Brazing corrosion inhibition method

Abstract

The invention relates to the technical field of brazing, and discloses a brazing corrosion inhibition method which comprises the following steps: predicting the corrosion tendency of a brazing system based on a thermodynamic phase diagram; dynamically releasing a corrosion inhibitor according to the corrosion tendency to neutralize corrosive substances; brazing process parameters are optimized through multi-parameter feedback; a gradient wettability solder mask layer is formed on the surface of the base material, and a solder flowing path is dynamically regulated and controlled; residues are removed through physical and chemical synergy after brazing, the thermodynamic phase diagram is constructed through a CALPHAD method, and the corrosion tendency is quantified through a corrosion tendency index Pc. According to the method, the dynamic prediction model and the self-adaptive microcapsules are combined with multi-parameter optimization, gradient solder mask collaborative electromagnetic regulation and control and ultrasonic-dry ice collaborative treatment, brazing corrosion inhibition, interface protection and residue removal are achieved, the corrosion resistance of a connector is remarkably improved, and the service life of the connector is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of brazing technology, and in particular to a method for inhibiting brazing corrosion. Background Technology

[0002] During brazing, residual Cl in the flux - Corrosive ions can easily trigger interfacial corrosion, leading to decreased joint strength and shortened service life. With the rapid development of high-precision electronic packaging, aerospace hot-end components, and other fields, the requirements for the corrosion resistance of brazed joints are becoming increasingly stringent. However, traditional brazing technology struggles to achieve dynamic prediction of corrosion risk, on-demand release of corrosion inhibitors, and complete removal of residues. Therefore, there is an urgent need to develop a comprehensive corrosion suppression method that integrates thermodynamic modeling, intelligent response, and synergistic treatment.

[0003] Existing brazing corrosion inhibition technologies mainly include the following two types of schemes: thermodynamically guided corrosion inhibitor pre-addition: based on the thermodynamic phase diagram of fixed temperature and composition, corrosion inhibitors (such as silicates and benzotriazoles) are premixed in the flux, and corrosion is inhibited by uniform release of the corrosion inhibitors; homogeneous solder resist layer and chemical cleaning: a single wettable solder resist layer (such as pure PTFE coating) is coated on the substrate surface, and the residues are removed by acid pickling or alkaline cleaning after brazing.

[0004] However, existing technologies still have some shortcomings, such as delayed release of corrosion inhibitors: the release rate of premixed corrosion inhibitors cannot match the dynamic changes in corrosion tendency, resulting in insufficient inhibitor concentration in the high corrosion stage and excessive consumption in the low corrosion stage; rigidity of solder resist wettability: the single contact angle design of the homogeneous solder resist layer cannot suppress the penetration of solder in sensitive areas such as grain boundaries, exacerbating local dissolution; and risk of secondary damage: chemical cleaning is prone to leaving corrosive solvents, while mechanical cleaning is prone to scratching the substrate surface. Summary of the Invention

[0005] The purpose of this invention is to provide a brazing corrosion inhibition method that solves the problems of interface corrosion caused by delayed corrosion tendency prediction, rigid release of corrosion inhibitors, and incomplete removal of residues in existing brazing technologies.

[0006] To achieve the above objectives, the present invention provides a method for inhibiting brazing corrosion, the method comprising the following steps: Predicting the corrosion susceptibility of brazing systems based on thermodynamic phase diagrams; Dynamically release corrosion inhibitors based on the described corrosion tendency to neutralize corrosive substances; Optimize brazing process parameters through multi-parameter feedback; A gradient wettability solder resist layer is formed on the substrate surface and the solder flow path is dynamically controlled; The residue is removed by a combination of physical and chemical methods after brazing.

[0007] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention uses thermodynamic phase diagrams to predict corrosion tendency indices in real time, establishing a dynamic correlation mechanism between corrosion risk and corrosion inhibitor release, overcoming the protection lag problem caused by static slow release in traditional methods. This invention achieves precise matching between corrosion inhibitor release rate and corrosion process through deep coupling of thermodynamic models and microcapsule response logic, significantly improving protection efficiency.

