A magnesium-silver alloy cleaning agent, a preparation method thereof and a cleaning method

Abstract

This invention relates to the field of metal surface treatment technology, and discloses a magnesium-silver alloy cleaning agent and its preparation and cleaning methods, comprising: a shear coupling step, in which dodecylamine and organophosphonic acid are mixed in an alcohol ether solvent at 60-65℃ and 2500-3000rpm under high shear to construct a high-energy acid-amine assemblage; a hysteresis locking step, in which the shear rate is maintained constant and the temperature is lowered to 35-40℃ at a rate of 1.5-2.0℃ / min to inhibit crystallization and lock it into a metastable precursor; and a dispersion stabilization step, in which a nonionic surfactant is added and dispersed to a semi-transparent state. This invention utilizes the rheological antagonistic mechanism of shear thinning and cooling viscosity increase to construct a metastable system with synchronous transport characteristics, eliminates the kinetic lag caused by preferential solvent wetting, realizes zero-time-difference synchronous adsorption of corrosion inhibitor and solvent on the magnesium-silver interface, and improves the storage stability of the cleaning agent.

Description

Technical Field

[0001] This invention relates to a magnesium-silver alloy cleaning agent and its preparation and cleaning methods, belonging to the field of metal surface treatment technology. Background Technology

[0002] Currently, magnesium-silver alloys, possessing both the biocompatibility of the magnesium matrix and the conductive and antibacterial properties of the silver phase, are used in the manufacture of precision electronic contacts and implantable medical devices. For the removal of oil and oxide scale from the surfaces of highly active biphase alloys, existing technologies typically employ a compound system containing organophosphonic acid anodic corrosion inhibitors and organic amine cathodic shielding agents. The industry-standard preparation method is a physical mixing method, where components are dissolved in alcohol-ether solvents by mechanical stirring at room or medium temperature. The acid-base neutralization products are then chemically adsorbed onto the metal surface to form a film that inhibits substrate corrosion during the cleaning process. However, when treating magnesium-silver pairs with high electrode potential differences, the physical mixing process for preparing the cleaning agent suffers from kinetic defects, as magnesium, as an active anode... There is a huge potential difference between the phase and the silver cathode phase. The initial stage of the cleaning solution wetting the metal surface is the critical window for corrosion control. In conventional physical mixing systems, the components exist in a discrete state. The diffusion coefficient of small molecule solvents with smaller hydrodynamic radii is much higher than that of large molecule corrosion inhibitors. The difference in physical properties causes solvent molecules to preferentially wet and spread on the metal surface. Corrosion inhibitor molecules do not reach the active sites in time to form a complete protective film. This results in a lag in wetting and adsorption kinetics, causing the highly active magnesium matrix to be briefly exposed to an environment lacking protective electrolyte in the initial stage of contact with the liquid. This activates the micro-battery circuit and triggers transient galvanic corrosion, leading to pitting corrosion or a decrease in gloss on the workpiece surface.

[0003] Addressing the challenges of cleaning reactive metals, even with the shift to alkaline cleaning systems, there are generally shortcomings in the technical approach. For example, Chinese invention patent CN112126936B discloses a high-efficiency surface cleaner for die-cast aluminum and magnesium alloys and its preparation method. The cleaner uses narrow-distribution fatty alcohol polyoxyethylene ether as the main surfactant, combined with sodium bicarbonate, sodium hydroxide, monoethanolamine, and sodium oxalate to construct an alkaline system. This solution aims to improve cleaning efficiency while reducing corrosion to the substrate through the compounding of specific alkaline substances. However, the technical solution remains at the level of physical mixing of components, lacking an understanding of the transient corrosion kinetics at the interface of reactive alloys. In actual cleaning, the small-molecule solvent in the cleaning solution preferentially wets the alloy surface. The large molecular corrosion inhibitors and surfactants responsible for corrosion protection have a time lag in reaching the active sites, resulting in transient galvanic corrosion caused by the micro-battery effect at the moment of wetting. This problem is particularly prominent when dealing with high potential difference magnesium alloys or complex structures where alloys are embedded with other metals. This physical mixture system based on thermodynamic stability is difficult to fundamentally solve the problem of interface protection lag in the early stage of cleaning. There are still problems in pursuing higher cleaning efficiency and longer bath life. The industry urgently needs cleaning agents and preparation methods that can change the microscopic existence state and transport characteristics of active components in the solvent system through preparation process control, eliminate interface protection lag in the early stage of cleaning, and maintain long-term homogeneous stability of the system at high concentrations.

[0004] Therefore, the technical problem to be solved by this invention is how to control the microscopic state and transport characteristics of the active component in the solvent system through the preparation process, so as to avoid the lag of interface protection in the early stage of cleaning and maintain the long-term homogeneous stability of the system at high concentrations. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A method for preparing a magnesium-silver alloy cleaning agent, the method comprising the following steps: constructing a rheologically locked metastable system to eliminate the kinetic time lag between solvent wetting and corrosion inhibitor adsorption.

[0006] In the shear coupling step, under constant temperature conditions of 60°C to 65°C, dodecylamine and organophosphonic acid are added sequentially to an alcohol ether solvent at a molar ratio of 1.1:1 to 1.3:1. Forced mixing is carried out at a shear rate of 2500 rpm to 3000 rpm. The high shear force forces the dodecylamine to overcome steric hindrance and insert into the molecular gaps of the organophosphonic acid until the dynamic viscosity of the system decreases to a stable value and transforms into a transparent homogeneous solution.

