Corrosion simulation experiment system and method for surface-treated metal contact

Abstract

The invention relates to a corrosion simulation experiment system and method for a surface-treated metal contact, and the system comprises a constant temperature and humidity chamber which is used for controlling the temperature and humidity in an experiment environment; the electrochemical testing device is arranged in a temperature and humidity control experiment environment and comprises an auxiliary electrode, a reference electrode and a working electrode, one end of the auxiliary electrode is exposed in the constant-temperature and constant-humidity box, the other end of the auxiliary electrode is soaked in corrosive liquid, and the electrochemical testing device takes metal contact samples subjected to different surface treatments as the working electrode; the reference electrode is used for providing stable reference potential, and a voltmeter is arranged between the reference electrode and the working electrode; an ampere meter is arranged between the auxiliary electrode and the working electrode to form a current loop; and the computer fits the polarization curve and the electrochemical impedance spectroscopy data, and calculates and compares key electrochemical parameters. Compared with the prior art, multi-level evaluation of the contact is realized, more comprehensive experimental data can be provided, and the corrosion behavior of the copper contact in an actual high-humidity environment can be deeply understood.

Description

Technical Field

[0001] The invention relates to the field of life assessment of electrical equipment, and in particular to a corrosion simulation experimental system for copper contacts in a high-voltage switch cabinet after surface treatment. Background Art

[0002] The power industry is an important basic industry of the country, which is directly related to the country's economic development and the quality of life of the people. With the continuous advancement of science and technology and the improvement of people's living standards, the demand for electricity and the requirements for power supply reliability are also increasing. High-voltage switchgear is a key equipment in the power system, which undertakes the functions of power distribution and fault isolation, ensuring the safe and stable operation of the power system in power generation, transmission, distribution and other links. The copper contacts in high-voltage switchgear are widely used in key parts of electrical equipment due to their excellent electrical and thermal conductivity. However, in a high-humidity environment, condensation and corrosion products such as copper green (basic copper carbonate) are easily formed on the surface of copper contacts. These corrosion products will significantly reduce the electrical contact performance and mechanical strength of the contacts, and in severe cases may cause failure of power equipment or even system paralysis. Therefore, studying the corrosion behavior of copper contacts of high-voltage switchgear and its protection methods is of great significance to improving the reliability and safety of power systems.

[0003] In the prior art, sealed high-voltage switchgear is often used to improve the safety and stability of equipment in dry environments. However, in humid environments, it is difficult for moisture inside the cabinet to be discharged, resulting in condensation. Conventional moisture-proof measures, such as electric heating, reduce relative humidity by heating the air, but this method does not fundamentally solve the problem of excessive humidity inside the high-voltage switchgear, and moisture may still re-condense in areas with lower temperatures. In addition, existing high-voltage switchgears mostly use silver plating to treat the surface of copper contacts, but the silver plating layer will still be worn and corroded after long-term operation, making it difficult to effectively prevent the formation of verdigris in the long term.

[0004] After searching the existing switch cabinet simulation device patents, it was found that the current patents mainly involve overheating temperature rise failures of switch cabinets. For example, Chinese patent document number CN209640456U, published on November 15, 2019, discloses a GW6-252 type disconnector abnormal heating simulation experimental device. This patent uses a temperature sensor to simulate overheating failures in disconnector equipment. However, there are few studies on simulation experimental systems for copper contact corrosion. 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 corrosion simulation experimental system and method for surface treated metal contacts.

[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 corrosion simulation experimental system for a surface-treated metal contact is provided, the system comprising:

[0008] Constant temperature and humidity chamber, used to control the temperature and humidity in the experimental environment;

[0009] The electrochemical test device is arranged in a temperature and humidity controlled experimental environment, and comprises an auxiliary electrode, a reference electrode and a working electrode, one end of which is exposed in a constant temperature and humidity chamber and the other end of which is immersed in a corrosive liquid. The electrochemical test device uses metal contact samples with different surface treatments as working electrodes; the reference electrode is used to provide a stable reference potential, and a voltmeter is arranged between the reference electrode and the working electrode; an ammeter is arranged between the auxiliary electrode and the working electrode to form a current loop;

[0010] The computer is connected to the current meter and voltage meter signals of the electrochemical test device, and is used to process the electrochemical test data, fit the polarization curve and electrochemical impedance spectrum data, calculate and compare key electrochemical parameters to evaluate the effects of different surface treatment technologies on the corrosion resistance of copper contacts.