[0008] 2. This invention dynamically adjusts the thickness of the polydopamine shell based on the corrosion tendency index, ensuring the slow release of the corrosion inhibitor under high corrosion risk conditions and rapid response under low risk conditions. The key feature of this invention is that, through a non-linear control mechanism of the shell thickness, it avoids premature depletion or insufficient release of the corrosion inhibitor, extending the protection period and reducing material loss.

[0009] 3. This invention combines ambient humidity, brazing seam temperature, and Cl... - By employing multi-dimensional feedback of concentration, a corrosion rate response surface model is constructed and process parameters are optimized to solve the problem of localized uncontrolled dissolution caused by single-parameter control in traditional brazing. This invention achieves a global balance between solder flowability and substrate protection through parameter coupling and intelligent algorithms.

[0010] 4. This invention utilizes the synergistic effect of a nano-ZnO / PTFE composite coating and an alternating electromagnetic field to suppress the penetration of molten solder into sensitive areas of the substrate. This invention overcomes the limitations of traditional rigid solder resist layers by precisely matching gradient wettability design with electromagnetic force distribution, thereby reducing interfacial microcracks and grain boundary corrosion.

[0011] 5. This invention utilizes the combined action of ultrasonic cavitation and dry ice blasting to efficiently remove brazing residues and solder resist fragments, avoiding secondary damage to the substrate caused by chemical cleaning. This invention addresses the long-term corrosion risks caused by incomplete residue removal in traditional post-treatment processes through a synergistic mechanism of physical peeling and low-temperature impact. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0013] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below.

[0014] This invention provides a brazing corrosion suppression method, which achieves brazing corrosion suppression, interface protection and residue removal by combining a dynamic prediction model with adaptive microcapsules, multi-parameter optimization, gradient resist layer synergistic electromagnetic control and ultrasonic-dry ice synergistic treatment.

[0015] like Figure 1 As shown, the brazing corrosion inhibition method may include the following steps: S1. Predicting the corrosion tendency of brazing systems based on thermodynamic phase diagrams; In this embodiment, the corrosion tendency of the brazing system is predicted based on a thermodynamic phase diagram. The core of this method lies in establishing a thermodynamic database of the brazing system and calculating the corrosion tendency index, thereby providing a theoretical basis for subsequent corrosion inhibitor release strategies. Specifically, this is achieved through the following technical solution: In this embodiment, the CALPHAD (CAL calculation of PHAse Diagrams) method is used to construct a thermodynamic database for the brazing system. The brazing system includes a metallic substrate (such as aluminum, copper, etc.), flux components (such as fluorides, chlorides), and potential corrosion products (such as AlF3·3H2O, AlCl3). Thermodynamic property data of each component, including the Gibbs free energy function of the pure substances, interphase interaction parameters, and multiphase equilibrium relationships, are imported using commercial thermodynamic calculation software (such as Thermo-Calc or Pandat). The Gibbs free energy function defines the molar Gibbs free energy of the mixed phase using the following expression: Among them, G m x represents the molar Gibbs free energy of a mixture, characterizing the thermodynamic state of the system at a specific temperature, pressure, and composition; i This represents the mole fraction of the corrosion products. Let be the standard molar Gibbs free energy of the i-th pure component (unit: J / mol); let be the thermodynamic property of the pure substance under reference conditions (normal pressure, specified temperature), obtained through experiments or thermodynamic databases; R is the ideal gas constant; T is the absolute temperature during brazing; lnx i G is the natural logarithm function, used to describe the contribution of the ideal mixture entropy to the Gibbs free energy; ex For excess Gibbs free energy.