[0007] In the hysteresis locking step, while maintaining a constant shear rate in the shear coupling step, the transparent homogeneous solution is continuously cooled at a rate of 1.5°C to 2.0°C per minute. The continuous shear flow field is used to counteract the thermodynamic crystallization tendency of the reaction products formed by dodecylamine and organophosphonic acid during the cooling process. Shearing is stopped when the system temperature drops to the phase transition critical region of 35°C to 40°C, thereby freezing the reaction products into metastable precursors in a non-equilibrium state.

[0008] In the dispersion stabilization step, a nonionic surfactant is slowly added dropwise to the metastable precursor at a temperature of 35°C to 40°C while maintaining a low stirring speed of 200 rpm to 400 rpm. The metastable precursor is solvated and encapsulated by the nonionic surfactant until the system exhibits a translucent state with the Tyndall effect, thus obtaining a magnesium-silver alloy cleaning agent.

[0009] Preferably, in the shear coupling step, the organophosphonic acid is phytic acid or hydroxyethylidene diphosphonic acid, and the organophosphonic acid is pre-prepared as an aqueous solution with a concentration of 45% to 55% by weight before being added to the alcohol ether solvent; the dodecylamine is a white flaky crystal with a purity of not less than 98%; the duration of the shear coupling step is limited to 40 to 60 minutes to ensure that the dodecylamine and organophosphonic acid complete molecular-level association.

[0010] Preferably, the alcohol ether solvent is dipropylene glycol methyl ether or dipropylene glycol butyl ether, and the water content of the alcohol ether solvent is controlled to be less than 0.1% by weight. In the shear coupling step, the order of addition of dodecylamine and organophosphonic acid is as follows: dodecylamine is completely dissolved in the alcohol ether solvent, and an aqueous solution of organophosphonic acid is slowly added dropwise while maintaining the shear rate. The addition time is controlled between 20 and 30 minutes to prevent instantaneous gelation caused by excessively high local concentration.

[0011] Preferably, in the hysteresis locking step, to ensure that the metastable precursor structure does not undergo phase separation, the rate of continuous cooling is numerically... Numerical value of shear rate The following process constraints must be satisfied between them: ,in, The unit is revolutions per minute. The unit is degrees Celsius per minute; the process constraints limit the shear energy input density required per unit temperature drop, which is used to maintain the dispersion of reaction products during the process in which the viscosity of the system increases suddenly as the temperature decreases.

[0012] Preferably, the nonionic surfactant is selected from isomeric tridecyl alcohol polyoxyethylene ether or fatty alcohol polyoxyethylene ether, and its hydrophilic-lipophilic balance value is controlled in the range of 12 to 14; in the dispersion stabilization step, the amount of nonionic surfactant added is 5% to 10% of the total weight of the metastable precursor, and the dropping rate is controlled at 5 ml per minute to 10 ml per minute to maintain the homogeneous stability of the system.

[0013] Preferably, the method further includes a final formulation step: after the dispersion stabilization step is completed, a pH adjuster is added to the system to adjust the pH value of the system to the range of 8.5 to 9.5; the pH adjuster is monoethanolamine or triethanolamine; the adjusted magnesium-silver alloy cleaning agent is filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.2 micrometers to 0.5 micrometers to remove any trace mechanical impurities.

[0014] Preferably, the amount of alcohol ether solvent used in the preparation method is 70% to 85% of the total weight of the magnesium-silver alloy cleaning agent; the final surface tension of the magnesium-silver alloy cleaning agent is controlled within the range of 25 mN / m to 30 mN / m by the amount of nonionic surfactant added; the shear coupling step is carried out in a reactor equipped with a heating jacket and an online high-shear disperser, the stator-rotor gap of the high-shear disperser is set to 0.2 mm to 0.5 mm; a slightly positive pressure nitrogen atmosphere is maintained in the reactor to prevent dodecylamine from oxidizing and discoloring at high temperature.

[0015] Preferably, in the hysteresis locking step, when the system temperature drops to 35°C to 40°C, the solute in the metastable precursor is dispersed in the alcohol ether solvent in the form of solvated ion pairs with an average particle size of 10 nm to 100 nm, and this state is maintained for at least 24 hours without precipitation after shearing stops. The magnesium-silver alloy cleaning agent obtained by the preparation method is used to remove oil and oxide scale from the surface of magnesium-silver alloy precision electronic contacts or medical device components. During the cleaning process, the magnesium-silver alloy cleaning agent utilizes the synchronous adsorption characteristics of the metastable precursor to form an adsorption film while the solvent wets the metal surface, thereby inhibiting transient galvanic corrosion caused by preferential wetting by the solvent.

[0016] A magnesium-silver alloy cleaning agent, which is prepared by the method described above.

[0017] A cleaning method for a magnesium-silver alloy cleaning agent includes the step of cleaning the surface of a magnesium-silver alloy using the magnesium-silver alloy cleaning agent prepared by the aforementioned preparation method.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. In the preparation of magnesium-silver alloy cleaning agent, the metal-affinity properties of the shell of nonionic surfactant are used to confine the organic amine and organic phosphonic acid corrosion inhibitor components within a unified transport unit. This eliminates the interface protection lag caused by the small solvent molecules' wetting speed being greater than the large corrosion inhibitor molecules' diffusion speed in traditional physical mixing systems. In the instant the cleaning solution wets the magnesium-silver alloy surface, the active components arrive simultaneously with the solvent front and cover the active sites. A complete interface protective layer is formed before the electrolyte circuit is connected, blocking the establishment of transient galvanic corrosion circuits on the high potential difference alloy surface and avoiding microscopic corrosion in the early stage of the cleaning process.

