Method and device for evaluating galvanic effect of multi-metal system based on critical dimension of galvanic couple

Abstract

The application discloses a kind of based on galvanic critical dimension of multi-metal system galvanic effect evaluation method and device, and it is related to electrochemical corrosion evaluation technical field.Multi-metal system galvanic effect evaluation method includes steps: obtaining the polarization curve and self-corrosion potential of each metal in multi-metal system, determine galvanic anode and galvanic cathode on each lap surface;Calculate the galvanic critical dimension of any two groups of metals in multi-metal system;Compare the size of actual interface distance and combined critical distance, determine the galvanic corrosion form of multi-metal system;If the galvanic of two lap surfaces has no mutual influence, then carry out independent galvanic analysis, if the galvanic of two lap surfaces exists potential competition, then carry out coupling analysis to the galvanic of two lap surfaces.The application fully considers the complex potential coupling, interface interference and mutual influence effect between multi-metals, and improves the accuracy, applicability and scientificity of multi-metal lap joint structure galvanic corrosion evaluation.

Description

Technical Field

[0001] This invention relates to the field of electrochemical corrosion assessment technology, and in particular to a method and apparatus for assessing the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode. Background Technology

[0002] When dissimilar metal materials are in contact with each other in the same electrolyte environment, the potential difference between them will drive electrons to flow from the material with the lower corrosion potential to the material with the higher corrosion potential due to the difference in corrosion potential. This will accelerate the corrosion of the anodic material by the galvanic corrosion. The degree of anodic corrosion is mainly affected by factors such as the potential difference between the metals, the conductivity of the electrolyte, and the ratio of the anode and cathode areas. Galvanic corrosion often occurs at the junctions of different metals, the bonding between the coating and the substrate, and is one of the common failure modes of metal components in engineering.

[0003] Galvanic corrosion of multi-metal systems (at least three metals) is more complex than conventional bimetallic galvanic corrosion, exhibiting multiple cathode and multiple anode characteristics. It also presents problems such as multi-potential competition and interaction of corrosion products. Traditional galvanic corrosion assessment methods are mostly limited to bimetallic galvanic systems. For trimetallic and above systems, they only use pairwise combinations for simplification, that is, decomposing the multi-metal system into a bimetallic system for coupled analysis. This method cannot accurately identify the anode and cathode components in the multi-metal system, ignores the potential synergy effect between the multiple metals, and has a large analytical error. Summary of the Invention

[0004] This invention provides a method and apparatus for evaluating the galvanic effect of multi-metal systems based on the critical size of the galvanic electrode, aiming to scientifically and accurately evaluate the galvanic corrosion of multi-metal systems.

[0005] The method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode provided by this invention includes the following steps: S1, obtain the polarization curve and self-corrosion potential of each metal in the multi-metal system, and determine the galvanic anode and galvanic cathode on each lap surface according to the actual lap structure and the level of self-corrosion potential. S2, Calculate the critical galvanic dimension of any two metal groups in the multi-metal system, where the critical galvanic dimension includes the anode critical distance and the cathode critical distance; S3. Compare the actual interface distance with the combined critical distance to determine the galvanic corrosion mode of the multi-metal system. The actual interface distance is the distance between two overlapping surfaces, and the combined critical distance is the sum of the critical dimensions of the galvanic electrodes between the two overlapping surfaces. The galvanic corrosion mode includes a first corrosion mode and a second corrosion mode. The first corrosion mode indicates that the galvanic electrodes of the two overlapping surfaces do not affect each other, and the second corrosion mode indicates that there is potential competition between the galvanic electrodes of the two overlapping surfaces. Wherein, if the actual overlap distance is greater than or equal to the combined critical distance, the galvanic couple of the two overlap surfaces is determined to be a first corrosion form; if the actual overlap distance is less than the combined critical distance, the galvanic couple of the two overlap surfaces is determined to be a second corrosion form. S4, For the first corrosion form, perform independent galvanic analysis on the galvanic couple of each lap surface, wherein the independent galvanic couple analysis includes obtaining galvanic corrosion current parameters based on polarization curves; For the second corrosion form, the overall galvanic potential of the multi-metal system is measured. Metal components with self-corrosion potential positive than the overall galvanic potential are identified as cathodes, and metal components with self-corrosion potential negative than the overall galvanic potential are identified as anodes. Coupled analysis is performed on the galvanic potentials of the two overlapping surfaces. The coupling analysis includes: dividing the current generated by galvanic corrosion into a first type of current that directly forms galvanic corrosion through the lap interface and a second type of current that does not form corrosion effects through the lap interface; for the first type of metal component located between two lap interfaces, the current on the first type of metal component is calculated as the net current of the first type of current; for the second type of metal component not located between two lap interfaces, the current on the second type of metal component is calculated as the net current after the first type of current and the second type of current are superimposed or canceled out.

[0006] Optionally, the critical dimension of the galvanometer is calculated using the following formula: Formula for calculating the critical anode distance: ; In the formula, This is the critical distance to the anode. The characteristic length factor of anode potential decay. This is the coupling potential. This is the anodic self-corrosion potential. This represents the critical polarization threshold of the anode of the thermocouple. Cathode critical distance calculation formula: ; In the formula, This is the critical distance to the cathode. The characteristic length factor of cathode potential decay. This is the coupling potential. This is the cathode self-corrosion potential. This is the critical polarization threshold of the galvanic cathode.