[0016] In this embodiment, the corrosion tendency index P c The calculation of corrosion risk is a crucial step in predicting corrosion risk. Within the target brazing temperature range (e.g., 573-773 K), the mole fraction x of each corrosion product is determined through thermodynamic equilibrium calculations. i And based on the following formula, the corrosion tendency index is quantified: Where, x i This represents the mole fraction of the corrosion products. The standard Gibbs free energy change is given by R; the ideal gas constant is given by T; and the absolute temperature during brazing is given by P. c This is a corrosion tendency index.

[0017] In this embodiment, the thermodynamic database needs to cover the entire temperature range and component concentration range involved in the brazing process. Preferably, the accuracy of the thermodynamic model is verified by combining experimental calibration with literature data. For example, for aluminum-based brazing systems, the database needs to include the main phase equilibrium relationships in the Al-F-Si-Cl-O pentagonal system to ensure that the model can predict the formation conditions of key corrosion products such as AlF3 and AlCl3.

[0018] In this embodiment, the corrosion tendency index P c The calculation results directly guide the dynamic release strategy of the corrosion inhibitor in subsequent steps. Preferably, when P c When the threshold value exceeds a preset threshold (e.g., 0.8), the system identifies it as a high-corrosion-risk condition and triggers the microcapsule shell thickening mechanism. The threshold value can be adjusted according to the corrosion resistance requirements of the specific brazing material to ensure that the corrosion inhibitor release rate matches the corrosion process.

[0019] S2. Dynamically release corrosion inhibitors based on corrosion tendency to neutralize corrosive substances; In this embodiment, the technical solution of dynamically releasing the corrosion inhibitor based on corrosion tendency is achieved through pH-responsive microcapsules. Its core lies in constructing a corrosion inhibitor carrier with environmentally responsive characteristics and dynamically controlling the release rate based on corrosion risk. Specifically, this is achieved through the following technical solution: In this embodiment, the pH-responsive microcapsules employ a core-shell structure design, using polydopamine (PDA) as the shell material and a mixture of sodium silicate (Na2SiO3) and benzotriazole (BTA) as the core material. The polydopamine shell is formed on the surface of the core material through an oxidative self-polymerization reaction, and its thickness is determined based on the corrosion susceptibility index P calculated in step S1. c Dynamic adjustment. Preferably, the formula for calculating the shell thickness d is: d=d0·(1+α·ln(P c +1)); Where d is the actual thickness of the polydopamine shell; d0 is the reference thickness of the shell; α is the shell thickness adjustment coefficient; P c is the corrosion tendency index; ln is the natural logarithm function; by introducing the natural logarithm function, a gradual response of the shell thickness to corrosion risk is achieved, avoiding uncontrolled shell rupture caused by abrupt changes in corrosion tendency.

[0020] In this embodiment, the polydopamine shell is formed through the oxidative polymerization of dopamine hydrochloride under alkaline conditions. Specifically, the core material solution (a mixture of sodium silicate and BTA) is dispersed in deionized water, and the pH is adjusted to 8.5-9.0 with Tris buffer solution. Then, dopamine hydrochloride is added and the mixture is continuously stirred. Under the action of dissolved oxygen, dopamine molecules form a dense shell on the surface of the core material droplets through an oxidative cross-linking reaction. Preferably, the polymerization reaction temperature is 25-35°C, and the reaction time is 4-8 hours to ensure the integrity and mechanical strength of the shell structure.

[0021] In this embodiment, the sodium silicate core material remains stable in a neutral environment. However, when the brazing area is affected by flux residue (such as Cl), the core material remains stable. - When the local pH decreases, the polydopamine shell undergoes protonation swelling and ruptures, releasing sodium silicate and BTA from the core material. Sodium silicate reacts with acidic substances (such as HCl and HF) to form a SiO2 protective film, which covers the substrate surface to block corrosive media; BTA, on the other hand, forms a passivation film by adsorbing onto the metal surface, further inhibiting electrochemical corrosion. The preferred mass ratio of sodium silicate to BTA in the core material is 9:1-19:1 to balance corrosion inhibition efficiency and core material loading.