[0011] As a preferred technical solution, the reference electrode is a saturated calomel electrode, and the auxiliary electrode is a platinum sheet.

[0012] As a preferred technical solution, the corrosive liquid includes an alkaline corrosive liquid or an acidic corrosive liquid.

[0013] As a preferred technical solution, the alkaline etching solution is a mixture of NaOH and NaHCO3.

[0014] As a preferred technical solution, the acidic etching solution is a mixture of H2SO4 and H2SO3.

[0015] As a preferred technical solution, the constant temperature and humidity chamber is provided with a plurality of experimental windows, and the plurality of experimental windows are used to place metal contact samples with different surface treatments.

[0016] As a preferred technical solution, the constant temperature and humidity chamber is equipped with multiple temperature and humidity sensors for real-time monitoring and adjustment of the environmental parameters in the chamber.

[0017] As a second aspect of the present invention, a corrosion simulation test method for a surface-treated metal contact is provided, characterized in that the method adopts a corrosion simulation test system as described in any one of claims 1 to 7, and the steps include:

[0018] Preparation includes ammeter, voltmeter, auxiliary electrode, reference electrode and working electrode, zero setting and initialization;

[0019] The metal contact samples with different surface treatments are installed at the working electrode position of the electrochemical test device, and the type and concentration of the corrosion solution are set;

[0020] Place the electrochemical test device in a constant temperature and humidity chamber and set the required temperature and humidity conditions to stabilize the experimental environment, and measure the polarization curve and electrochemical impedance spectrum of the metal contact;

[0021] Analyze and process the experimental data, fit the polarization curve and electrochemical impedance spectrum, and calculate the electrochemical parameters, including corrosion potential, corrosion current, capacitive arc radius and low-frequency impedance mode;

[0022] According to the experimental results of metal contact samples with different surface treatments, various electrochemical parameters were compared and the effects of various surface treatment technologies on the corrosion resistance of metal contacts were evaluated.

[0023] As a preferred technical solution, the corrosion potential and corrosion current calculation process is as follows:

[0024] The anodic and cathodic Tafel polarization curves were obtained by fitting the Tafel polarization curves, and the corrosion potential and corrosion current were calculated based on the anodic and cathodic Tafel polarization curves to evaluate the corrosion tendency and corrosion rate of the copper contacts after different surface treatments.

[0025] As a preferred technical solution, the calculation process of the capacitive reactance arc radius and the low-frequency impedance modulus is as follows:

[0026] Based on the AC signal response in the electrochemical process, the real part, imaginary part and modulus of the impedance of the electrochemical system equivalent circuit at different frequencies are determined;

[0027] The real and imaginary parts of the composite impedance are plotted as a Nyquist diagram, where the real part is on the horizontal axis and the imaginary part is on the vertical axis, to obtain information about the electrochemical process, including reaction rate and charge transfer;

[0028] The frequency, the modulus value and the phase difference of the composite impedance are plotted in logarithmic form into Bode diagrams;

[0029] The capacitive arc radius and low-frequency impedance modulus of the electrochemical system equivalent circuit were obtained based on the electrochemical impedance spectroscopy, and the corrosion resistance of the copper contacts after different surface treatments was evaluated.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1) The corrosion simulation experimental system of the present invention uses a multi-angle and multi-level method to evaluate the corrosion resistance of copper contacts by different surface treatment technologies. This not only includes conventional analysis of electrochemical tests, but also combines real-time monitoring of multi-point temperature and humidity sensors to ensure the stability of experimental conditions. This multi-level evaluation method can provide more comprehensive experimental data and help to deeply understand the corrosion behavior of copper contacts in actual high humidity environments.

[0032] 2) The design of the present invention takes into account the simulation of corrosion behavior under different environmental conditions. The corrosive liquid in the device can be set to an alkaline corrosive liquid mixed with NaOH and NaHCO3, or an acidic corrosive liquid mixed with H2SO4 and H2SO3 according to the needs. By adjusting the humidity, temperature, and pH, the corrosion of the copper contact under different operating conditions is comprehensively simulated.