[0020] 2. By utilizing the rheological counter-mechanical mechanism of shear thinning and cooling viscosity increase, a high shear effect is maintained in the critical temperature range where the system viscosity changes abruptly, suppressing the thermodynamic equilibrium crystallization tendency of the salt-forming components. The process forces organic amine molecules to avoid steric hindrance and embed themselves in the gaps of the organophosphonic acid framework, freezing the high-energy molecular arrangement in the metastable micelle system, preventing the precipitation of salt crystals and phase separation during the cooling process. The resulting cleaning agent is homogeneous and transparent, and maintains thermodynamic stability for a long time. This solves the problem of turbidity and precipitation that easily occurs in the preparation of high-concentration acid-base complex systems by conventional dissolution processes.

[0021] 3. Based on the process, a solvent cage structure is constructed to isolate the active acid and base groups inside by utilizing the steric hindrance effect. This blocks unexpected chemical condensation or side reactions between active components during storage and transportation. The microstructure keeps the active components in a latent state. When they enter the metal interface diffusion layer and are induced by changes in the interface pH microenvironment, the micelle structure dissociates and releases active ions. The interface-responsive on-demand release mechanism reduces the decay rate of active components in the non-working state of the cleaning agent, maintains the consistency of cleaning capacity and anti-corrosion performance in continuous operation cycles, and extends the replacement cycle of the cleaning tank solution. In response to the high potential difference characteristics of the magnesium-silver alloy system, a non-equilibrium system is prepared to achieve synchronous shielding of the anode and cathode. After the ion cluster interface dissociates, it forms an oxide film to repair the magnesium anode and an adsorption shield to form an adsorption shield for the silver cathode. The synchronous action avoids the preferential adsorption of a single component that induces a surge in local corrosion current density. While removing surface oil and oxide scale, it maintains the metallic luster and surface smoothness of the alloy matrix. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation process of the magnesium-silver alloy cleaning agent based on the shear coupling and hysteresis locking mechanism of the present invention.

[0023] Figure 2 This is a statistical diagram showing the nanoparticle size distribution of metastable solvated ion pair clusters in the cleaning agent of this invention;

[0024] Figure 3 This is a schematic diagram illustrating the interaction between cleaning agent preparation and precision cleaning operations using the integrated rheological closed-loop control of this invention. Detailed Implementation

[0025] This detailed description aims to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a magnesium-silver alloy cleaning agent, its preparation method, and a cleaning method thereof. The core of the preparation method lies in utilizing the rheological counter-mechanism of shear thinning and cooling viscosity increase to construct a metastable system with synchronous transport characteristics through strictly controlled process steps. The preparation process mainly includes three core stages: a shear coupling step, a hysteresis locking step, and a dispersion stabilization step. In the shear coupling step, high temperature and high shear forces amine molecules to overcome steric hindrance and embed into the phosphonic acid framework. In the hysteresis locking step, a continuous shear field counteracts the thermodynamic crystallization tendency during cooling, forcibly freezing the reaction products in a non-equilibrium state. In the dispersion stabilization step, the metastable precursor is transformed into a homogeneous and stable cleaning agent system through solvation encapsulation with a nonionic surfactant. This specific process sequence and conditions not only eliminate kinetic lag but also improve the thermodynamic stability of the cleaning agent during storage and transportation. Addressing the challenge of transient galvanic failure that easily occurs in magnesium-silver alloys in electrolyte environments, this invention reshapes the system through specific physical field intervention in the shear coupling step. In traditional physical mixing processes, the microscopic arrangement of molecules between organophosphonic acids and alkylamines usually only involves a simple acid-base neutralization reaction. The resulting salts are discretely distributed in the solvent, leading to pitting corrosion caused by the preferential wetting of metal surfaces by small-molecule solvents in the initial cleaning stage. The present invention constructs a high-energy acid-amine associative compound using the following procedure: In a reactor equipped with a heating jacket and an online high-shear disperser, the system temperature is kept constant between 60°C and 65°C. At this temperature, molecular thermal motion intensifies, and the hydrogen bond network within organophosphonic acid molecules weakens. Dodecylamine and organophosphonic acid are added to an alcohol ether solvent at a molar ratio of 1.1:1 to 1.3:1. The high-shear disperser is operated at a rate of 2500 rpm to 3000 rpm, generating a strong hydraulic shear field. This shear field forces dodecylamine molecules to overcome steric hindrance and forcibly embed into the intermolecular gaps of organophosphonic acid until the system changes from turbid to a transparent homogeneous solution. This process constructs a high-energy intercalated supramolecular structure, providing the necessary structural basis for subsequent metastable locking.

[0027] To prevent the aforementioned high-energy associative polymers from undergoing phase separation or crystallization during cooling due to thermodynamic drive, this embodiment of the invention introduces a hysteresis-locking step. During conventional natural cooling, solute molecules tend to rearrange to lower the system energy, thereby precipitating large-sized crystals and disrupting the microscopic uniformity of the precursor. The system employs the following procedure: while maintaining a shear rate of 2500 rpm to 3000 rpm, the system is continuously cooled at a rate of 1.5 °C / min to 2.0 °C / min. The system viscosity increases non-linearly exponentially with decreasing temperature. The continuously input high shear energy effectively counteracts the tendency for ordered packing between molecules. When the temperature drops to the phase transition critical region of 35 °C to 40 °C, the solute in the system is forcibly frozen in a submicron-level supersaturated non-equilibrium state, stopping the shearing. The resulting product is the metastable precursor locked in a solvent cage. This step successfully locks the special precursor constructed at high temperatures... The molecular configuration is retained at room temperature to prevent phase separation. After obtaining the metastable precursor, to ensure its long-term dispersion stability in the final cleaning agent system and improve interfacial activity, the embodiments of the present invention perform a dispersion stabilization step. Although the precursor is already in a metastable state, in the absence of effective isolation, solute molecules still have the risk of slow aggregation. The system adopts the following procedure: at a temperature of 35°C to 40°C, a nonionic surfactant is slowly added dropwise to the metastable precursor, with the drop rate controlled at 5 mL / min to 10 mL / min, while maintaining a low stirring speed of 200 rpm to 400 rpm. The nonionic surfactant molecules are rapidly adsorbed onto the interface of the metastable precursor, forming a solvated encapsulation layer, which transforms the precursor into a semi-transparent micelle system with Tyndall effect. This micelle structure ensures the homogeneous stability of the cleaning agent on a macroscopic level and constitutes independent units with synchronous transport characteristics on a microscopic level.

