Corrosion resistance detection method, apparatus, and system

Abstract

This application discloses a corrosion resistance testing method, equipment, and system, belonging to the field of corrosion testing technology. In this application, firstly, the polarization curve of the electrode under test is differentiated to obtain a differential curve. Then, a linear interval is determined based on the polarization curve and the differential curve. Finally, the curve data of at least one of the polarization curve and the differential curve within the linear interval are analyzed to obtain the corrosion resistance test result of the electrode under test. Therefore, in this application, the linear interval is determined by combining the common characteristics of the polarization curve and the differential curve. Compared to directly finding the linear interval on the polarization curve, the addition of the constraint of the differential curve allows for faster and more accurate location of the linear interval, thereby improving the accuracy of the obtained linear interval and ultimately improving the corrosion resistance test result of the electrode under test.

Description

Technical Field

[0001] This application relates to the field of corrosion testing technology, specifically to a corrosion resistance testing method, equipment, and system. Background Technology

[0002] In electrochemical corrosion, the Tafel extrapolation method, based on the linear relationship between electrode potential and electrode current density in the strongly polarized region, is a key technique for evaluating the corrosion rate of metal electrodes. The core of the Tafel extrapolation method is to first identify the Tafel linear interval on the polarization curve, and then fit the slope of the polarization curve within this linear interval to determine corrosion parameters such as corrosion current density and corrosion potential of the metal electrode. However, finding the linear interval on the polarization curve is difficult; improper definition of the linear interval can lead to inaccurate corrosion parameters. Summary of the Invention

[0003] The main objective of this application is to provide a corrosion resistance testing method, equipment, and system, which aims to at least partially solve the aforementioned technical problems.

[0004] To achieve the above objectives, firstly, a corrosion resistance testing method is provided, comprising the following steps: The polarization curve of the electrode under test is differentiated to obtain a differential curve. The polarization curve represents the relationship between electrode potential and current density, while the differential curve represents the relationship between the differential of electrode potential and current density. The linear interval is determined based on the polarization curve and the differential curve; The corrosion resistance test results of the electrode under test are obtained by analyzing the curve data of at least one of the polarization curve and differential curve in the linear interval.

[0005] In some embodiments, determining the linear interval based on the polarization curve and the differential curve includes: The preset potential range is determined based on the maximum point of the differential curve and the branching properties of the polarization curve; When both the polarization curve and the differential curve are linear within the preset potential range, the first potential interval corresponding to the preset potential range is taken as the linear interval. When either the polarization curve or the differential curve is not linear within the preset potential range, the preset potential range is adjusted to obtain the optimized potential range until both the polarization curve and the differential curve are linear within the optimized potential range. Then, the second potential interval corresponding to the optimized potential range is taken as the linear interval.

[0006] In some embodiments, the method further includes: Within a preset potential range, the polarization curve is linearly fitted to obtain the first degree of linear fit. Within a preset potential range, the differential curve is linearly fitted to obtain a second degree of linear fit. When the first linear fit is greater than the preset fit, the polarization curve is determined to be linear within the preset potential range; When the second linear fit is greater than the preset fit, the differential curve within the preset potential range is determined to be linear.

[0007] In some embodiments, the curve data of at least one of the polarization curve and the differential curve in the linear interval are analyzed to obtain the corrosion resistance test results of the electrode under test, including: By analyzing the differential data of the differential curve within the linear interval, the Tafel slope of the polarization curve can be obtained. The corrosion resistance test results of the electrode under test are obtained based on the Tafel slope.

[0008] In some embodiments, analyzing the differential data of the differential curve within the linear interval to obtain the Tafel slope of the polarization curve includes: Obtain a preset slope range, wherein the preset slope range includes multiple preset slopes; For each preset slope, the differential error is obtained based on the preset slope, the differential current density data of the differential curve in the linear interval, and the current density data of the polarization curve in the linear interval. The target slope that satisfies the condition of minimizing the differential error is determined from multiple preset slopes and is taken as the Tafel slope.

[0009] In some embodiments, analyzing the differential data of the differential curve within the linear interval to obtain the Tafel slope of the polarization curve includes: Within the linear interval, the differential curve is traversed using a preset potential window to fit the first differential slope and the third linear fit degree within the preset potential window, thereby obtaining multiple first differential slopes and corresponding multiple third linear fit degrees within the linear interval. From a plurality of first differential slopes, determine at least one second differential slope whose corresponding third linear fit is greater than or equal to a preset fit threshold; Adjust the window width of the preset potential window and the preset fit threshold, and re-obtain at least one second differential slope based on the adjusted preset potential window and preset fit threshold until the window width is the extreme value of the preset window range and the preset fit threshold is the extreme value of the preset fit range. Divide the multiple second differential slopes into multiple differential slope ranges; Based on the number of preset potential windows corresponding to the second differential slope contained within the differential slope range, the target differential slope range with the largest number of windows is determined among multiple differential slope ranges. From multiple second differential slopes within the target differential slope range, the target differential slope with the largest third linear fit is determined as the Tafel slope.