[0007] Optionally, the anode potential decay characteristic length factor or the cathode potential decay characteristic length factor is calculated by the following formula: ; In the formula, The characteristic length factor of potential decay, The polarization resistance of the material. The resistivity of the solution This is the electrolyte film thickness coefficient.

[0008] Optionally, in the coupling analysis, for the first type of metal component located between two overlapping surfaces, calculating the current on the first type of metal component as the net current of the first type of current specifically includes: If both anodic and cathodic currents exist on the first type of metal component, the current on the first type of metal component is calculated as the net current after the anodic and cathodic currents cancel each other out. If only anodic current or only cathode current exists on the first type of metal component, the current on the first type of metal component is calculated as the superposition of anodic current or cathode current.

[0009] Optionally, the second type of current is calculated using the following method: If the high-potential metal component has a corrosive effect on the second type of metal component, thereby forming a second type of current on the second type of metal component, then the anodic polarization potential generated by the high-potential metal component on the second type of metal component can be calculated based on the voltage decay equation. ; Based on the polarization curve of the second type of metal component, the value of the second type of current is determined to be the potential plus the self-corrosion potential of the second type of metal component. The corresponding current value at that time.

[0010] Optionally, the anodic polarization potential Calculated using the following formula: ; In the formula, x is the distance between the anode metal and the high-potential metal. Let x be the corrosion potential at a distance x between the anode metal and the high-potential metal. This is the anodic self-corrosion potential. This is the coupling potential. This is the potential decay characteristic length factor.

[0011] The device for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode provided by this invention includes: The system parameter acquisition unit is used to acquire the polarization curves and self-corrosion potentials of each metal in the multi-metal system.

[0012] Overlap structure design unit, used to model multi-metal systems based on actual overlap structures; The galvanic critical size calculation unit is used to calculate the galvanic critical size of any two groups of metals in a multi-metal system. The galvanic critical size includes the anode critical distance and the cathode critical distance. A corrosion pattern discrimination unit is used to compare the actual interface distance with the combined critical distance to determine the galvanic corrosion pattern of the multi-metal system. The actual interface distance is the distance between two overlapping surfaces, and the combined critical distance is the sum of the critical dimensions of the galvanic electrodes between the two overlapping surfaces. The galvanic corrosion pattern includes a first corrosion pattern and a second corrosion pattern. The first corrosion pattern indicates that the galvanic electrodes of the two overlapping surfaces do not affect each other, and the second corrosion pattern indicates that the galvanic electrodes of the two overlapping surfaces compete for potential. If the actual overlap distance is greater than or equal to the combined critical distance, the galvanic electrodes of the two overlapping surfaces are determined to be in the first corrosion pattern; if the actual overlap distance is less than the combined critical distance, the galvanic electrodes of the two overlapping surfaces are determined to be in the second corrosion pattern. An independent galvanic analysis unit is used to perform independent galvanic analysis on the galvanic of each lap surface for the first corrosion mode. The independent galvanic analysis includes obtaining galvanic corrosion current parameters based on polarization curves. The coupling analysis unit is used to divide the current generated by galvanic corrosion into a first type of current that directly forms galvanic corrosion through the lap interface and a second type of current that does not form corrosion effects through the lap interface. For the first type of metal component located between two lap interfaces, the current on the first type of metal component is calculated as the net current of the first type of current. For the second type of metal component not located between two lap interfaces, the current on the second type of metal component is calculated as the net current after the first type of current and the second type of current are superimposed or canceled out.

[0013] Optionally, the system parameter acquisition unit is also used to acquire the overall galvanic potential of the multi-metal system.

[0014] Optionally, in the galvanic critical size calculation unit, the galvanic critical size is calculated using the following formula: Formula for calculating the critical anode distance: ; In the formula, This is the critical distance to the anode. The characteristic length factor of anode potential decay. This is the coupling potential. This is the anodic self-corrosion potential. This represents the critical polarization threshold of the anode of the thermocouple. Cathode critical distance calculation formula: ; In the formula, This is the critical distance to the cathode. The characteristic length factor of cathode potential decay. This is the coupling potential. This is the cathode self-corrosion potential. This is the critical polarization threshold of the galvanic cathode.

[0015] The present invention also provides a computer device, the computer device including a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to implement the steps of the above-described method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic couple.

[0016] The present invention has the following beneficial effects: This invention proposes a method for evaluating the galvanic effect in multi-metal systems based on the voltage drop principle and the critical size of the galvanic electrode. It specifically addresses the technical challenges of traditional bimetallic galvanic analysis methods, which cannot adapt to multi-metal systems with multiple dissimilar metal contact interfaces, concentrated galvanic corrosion regions, and complex potential competition relationships. It can fully consider the complex potential coupling, interface interference, and mutual influence effects between multiple metals, accurately characterize the galvanic corrosion characteristics and potential competition laws of different contact interfaces, and achieve refined, quantitative calculation and objective analysis of the galvanic corrosion behavior of complex multi-metal systems. This significantly improves the accuracy, applicability, and scientific rigor of galvanic corrosion assessment for multi-metal lap structures. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of some embodiments of the method for evaluating the galvanic effect in a multi-metal system based on the critical size of the galvanic electrode according to the present invention; Figure 2 This is a schematic diagram illustrating the attenuation principle of the galvanic couple effect. Figure 3 This is a schematic diagram illustrating the analysis of the actual interface distance and combined critical distance of the ABC ternary electrocouple system (in series) in some embodiments of the present invention; Figure 4 This is a schematic diagram of the polarization curves of the three metals A, B, and C in the ABC ternary electrocouple system in some embodiments of the present invention. Figure 5 This is a schematic diagram of the process for determining the anode and cathode of a thermocouple based on the overall thermocouple potential in some embodiments of the present invention. Detailed Implementation