[0028] In this embodiment of the invention, phytic acid or hydroxyethylidene diphosphonic acid is preferably used, and it is pre-prepared as a 45wt% to 55wt% aqueous solution before being added to the reaction system. This specific concentration range and solvation state are beneficial for its dispersion and reaction in a high shear field. Dodecylamine is selected as white flaky crystals with a purity of not less than 98% to reduce the interference of impurities on the stability of the system. The duration of the shear coupling step is strictly limited to 40 to 60 minutes. This time window ensures the full progress of the intermolecular association reaction, while avoiding solvent evaporation or side reactions caused by excessive shearing. In the specific feeding operation, dipropylene glycol methyl ether or dipropylene glycol butyl ether is preferred as the alcohol ether solvent. Furthermore, the moisture content is controlled below 0.1 wt%. This extremely low moisture content is a prerequisite for maintaining ion pair stability and avoiding premature dissociation caused by water molecules. In the shear coupling step, a specific feeding sequence is followed: dodecylamine is completely dissolved in an alcohol ether solvent, and an organophosphonic acid aqueous solution is slowly added dropwise while maintaining a high shear rate. The addition time is controlled between 20 and 30 minutes. This acid-to-amine addition method, combined with high-shear stirring, effectively prevents instantaneous gelation caused by excessively high local concentrations, ensuring the homogeneity of the reaction system. To quantitatively describe the matching relationship between shear energy input and system viscosity change during cooling, the embodiments of this invention set a cooling rate. (Unit: °C / min) and shear rate Process constraints between (unit: rpm): This ratio defines the shear energy input density required per unit temperature drop. When this ratio is within a certain range, the input mechanical energy is just enough to overcome the barrier to the formation of long-range ordered structures between molecules and maintain the dispersion state of the reaction products during the sudden increase in viscosity.

[0029] In the dispersion and stabilization step, the nonionic surfactant used is isomeric tridecyl alcohol polyoxyethylene ether or fatty alcohol polyoxyethylene ether, with its hydrophilic-lipophilic balance (HLB) controlled within the range of 12 to 14. This HLB range allows it to effectively encapsulate polar acid amine associates while also dispersing well in weakly polar alcohol ether solvents. The amount of nonionic surfactant added is 5 wt% to 10 wt% of the total weight of the metastable precursor. This amount is sufficient to form a complete protective layer without causing surface residue after washing due to excessive addition. In the final preparation stage, the pH of the system is finely adjusted to the range of 8.5 to 9.5 (measured at 25°C) by adding a pH adjuster. The pH adjuster used is monoethanolamine or triethanolamine. This weakly alkaline environment is suitable for organophosphorus compounds. The optimal pH window for acid corrosion inhibition efficiency is found, which also helps maintain the passivation state of the magnesium alloy surface. Finally, the product is filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.2μm to 0.5μm to remove any possible trace mechanical impurities, thus obtaining the finished magnesium-silver alloy cleaning agent. The cleaning agent prepared by this invention is microscopically composed of solvated ion clusters with an average particle size of 10nm to 100nm dispersed in the solvent. When cleaning precision electronic contacts or medical device components of magnesium-silver alloys, the corrosion-inhibiting components are simultaneously adsorbed onto the interface along with the solvent the instant the cleaning agent wets the metal surface. With the induction of the interface microenvironment, such as pH or potential, the ion clusters dissociate in situ, achieving zero-time-difference shielding protection for the magnesium anode and silver cathode, respectively, and inhibiting transient galvanic corrosion caused by preferential wetting by the solvent.

[0030] Example 1: In a real industrial scenario of precision electronic contact manufacturing, the production line faces the challenge of cleaning magnesium-silver alloy micro relay contacts. These contacts are composed of a highly active magnesium matrix tightly embedded with a precious silver phase. Their surfaces are covered with oil stains and oxide scale generated during stamping. When conventional physical cleaning agents are used, pitting corrosion occurs on the contact surface the instant it comes into contact with the cleaning solution, leading to unstable contact resistance and severely affecting the long-term reliability of the relay. This application-level obstacle stems directly from the kinetic time lag where the small molecules of the solvent in conventional cleaning agents wet faster than the diffusion rate of the large molecules of corrosion inhibitors. This causes the magnesium matrix to be exposed to the electrolyte environment first without protection, thus connecting the magnesium-silver micro-battery circuit. To address this challenge, this example uses a specially prepared magnesium-silver alloy cleaning agent. During the cleaning process, this cleaning agent is not a simple mixed solution. Instead of acting on the metal surface, the cleaning agent relies on the solvated ion clusters constructed internally through shear coupling and hysteresis locking processes to play a crucial role. When the cleaning agent is sprayed onto the magnesium-silver alloy surface, the solvated ion clusters utilize the metal-philic properties of their outer nonionic surfactants to maintain a strictly synchronized transport state with the solvent front. This synchronicity eliminates the time window for the solvent to wet the metal surface alone, ensuring that the corrosion inhibitor reaches the active site at the same moment the solvent contacts the metal. At this time, the pH jump of the interfacial microenvironment induces the metastable ion clusters to dissociate in situ. The released organophosphonate ions rapidly coordinate with the metal ions on the magnesium anode surface to form a film, while the dissociated long-chain alkylamines cover the silver cathode surface through electrostatic adsorption. This dual-synchronous interfacial response mechanism blocks the charge transfer channel before the electrolyte circuit is fully conductive, inhibiting the occurrence of transient galvanic corrosion.