[0022] In this embodiment, the microcapsules are incorporated by mixing them with potassium fluorochlorate-based flux powder. Preferably, the amount of microcapsules added is 5%-10% of the total mass of the flux to ensure effective coverage of the corrosion inhibitor. The mixing process uses a planetary ball mill with a ball-to-material ratio of 5:1-10:1, a rotation speed of 200-400 rpm, and a mixing time of 1-3 hours to achieve uniform dispersion of the microcapsules in the flux. During the ball milling process, the impact energy needs to be controlled to prevent premature rupture of the microcapsule shell due to mechanical force.

[0023] In this embodiment, the shell thickness adjustment coefficient α ranges from 0.1 to 0.3, and its value is related to the corrosion sensitivity of the brazing system. For high Cl... - For brazing environments with high corrosion content (such as marine applications), α = 0.3 is preferred to enhance the shell's thickening capability under high corrosion risk. The typical value for the baseline shell thickness d0 is 40-60 nm, calibrated by transmission electron microscopy (TEM) to ensure it is within a corrosion-free environment (P... c Even when the value is 0, the microcapsule still retains basic sealing properties.

[0024] S3. Optimize brazing process parameters through multi-parameter feedback; In this embodiment, the technical solution of optimizing brazing process parameters through multi-parameter feedback aims to monitor and dynamically adjust environmental and process parameters in real time to minimize corrosion risks during brazing. Specifically, this is achieved through the following technical solution: In this embodiment, multi-parameter feedback optimization includes real-time acquisition of ambient humidity, brazing seam temperature, and flux residue Cl. - Three key parameters are classified by concentration. Environmental humidity (RH) is monitored using a capacitive sensor, based on the characteristic that the dielectric constant changes with humidity. Preferably, the sensor probe is positioned within a 10-20cm radius around the brazing area to reflect the actual humidity of the brazing microenvironment. The brazing seam temperature (T) is measured using non-contact infrared thermometry. This involves capturing the infrared radiation intensity of the brazing seam area and retrieving the temperature value based on Planck's law. Preferably, the measurement points cover the front, middle, and rear sections along the length of the brazing seam, and the average value is used as the feedback signal. Flux residue Cl... - concentration The detection is achieved by X-ray fluorescence spectroscopy (XRF), which utilizes the linear relationship between the intensity and concentration of characteristic X-rays of Cl element for quantitative analysis. Preferably, the detection window is located on the surface of the substrate after the solder has solidified.

[0025] In this embodiment, a response surface model of corrosion rate (CR) is constructed based on multiple parameters, and its mathematical expression is as follows: Where k1, k2, and k3 are weight coefficients (calibrated through multiple linear regression, dimensionless); E a R is the activation energy of the corrosion reaction; T is the absolute temperature during brazing; RH is the ambient relative humidity. threshold This is the critical moisture absorption threshold. Cl in flux residue - The mass concentration.

[0026] The model uses exponential terms Describes the Arrhenius-type effect of temperature on corrosion rate, with the linear term |RH-RH threshold This reflects the accelerated corrosion effect when humidity deviates from the threshold. Term characterization Cl - The promoting effect of concentration on localized corrosion.

[0027] In this embodiment, the weighting coefficients k1, k2, and k3 are calibrated based on the mapping relationship between historical process data and corrosion rates. Preferably, the least squares method is used to fit the experimental data. In specific implementation, orthogonal experiments (temperature, humidity, Cl) are designed. - Multiple sets of measured corrosion rate values ​​were obtained using a three-factor, five-level concentration method, and the coefficient combination that minimizes the mean square error between the model prediction and the measured values ​​was determined. Activation energy E a The Tafel curves were obtained by testing with an electrochemical workstation. The preferred testing conditions were a simulated brazing environment (same temperature, humidity, and Cl₂). - (Concentration), scan rate set to 0.5mV / s.