[0010] In some embodiments, the differential curve includes a multi-order differential curve; Based on the Tafel slope, the corrosion resistance test results of the electrode under test are obtained, including: The corrosion resistance test results are obtained by averaging the Tafel slopes of the multi-order differential curves.

[0011] In some embodiments, the curve data of at least one of the polarization curve and the differential curve in the linear interval are analyzed to obtain the corrosion resistance test results of the electrode under test, including: Analyze the curve data of at least one of the polarization curve and differential curve in the linear interval to obtain the anodic Tafel slope and the cathode Tafel slope of the polarization curve. The corrosion potential and corrosion current are obtained based on the anodic Tafel slope, the cathode Tafel slope, and the Tafel fitted line equation. The polarization resistance is obtained based on the anode Tafel slope, the cathode Tafel slope, and the corrosion current. The corrosion rate is obtained based on the corrosion current, Faraday constant, molar mass of the electrode under test, number of electrons gained or lost during corrosion, and metal density. The corrosion resistance test results are obtained based on at least one of corrosion potential, corrosion current, polarization resistance, and corrosion rate.

[0012] Secondly, a corrosion resistance testing device is also provided, including a memory and a processor, wherein a computer program is stored in the memory, and the computer program is executed by the processor to implement any of the methods described above.

[0013] Thirdly, a corrosion resistance testing system is also provided, comprising: The testing device is used to perform corrosion tests on the electrode under test and obtain corrosion test data. The corrosion resistance testing equipment mentioned above is connected to the testing device and is used to obtain corrosion resistance test results based on corrosion test data.

[0014] In summary, this application first differentiates the polarization curve of the electrode under test to obtain a differential curve. Then, it determines the linear interval based on the polarization curve and the differential curve. Finally, it analyzes the curve data of at least one of the polarization curve and the differential curve within the linear interval to obtain the corrosion resistance test result of the electrode under test. Therefore, in this application, the linear interval is determined by combining the common characteristics of the polarization curve and the differential curve. Compared to directly finding the linear interval on the polarization curve, the addition of the constraint of the differential curve allows for faster and more accurate location of the linear interval, thereby improving the accuracy of the obtained linear interval and improving the corrosion resistance test result of the electrode under test.

[0015] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of the corrosion resistance testing method provided in an exemplary embodiment of this application; Figure 2 This is a schematic diagram of the polarization curve and differential curve provided in an exemplary embodiment of this application; Figure 3 This is another schematic flowchart of the corrosion resistance testing method provided by an exemplary embodiment of this application; Figure 4 This is a schematic diagram of the corrosion resistance testing equipment provided in an exemplary embodiment of this application.

[0018] The realization of the objectives, functional features and advantages of the embodiments of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] "A and / or B" includes the following three combinations: A only, B only, and a combination of A and B.

[0022] The use of "applies to" or "configured to" in this application implies open and inclusive language, which does not exclude the applicability to or configuration to devices performing additional tasks or steps. Additionally, the use of "based on" implies openness and inclusivity, because processes, steps, calculations, or other actions "based on" one or more of the stated conditions or values ​​may in practice be based on additional conditions or values ​​beyond those stated.

[0023] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any embodiment described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0024] First, the background technology involved in corrosion resistance testing methods, equipment and systems will be further introduced.

[0025] Electrical contacts are core components in electrical switching equipment, enabling circuit switching and power transmission. The stability of their contact surfaces directly determines the electrical performance, operational safety, and service life of the switching equipment. Traditional electrical contact materials (such as silver / copper and their alloys) are prone to electrochemical and chemical corrosion in harsh industrial or marine environments with high humidity, high salinity, and sulfide content. This leads to irreversible increases in contact resistance and accelerated temperature rise, ultimately causing electrical switching equipment failure. Therefore, accurate and reliable corrosion rate assessment of electrical contact materials or new high-performance materials is a crucial step in the research, development, quality control, and life prediction of electrical contact materials. Graphene, as a two-dimensional material with a single atomic layer thickness, is widely used as a reinforcing phase or protective coating for electrical contacts due to its exceptional conductivity, mechanical strength, and excellent barrier properties. Introducing graphene into a metal matrix (such as preparing graphene / silver composites) or constructing a graphene-based coating on its surface aims to utilize its dense physical barrier effect to delay the penetration and diffusion of corrosive media, thereby significantly improving the corrosion resistance of electrical contacts. However, the introduction of graphene also complicates the corrosion behavior of electrical contact materials. Defects in graphene itself (such as vacancies and grain boundaries), the interfacial bonding state with the metal matrix, and structural evolution under high electric fields or electric arcs can all become the initiation point of corrosion or affect the corrosion process. Therefore, developing methods to accurately quantify the corrosion rate of graphene electrical contacts is crucial for revealing their protective mechanism and optimizing material systems.

[0026] Among related technologies, the Tafel extrapolation method, based on the linear relationship between electrode potential and electrode current density in the strongly polarized region, is a key technique for evaluating the corrosion rate of metal electrodes. The core of the Tafel extrapolation method is to first identify the Tafel linear interval on the polarization curve, and then calculate the slope of this linear interval to determine corrosion parameters such as corrosion current density and corrosion potential of the metal electrode. However, finding the linear interval on the polarization curve is very difficult, and improper definition of the linear interval can lead to inaccurate corrosion parameters.