[0033] 3) In addition to evaluating the effect of surface treatment technology on the corrosion resistance of copper contacts, the corrosion simulation experimental system of the present invention can also be used to study the corrosion conditions under different temperature conditions. In actual operation, the temperature of the experimental environment can be accurately controlled by a constant temperature and humidity chamber to simulate different working conditions. During the experiment, the copper contact sample is placed in a set temperature environment, and combined with an electrochemical testing device, its polarization curve and electrochemical impedance spectrum at different temperatures are measured to analyze its corrosion rate and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the corrosion simulation experimental system of the copper contact after surface treatment of the present invention;

[0035] Figure 2 It is a flow chart of the corrosion simulation experiment of the copper contact after the surface treatment of the present invention;

[0036] The numbers in the figure are as follows: 1. ammeter, 2. voltmeter, 3. auxiliary electrode, 4. reference electrode, 5. working electrode, 6. electrochemical testing device, 7. constant temperature and humidity chamber, 8. computer. 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] The present invention relates to a corrosion simulation experimental system for metal contacts after surface treatment, which aims to accurately evaluate the influence of different surface treatment technologies on the corrosion resistance of copper contacts in high-voltage switch cabinets by simulating corrosion conditions in a high-humidity environment. The system mainly includes an electrochemical testing device, a constant temperature and humidity chamber 7, and data analysis software. The electrochemical testing device is used to measure the polarization curve and electrochemical impedance spectrum of the metal contact, the constant temperature and humidity chamber 7 is used to simulate a high-humidity environment, and the data analysis software is used to process the experimental data and generate an analysis report. The present invention systematically studies the influence of different surface treatment technologies on the corrosion resistance of metal contacts through multi-angle and multi-level experimental methods, and provides a scientific basis for optimizing the surface treatment technology of copper contacts in high-voltage switch cabinets.

[0040] The corrosion simulation experimental system of the present invention is as follows Figure 1 As shown, it is mainly composed of an electrochemical test device 6, a constant temperature and humidity chamber 7 and a computer 8. The electrochemical test device includes an ammeter 1, a voltmeter 2, an auxiliary electrode 3, a reference electrode 4, and a working electrode 5. The working electrode 5 is a copper contact sample, the reference electrode 4 uses a saturated calomel electrode, and the auxiliary electrode 3 uses a platinum sheet. The constant temperature and humidity chamber 7 can accurately control the temperature and humidity in the experimental environment, and monitor the environment in the chamber in real time through a multi-point temperature and humidity sensor to ensure the stability of the experimental conditions. The computer 8 is used to process and analyze electrochemical test data, including the fitting and analysis of polarization curves and electrochemical impedance spectra, and automatically calculate parameters such as corrosion potential, corrosion current, capacitive arc radius and low-frequency impedance mode. The working electrode 5 simulates the electrochemical reaction in the actual working environment by applying an external potential or current. The reference electrode 4 provides a stable reference potential to ensure the accuracy of the measurement, and the auxiliary electrode 3 is used to complete the current loop to ensure the normal operation of the entire electrochemical system. The test object is a copper contact with different silver plating thicknesses, and the coating thickness is 5-34μm.

[0041] The constant temperature and humidity chamber 7 of the present application is specially designed for corrosion testing of copper contacts of different high-voltage switch cabinets. Its design takes into account and simulates the corrosion behavior under different high humidity environments and different acidic and alkaline environmental conditions.

[0042] The constant temperature and humidity chamber 7 is used to simulate a high humidity environment to ensure the stability of temperature and humidity during the experiment. The device can accurately control the temperature and humidity range, and monitor and adjust the environmental parameters in the box in real time through the built-in multi-point temperature and humidity sensors. The constant temperature and humidity chamber 7 is designed with multiple experimental windows to facilitate the placement of copper contact samples after different surface treatments. The air flow system in the box can simulate the humidity changes in the actual environment to ensure the authenticity of the experimental conditions. By setting different temperature and humidity conditions, the corrosion behavior of copper contacts in different environments can be studied and the effectiveness of various surface treatment technologies can be evaluated. It not only includes electrochemical test analysis, but also combines real-time monitoring of multi-point temperature and humidity sensors to ensure the stability of experimental conditions. This multi-level evaluation method can provide more comprehensive experimental data, which helps to deeply understand the corrosion behavior of copper contacts in actual high humidity environments.