[0028] In this embodiment, the process parameter optimization employs a simplex algorithm to search for the optimal solution set. The algorithm constructs an initial simplex (such as a hypergeometry composed of temperature, holding time, and flux dosage), iteratively calculates the corrosion rate value corresponding to each vertex, and reflects, expands, or contracts the simplex to approximate the optimal solution. Constraints include: a lower temperature limit T. min1 Determined by the liquidus temperature of the solder, the upper limit is T. max Limited by the thermal damage threshold of the substrate; Cl - Concentration threshold The algorithm is set based on the corrosion resistance of the substrate. Preferably, the algorithm terminates when the rate of change of the objective function is less than 1% for three consecutive iterations.

[0029] S4. Form a gradient wettability solder resist layer on the substrate surface and dynamically control the solder flow path; In this embodiment, the technical solution of forming a gradient wettability solder resist layer on the substrate surface and dynamically controlling the solder flow path aims to suppress excessive erosion of the substrate by molten solder through a combination of material design and external field control. Specifically, this is achieved through the following technical solution: In this embodiment, the gradient wettability solder resist layer is composed of a composite coating of nano-zinc oxide (ZnO) and polytetrafluoroethylene (PTFE). The nano-ZnO preferably has a particle size of 30-80 nm and is prepared by high-energy ball milling; its high surface energy enhances the adhesion between the coating and the substrate. PTFE, as a low surface energy component, is used to regulate the overall wettability of the coating. Preferably, the mass percentage of PTFE is 20%-40% of the total coating mass; by adjusting the ratio of the two components, a gradient change in wettability from the coating edge to the center is achieved.

[0030] In this embodiment, the gradient wettability solder resist layer is prepared by atmospheric plasma spraying. During the spraying process, a mixed powder of nano-ZnO and PTFE is fed into the plasma flame to form a coating structure with a compositional gradient on the substrate surface. Preferably, the spraying parameters include plasma power, spraying distance, and powder feed rate. By controlling the spraying speed v and angle θ, the local contact angle θ of the coating is adjusted. local The following relationship must be satisfied: Where, θ local θ is the contact angle of a local area on the substrate surface. max θ is the maximum contact angle at the edge of the coating. min θ is the minimum contact angle at the center of the coating; v is the plasma spraying speed; θ is the spraying angle; v0 is the reference spraying speed. Through the coupling effect of speed and angle, it quantifies the control effect of the spraying trajectory on the wettability distribution. The high contact angle area at the edge restricts the spread of the solder, while the low contact angle area at the center guides the solder to fill in the direction.

[0031] In this embodiment, dynamic control is achieved by applying an alternating electromagnetic field. The electromagnetic field frequency f is related to the brazing temperature T optimized in step S3. * Related, its calculation formula is: Where f is the electromagnetic field frequency; k is a constant related to the coating material; T * T represents the brazing temperature optimized using the simplex algorithm. min This is the critical temperature at which the wettability of the coating undergoes a sudden change.

[0032] Real-time frequency adjustment can alter the Lorentz force distribution within the molten solder, suppressing its penetration into the substrate grain boundaries or sensitive areas. Preferably, the electromagnetic field generator employs a ring coil structure, positioned 10-20 mm above the brazing area, with a magnetic field strength ranging from 0.1 to 0.5 T.

[0033] In this embodiment, the compositional gradient of the nano-ZnO / PTFE composite coating is achieved through a dual-channel powder feeding system. The first channel delivers ZnO-rich powder (ZnO content ≥ 80 wt%), and the second channel delivers PTFE-rich powder (PTFE content ≥ 70 wt%). By adjusting the powder feeding rate ratio of the two channels (e.g., 1:3 to 3:1), a gradient distribution of decreasing ZnO concentration and increasing PTFE concentration is formed on the substrate surface from the edge to the center. Preferably, the powder carrier gas is argon, and the flow rate is set to 3-5 L / min to ensure uniform powder transport.