[0027] Therefore, this application provides a corrosion resistance testing method, device, and system. First, the polarization curve of the electrode under test is differentiated to obtain a differential curve. Then, a linear interval is determined based on the polarization curve and the differential curve. Finally, the curve data of at least one of the polarization curve and the differential curve within the linear interval are analyzed to obtain the corrosion resistance test result of the electrode under test. Thus, in this application, the linear interval is determined by combining the common characteristics of the polarization curve and the differential curve. Compared to directly finding the linear interval on the polarization curve, the addition of the constraint of the differential curve allows for faster and more accurate location of the linear interval, thereby improving the accuracy of the obtained linear interval and improving the corrosion resistance test result of the electrode under test.

[0028] In addition, this application also analyzes and processes the differential data on the differential curve within the linear interval to obtain the Tafel slope of the polarization curve in a non-fitting manner, without the need for linear fitting of the polarization curve, thus simplifying the algorithm for obtaining the Tafel slope and improving the efficiency of corrosion resistance detection.

[0029] Secondly, the application scenarios of the corrosion resistance testing method provided in this application are introduced.

[0030] This embodiment provides a corrosion resistance testing system, which may include a testing device and a corrosion resistance testing equipment according to any of the embodiments below. The testing device is used to perform corrosion testing on the electrode under test and obtain corrosion test data. The corrosion resistance testing equipment is connected to the testing device and is used to obtain corrosion resistance testing results based on the corrosion test data.

[0031] In this embodiment, the testing device can perform corrosion tests on the graphene contact in a 3.5% NaCl corrosion solution, using a graphene contact as the test electrode, a saturated calomel electrode as the reference electrode, and a platinum electrode as the auxiliary electrode, to obtain corrosion test data. The corrosion resistance testing equipment may include an electrochemical workstation used to plot polarization curves based on the electrode potential and electrode current in the corrosion test data at a scan rate of 0.5 mV / s, and to implement the corrosion resistance testing method of any of the embodiments described below based on the obtained polarization curves.

[0032] Based on this, firstly, this embodiment provides a corrosion resistance testing method, such as... Figure 1 As shown, the following steps may be included: S101: Differentiate the polarization curve of the electrode under test to obtain a differential curve. The polarization curve characterizes the relationship between electrode potential and current density. In this embodiment, the corrosion resistance testing method is performed by the aforementioned corrosion resistance testing equipment, and the electrode under test can be a graphene contact. The horizontal axis of the polarization curve represents the electrode potential E, and the vertical axis represents the current density J(E). The corrosion resistance testing equipment can differentiate the polarization curve using the central difference method or the forward and backward difference method to obtain a differential curve; that is, the differential curve characterizes the difference between the electrode potential and the current density d. NThe correspondence between J(E) / dE is defined. The differential curve can include one or more curves. When there is only one differential curve, it can be any order of differential curve of the polarization curve; for example, it can be a first-order or second-order differential curve of the polarization curve. When there are multiple differential curves, they can include multiple orders of differential curves of the polarization curve; for example, they can include first-order and second-order differential curves of the polarization curve. It is understood that the first-order differential curve is obtained by differentiating the polarization curve, the second-order differential curve is obtained by differentiating the first-order differential curve, and so on, up to the Nth-order differential curve of the polarization curve.

[0033] S102: Determine the linear interval based on the polarization curve and the differential curve. In this embodiment, the linear interval is the potential interval [Emin, Emax] where both the polarization curve and the differential curve are linear. Emin is the minimum electrode potential value of the linear interval, and Emax is the maximum electrode potential value of the linear interval. It should be noted that the polarization curve may include an anodic branch and a cathode branch, and the Tafel curve is derived from the following Butler curve. Volmer equation: ; Where j is the net current density, j0 is the exchange current density, and α a α is the anode transfer coefficient. c Let be the cathode transfer coefficient, F be the Faraday constant, R be the gas constant, T be the thermodynamic temperature, and η be the overpotential. Therefore, for the anode branch, the overpotential η... a have: ; As can be seen, the Tafel slope = 2.303RT / αF, determined by the apparent mass transfer coefficient, ensures that both the polarization curve and its Nth-order differential curve remain linear within the linear interval. Therefore, the potential interval [Emin, Emax] where both the polarization curve and differential curve are linear can be considered the linear interval. It can be understood that the linear interval can include the potential interval [Emin1, Emax1] corresponding to the anode branch and the potential interval [Emin2, Emax2] corresponding to the cathode branch.

[0034] Specifically, the above overpotential η can be... a The formula is transformed into overpotential η a As the independent variable, with net current density j a The formula for net current density as the dependent variable is: ; Among them, net current density j a The slope on the semi-logarithmic graph is α.a F / RT, i.e., net current density j a It will appear linear on a semi-log plot.

[0035] In addition, net current density j a The first derivative is: ; Net current density j a The slope of the first derivative on the semi-logarithmic graph is still α. a F / RT, i.e., net current density j a The first derivative of is linear on a semi-logarithmic graph.