[0031] After being treated with this cleaning agent, the miniature relay contacts not only have oil and oxide scale removed, but also retain their original metallic luster and smoothness. No pitting or decrease in gloss was observed. Subsequent electrical performance tests showed that the root mean square deviation of the contact resistance was reduced, meeting the stringent requirements of high-precision electronic devices for surface integrity.

[0032] Example 2: To verify the kinetic advantages and stability of the metastable ion-pair cluster system in actual cleaning processes and to evaluate its technical effectiveness in addressing the high potential difference corrosion problem of magnesium-silver alloys, this example establishes a comparative experimental scheme. The experiment simulates industrial cleaning conditions. The experimental platform uses an ultrasonic cleaning tank equipped with a temperature control and online electrochemical monitoring system. The tank has a volume of 50L, the ultrasonic frequency is set to 40kHz, and the power density is 0.5W / cm². For the test object, uniformly sized magnesium-silver alloy Mg90-Ag10 sample pieces are selected. The surface is pre-treated with standardized oil coating at a coating amount of 0.5mg / cm². To capture the transient corrosion behavior in the initial stage of cleaning, the experiment... High-frequency electrochemical noise monitoring technology was used, with a sampling frequency set to 100Hz, which can identify microsecond-level potential fluctuations and current surges. To demonstrate the technical effect of the present invention, multiple parallel experiments were designed, including the present invention sample group, the comparative sample group, conventional physical mixing, and control groups with multiple parameter deviations. The specific group settings and key parameters are shown in Table 1. The present invention sample group was prepared according to the shear coupling and hysteresis locking process described in the specific implementation method. The comparative sample group used the same raw material components, but only underwent conventional mechanical stirring and mixing, without experiencing high-temperature shearing and hysteresis cooling processes. Control groups A and B were set beyond the range for the process parameter of the ratio of cooling rate to shear rate.

[0033] Table 1: Experimental Grouping and Key Parameter Settings

[0034]

[0035] After the experiment was started, the cleaning agents of each group were injected into the cleaning tank and heated to a working temperature of 50°C. The pretreated magnesium-silver alloy sample was completely immersed in the cleaning solution, and ultrasonic cleaning and electrochemical monitoring were started simultaneously. During the first 60 seconds of the cleaning process, the instantaneous peak value of the corrosion current density and the fluctuation amplitude of the potential noise were monitored. The test results showed differences. For the comparative sample group, in the first 50ms to 100ms after the sample came into contact with the cleaning solution, the monitoring system captured a negative potential shift with an amplitude of more than 150mV and a current pulse with a peak current density of 25μA / cm². This indicates that the solvent molecules preferentially wet the magnesium matrix, connect the corrosion microcell, and induce transient galvanic corrosion. In contrast, the potential fluctuation of the sample group of this invention was extremely small in the same time window, less than 10mV, and the current density was maintained at the background noise level, less than 0.5μA / cm².

[0036] Further comparison with the control group data revealed, as shown in Table 2, that the performance of the cleaning agent deteriorated when the process parameters deviated from the range defined in this invention. In control group A, the cooling rate was too fast, resulting in insufficient shear energy input and a ratio of 933 less than 1200, which led to the failure of the precursor to be effectively locked, resulting in the precipitation of tiny crystals in the system. Its transient corrosion inhibition ability decreased, and the peak corrosion current rebounded to 12.5 μA / cm². Although control group B had sufficient shear energy and a ratio of 3000 greater than 2000, the excessively long shearing time led to the evaporation of some solvents and the degradation of components. Slight organic residue spots appeared on the surface of the cleaned sample, and the cleaning agent showed slight stratification after standing for 48 hours.

[0037] Table 2: Comparison of Key Performance Indicator Test Results

[0038]

[0039] Based on the above data, it can be concluded that this invention, through specific shear coupling and hysteresis locking processes, constructs a metastable system capable of eliminating dynamic time delays, and the defined range of process parameters, in particular... The critical window is the key to ensuring the optimal performance of the system. Below the lower limit of the window, crystallization cannot be effectively suppressed, while above the upper limit of the window, stability problems will occur. Only within the limited range can the best balance be achieved in suppressing transient corrosion, maintaining surface gloss, and maintaining system stability.