[0034] S5. Post-brazing physical and chemical synergistic removal of residues; In this embodiment, the physicochemical synergistic removal of residues after brazing is achieved through the combined action of ultrasonic vibration and dry ice blasting. This aims to efficiently remove corrosive residues and solder resist fragments from the brazing seam and substrate surface, while avoiding secondary damage to the substrate. Specifically, this is achieved through the following technical solution: In this embodiment, ultrasonic vibration generates high-frequency mechanical vibration through a piezoelectric transducer, utilizing the cavitation effect to break the interfacial bond between the residue and the substrate. Preferably, the ultrasonic frequency is set to 20-40kHz, which balances cavitation intensity and penetration depth. The low-frequency range (20-28kHz) is suitable for removing large-particle residues, while the high-frequency range (35-40kHz) is suitable for removing micron-sized residues. The transducer power density is preferably 0.3-0.8W / cm³. 2 By adjusting the power output to match the peeling threshold of different residues, excessive energy can be avoided to prevent micro-cracks on the substrate surface.

[0035] In this embodiment, CO2 dry ice blasting uses high-pressure gas to drive solid dry ice particles to impact the surface of the residue, achieving residue removal through the synergistic effect of thermal stress and mechanical impact. The phase change endothermic effect of the dry ice particles can instantly lower the interface temperature between the residue and the substrate, weakening their bonding strength; simultaneously, the gas expansion generated by dry ice sublimation further exacerbates residue fragmentation. Preferably, the blasting pressure is set to 0.3-0.5 MPa, and the particle size is 0.5-1.5 mm to balance impact energy and coverage uniformity.

[0036] In this embodiment, the synergistic effect of ultrasound and dry ice blasting is achieved through a phased process. The first phase uses ultrasonic vibration to remove large-sized residues (such as unreacted flux clusters and microcapsule shell fragments), and the second phase uses dry ice blasting to remove submicron-sized residues (such as nano-ZnO particles and PTFE coating debris). Preferably, the two phases are separated by 5-10 seconds, and the residues loosened by ultrasonic vibration are removed by the sublimation airflow of dry ice, thus avoiding secondary deposition.

[0037] In this embodiment, the types of residues include sodium silicate reaction products (such as SiO2 gel) released from microcapsules in step S2, peeling fragments of the gradient solder resist layer (such as nano-ZnO / PTFE composite material) in step S4, and metal oxides (such as Al2O3) formed by solder oxidation. To optimize the impact contact area, the ultrasonic treatment time is preferably set to 2-5 minutes, and the dry ice spray angle is adjusted to 30° to 60°, taking into account the physicochemical properties of different residues.

[0038] In this embodiment, temperature control during the processing is achieved by real-time monitoring of the substrate surface temperature. Preferably, an infrared thermometer is used to provide temperature data. When the temperature exceeds 30% of the substrate recrystallization temperature, the processing is paused and a cooling air curtain (such as nitrogen injection) is activated to prevent heat accumulation from causing microstructure deterioration of the substrate.

[0039] In this embodiment, the process parameters are set based on factors including residue adhesion strength, substrate hardness, and thermal sensitivity. For high-hardness substrates (such as ceramic matrix composites), lower ultrasonic power (0.3-0.5 W / cm²) is preferred. 2 Use smaller dry ice particles (0.5-1.0 mm); for heat-sensitive substrates (such as magnesium alloys), shorten the single treatment time (1-3 minutes) and increase the cooling interval.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for inhibiting brazing corrosion, characterized in that, The method includes the following steps: Predicting the corrosion susceptibility of brazing systems based on thermodynamic phase diagrams; Dynamically release corrosion inhibitors based on the described corrosion tendency to neutralize corrosive substances; Optimize brazing process parameters through multi-parameter feedback; A gradient wettability solder resist layer is formed on the substrate surface and the solder flow path is dynamically controlled; The residue is removed by a combination of physical and chemical methods after brazing.