[0036] Net current density j a The second derivative is: ; ; Net current density j a The slope of the second derivative on the semi-logarithmic graph is still α. a F / RT, net current density j a The second derivative will be linear on a semi-logarithmic graph.

[0037] In summary, according to e x The properties of the function are evident, and the net current density j a The slope of the Nth derivative on the semi-logarithmic plot remains α. a F / RT, i.e., net current density j a The Nth derivative of is linear on the semi-logarithmic plot.

[0038] S103: Analyze the curve data of at least one of the polarization curve and differential curve within the linear interval to obtain the corrosion resistance test result of the electrode under test. In this embodiment, linear fitting of the polarization curve and / or differential curve within the linear interval can obtain the anodic taffervescent slope of the anodic branch and the cathodic taffervescent slope of the cathode branch, respectively; then, Tafel extrapolation based on the anodic taffervescent slope and the cathodic taffervescent slope can obtain the corrosion potential E of the electrode under test. corr and corrosion current density i corr And the polarization resistance R is calculated. p Corrosion parameters are obtained; finally, based on the corrosion parameters of the electrode under test, the corrosion resistance test results of the electrode under test can be obtained.

[0039] Therefore, in this embodiment, the linear interval is determined by combining the common characteristics of the polarization curve and the differential curve. Compared with the linear interval obtained directly from the polarization curve, the constraint of the differential curve can locate the linear interval more quickly and accurately, thereby improving the accuracy of the obtained linear interval and improving the corrosion resistance test results of the electrode under test.

[0040] Next, we will describe in detail some specific implementation methods that may be used to divide linear intervals.

[0041] In some embodiments, in step S102, a preset potential range can be determined first based on the maximum point of the differential curve and the branching properties of the polarization curve. Then, when both the polarization curve and the differential curve are linear within the preset potential range, the first potential interval corresponding to the preset potential range is taken as the linear interval. Alternatively, when either the polarization curve or the differential curve is not linear within the preset potential range, the preset potential range is adjusted to obtain an optimized potential range until both the polarization curve and the differential curve are linear within the optimized potential range, at which point the second potential interval corresponding to the optimized potential range is taken as the linear interval.

[0042] In this embodiment, when there are multiple differential curves, the maximum point is the maximum point of the differential curve with the highest order. Branching attributes can include anodic and cathodic branches. A preset potential range can be pre-set; the electrode potential value corresponding to the maximum point is the first extreme value of the preset potential range, and the second extreme value of the preset potential range is determined based on the branching attributes and the size of the potential interval within the preset potential range. In specific implementations, such as... Figure 2 As shown, the blue curve L1 is the polarization curve, the orange curve L2 is the first-order differential curve, and the gray curve L3 is the second-order differential curve. For the cathode branch, when determining the linear interval, firstly, in the coordinate system of the polarization curve and the differential curve, the electrode potential value corresponding to the maximum point is taken as the maximum value of the preset potential range. Then, based on the preset potential range, the minimum value of the preset potential range is determined on the side where the potential decreases from the maximum point. Next, it is determined whether the polarization curve and the differential curve are linear within the preset potential range. If both the polarization curve and the differential curve are linear within the preset potential range, the first potential interval corresponding to the maximum and minimum values ​​of the preset potential range is taken as the linear interval. If either the polarization curve or the differential curve is not linear within the preset potential range, the preset potential range is reduced, and the electrode potential value corresponding to the maximum point is taken as the maximum value of the optimized potential range. Based on the adjusted potential interval size, the minimum value of the optimized potential range is determined on the side where the potential decreases from the maximum point. The linearity of the polarization curve and the differential curve within the optimized potential range is then re-evaluated. This process continues until both the polarization curve and the differential curve are linear within the optimized potential range. Finally, the second potential interval corresponding to the maximum and minimum values ​​of the optimized potential range is taken as the linear interval.

[0043] Similarly, for the anode branch, when determining the linear interval, firstly, in the coordinate system of the polarization curve and the differential curve, the electrode potential value corresponding to the maximum point is taken as the minimum value of the preset potential range, and the maximum value of the preset potential range is determined on the side where the potential increases from the maximum point, based on the preset potential range. Then, it is determined whether the polarization curve and the differential curve are linear within the preset potential range. If both the polarization curve and the differential curve are linear within the preset potential range, the first potential interval corresponding to the maximum and minimum values ​​of the preset potential range is taken as the linear interval. If either the polarization curve or the differential curve is not linear within the preset potential range, the preset potential range is reduced, the electrode potential value corresponding to the maximum point is taken as the minimum value of the optimized potential range, and the maximum value of the optimized potential range is determined on the side where the potential increases from the maximum point, based on the adjusted potential interval size. The linearity of the polarization curve and the differential curve within the optimized potential range is then re-evaluated. This process continues until both the polarization curve and the differential curve are linear within the optimized potential range, at which point the second potential interval corresponding to the maximum and minimum values ​​of the optimized potential range is taken as the linear interval.