[0040] Example 3: This example combines Figures 1 to 3 This document describes a magnesium-silver alloy cleaning agent, its preparation method, and the cleaning method thereof. Figure 1 As shown, dodecylamine is completely dissolved in alcohol ether solvents in a non-crystalline state. Organophosphonic acid is pre-prepared as a 45-55 wt% aqueous solution. The reaction system enters a shear coupling step, where, under conditions of 60-65℃ and 2500-3000 rpm, a high-energy acid-amine associative complex is constructed by overcoming steric hindrance and forced molecular intercalation. This is followed by a hysteresis-locking step, where, under the constraint of the rheological parameter control module—specifically, by the shear / cooling ratio constraint—the energy input per unit temperature drop is ensured, maintaining a high shear rate at 1.5-2.0℃ / min. The temperature is gradually reduced to a certain rate, and rheological resistance is used to suppress thermodynamic crystallization, producing a metastable precursor at a temperature of 35-40℃. A dispersion stabilization step is performed by slowly adding a nonionic surfactant and solvating it under low-speed stirring at 200-400 rpm to form a semi-transparent homogeneous micelle system with a solvent cage structure. Finally, in a formulation step, the pH is adjusted to 8.5-9.5 using monoethanolamine or triethanolamine, and mechanical impurities are removed by 0.2-0.5μm precision filtration, ultimately obtaining a metastable magnesium-silver alloy cleaning agent with synchronous transport characteristics.

[0041] like Figure 2 As shown, the vertical axis represents the particle size range in nm, and the horizontal axis represents the percentage of particles in %. Statistical data indicates that the particle size in the system is entirely distributed within the range of 10 nm to 100 nm. The distribution within each range exhibits a discrete bar chart pattern, covering the smallest 10-20 nm range to the largest 90-100 nm range, with the 30-40 nm particle size range being the dominant percentage. Figure 3 As shown, the process engineer, as the main executor, is responsible for preparing the magnesium-silver alloy cleaning agent. The operation path sequentially includes performing a shear coupling step to construct a high-energy acid-amine associative compound, performing a hysteresis-locking step to inhibit crystallization and freeze the metastable state, and performing a dispersion stabilization step to achieve solvation encapsulation and present a semi-transparent state. In this preparation process, the intelligent control system intervenes and performs online monitoring and feedback, implements closed-loop control of rheological parameters, focuses on regulating the shear / cooling rate ratio, and finally the cleaning operator performs a precision cleaning operation, using the cleaning agent to achieve synchronous adsorption at the interface to eliminate kinetic time lag.

[0042] Example 4: In the industrial implementation of precision cleaning processes, the flow field distribution, temperature gradient, and dynamic balance of component concentrations within the cleaning tank directly determine the consistency of cleaning results and the service life of the tank solution. To address potential issues arising from laboratory-scale parameters during engineering scale-up, this example constructs a systematic process control procedure based on online monitoring and feedback adjustment. This procedure establishes a quantitative correlation between key physicochemical parameters and cleaning performance to intervene in the cleaning process, ensuring that the cleaning agent remains within its optimal operating window even in complex and variable production environments. Addressing potential component concentration fluctuations and impurity accumulation during cleaning, this procedure employs a dynamic balance control strategy. It uses an online conductivity meter and refractometer to monitor the total ion concentration and refractive index of the tank solution in real time. Using a pre-calibrated standard curve, the real-time concentration of active components (organophosphonic acid and alkylamine) in the cleaning agent is calculated. If the monitored value deviates from the set range... The automatic replenishment system is immediately activated, injecting concentrated solution or deionized water according to the precisely calculated replenishment amount to maintain a constant component concentration. At the same time, the turbidity sensor continuously monitors the content of suspended particulate matter in the tank solution. When the turbidity exceeds the critical threshold, the circulation filtration system is automatically triggered to remove micron-sized impurities through multi-stage precision filter elements, preventing them from being deposited secondary on the workpiece surface.

[0043] To address the common issue of uneven temperature and flow field in large cleaning tanks, this procedure introduces a multi-point temperature control and variable frequency ultrasonic synergy mechanism. Multiple high-precision temperature sensors are deployed at different depths and locations within the tank. A PLC control system adjusts the heating power in zones to ensure the overall temperature difference of the tank solution is controlled within a specified range. Within a certain range, the cleaning efficiency difference caused by temperature gradient is eliminated. Furthermore, a swept-frequency ultrasonic generator is used to periodically change the ultrasonic frequency within a certain range, eliminating the standing wave blind zone in the tank and ensuring that the cavitation effect is evenly distributed across all surfaces of the workpiece. This ensures that even deep holes and blind holes with complex geometries can be thoroughly cleaned. To quantitatively evaluate the actual effectiveness of the above process control procedure, a long-term continuous production verification test was conducted. During 30 days of continuous operation, the system processed standard load magnesium-silver alloy workpieces daily, and samples of the tank solution were periodically taken for physicochemical index analysis. Simultaneously, the surface quality of the cleaned workpieces was inspected. The test data shows that after applying this control procedure, the concentration fluctuation of the active components in the tank solution was effectively controlled within a certain range. Within this period, the turbidity of the bath solution remained at a low level, with no obvious accumulation of impurities. The root mean square deviation of the surface contact resistance of the workpiece after cleaning was further reduced, and it remained highly stable throughout the entire test cycle, without any decline in cleaning quality due to bath solution aging.

[0044] Example 5: To avoid applicability issues of process parameters due to differences in equipment specifications under different industrial environments, this example establishes a systematic offline calibration and data filling procedure. This procedure aims to map the ideal parameter set optimized in the laboratory into engineering control commands suitable for specific production lines by constructing a standardized parameter response model. A set of gradient-varying temperatures (40-70℃), shear rates (2000-3500rpm), and ultrasonic power densities (0.3-0.8W / cm²) are selected as input variables. A full-factor orthogonal experiment is conducted on a standard testing platform, recording the turbidity change rate, pH stability, and corrosion current density of the cleaning agent on standard magnesium-silver test pieces under each condition. Based on the experimental data, a functional relationship model between key performance indicators and process parameters is established using multiple linear regression analysis. ,in For performance indicators, These parameters are temperature, shear rate, and power density, respectively. This model, as the core algorithm, is embedded in the preset database of the industrial control system, enabling the system to automatically retrieve and lock the optimal combination of process parameters based on real-time monitored environmental variables.