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

[0020] The essence of galvanic corrosion is the formation of an electrochemical cell effect when two different metals come into contact in an electrolyte. When the two metals form a circuit through a wire or in direct contact, a potential difference is generated due to their different electrode potentials. This potential difference drives electrons to flow from the metal with a more negative potential (anode) to the metal with a more positive potential (cathode), and at the same time, a corresponding ionic current is formed in the solution, thus forming a complete corrosion cell circuit. During galvanic corrosion, the galvanic current is transmitted between the two metals through the solution. This process is inevitably affected by the solution resistance. The existence of solution resistance causes a voltage drop in the current transmission path, making the galvanic effect weaker the farther away from the contact interface.

[0021] During galvanic corrosion, a corrosion cell is formed after dissimilar metals come into contact. The galvanic current is transmitted in the solution along the line connecting the two metal interfaces, and the current path is transmitted along the divergent channel. Due to the resistance of the solution to the ionic current, the distance between the galvanic current and the contact surface of the dissimilar metal follows the rule: the greater the distance from the contact surface, the greater the current attenuation. When the distance increases to a certain extent, the galvanic effect attenuates to the point that it can be ignored. That is, the influence range of the dissimilar galvanic effect is self-limiting.

[0022] The attenuation of the galvanic effect is as follows Figure 2 As shown, according to Ohm's law, the voltage drop caused by the solution resistance can theoretically be expressed as: (1) In the formula, I is the galvanic current, determined by the electrode potential difference between the two metals, the solution resistance, and the polarization resistance; ρ is the solution resistivity (unit: Ω·m), which is related to the solution concentration, temperature, and ion species; L is the straight-line distance between the interfaces of the dissimilar metals, i.e., the effective path length for current transmission in the solution; S is the equivalent cross-sectional area of ​​the current path (unit: m²). 2 ), which is approximately equal to the contact projection area of ​​the two metals or the effective cross-sectional area for ion migration in the solution.

[0023] However, in actual galvanic corrosion processes, the decay of the galvanic current is not linear. This is because the galvanic current I is not a constant value, but rather depends on the open-circuit potential difference ΔE between the two metals and the total resistance R. total Jointly determined (I=ΔE / R) total ), Rtotal Including solution resistance R sol Metal body resistance R metal (Negligible) and the polarization resistance R of the two metals p (Anodic polarization resistor R) a +Cathode polarization resistance R c In addition to factors such as the accumulation of interfacial corrosion products and changes in the cross-sectional area S of the current path, there are also other factors.

[0024] Taking the galvanic anode as an example, the corrosion potential of the anode decreases exponentially with distance from the interface. The potential E(x) at any position on the anode surface is essentially the coupling potential E. g Subtract the cumulative voltage drop of the solution from the contact surface to that location. ,Right now Due to current divergence, the cumulative voltage drop in the solution... The distance x decreases exponentially (not nonlinearly), eventually causing E(x) to decrease from E g Gradually approaching the anodic self-corrosion potential E corr,A The voltage decay equation can be described as follows: (2) In the formula, E(x) is the corrosion potential at a distance x from the contact surface on the anode (unit: V); corr,A E is the anodic self-corrosion potential (unit: V), which is theoretically the limiting potential as x→∞ (at which point the galvanic current is 0); g It is the coupling potential (unit: V) at the interface of dissimilar metals. The initial potential at time; x is the vertical distance (in meters) from a point on the anode to the contact surface. The potential decay characteristic length factor reflects the decay rate, with units of meters (m), and its expression is: (3) In the formula, The polarization resistance of the material (Ω) cm 2 ), Solution resistivity (Ω) (cm), all of which can be obtained through actual measurement; The electrolyte film thickness coefficient is set as follows: when the actual electrolyte thickness is greater than 400 μm, it is considered a solution system. When the value is 1, and the actual electrolyte thickness is 100~400μm, it is considered a thin liquid film system. In this case, the potential decay will be limited by the z-direction of the electrolyte domain, and the effective range of the galvanometer will be greatly reduced. (Refer to engineering experience.) The value is set to 0.1 when the actual electrolyte thickness is less than 100 μm. The value is 0.01.

[0025] The physical meaning of the potential decay characteristic length factor λ is the distance at which the potential decays to 1 / e (approximately 37%) of the initial difference. It is a comprehensive characterization of all resistance terms and anodic reaction kinetics. The larger the value, the faster the potential decays, and the smaller the range of influence of the galvanic effect. The smaller the value, the slower the decay, and the farther the effect of galvanic corrosion extends.