[0044] In some specific embodiments, the corrosion resistance testing method may further perform linear fitting on the polarization curve within a preset potential range to obtain a first linear fit degree, and then perform linear fitting on the differential curve within the preset potential range to obtain a second linear fit degree. Then, when the first linear fit degree is greater than the preset fit degree, the polarization curve within the preset potential range is determined to be linear; when the second linear fit degree is greater than the preset fit degree, the differential curve within the preset potential range is determined to be linear.

[0045] In this embodiment, linear fitting can be performed on the polarization curve and the differential curve within a preset potential range to obtain their respective linear fitting degrees, and to determine whether the polarization curve and the differential curve are linear within the preset potential range. Specifically, when the first linear fitting degree is greater than the preset fitting degree, the polarization curve within the preset potential range is determined to be linear; when the first linear fitting degree is less than or equal to the preset fitting degree, the polarization curve within the preset potential range is determined to be non-linear. Similarly, when the second linear fitting degree is greater than the preset fitting degree, the differential curve within the preset potential range is determined to be linear; when the second linear fitting degree is less than or equal to the preset fitting degree, the differential curve within the preset potential range is determined to be non-linear. Likewise, linear fitting can be performed on the polarization curve and the differential curve within an optimized potential range to obtain their respective linear fitting degrees, and to determine whether the polarization curve and the differential curve are linear within the optimized potential range.

[0046] Next, we will describe in detail some specific implementation methods that may be used to obtain the corrosion resistance test results of the electrode under test.

[0047] In some of these embodiments, such as Figure 3As shown, step S103 may include A1031 to A1035. A1031: Analyze the curve data of at least one of the polarization curve and differential curve in the linear interval to obtain the anodic and cathodic Tafel slopes of the polarization curve. A1032: Obtain the corrosion potential and corrosion current based on the anodic and cathodic Tafel slopes and the Tafel fitted line equation. A1033: Obtain the polarization resistance based on the anodic and cathodic Tafel slopes and the corrosion current. A1034: Obtain the corrosion rate based on the corrosion current, Faraday constant, molar mass of the electrode under test, the number of electrons gained or lost during corrosion, and metal density. A1035: Obtain the corrosion resistance test result based on at least one of the corrosion potential, corrosion current, polarization resistance, and corrosion rate.

[0048] In this embodiment, the anode Tafel slope β can be obtained by linearly fitting the polarization curve or the differential curve within the linear interval corresponding to the anode branch. a By linearly fitting the polarization curve within the linear interval corresponding to the cathode branch, or by linearly fitting the differential curve, the cathode Tafel slope β can be obtained. c Then, the corrosion potential E can be obtained by Tafel extrapolation. corr and corrosion current i corr Then, based on the following formulas for calculating polarization resistance and corrosion rate, the polarization resistance R can be obtained respectively. p And the corrosion rate Vcorr. The formula for calculating polarization resistance is: ; The formula for calculating the corrosion rate is: Vcorr = i corr ×M / (n×F×D); where M is the molar mass of the electrode under test, n is the number of electrons gained or lost (electron transfer) during corrosion of the electrode under test, D is the density of the electrode under test, and F is the Faraday constant. Finally, since a more positive corrosion potential indicates better corrosion resistance, a lower corrosion current density indicates a slower corrosion rate, a higher polarization resistance indicates better corrosion resistance, and a lower corrosion rate indicates better corrosion resistance, the corrosion resistance test results of the electrode under test can be obtained by analyzing at least one of the corrosion potential, corrosion current, polarization resistance, and corrosion rate.

[0049] In some embodiments, in step S103, the differential data of the differential curve within the linear interval can be analyzed to obtain the Tafel slope of the polarization curve. Then, based on the Tafel slope, the corrosion resistance test result of the electrode under test is obtained.

[0050] In some embodiments, the Tafel slope of the polarization curve can be obtained in a non-fitting manner by analyzing the variation of the differential data of the differential curve in the linear interval, so as to perform corrosion resistance testing on the electrode under test, simplifying the algorithm for obtaining the Tafel slope and improving the efficiency of corrosion resistance testing.

[0051] In some embodiments, when obtaining the Tafel slope of the polarization curve, a preset slope range can be obtained first. Then, for each preset slope, a differential error is obtained based on the preset slope, the differential current density data of the differential curve within the linear interval, and the current density data of the polarization curve within the linear interval. Finally, a target slope that satisfies the condition of minimizing the differential error is determined from multiple preset slopes and is taken as the Tafel slope. Wherein, differential error = J N (E)-(ln(10) / T f ) N J(E), J N (E) represents the differential current density data of the Nth-order differential curve within the linear interval, J(E) represents the current density data of the polarization curve within the linear interval, N is the order of the differential curve, and T is the current density of the polarization curve within the linear interval. f To preset the slope, ideally N=2. In specific implementations, this can be achieved by using min|J N (E)-(ln(10) / T f ) N J(E)| represents the constraint condition for the differential error, and the target slope that satisfies the condition of minimizing the differential error is determined. It should be noted that for the differential current density data and current density data corresponding to every two adjacent polarization potentials within the linear interval, a differential error can be calculated. Therefore, multiple differential errors can be calculated for each preset slope.

[0052] In some embodiments, after obtaining the Tafel slope of the polarization curve, the corrosion resistance test result can also be obtained based on the average value of the Tafel slope of the multi-order differential curve.