[0043] The corrosion liquid in the electrochemical test device 6 can be set as an alkaline corrosion liquid mixed with NaOH and NaHCO3, or an acidic corrosion liquid mixed with H2SO4 and H2SO3 according to the needs. By adjusting the humidity, temperature, and pH, the corrosion of the copper contact under different operating conditions is comprehensively simulated.

[0044] During the experiment, the copper contact samples were exposed in the constant temperature and humidity chamber 7 for a certain period of time and then subjected to electrochemical testing to systematically evaluate their corrosion performance in a high humidity environment.

[0045] Computer 8 is used to process electrochemical test data and provide detailed corrosion behavior analysis results. It can not only fit polarization curves and electrochemical impedance spectrum data, but also calculate multiple key electrochemical parameters including corrosion potential, corrosion current, capacitive arc radius and low-frequency impedance mode. In actual operation, the copper contact samples after different surface treatments are first installed at the working electrode position of the electrochemical test device, and the reference electrode 4 and the auxiliary electrode 3 are connected to the corresponding positions respectively. The device is placed in a constant temperature and humidity chamber 7, and the required temperature and humidity conditions are set. After the experimental environment is stabilized for a period of time, the electrochemical test is started. The test includes measuring the polarization curve and electrochemical impedance spectrum of the copper contact, and processing the experimental data through computer 8. According to the experimental results of different surface treatment technologies, various electrochemical parameters are compared to evaluate their influence on the corrosion resistance of the copper contact.

[0046] Example 2

[0047] As another embodiment of the present invention, this embodiment also provides a simulation experiment method based on the system described in the above embodiment, the process is as follows: Figure 2 As shown:

[0048] S1. Experimental preparation includes zeroing and initialization of the ammeter 1, voltmeter 2, auxiliary electrode 3 (platinum sheet), reference electrode 4 (saturated calomel electrode) and working electrode 5 (copper contact sample).

[0049] S2. Sample processing: The copper contact samples after different surface treatments are installed at the working electrode 5 position of the electrochemical testing device 6, and the type and concentration of the corrosion solution are set according to the experimental requirements.

[0050] S3. Experimental setup specifically includes placing the electrochemical test device 6 in a constant temperature and humidity chamber 7 and setting the required temperature and humidity conditions to stabilize the experimental environment; the electrochemical test includes measuring the polarization curve and electrochemical impedance spectrum of the copper contact.

[0051] S4. Data analysis: Process the experimental data and fit the polarization curve and electrochemical impedance spectrum to calculate the corrosion potential, corrosion current, capacitive arc radius and low-frequency impedance mode. The details are as follows:

[0052] 4.1) The anode and cathode Tafel polarization curves are obtained by fitting the Tafel polarization curves, and the corrosion potential and corrosion current are calculated based on the anode and cathode Tafel polarization curves to evaluate the corrosion tendency and corrosion rate of the copper contacts after different surface treatments.

[0053] In the polarization curve, the Tafel region can be identified in the linear part of the anode and cathode (usually at higher potential offsets). Based on the potential-current density curve, find the potential value E corresponding to the minimum current density. 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 was fitted using the least square method combined with the following formula.

[0054] η=a+blgi

[0055] Where η is the overpotential (η=EE corr ), i is the current density, a and b are the intercept and slope of the Tafel curve respectively. Linear fit is performed on the data of the anode and cathode Tafel regions. The Tafel slope b can be obtained by linear fitting. a (anode) and b c (cathode), and the corresponding intercept a a and a c .

[0056] The corrosion current density I is calculated based on the fitted Tafel straight lines of the anode and cathode. corr . Corrosion potential E corris the intersection point of the anodic and cathodic Tafel curves:

[0057]

[0058] 4.2) The real part, imaginary part and modulus of the impedance of the circuit at different frequencies were measured. The capacitive arc radius and low-frequency impedance modulus of the electrochemical system equivalent circuit were obtained based on the electrochemical impedance spectrum. The corrosion resistance of the copper contacts after different surface treatments was evaluated.