[0026] Based on the decay law of galvanic potential during galvanic corrosion, taking the bimetallic galvanic effect as an example, the critical influence range of 10mV positive polarization of anodic corrosion potential and 10mV negative polarization of cathodic corrosion potential is set as the critical influence size L of bimetallic galvanic corrosion. c The critical size affected by bimetallic galvanic corrosion is: (4) Galvanic corrosion affects critical dimensions including anodic critical distance. Critical distance to cathode .

[0027] The formula for calculating the critical anode distance is as follows: (5) In the formula, This is the critical distance to the anode. The characteristic length factor of anode potential decay. This is the coupling potential. This is the anodic self-corrosion potential. This represents the critical polarization threshold of the anode of the thermocouple. The formula for calculating the cathode critical distance is: (6) In the formula, This is the critical distance to the cathode. The characteristic length factor of cathode potential decay. This is the coupling potential. This is the cathode self-corrosion potential. This is the critical polarization threshold of the galvanic cathode.

[0028] Based on relevant experience, the critical polarization threshold of the galvanic anode is... Critical polarization threshold of the electrode cathode We can take 10mV, which means that the galvanic effect caused by polarization within 10mV can be ignored.

[0029] In practical engineering, the critical size affecting galvanic corrosion is... The main factors include: the influence of metal combinations, as different metal combinations have different electrode potential differences; the greater the potential difference, the larger the influence range. For example, the potential difference of a magnesium-copper combination exceeds 2V, and its influence range is much larger than that of a steel-copper combination. The influence of solution properties, as the higher the conductivity of the solution, the larger the influence range. For example, the conductivity of seawater (about 4 S / m) is much higher than that of freshwater (about 0.01 S / m), so the influence range of galvanic corrosion in seawater is larger. The influence of temperature, as increased temperature reduces the viscosity of the solution and increases the migration rate of ions, thereby increasing the influence range. The influence of geometric factors, as the shape, size, and relative position of the metals all affect the current distribution, and thus the influence range. For example, in a pipeline system, the larger the pipe diameter, the larger the influence range of galvanic corrosion.

[0030] Based on the above analysis of the galvanic corrosion principle, this invention provides a method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode.

[0031] See Figure 1 In some embodiments, the method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode includes the following steps S1 to S4: S1, obtain the polarization curve and self-corrosion potential of each metal in the multi-metal system, and determine the galvanic anode and galvanic cathode on each lap surface according to the actual lap structure and the level of self-corrosion potential.

[0032] The self-corrosion potential refers to the steady-state open-circuit potential established when the anodic oxidation and cathodic reduction reactions on the surface of a metal electrode reach a kinetically stable state and the net current density on the electrode surface is zero in a given corrosive medium. The polarization curve refers to the electrochemical characteristic curve characterizing the functional relationship between the electrode potential and the polarization current density, measured under steady-state or quasi-steady-state test conditions by causing the metal electrode potential to deviate from its self-corrosion potential through external polarization. It includes the anodic polarization curve and the cathodic polarization curve. The self-corrosion potential can be determined using a three-electrode electrochemical test system. The polarization curve is determined by potentiodynamic scanning method after the self-corrosion potential is determined and the system reaches an electrochemical steady state. This invention does not limit the specific electrochemical test method.

[0033] In this step, the polarization curve data of each metal in the multi-metal system are obtained by testing, forming a corrosion potential sequence. The metal with the high self-corrosion potential is the galvanic cathode, and the metal with the low self-corrosion potential is the galvanic anode.

[0034] S2, calculate the critical size of the galvanic couple of any two metals in the multi-metal system. The critical size of the galvanic couple includes the critical distance of the anode and the critical distance of the cathode. The critical distance of the anode is calculated by formula (5), the critical distance of the cathode is calculated by formula (6), and the potential decay characteristic length factor is calculated by formula (3).

[0035] S3. Compare the actual interface distance with the combined critical distance to determine the galvanic corrosion mode of the multi-metal system. The actual interface distance is the distance between two overlapping surfaces, and the combined critical distance is the sum of the critical dimensions of the galvanic electrodes between the two overlapping surfaces. The galvanic corrosion mode includes a first corrosion mode and a second corrosion mode. The first corrosion mode indicates that the galvanic electrodes of the two overlapping surfaces do not affect each other, and the second corrosion mode indicates that there is potential competition between the galvanic electrodes of the two overlapping surfaces. Wherein, if the actual overlap distance is greater than or equal to the combined critical distance, the galvanic couple of the two overlap surfaces is determined to be a first corrosion form; if the actual overlap distance is less than the combined critical distance, the galvanic couple of the two overlap surfaces is determined to be a second corrosion form. This step is the core step in the evaluation method of galvanic effect in multi-metal systems based on the critical size of the galvanic couple. By comparing the actual interface distance with the combined critical distance, it is determined whether the complex galvanic couple system can be separated.

[0036] Specifically, with Figure 3 The overlapping structure shown is an example, where A, B, and C are three metal components that form two electrocouple overlapping interfaces, AB and BC. This indicates the critical dimension of the AB galvanic couple formed on the B metal side. This indicates the critical dimension of the BC galvanic couple formed on the B metal side, where L represents the distance between the two lap interfaces; for example... Figure 3 As shown in Figure (1), If the AB interface thermocouple and the BC interface thermocouple are considered to have no mutual influence, the ABC series thermocouple system can be analyzed by breaking it down into pairwise combinations; if so... Figure 3 As shown in Figure (2), This indicates potential competition between the AB interface coupler and the BC interface coupler, requiring inclusion in the coupling analysis. It is important to note that... , All are the critical dimensions of the galvanometer on one side of the interface.