[0053] In this embodiment, when there are multiple differential curves, the Tafel slope of each differential curve can be obtained first, and the average of the Tafel slopes of multiple differential curves can be calculated to obtain the Tafel slope of the polarization curve. Therefore, obtaining the Tafel slope by averaging the slopes of multiple differential curves improves the accuracy of the Tafel slope compared to obtaining it from the slope of only one differential curve.

[0054] In other embodiments, when obtaining the Tafel slope of the polarization curve, the differential curve can first be traversed within the linear interval using a preset potential window to fit and obtain a first differential slope and a third linear fit within the preset potential window, thus obtaining multiple first differential slopes and corresponding multiple third linear fits within the linear interval. Then, from the multiple first differential slopes, at least one second differential slope whose corresponding third linear fit is greater than or equal to a preset fit threshold is determined. Next, the window width of the preset potential window and the preset fit threshold are adjusted, and at least one second differential slope is obtained again based on the adjusted preset potential window and preset fit threshold, until the window width is the extreme value of the preset window range and the preset fit threshold is the extreme value of the preset fit range. Then, the multiple second differential slopes are divided into multiple differential slope ranges. Finally, based on the number of preset potential windows corresponding to the second differential slopes contained within the differential slope range, a target differential slope range with the largest number of windows is determined from the multiple differential slope ranges. Finally, from the multiple second differential slopes within the target differential slope range, the target differential slope with the largest third linear fit is determined as the Tafel slope.

[0055] In this embodiment, the preset window range may include multiple preset potential windows, and the preset window range can be determined according to the potential window size corresponding to the linear interval. The preset fit range may include multiple preset fit thresholds, and the preset fit range can be set according to accuracy requirements. During actual fitting, preset potential windows can be determined sequentially from the preset window range according to the window width from small to large, and a corresponding preset fit threshold can be determined from the preset fit range.

[0056] Additionally, for Butler The Volmer equation can be expanded using Taylor to obtain the Butler equation. The Volmer equation is: ; Butler after Taylor expansion Differentiating the Volmer equation yields: ; Therefore, the formula for calculating the third linear fit is R1=||dJ(η) / dη-J0×nF / RT||.

[0057] In specific implementation, for the cathode branch, firstly, a preset potential window dη and a preset fitting degree threshold are determined. The differential current density data within the preset potential window are used for linear regression fitting η = a + b × log∣j∣ to obtain the first differential slope b, and the corresponding third linear fitting degree is calculated. This yields multiple first differential slopes and multiple third linear fitting degrees within the linear interval corresponding to the preset potential window. Simultaneously, multiple second differential slopes corresponding to the preset potential window are obtained by filtering according to the preset fitting degree threshold. Then, the window width of the preset potential window and the preset fitting degree threshold are adjusted to re-obtain multiple second differential slopes and multiple third linear fitting degrees corresponding to the adjusted preset potential window. This results in multiple preset potential windows within the preset window range, and multiple second differential slopes and multiple third linear fitting degrees corresponding to each preset potential window. Subsequently, the multiple second differential slopes are divided into multiple differential slope ranges, such that the second differential slope within each differential slope range corresponds to at least one preset potential window. Therefore, the target differential slope range can be determined based on the number of preset potential windows included in the differential slope range. Finally, the target differential slope with the largest third linear fit among multiple second slopes within the target differential slope range is the cathode Tafel slope. Similarly, the anode Tafel slope of the anode branch can also be obtained.

[0058] In one example, for ease of explanation, it is assumed that the linear interval of the first-order differential curve is [0, 250] mV, and the resolution of the first-order differential curve is 1 mV / point. Therefore, there are 251 current density data points on the first-order differential curve. The preset window range includes five preset potential windows: [20 mV, 40 mV, 60 mV, 80 mV, 100 mV], and the preset goodness-of-fit range is [0.98, 0.99]. In the first round, the preset potential window is set to 20 mV. Starting from an electrode potential of 0, data points [0 mV, 20 mV] are fitted to obtain the first differential slope b = 110 and the third linear goodness-of-fit = 0.985. It is then determined whether the third linear goodness-of-fit is greater than the preset goodness-of-fit threshold of 0.98. If the third linear goodness-of-fit is greater than or equal to 0.98, the second differential slope is recorded as 110, and the corresponding third linear goodness-of-fit is recorded as 0.985. Then, the preset potential window is slid, and [1mV, 21mV], [2mV, 22mV] are successively fitted until the maximum value of the preset potential window is the maximum value of the linear interval, obtaining multiple second differential slopes and corresponding third linear fits when the preset potential window is 20mV. In the second round, the preset potential window = 40mV is fitted, obtaining a first differential slope = 118 and a third linear fit = 0.992. It is then determined whether the third linear fit is greater than the preset fit threshold of 0.99. This process is repeated to obtain multiple second differential slopes and third linear fits when the preset potential window = 40mV, 60mV, and 80mV. Finally, the multiple second differential slopes are divided into multiple differential slope ranges. At this point, if the preset potential window = 40mV, and the second slope within the potential interval [0-10]mV is 118 within the first differential slope range; if the preset potential window = 60mV, and the second slope within the potential interval [5-15]mV is also 118 within the first differential slope range; if the preset potential window = 80mV, and the second slope within the potential interval [10-20]mV is also 118 within the first differential slope range; then the statistical result is that the number of preset potential windows corresponding to the second differential slope within the first differential slope range is 3. Similarly, if the preset potential windows corresponding to the second differential slope within the second differential range include preset potential windows = 20mV and preset potential windows = 40mV, then the statistical result is that the number of preset potential windows corresponding to the second differential slope within the second differential slope range is 2. And so on, the number of preset potential windows corresponding to the second differential slope within each differential slope range can be obtained.Next, the target differential slope range can be selected based on the number of windows for each differential slope range. The selection principle is that the range with the largest number of windows is the target differential slope range. In the above embodiment, since the first differential slope range corresponds to 3 windows and the second differential slope corresponds to 2 windows, and since 3 is greater than 2, the target differential slope range is the first differential slope range. Finally, if the target differential slope range (i.e., the first differential slope range) includes two second differential slopes with values ​​of 118.3 (corresponding to a third linear fit of 0.995) and 117.9 (corresponding to a third linear fit of 0.993), then based on the fact that a third linear fit of 0.995 is greater than a third linear fit of 0.993, the target differential slope is 118.3, which serves as the Tafel slope of the differential curve.