[0059] Electrochemical impedance spectroscopy is a method used to study electrochemical systems and is widely used to evaluate the corrosion resistance of materials. The electrochemical system can be equivalent to a circuit containing the basic components of R, C, and Z, where R represents the solution resistance from the nozzle of the reference electrode to the electrode being measured, C represents the capacitance of the double layer on the electrode surface, and Z represents the impedance of the Faraday current flowing between the two phases of the electrode system when the electrode surface area is unit value. Based on the AC signal response in the electrochemical process, the real part, imaginary part, and modulus of the impedance of the circuit at different frequencies are measured to provide information about the reactions occurring on the electrode surface and in the electrolyte.

[0060] Specifically, the real and imaginary parts of the composite impedance can be plotted as a Nyquist diagram, where the real part is on the horizontal axis and the imaginary part is on the vertical axis. The Nyquist diagram provides information about the electrochemical process, such as reaction rate, charge transfer, etc.; the frequency and the modulus and phase difference of the composite impedance can also be plotted in logarithmic form as a Bode diagram, which provides an intuitive graphical tool for studying the frequency response, kinetic characteristics and impedance changes of the electrochemical system. In the electrochemical impedance spectroscopy measurement of solid electrodes, it is found that the curve often appears as a circular arc, so it is called a capacitive reactance arc. Generally speaking, the larger the capacitive reactance arc radius or the larger the impedance modulus, the better its corrosion resistance and the lower its sensitivity to corrosion. Therefore, the capacitive reactance arc radius and the impedance modulus at low frequency of the equivalent circuit of the electrochemical system can be obtained according to the electrochemical impedance spectrum, and the corrosion resistance of copper contacts after different surface treatments can be evaluated.

[0061] S5. Result evaluation is based on the experimental results of different surface treatment technologies, comparing various electrochemical parameters and evaluating the impact of each surface treatment technology on the corrosion resistance of copper contacts.

[0062] The experimental results are shown in Tables 1 and 2. Different silver plating thicknesses have a significant effect on the corrosion resistance of copper contacts. As the thickness of the silver plating layer gradually increases, a decrease in corrosion current and an increase in corrosion potential can be observed. This phenomenon is attributed to the fact that the thickening of the silver plating layer improves the electrochemical stability and reduces the contact between the working electrode surface and the environment, thereby enhancing its corrosion resistance. Too thick a silver plating layer may produce cracks and holes, especially at the junction of the silver plating layer and the copper substrate. These defects may provide a penetration path for the corrosive medium, making the substrate more susceptible to corrosion, increasing the probability of corrosion reaction, and expanding the affected surface area. In addition, too thick a silver plating layer may also lead to a decrease in the uniformity of the working electrode surface, causing fluctuations in local current density, which may make specific areas more prone to local corrosion, ultimately leading to an increase in the overall corrosion current. The results of electrochemical impedance spectroscopy show that as the thickness of the coating increases, the capacitive arc radius has an inflection point at 16μm, and generally shows a trend of decreasing first and then increasing. The larger the capacitive arc radius and the larger the impedance mode at low frequency, the smaller the corrosion tendency. Through this simulation experimental system, the corrosion of copper contacts under different surface treatment methods can be effectively evaluated.

[0063] Table 1 Polarization curve fitting data of samples with different silver coating thickness

[0064]

[0065] Table 2 Electrochemical impedance spectroscopy fitting data of samples with different silver coating thickness

[0066]

[0067] 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 corrosion simulation experimental system for surface treated metal contacts, characterized in that: The system comprises: A constant temperature and humidity chamber (7), used to control the temperature and humidity in the experimental environment; An electrochemical testing device (6) is arranged in a temperature and humidity controlled experimental environment, and comprises an auxiliary electrode (3) with one end exposed in a constant temperature and humidity chamber (7) and the other end immersed in a corrosive liquid, a reference electrode (4) and a working electrode (5), wherein the electrochemical testing device (6) uses metal contact samples with different surface treatments as the working electrode (5); the reference electrode (4) is used to provide a stable reference potential, and a voltmeter (2) is arranged between the reference electrode (4) and the working electrode (5); an ammeter (1) is arranged between the auxiliary electrode (3) and the working electrode (5) to form a current loop; The computer (8) is connected to the signals of the ammeter (1) and the voltmeter (2) of the electrochemical testing device (6) and is used to process the electrochemical test data, fit the polarization curve and the electrochemical impedance spectrum data, calculate and compare the key electrochemical parameters to evaluate the influence of different surface treatment technologies on the corrosion resistance of the copper contact.