[0045] To address the potential microstructural relaxation of cleaning agents after long-term storage or transportation, this embodiment establishes a pre-deployment calibration procedure. Before the cleaning agent is put into formal use, a thermodynamic state awakening procedure must be performed. Specifically, the cleaning agent in the storage tank is introduced into the circulation pipeline, and an online high-shear disperser is turned on to perform low-energy shear treatment at a rate of 1500 rpm for 30 minutes. Simultaneously, the system temperature is slowly increased to the operating temperature at a rate of 0.5℃ / min. This process utilizes shear input energy to reactivate the metastable structure of ion-pair clusters, eliminating the tendency for microphase separation caused by static storage. Samples are taken to test the Tyndall effect intensity and conductivity. If the indicators deviate from the standard value by more than [a certain amount], [further action is taken]. If the micro-addition program is automatically triggered, a premixed nonionic surfactant concentrate will be injected for modification until all physicochemical indicators return to the baseline range.

[0046] Example 6: In a large-scale continuous industrial cleaning line scenario, the system faces the risk of process parameter drift due to batch fluctuations in raw materials and seasonal changes in ambient temperature. To ensure the reproducibility and stability of the cleaning process, this example establishes a standardized pre-deployment calibration and process control procedure. This procedure performs a key physicochemical baseline test on each batch of newly purchased organophosphonic acid and alkylamine raw materials, using a high-precision automatic potentiometric titrator to determine the molar equivalent of their active functional groups and comparing it with the benchmark values ​​in the standard database. If the absolute value of the deviation exceeds... The system automatically corrects the mass flow meter settings in the subsequent batching system based on the deviation to compensate for the molar ratio imbalance caused by fluctuations in raw material purity. Before the production line is officially started, an online calibration process based on rheological response must be performed. The system heats the solvent in the reactor to the preset process temperature and adjusts the speed of the high-shear disperser in a gradient manner. At the same time, the apparent viscosity of the system is monitored in real time using an online viscometer. When the shear rate reaches the critical value, the viscosity of the system will show a characteristic nonlinear decreasing inflection point. The shear rate corresponding to this inflection point is locked by the system as the optimal shear parameter under the current environment.

[0047] To address potential abnormal conditions during the cleaning process, this procedure integrates an adaptive fault-tolerant mechanism based on multi-sensor fusion. The system collects real-time data on the pH, conductivity, and turbidity of the tank solution and inputs this data to the logic discrimination module of the central control unit. If a unidirectional pH drift is detected and its rate exceeds [a certain threshold], [the system will take action]. The system not only automatically triggers the pH adjuster metering pump for compensation, but also synchronously adjusts the flow rate of the circulation pump to enhance the mixing effect of the tank solution and prevent local concentration polarization. At the same time, if the turbidity sensor detects a sudden increase, the system will immediately switch to a backup set of high-precision filtration units and automatically adjust the power distribution of the ultrasonic generator to suppress secondary agglomeration of particles. This series of automated response strategies based on deterministic input and quantization logic gates enables the cleaning system to autonomously maintain itself in the optimal operating range without human intervention.

[0048] Example 7: This example describes a method for preparing a magnesium-silver alloy cleaning agent. High-energy molecule construction, rheological hysteresis locking, and online robustness calibration are integrated into an automated control system. Before batch production, a standardized critical viscosity calibration procedure is used to pre-calibrate the process boundaries: a reaction vessel equipped with an online high-shear disperser and a high-precision online viscosity sensor is used. After shear coupling is completed, the shear rate is systematically changed. With cooling rate The combination of these factors records the inflection point of nonlinear exponential growth in system viscosity or when turbidity exceeds a certain threshold. The critical value at which the shear / cooling ratio is determined; the critical value determines the shear / cooling ratio. The critical range is to This range defines the shear energy input density required to maintain the dispersion of the system.

[0049] To eliminate equipment deviation, before the hysteresis locking step, the controller initiates online rheological calibration: the system uses... Rate gradient increasing shear rate Simultaneously, the apparent viscosity is calculated in real time using a torque sensor. ;when Follow When the rate of change reaches a non-linear decreasing inflection point (the second derivative first drops to zero), the point corresponding to this inflection point is... Locked to the critical shear rate of the system The actual hysteresis locking step The range of values ​​is Between; after the cleaning agent is put into use, the system uses multiple sensors (conductivity) Refractive index ) Activate adaptive correction mechanism: Perform adaptive correction on each batch of new solution. , and amine molar concentration Physicochemical baseline calibration; systematic periodic monitoring of the tank solution. and When any relative deviation exceeds When this occurs, an automatic replenishment correction is triggered; the correction system calculates the required replenishment volume of concentrated ions to the premixed solution based on the dilution law. This makes it linearly proportional to the conductivity deviation; when the refractive index deviates by more than [a certain amount]... At that time, based on the preset refractive index-ratio correction curve, nonionic surfactants or deionized water are automatically metered and added. Through this mechanism, the fluctuation range of the active component concentration in the bath solution is controlled within a certain range. Within.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a magnesium-silver alloy cleaning agent, characterized in that, The method eliminates the kinetic time lag between solvent wetting and corrosion inhibitor adsorption by constructing a rheologically locked metastable system, and includes the following steps: In the shear coupling step, under constant temperature conditions of 60°C to 65°C, dodecylamine and organophosphonic acid are added sequentially to an alcohol ether solvent at a molar ratio of 1.1:1 to 1.3:

1. Forced mixing is carried out at a shear rate of 2500 rpm to 3000 rpm. The high shear force forces the dodecylamine to overcome steric hindrance and insert into the molecular gaps of the organophosphonic acid until the dynamic viscosity of the system decreases to a stable value and transforms into a transparent homogeneous solution. In the hysteresis locking step, while maintaining a constant shear rate in the shear coupling step, the transparent homogeneous solution is continuously cooled at a rate of 1.5°C to 2.0°C per minute. The continuous shear flow field is used to counteract the thermodynamic crystallization tendency of the reaction products formed by dodecylamine and organophosphonic acid during the cooling process. Shearing is stopped when the system temperature drops to the phase transition critical region of 35°C to 40°C, thereby freezing the reaction products into metastable precursors in a non-equilibrium state. In the dispersion stabilization step, a nonionic surfactant is slowly added dropwise to the metastable precursor at a temperature of 35°C to 40°C while maintaining a low stirring speed of 200 rpm to 400 rpm. The metastable precursor is solvated and encapsulated by the nonionic surfactant until the system exhibits a translucent state with the Tyndall effect, thus obtaining a magnesium-silver alloy cleaning agent.

2. The preparation method of the magnesium-silver alloy cleaning agent according to claim 1, characterized in that, In the shear coupling step, the organophosphonic acid is selected from phytic acid or hydroxyethylidene diphosphonic acid, and the organophosphonic acid is prepared in advance as an aqueous solution with a concentration of 45% to 55% by weight before being added to the alcohol ether solvent; the dodecylamine is a white flaky crystal with a purity of not less than 98%; the duration of the shear coupling step is limited to 40 to 60 minutes.

3. The method for preparing a magnesium-silver alloy cleaning agent according to claim 1, characterized in that, The alcohol ether solvent is selected as dipropylene glycol methyl ether or dipropylene glycol butyl ether, and the water content of the alcohol ether solvent is controlled to be less than 0.1% by weight. In the shear coupling step, the order of addition of dodecylamine and organophosphonic acid is as follows: dodecylamine is completely dissolved in alcohol ether solvent, and while maintaining the shear rate, an aqueous solution of organophosphonic acid is slowly added dropwise, with the addition time controlled between 20 and 30 minutes.

4. The preparation method of the magnesium-silver alloy cleaning agent according to claim 1, characterized in that, In the hysteresis-locking step, to ensure that the metastable precursor does not undergo phase separation, the numerical value of the rate of continuous cooling is... Numerical value of shear rate The following process constraints must be satisfied between them: ,in, The unit is revolutions per minute. The unit is degrees Celsius per minute; the process constraints limit the shear energy input density required per unit temperature drop, which is used to maintain the dispersion of reaction products during the process in which the viscosity of the system increases suddenly as the temperature decreases.

5. The method for preparing a magnesium-silver alloy cleaning agent according to claim 1, characterized in that, The nonionic surfactant is selected from isomeric tridecyl alcohol polyoxyethylene ether or fatty alcohol polyoxyethylene ether, and the hydrophilic-lipophilic balance value is controlled in the range of 12 to 14. In the dispersion stabilization step, the amount of nonionic surfactant added is 5% to 10% of the total weight of the metastable precursor, and the dropping rate is controlled at 5 ml per minute to 10 ml per minute.

6. The method for preparing a magnesium-silver alloy cleaning agent according to claim 1, characterized in that, The method also includes a final formulation step: after the dispersion stabilization step is completed, a pH adjuster is added to the system to adjust the pH value of the system to the range of 8.5 to 9.5; the pH adjuster is monoethanolamine or triethanolamine; the adjusted magnesium-silver alloy cleaning agent is filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.2 micrometers to 0.5 micrometers.

7. The method for preparing a magnesium-silver alloy cleaning agent according to claim 1, characterized in that, The amount of alcohol ether solvent used in the preparation method is 70% to 85% of the total weight of the magnesium-silver alloy cleaning agent; the final surface tension of the magnesium-silver alloy cleaning agent is controlled within the range of 25 mN / m to 30 mN / m by the amount of nonionic surfactant added; the shear coupling step is carried out in a reactor with a heating jacket and an online high-shear disperser, the stator-rotor gap of the high-shear disperser is set to 0.2 mm to 0.5 mm.

8. The method for preparing a magnesium-silver alloy cleaning agent according to claim 1, characterized in that, In the hysteresis locking step, when the system temperature drops to 35°C to 40°C, the solute in the metastable precursor is dispersed in the alcohol ether solvent in the form of solvated ion pairs with an average particle size of 10 nm to 100 nm. This state is maintained for at least 24 hours after shearing stops without precipitation. The magnesium-silver alloy cleaning agent obtained by the preparation method is used to remove oil and oxide scale from the surface of magnesium-silver alloy precision electronic contacts or medical device components. During the cleaning process, the magnesium-silver alloy cleaning agent utilizes the synchronous adsorption characteristics of the metastable precursor to form an adsorption film while the solvent wets the metal surface.

9. A magnesium-silver alloy cleaning agent, characterized in that, The magnesium-silver alloy cleaning agent is prepared by the preparation method of the magnesium-silver alloy cleaning agent according to claim 1.

10. A cleaning method for a magnesium-silver alloy cleaning agent, characterized in that, The method includes the step of cleaning the surface of a magnesium-silver alloy using a magnesium-silver alloy cleaning agent prepared by the preparation method described in claim 1.

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