[0037] The above critical distance criterion can quickly simplify complex multi-metal coupling systems, break down complex multi-element electric couple behavior into simple components for analysis, and avoid over-computation.

[0038] S4. For the first corrosion form, perform independent galvanic analysis on the galvanic couples of each lap joint. The independent galvanic couple analysis includes obtaining the galvanic corrosion current parameters based on the polarization curve.

[0039] Specifically, for systems that can be separated into pairs for independent galvanic analysis, it is only necessary to obtain the galvanic corrosion rate of the material at the interface where the two metals overlap, without considering the galvanic effect of other metals outside the interface. In this case, the traditional bimetallic galvanic corrosion parameter identification method can be used to obtain the galvanic corrosion current parameters, that is: determine the galvanic current, as well as the corresponding cathode and anode, based on the intersection of the polarization curves of the two metals, and perform statistical analysis on the galvanic current generated at each interface, with the anode galvanic current being positive and the cathode galvanic current being negative.

[0040] Taking the ABC ternary galvanometer system as an example, the self-corrosion potentials of the three metals > If the system can be divided into two independent galvanic interfaces, AB and BC, which do not interfere with each other, then the corrosion parameters of the galvanic system are analyzed as follows: For the AB interface, where A is the cathode and B is the anode, the anodic galvanic current generated on component B is +I. A-B The cathode galvanic current generated on component A is -I A-B For the BC interface, where B is the cathode and C is the anode, the cathodic galvanic current generated on component B is -I. B-C The anodic galvanic current generated on component C is +I B-C .

[0041] At this point, in the ABC ternary thermocouple system, the anodic thermocouple current on the surface of component C, which has the lowest potential, is +I. B-C Component B is the anode component; component B, with its potential in the middle, simultaneously generates the anode current +I. A-B and cathode current -I B-C The currents at the two interfaces do not affect each other; component B follows the anode current + I. A-B Analyze the risk of galvanic corrosion; component A, with the highest potential, is the cathode, and the resulting cathodic current is -I. B-C .

[0042] I A-B The value I represents the current value corresponding to the coupling potential at the polarization curves of metal A and metal B. B-C The value represents the current value corresponding to the coupling potential at the polarization curves of metals B and C, such as... Figure 4 As shown.

[0043] For the second corrosion form, the overall galvanic potential of the multi-metal system is measured. Metal components with self-corrosion potential positive than the overall galvanic potential are identified as cathodes, and metal components with self-corrosion potential negative than the overall galvanic potential are identified as anodes. Coupled analysis is then performed on the galvanic potentials of the two overlapping surfaces.

[0044] The coupling analysis includes: dividing the current generated by galvanic corrosion into a first type of current that directly forms galvanic corrosion through the lap interface and a second type of current that does not form corrosion effects through the lap interface; for the first type of metal component located between two lap interfaces, the current on the first type of metal component is calculated as the net current of the first type of current; for the second type of metal component not located between two lap interfaces, the current on the second type of metal component is calculated as the net current after the first type of current and the second type of current are superimposed or canceled out.

[0045] Specifically, for galvanic couple systems that cannot be separated into pairs, i.e., where the interfacial distance is less than the critical distance, it is necessary to perform a holistic analysis of all influencing components. The method adopted is holistic corrosion potential analysis: firstly, the galvanic couple potential E of the entire coupled system is measured. g Then E g When placed in the corrosion potential sequence of a multi-metal system, the self-corrosion potential is positive at E. g The component is the cathode, and the corrosion potential is negative than E. g The component is the anode, and the overall corrosion potential process is as follows: Figure 5 As shown.

[0046] The reason for using the above method for non-separable multi-metal systems is that, for separable multi-metal galvanic couple systems, they are actually already divided into multiple binary galvanic couple combinations. For binary galvanic couple combinations, it is only necessary to compare the self-corrosion potentials between the two materials to identify the anode and cathode components. There is no influence from a third component, therefore, there is no need for the coupling potential of the multi-component system. However, for non-separable multi-metal systems, there are mutual influences between the multiple components, and the comprehensive result of these mutual influences is the overall galvanic couple potential E. g Therefore, for an indivisible galvanic system, it is necessary to compare and analyze the overall coupling potential to determine the anode and cathode of galvanic corrosion.

[0047] After determining the cathode and anode components in the multi-metal system using the overall potential analysis method, it is necessary to further determine the magnitude of the galvanic current.

[0048] In coupling analysis, for a first-class metal element located between two overlapping surfaces, calculating the current on the first-class metal element as the net current of the first-class current includes two cases: First, if both anodic and cathodic currents exist on the first type of metal component, the current on the first type of metal component is calculated as the net current after the anodic and cathodic currents cancel each other out. Secondly, if only anodic current or only cathodic current exists on the first type of metal component, the current on the first type of metal component is calculated as the superposition value of anodic current or cathodic current.

