)]]> <![CDATA[Corrosion current I corr (A)]]> Copper / -0.329 <![CDATA[2.84×10 -4 ]]> Gold-plated copper 0.208 -0.242 <![CDATA[1.82×10 -5 ]]> Copper plated with silver and then gold 8.208 -0.185 <![CDATA[1.35×10 -5 ]]>

[0089] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for evaluating metal contact corrosion based on Tafel polarization curve, characterized in that the steps include: The sample to be evaluated is installed in an electrochemical test device and the corrosion conditions of the working environment are simulated; An electrochemical workstation was used to perform linear polarization scanning on the sample to be evaluated, and the changes in electrode potential and current density were recorded to generate Tafel polarization curves. The strong polarization interval is selected according to the measured Tafel polarization curve data, and the Tafel curves of the anode and cathode are obtained by mathematical fitting; The corrosion potential E was calculated based on the fitted Tafel curves of the anode and cathode. corr and corrosion current density I corr .

2. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 1, characterized in that: The Tafel curves of the anode and cathode obtained by mathematical fitting are as follows: According to the measured Tafel polarization potential-current density curve data, find the potential value E corresponding to the minimum current density min ; Select the strong polarization interval based on the potential value E corresponding to the minimum current density min And the strong polarization interval obtains the corresponding cathode fitting interval and anode fitting interval; The least square method is used in the fitting interval to fit the relationship between the potential and the logarithmic current density using the Tafel formula: η=a+blgi Where η is the overpotential, i is the current density, a and b are the Tafel constants, which are the intercept and slope of the Tafel curve, respectively; The slope b of the Tafel curves of the anode and cathode is obtained by linear fitting a and b c and the corresponding intercept b a and a c .

3. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 2, characterized in that: The method calculates the corrosion current density I according to the Tafel curves of the anode and cathode obtained by fitting. corr : The intersection of the anode and cathode Tafel curves is the corrosion potential E corr .

4. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 1, characterized in that: The samples to be evaluated include a variety of metal contacts that have undergone different surface treatments based on different coating materials. The corrosion potential E of each sample to be evaluated is calculated. corr and corrosion current density I corr , and conduct comparative evaluation on their corrosion resistance.

5. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 4, characterized in that: The surface treatment of the metal contact sheet includes silver plating, gold plating and gold plating after silver plating.

6. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 1, characterized in that: The electrochemical test device adopts a standard three-electrode system, including a working electrode, a reference electrode and an auxiliary electrode. The working electrode is the sample to be evaluated, and the corrosion conditions of the marine environment are simulated by the electrolyte.

7. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 6, characterized in that: The reference electrode is a saturated calomel electrode.

8. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 6, characterized in that: The auxiliary electrode is a platinum sheet.

9. The method for evaluating metal contact corrosion based on Tafel polarization curve according to claim 6, characterized in that: During the test of the sample to be evaluated, the temperature and concentration conditions of the electrodes and the electrolyte of the electrochemical testing device are kept constant.

10. A metal contact corrosion assessment system based on Tafel polarization curve, characterized in that: The system implements the corrosion assessment method according to any one of claims 1 to 9, comprising: Electrochemical testing device, used to measure the changes in electrode potential and current density of the sample to be evaluated under the corrosion conditions of the working environment, and generate Tafel polarization curve; Corrosion assessment module: Based on the measured Tafel polarization curve data, the strong polarization interval is selected, and the Tafel curves of the anode and cathode are obtained by mathematical fitting, and the corrosion potential E is further calculated. corr and corrosion current density I corr .

Images