2. The brazing corrosion inhibition method according to claim 1, characterized in that, The thermodynamic phase diagram was constructed using the CALPHAD method, and corrosion susceptibility was expressed as a corrosion susceptibility index P. c Quantification, the calculation formula is: Where, x i This represents the mole fraction of the corrosion products. The standard Gibbs free energy change is given by R; the ideal gas constant is given by T; and the absolute temperature during brazing is given by P. c This is a corrosion tendency index.

3. The brazing corrosion inhibition method according to claim 1, characterized in that, The dynamic release corrosion inhibitor is achieved through pH-responsive microcapsules, which comprise a polydopamine shell and a sodium silicate core, wherein the shell thickness d satisfies: d=d0·(1+α·ln(P c +1)); Where d is the actual thickness of the polydopamine shell; d0 is the reference thickness of the shell; α is the shell thickness adjustment coefficient; P c is the corrosion tendency index; ln is the natural logarithm function.

4. The brazing corrosion inhibition method according to claim 1, characterized in that, The sodium silicate core material also contains benzotriazole, which accounts for 5%-15% of the sodium silicate by mass.

5. The brazing corrosion inhibition method according to claim 1, characterized in that, The multi-parameter feedback optimization includes real-time monitoring of the following parameters: Ambient humidity (RH) is measured using a capacitive sensor. The weld seam temperature T was obtained using an infrared thermometer. Flux residue Cl - Concentration C Cl - The X-ray fluorescence spectrometer was used for detection.

6. The brazing corrosion inhibition method according to claim 5, characterized in that, The optimal combination of process parameters is solved using the simplex algorithm, with the objective function being to minimize the corrosion rate CR. Where k1, k2, and k3 are weight coefficients (calibrated through multiple linear regression, dimensionless); E a RH is the activation energy of the corrosion reaction; R is the ideal gas constant; T is the absolute temperature during brazing; RH is the ambient relative humidity; threshold This is the critical moisture absorption threshold. Cl in flux residue - mass concentration; The constraints are: T min1 ≤T≤T max ; Where T is the absolute temperature during the brazing process, which is monitored in real time using an infrared thermometer; T min1 The minimum permissible temperature for brazing is determined by the melting point of the base material or the liquidus temperature of the brazing filler metal; T max This is the highest temperature allowed for the brazing process.

7. The brazing corrosion inhibition method according to claim 1, characterized in that, The gradient wettability solder resist layer is formed by plasma spraying a nano-ZnO / polytetrafluoroethylene composite coating, with a local contact angle θ local satisfy: Where, θ local θ is the contact angle of a local area on the substrate surface. max θ is the maximum contact angle at the edge of the coating. min θ is the minimum contact angle at the center of the coating; v is the plasma spraying speed; θ is the spraying angle; v0 is the reference spraying speed.

8. The brazing corrosion inhibition method according to claim 7, characterized in that, The nano-ZnO has a particle size of 30-80 nm, and the mass ratio of polytetrafluoroethylene is 20%-40% of the total mass of the coating.

9. The brazing corrosion inhibition method according to claim 1, characterized in that, The dynamic control is achieved through the electromagnetic field frequency f, which is related to the optimized brazing temperature T. * satisfy: Where f is the electromagnetic field frequency; k is a constant related to the coating material; T * T represents the brazing temperature optimized using the simplex algorithm. min This is the critical temperature at which the wettability of the coating undergoes a sudden change.

10. The brazing corrosion inhibition method according to claim 1, characterized in that, The physicochemical synergistic removal of residues includes: The applied frequency is 20-40kHz, and the power density is 0.3-0.8W / cm². 2 Ultrasonic vibration; CO2 dry ice injection is used, with an injection pressure of 0.3-0.5 MPa.

Images