[0049] For a second-class metal element not located between two overlapping surfaces, the current on the second-class metal element is calculated as the net current resulting from the superposition or cancellation of the first-class and second-class currents; the second-class current is calculated using the following method: If the high-potential metal component has a corrosive effect on the second type of metal component, thereby generating a second type of current on the second type of metal component, then the anodic polarization potential generated by the high-potential metal component on the second type of metal component is calculated based on the voltage decay equation (i.e., formula (2)). Based on the polarization curves of the second type of metal component, the value of the second type of current is determined to be the self-corrosion potential of the second type of metal component + The corresponding current value at that time.

[0050] The anodic polarization potential generated by the high-potential metal component on the second type of metal component Calculated using the following formula: (7) In the formula, x is the distance between the anode metal and the high-potential metal. Let x be the corrosion potential at a distance x between the anode metal and the high-potential metal. This is the anodic self-corrosion potential. This is the coupling potential (here referring to the galvanic couple potential between the high-potential metal and the anode metal at x=0). This is the potential decay characteristic length factor (here, the potential decay characteristic length factor of the anode metal).

[0051] Specifically, taking the ABC ternary galvanometer system as an example, the self-corrosion potentials of the three metals... > If the interfaces of the two thermocouples AB and BC interact, the current distribution at the anode of the ABC ternary thermocouple system is as follows: (1) Component B, whose potential is in the middle, generates an anodic current +I on the two interface couplers AB and BC respectively. A-B and cathode current -I B-C The thermocouple currents at the two interfaces affect each other. At this time, the net current I on component B... net For |I A-B -I B-C |, if |I A-B |greater than|I B-C If the absolute value of the anodic current on component B is greater than the absolute value of the cathode current, then component B has a net anodic current and is the anode in the system; otherwise, it is the cathode. A-B The value I represents the current value corresponding to the coupling potential at the polarization curves of metal A and metal B. B-C The value represents the current value corresponding to the coupling potential at the polarization curves of metals B and C.

[0052] (2) For component C, which has the lowest potential, it is always the anode in the system. If component C is located between two high-potential components, i.e., arranged in the pattern ACB (the same applies to BCA), then the galvanic current of component C is the physical superposition of the galvanic currents at the AC and CB interfaces, I A-C +I C-B ;I A-C The value I represents the current value corresponding to the coupling potential at the polarization curves of metals A and C. C-B The value represents the current value corresponding to the polarization curves of metal C and metal B at the coupling potential.

[0053] (3) If the three components are arranged in order of high to low potential, i.e., the arrangement is ABC (the same applies to CBA), then the basic anode current of component C is +I. B-C +I B-C That is, the first type of current. In addition, the influence of component A on component C must also be considered. That is, the high potential of metal A will also produce a certain anodic polarization effect on metal C. In this case, the anodic galvanic current of metal C needs to be +I B-C Add an extra current to the base , That is, the second type of current. The calculation method needs to consider the attenuation effect of the polarization potential in space. The detailed calculation method is based on the voltage attenuation equation. According to formula (7), the anodic polarization potential of component A at a distance x relative to component C is calculated. (In the formula, Let A and C be the electrocouple potentials at x=0. The self-corrosion potential of C metal , (where is the potential decay characteristic length factor of C metal), thus obtaining the anodic polarization value of C metal. Subsequently, based on the polarization curve of C metal, the potential at the self-corrosion potential of C metal was obtained. + The corresponding current value at that time is... .

[0054] This invention presents a method for analyzing galvanic corrosion in multi-metal systems based on the voltage drop principle and critical size analysis. This method specifically addresses the technical challenges of traditional bimetallic galvanic corrosion analysis methods, which cannot adapt to multi-metal systems with multiple dissimilar metal contact interfaces, concentrated galvanic corrosion regions, and complex potential competition relationships. It fully considers the complex potential coupling, interface interference, and mutual influence effects between multiple metals, accurately characterizing the galvanic corrosion features and potential competition laws of different contact interfaces. This enables refined, quantitative calculation and objective analysis of the galvanic corrosion behavior of complex multi-metal systems, significantly improving the accuracy, applicability, and scientific rigor of galvanic corrosion assessment for multi-metal lap structures.

[0055] The present invention also provides a device for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode. In some embodiments, the device includes a system parameter acquisition unit, a lap structure design unit, a critical size calculation unit, a corrosion mode discrimination unit, an independent galvanic electrode analysis unit, and a coupling analysis unit.

[0056] The system parameter acquisition unit is used to acquire the polarization curves and self-corrosion potentials of each metal in the multi-metal system, and also to acquire the overall galvanic potential of the multi-metal system; the system parameter acquisition unit can adopt an integrated electrochemical parameter testing device.

[0057] The overlap structure design unit is used to model multi-metal systems based on actual overlap structures.

[0058] The galvanic critical size calculation unit is used to calculate the galvanic critical size of any two metals in a multi-metal system. The galvanic critical size includes the anode critical distance and the cathode critical distance.

[0059] In the galvanic critical size calculation unit, the galvanic critical size is calculated using the following formula: Formula for calculating the critical anode distance: ; In the formula, This is the critical distance to the anode. The characteristic length factor of anode potential decay. This is the coupling potential. This is the anodic self-corrosion potential. This represents the critical polarization threshold of the anode of the thermocouple. Cathode critical distance calculation formula: ; In the formula, This is the critical distance to the cathode. The characteristic length factor of cathode potential decay. This is the coupling potential. This is the cathode self-corrosion potential. This is the critical polarization threshold of the galvanic cathode.