2. The corrosion simulation experimental system for surface treated metal contacts according to claim 1, characterized in that: The reference electrode (4) is a saturated calomel electrode, and the auxiliary electrode (3) is a platinum sheet.

3. The corrosion simulation experimental system for surface treated metal contacts according to claim 1, characterized in that: The corrosive liquid includes an alkaline corrosive liquid or an acidic corrosive liquid.

4. The corrosion simulation experimental system for surface treated metal contacts according to claim 3, characterized in that: The alkaline etching solution is a mixture of NaOH and NaHCO3.

5. The corrosion simulation experimental system for surface treated metal contacts according to claim 3, characterized in that: The acidic corrosive liquid is a mixture of H2SO4 and H2SO3.

6. The corrosion simulation experimental system for surface treated metal contacts according to claim 1, characterized in that: The constant temperature and humidity chamber (7) is provided with a plurality of experimental windows, and the plurality of experimental windows are used to place metal contact samples with different surface treatments.

7. The corrosion simulation experimental system for surface treated metal contacts according to claim 1, characterized in that: The constant temperature and humidity chamber (7) is equipped with multiple temperature and humidity sensors for real-time monitoring and adjustment of the environmental parameters in the chamber.

8. A corrosion simulation experimental method for surface treated metal contacts, characterized in that: The method adopts the corrosion simulation experiment system as described in any one of claims 1 to 7, and the steps include: Prepare an ammeter (1), a voltmeter (2), an auxiliary electrode (3), a reference electrode (4) and a working electrode (5), set the zero value and initialize; The metal contact samples with different surface treatments are mounted at the working electrode (5) position of the electrochemical testing device (6), and the type and concentration of the corrosion solution are set; Placing the electrochemical test device (6) in a constant temperature and humidity chamber (7) and setting the required temperature and humidity conditions to stabilize the experimental environment, and measuring the polarization curve and electrochemical impedance spectrum of the metal contact; Analyze and process the experimental data, fit the polarization curve and electrochemical impedance spectrum, and calculate the electrochemical parameters, including corrosion potential, corrosion current, capacitive arc radius and low-frequency impedance mode; According to the experimental results of metal contact samples with different surface treatments, various electrochemical parameters were compared and the effects of various surface treatment technologies on the corrosion resistance of metal contacts were evaluated.

9. A corrosion simulation test method for a surface treated metal contact according to claim 8, characterized in that: The calculation process of corrosion potential and corrosion current is as follows: The anodic and cathodic Tafel polarization curves were obtained by fitting the Tafel polarization curves, and the corrosion potential and corrosion current were calculated based on the anodic and cathodic Tafel polarization curves to evaluate the corrosion tendency and corrosion rate of the copper contacts after different surface treatments.

10. The corrosion simulation test method for surface treated metal contacts according to claim 8, characterized in that: The calculation process of the capacitive reactance arc radius and the low-frequency impedance modulus is as follows: Based on the AC signal response in the electrochemical process, the real part, imaginary part and modulus of the impedance of the electrochemical system equivalent circuit at different frequencies are determined; The real and imaginary parts of the composite impedance are plotted as a Nyquist diagram, where the real part is on the horizontal axis and the imaginary part is on the vertical axis, to obtain information about the electrochemical process, including reaction rate and charge transfer; The frequency, the modulus value and the phase difference of the composite impedance are plotted in logarithmic form into Bode diagrams; The capacitive arc radius and low-frequency impedance modulus of the electrochemical system equivalent circuit were obtained based on the electrochemical impedance spectroscopy, and the corrosion resistance of the copper contacts after different surface treatments was evaluated.

Images