[0059] Therefore, this embodiment first selects multiple second differential slopes that have the widest applicability within the linear interval of the differential curve to the preset potential window range, thus avoiding the situation where the Tafel slope is a local optimum. Then, the target differential slope with the highest linear fit is selected from the multiple second differential slopes to obtain the Tafel slope. The second differential slope with the highest linear fit can be used as the Tafel slope, thereby improving the accuracy of the Tafel slope.

[0060] As shown in Table 1 below, Table 1 includes the corrosion parameters obtained by the corrosion resistance testing methods provided in various embodiments of this application. Item 1 represents the corrosion parameters obtained by directly dividing the polarization curve into linear intervals and performing Tafel extrapolation. Item 2 represents the corrosion parameters obtained by linear fitting after determining the linear interval using the linear interval division method of this application. Item 3 represents the corrosion parameters obtained by calculating the Tafel slope using the first non-fitting method after determining the linear interval using the linear interval division method of this application. Item 4 represents the corrosion parameters obtained by calculating the Tafel slope using the second non-fitting method after determining the linear interval using the linear interval division method of this application. It can be seen that compared to directly dividing the polarization curve into linear intervals and performing Tafel extrapolation, the corrosion resistance testing methods provided in the embodiments of this application have smaller errors and better stability.

[0061] Table 1

[0062] On the other hand, this embodiment provides a corrosion resistance testing device, including a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, it implements the method as described in any of the embodiments above. Figure 4As shown, the corrosion resistance testing device may include components such as a processor 401 with one or more processing cores, a memory 402 with one or more computer-readable storage media, a power supply 403, and an input unit 404. Those skilled in the art will understand that... Figure 4 The structure of the corrosion resistance testing equipment shown does not constitute a limitation on the equipment. It may include more or fewer components than shown, or combine certain components, or have different component arrangements. The processor 401 is the control center of the corrosion resistance testing equipment. It connects various parts of the equipment via various interfaces and lines, and performs various functions and processes data by running or executing software programs and / or modules stored in the memory 402, and by calling data stored in the memory 402, thereby providing overall monitoring of the corrosion resistance testing equipment. Optionally, the processor 401 may include one or more processing cores; preferably, the processor 401 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, user interface, and computer programs, and the modem processor mainly handles wireless communication. It is understood that the modem processor may not be integrated into the processor 401.

[0063] The memory 402 can be used to store software programs and modules. The processor 401 executes various functional applications and data processing by running the software programs and modules stored in the memory 402. The memory 402 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, computer programs required for at least one function (such as corrosion resistance detection function), etc.; the data storage area may store data created according to the use of the server, etc. In addition, the memory 402 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device. Accordingly, the memory 402 may also include a memory controller to provide the processor 401 with access to the memory 402.

[0064] The corrosion resistance testing equipment also includes a power supply 403 that supplies power to the various components. Preferably, the power supply 403 can be logically connected to the processor 401 through a power management system, thereby enabling functions such as charging, discharging, and power consumption management through the power management system. The power supply 403 may also include one or more DC or AC power supplies, recharging systems, power fault detection circuits, power converters or inverters, power status indicators, and other arbitrary components.

[0065] The corrosion resistance testing device may also include an input unit 404, which can be used to receive input digital or character information, and generate keyboard, mouse, joystick, optical or trackball signal inputs related to user settings and function control.

[0066] Although not shown, the corrosion resistance testing device may also include a display unit, etc., which will not be described in detail here. Specifically, in this embodiment, the processor 401 in the corrosion resistance testing device loads the executable files corresponding to the processes of one or more computer programs into the memory 402 according to the following instructions, and the processor 401 runs the computer programs stored in the memory 402 to execute the corrosion resistance testing method as described in any of the above embodiments.