[0060] The characteristic length factor of anodic potential decay or the characteristic length factor of cathode potential decay are calculated by the following formula: ; In the formula, The characteristic length factor of potential decay, The polarization resistance of the material. The resistivity of the solution This is the electrolyte film thickness coefficient.

[0061] The corrosion pattern discrimination unit is used to compare the actual interface distance with the combined critical distance to determine the galvanic corrosion pattern of the multi-metal system. The actual interface distance is the distance between two overlapping surfaces, and the combined critical distance is the sum of the critical dimensions of the galvanic electrodes between the two overlapping surfaces. The galvanic corrosion pattern includes a first corrosion pattern and a second corrosion pattern. The first corrosion pattern indicates that the galvanic electrodes of the two overlapping surfaces do not affect each other, and the second corrosion pattern indicates that the galvanic electrodes of the two overlapping surfaces compete for potential. If the actual overlapping distance is greater than or equal to the combined critical distance, the galvanic electrodes of the two overlapping surfaces are determined to be in the first corrosion pattern; if the actual overlapping distance is less than the combined critical distance, the galvanic electrodes of the two overlapping surfaces are determined to be in the second corrosion pattern.

[0062] The independent galvanic analysis unit is used to perform independent galvanic analysis on the galvanic of each lap surface for the first corrosion mode. The independent galvanic analysis includes obtaining galvanic corrosion current parameters based on polarization curves.

[0063] The coupling analysis unit is used to classify the current generated by galvanic corrosion into a first type of current that directly forms galvanic corrosion through the lap interface and a second type of current that does not form corrosion effects through the lap interface for the second type of corrosion. For the first type of metal component located between two lap interfaces, the current on the first type of metal component is calculated as the net current of the first type of current. For the second type of metal component not located between two lap interfaces, the current on the second type of metal component is calculated as the net current after the first type of current and the second type of current are superimposed or canceled out.

[0064] In coupling analysis, for a first-class metal component located between two overlapping surfaces, the net current calculated as the first-class current on the first-class metal component specifically includes: If both anodic and cathodic currents exist on the first type of metal component, the current on the first type of metal component is calculated as the net current after the anodic and cathodic currents cancel each other out. If only anodic current or only cathode current exists on the first type of metal component, the current on the first type of metal component is calculated as the superposition of anodic current or cathode current.

[0065] The second type of current is calculated using the following method: If the high-potential metal component has a corrosive effect on the second-type metal component, thereby generating a second-type current on the second-type metal component, then the anodic polarization potential generated by the high-potential metal component on the second-type metal component can be calculated based on the voltage decay equation. ; Based on the polarization curves of the second type of metal component, the value of the second type of current is determined as the self-corrosion potential of the second type of metal component + The corresponding current value at that time.

[0066] Anodic polarization potential Calculated using the following formula: ; In the formula, x is the distance between the anode metal and the high-potential metal. Let x be the corrosion potential at a distance x between the anode metal and the high-potential metal. This is the anodic self-corrosion potential. This is the coupling potential. This is the potential decay characteristic length factor.

[0067] The device for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic ...

[0068] The present invention also provides a computer device, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, it implements the steps of the method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode provided in the above embodiments.

[0069] In the several embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0070] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0071] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0072] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods described in the various embodiments of this application through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0073] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for evaluating the galvanic effect in a multi-metal system based on the critical size of the galvanic electrode, characterized in that, Including the following steps: S1, obtain the polarization curve and self-corrosion potential of each metal in the multi-metal system, and determine the galvanic anode and galvanic cathode on each lap surface according to the actual lap structure and the level of self-corrosion potential. S2, Calculate the critical galvanic dimension of any two metal groups in the multi-metal system, where the critical galvanic dimension includes the anode critical distance and the cathode critical distance; S3. Compare the actual interface distance with the combined critical distance to determine the galvanic corrosion mode of the multi-metal system. The actual interface distance is the distance between two overlapping surfaces, and the combined critical distance is the sum of the critical dimensions of the galvanic electrodes between the two overlapping surfaces. The galvanic corrosion mode includes a first corrosion mode and a second corrosion mode. The first corrosion mode indicates that the galvanic electrodes of the two overlapping surfaces do not affect each other, and the second corrosion mode indicates that there is potential competition between the galvanic electrodes of the two overlapping surfaces. Wherein, if the actual overlap distance is greater than or equal to the combined critical distance, the galvanic couple of the two overlap surfaces is determined to be a first corrosion form; if the actual overlap distance is less than the combined critical distance, the galvanic couple of the two overlap surfaces is determined to be a second corrosion form. S4, For the first corrosion form, perform independent galvanic analysis on the galvanic couple of each lap surface, wherein the independent galvanic couple analysis includes obtaining galvanic corrosion current parameters based on polarization curves; For the second corrosion form, the overall galvanic potential of the multi-metal system is measured. Metal components with self-corrosion potential positive than the overall galvanic potential are identified as cathodes, and metal components with self-corrosion potential negative than the overall galvanic potential are identified as anodes. Coupled analysis is performed on the galvanic potentials of the two overlapping surfaces. The coupling analysis includes: dividing the current generated by galvanic corrosion into a first type of current that directly forms galvanic corrosion through the lap interface and a second type of current that does not form corrosion effects through the lap interface; for the first type of metal component located between two lap interfaces, the current on the first type of metal component is calculated as the net current of the first type of current; for the second type of metal component not located between two lap interfaces, the current on the second type of metal component is calculated as the net current after the first type of current and the second type of current are superimposed or canceled out.

2. The method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 1, characterized in that, The critical dimension of the galvanic electrode is calculated using the following formula: Formula for calculating the critical anode distance: ； In the formula, This is the critical distance to the anode. The characteristic length factor of anode potential decay. This is the coupling potential. This is the anodic self-corrosion potential. This represents the critical polarization threshold of the anode of the thermocouple. Cathode critical distance calculation formula: ； In the formula, This is the critical distance to the cathode. The characteristic length factor of cathode potential decay. This is the coupling potential. This is the cathode self-corrosion potential. This is the critical polarization threshold of the galvanic cathode.

3. The method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 2, characterized in that, The anode potential decay characteristic length factor or the cathode potential decay characteristic length factor is calculated by the following formula: ； In the formula, The characteristic length factor of potential decay, The polarization resistance of the material. The resistivity of the solution This is the electrolyte film thickness coefficient.

4. The method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 1, characterized in that, In the coupling analysis, the step of calculating the current on the first type of metal component as the net current of the first type of current, for the first type of metal component located between two overlapping surfaces, specifically includes: If both anodic and cathodic currents exist on the first type of metal component, the current on the first type of metal component is calculated as the net current after the anodic and cathodic currents cancel each other out. If only anodic current or only cathode current exists on the first type of metal component, the current on the first type of metal component is calculated as the superposition of anodic current or cathode current.

5. The method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 1, characterized in that, The second type of current is calculated using the following method: If the high-potential metal component has a corrosive effect on the second type of metal component, thereby forming a second type of current on the second type of metal component, then the anodic polarization potential generated by the high-potential metal component on the second type of metal component can be calculated based on the voltage decay equation. ; Based on the polarization curve of the second type of metal component, the value of the second type of current is determined to be the potential plus the self-corrosion potential of the second type of metal component. The corresponding current value at that time.

6. The method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 5, characterized in that, The anodic polarization potential Calculated using the following formula: ； In the formula, x is the distance between the anode metal and the high-potential metal. Let x be the corrosion potential at a distance x between the anode metal and the high-potential metal. This is the anodic self-corrosion potential. This is the coupling potential. This is the potential decay characteristic length factor.

7. A device for evaluating the galvanic effect in a multi-metal system based on the critical size of the galvanic electrode, characterized in that, include: The system parameter acquisition unit is used to acquire the polarization curves and self-corrosion potentials of each metal in the multi-metal system; Overlap structure design unit, used to model multi-metal systems based on actual overlap structures; The galvanic critical size calculation unit is used to calculate the galvanic critical size of any two groups of metals in a multi-metal system. The galvanic critical size includes the anode critical distance and the cathode critical distance. A corrosion pattern discrimination unit is used to compare the actual interface distance with the combined critical distance to determine the galvanic corrosion pattern of the multi-metal system. The actual interface distance is the distance between two overlapping surfaces, and the combined critical distance is the sum of the critical dimensions of the galvanic electrodes between the two overlapping surfaces. The galvanic corrosion pattern includes a first corrosion pattern and a second corrosion pattern. The first corrosion pattern indicates that the galvanic electrodes of the two overlapping surfaces do not affect each other, and the second corrosion pattern indicates that the galvanic electrodes of the two overlapping surfaces compete for potential. If the actual overlap distance is greater than or equal to the combined critical distance, the galvanic electrodes of the two overlapping surfaces are determined to be in the first corrosion pattern; if the actual overlap distance is less than the combined critical distance, the galvanic electrodes of the two overlapping surfaces are determined to be in the second corrosion pattern. An independent galvanic analysis unit is used to perform independent galvanic analysis on the galvanic of each lap surface for the first corrosion mode. The independent galvanic analysis includes obtaining galvanic corrosion current parameters based on polarization curves. The coupling analysis unit is used to divide the current generated by galvanic corrosion into a first type of current that directly forms galvanic corrosion through the lap interface and a second type of current that does not form corrosion effects through the lap interface. For the first type of metal component located between two lap interfaces, the current on the first type of metal component is calculated as the net current of the first type of current. For the second type of metal component not located between two lap interfaces, the current on the second type of metal component is calculated as the net current after the first type of current and the second type of current are superimposed or canceled out.

8. The device for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 7, characterized in that, The system parameter acquisition unit is also used to acquire the overall galvanic potential of the multi-metal system.

9. The device for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode according to claim 7, characterized in that, The critical dimension of the galvanic electrode is calculated using the following formula: Formula for calculating the critical anode distance: ； In the formula, This is the critical distance to the anode. The characteristic length factor of anode potential decay. This is the coupling potential. This is the anodic self-corrosion potential. This represents the critical polarization threshold of the anode of the thermocouple. Cathode critical distance calculation formula: ； In the formula, This is the critical distance to the cathode. The characteristic length factor of cathode potential decay. This is the coupling potential. This is the cathode self-corrosion potential. This is the critical polarization threshold of the galvanic cathode.

10. A computer device, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, it implements the method for evaluating the galvanic effect of a multi-metal system based on the critical size of the galvanic electrode as described in any one of claims 1-6.

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