[0067] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0068] The corrosion resistance testing method, equipment, and system provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for testing corrosion resistance, characterized in that, include: The polarization curve of the electrode under test is differentiated to obtain a differential curve, wherein the polarization curve characterizes the relationship between electrode potential and current density. The linear interval is determined based on the polarization curve and the differential curve; The corrosion resistance test results of the electrode under test are obtained by analyzing the curve data of at least one of the polarization curve and the differential curve in the linear interval.

2. The corrosion resistance testing method according to claim 1, characterized in that, Determining the linear interval based on the polarization curve and the differential curve includes: The preset potential range is determined based on the maximum point of the differential curve and the branching properties of the polarization curve; When both the polarization curve and the differential curve are linear within the preset potential range, the first potential interval corresponding to the preset potential range is taken as the linear interval. When either the polarization curve or the differential curve is not linear within the preset potential range, the preset potential range is adjusted to obtain an optimized potential range until both the polarization curve and the differential curve are linear within the optimized potential range. Then, the second potential interval corresponding to the optimized potential range is taken as the linear interval.

3. The corrosion resistance testing method according to claim 2, characterized in that, The method further includes: Within the preset potential range, the polarization curve is linearly fitted to obtain a first degree of linearity. Within the preset potential range, the differential curve is linearly fitted to obtain a second linear fit degree; When the first linear fit degree is greater than the preset fit degree, it is determined that the polarization curve is linear within the preset potential range; When the second linear fit is greater than the preset fit, the differential curve within the preset potential range is determined to be linear.

4. The corrosion resistance testing method according to claim 1, characterized in that, The step of analyzing the curve data of at least one of the polarization curve and the differential curve within the linear interval to obtain the corrosion resistance test result of the electrode under test includes: The Tafel slope of the polarization curve is obtained by analyzing the differential data of the differential curve within the linear interval. The corrosion resistance test result of the electrode under test is obtained based on the Tafel slope.

5. The corrosion resistance testing method according to claim 4, characterized in that, The step of analyzing the differential data of the differential curve within the linear interval to obtain the Tafel slope of the polarization curve includes: Obtain a preset slope range, wherein the preset slope range includes multiple preset slopes; For each preset slope, the differential error is obtained based on the preset slope, the differential current density data of the differential curve in the linear interval, and the current density data of the polarization curve in the linear interval; The target slope that satisfies the minimization condition of the differential error is determined from a plurality of preset slopes and is taken as the Tafel slope.

6. The corrosion resistance testing method according to claim 4, characterized in that, The step of analyzing the differential data of the differential curve within the linear interval to obtain the Tafel slope of the polarization curve includes: Within the linear interval, the differential curve is traversed using a preset potential window to fit and obtain the first differential slope and the third linear fit degree within the preset potential window, thereby obtaining multiple first differential slopes and corresponding multiple third linear fit degrees within the linear interval; From a plurality of first differential slopes, at least one second differential slope is determined such that the corresponding third linear fit is greater than or equal to a preset fit threshold; Adjust the window width of the preset potential window and the preset fit threshold, and re-obtain at least one second differential slope based on the adjusted preset potential window and the preset fit threshold, until the window width is the extreme value of the preset window range and the preset fit threshold is the extreme value of the preset fit range. Divide the multiple second differential slopes into multiple differential slope ranges; Based on the number of windows corresponding to the preset potential window included in the differential slope range, the target differential slope range with the largest number of windows is determined among the multiple differential slope ranges. From a plurality of second differential slopes within the target differential slope range, the target differential slope with the largest third linear fit is determined as the Tafel slope.

7. The corrosion resistance testing method according to claim 4, characterized in that, The differential curves include multi-order differential curves; The step of obtaining the corrosion resistance test result of the electrode under test based on the Tafel slope includes: The corrosion resistance test results are obtained based on the average value of the Tafel slopes of the multi-order differential curves.

8. The corrosion resistance testing method according to claim 1, characterized in that, The step of analyzing the curve data of at least one of the polarization curve and the differential curve within the linear interval to obtain the corrosion resistance test result of the electrode under test includes: Analyze the curve data of at least one of the polarization curve and the differential curve in the linear interval to obtain the anodic Tafel slope and the cathode Tafel slope of the polarization curve; The corrosion potential and corrosion current are obtained based on the anode Tafel slope, the cathode Tafel slope, and the Tafel fitted line equation. The polarization resistance is obtained based on the anode Tafel slope, the cathode Tafel slope, and the corrosion current. The corrosion rate is obtained based on the corrosion current, Faraday constant, molar mass of the electrode under test, number of electrons gained or lost during corrosion, and metal density. The corrosion resistance test result is obtained based on at least one of the corrosion potential, the corrosion current, the polarization resistance, and the corrosion rate.

9. A corrosion resistance testing device, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program that, when executed by the processor, implements the method as described in any one of claims 1-8.

10. A corrosion resistance testing system, characterized in that, include: The testing device is used to perform corrosion tests on the electrode under test and obtain corrosion test data. The corrosion resistance testing equipment as described in claim 9 is connected to the testing device and is used to obtain corrosion resistance testing results based on the corrosion test data.

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