An environment-friendly cleaning agent for bismuth-substituted terbium iron garnet Faraday rotator and a cleaning method thereof

Abstract

The present application relates to the technical field of precision cleaning agent for optical communication devices, and particularly relates to an environmentally-friendly cleaning agent for Bi-substituted Tb-Fe-Ga garnet Faraday rotator and a cleaning method thereof. The environmentally-friendly cleaning agent is composed of the following components by weight percentage: phosphate ester-based surfactant 1.0-5.0 wt%, wetting agent 0.5-3.0 wt%, diol bisether derivative 3.0-10.0 wt%, green chelating agent 4.0-15.0 wt%, citric acid 2.0-5.0 wt%, polyquaternary ammonium salt polymer 0.5-1.5 wt%, and the rest is deionized water, with pH value being 8.5-10.5. Through low, medium and high three-level ultrasonic wave from coarse to fine step-by-step transition, combined with high-pressure spraying, four-stage counterflow overflow rinsing, slow lifting dehydration and centrifugal drying, it is ensured that the surface is free of residue and water stains, and the requirements of ultra-high cleanliness before coating are met, and the process is safe, environmentally-friendly, stable and controllable.

Description

Technical Field

[0001] This invention relates to the field of precision cleaning agents for optical communication devices, and in particular to an environmentally friendly cleaning agent and cleaning method for bismuth-substituted terbium-iron-garnet Faraday rotating plates. Background Technology

[0002] Faraday rotators are core components of optical communication devices (such as optical isolators and circulators), and their performance directly depends on a flawless optical surface. Any minute contaminants, such as dust, polishing residue, or fingerprints, can lead to light scattering, increased energy loss, and even device damage. Faraday rotators are typically fabricated using bismuth-substituted rare-earth iron garnet single crystals. This material exhibits a significant Faraday enhancement effect in the near-infrared communication band (e.g., 1550 nm). Cleaning after polishing is a crucial step before coating; if residual polishing fluid particles are not thoroughly removed, they will severely affect coating adhesion and the final optical performance of the device.

[0003] In existing technologies, the cleaning of Faraday rotation plates mainly suffers from the following problems: Chinese invention patent CN106238402A discloses a cleaning method for Faraday particles, using a neutral cleaning agent combined with ultrasonic cleaning. However, this method is not effective for cleaning nano- to submicron-sized fine polishing fluid particles. This patent uses alcohol cleaning followed by infrared lamp baking, posing significant safety hazards. Furthermore, this patent removes debris using silicone adhesive, increasing process complexity and contamination risks. In actual production, some factories manually wipe Faraday rotation plates with alcohol, resulting in extremely low cleaning efficiency and inconsistent wiping force, easily causing surface scratches or incomplete cleaning.

[0004] In the field of optical glass cleaning agents, there are research reports involving phosphate ester-based surfactants. For example, some studies have indicated that phosphate ester-based formulations combined with tripolyphosphates can achieve superior cleaning effects compared to other types of surfactants during the chemical cleaning of glass lenses. Furthermore, peel-off water-based optical glass cleaning agents utilize combinations of isomeric alcohol polyoxyethylene ether phosphates and polyquaternary ammonium salts. However, none of these technologies are specifically designed for the surface contaminant characteristics (oxide particles containing elements such as Mg and Tc) of bismuth-substituted terbium-iron garnet, nor do they solve the dual challenges of particle re-adhesion and substrate protection during the cleaning process. Summary of the Invention

[0005] To meet the stringent requirements of efficient removal of nanoscale polishing particles, non-damaging optical surface, prevention of particle back-adhesion, and protection of magneto-optical properties during the precision cleaning of bismuth-substituted terbium-iron garnet Faraday rotation plates before coating, while overcoming the shortcomings of existing cleaning agents that are not thorough, have cumbersome processes, and pose significant safety hazards, this application provides an environmentally friendly cleaning agent and cleaning method for bismuth-substituted terbium-iron garnet Faraday rotation plates.

[0006] In a first aspect, this application provides an environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates, comprising the following components by weight percentage: Phosphate ester-based surfactants: 1.0-5.0 wt%; Wetting agent 0.5-3.0 wt%; Diol diether derivatives 3.0-10.0 wt%; Green chelating agent 4.0-15.0 wt%; Citric acid 2.0-5.0 wt%; Polyquaternary ammonium salt polymers 0.5-1.5 wt%; The remainder is deionized water; The pH value of the cleaning agent is 8.5-10.5; The phosphate-based surfactant is selected from one or more of alkyl phosphate salts and alkyl polyoxyethylene ether phosphate salts.

[0007] A three-pronged cleaning mechanism of "targeted stripping, synergistic chelation, and anti-redeposition" was constructed by combining a synergistic chelation system of phosphate-based surfactants, green chelating agents, and citric acid, polyquaternary ammonium salt polymers, wetting agents, and glycol diether derivatives. Specifically, the phosphate ester groups (-PO4) in the phosphate-based surfactant molecules exhibit strong complexing-stripping ability against polishing residue particles of metal oxides, mainly composed of Mg, Te, and Er, on the surface of the Faraday rotation plate, effectively separating the particles from the substrate surface. The synergistic chelation system formed by the combination of the green chelating agent and citric acid efficiently chelates the stripped Mg particles through a multidentate coordination structure. 2+ Metal ions dissolve oxide particles into soluble ions, preventing their redeposition. Simultaneously, polyquaternary ammonium salt polymers neutralize the negative charge of the polishing particles with their cationic groups, and the steric hindrance of the polymer chains keeps the stripped particles stably suspended in the cleaning solution. These three components work synergistically to achieve a complete "stripping-dissolution-suspension" cleaning chain. Furthermore, wetting agents effectively reduce the surface tension of the cleaning solution and enhance wetting and penetration capabilities. Diol diether derivatives dissolve organic contaminants and assist in surfactant dispersion. The weakly alkaline system provides sufficient cleaning power while exhibiting no chemical corrosion to the bismuth-substituted terbium-iron garnet substrate. Each component functions independently while working together synergistically to achieve highly efficient removal of nanoscale polishing particles from the Faraday rotation plate surface. This effectively prevents particle re-adhesion, protects the optical surface integrity and magneto-optical properties of the substrate, and is safe, environmentally friendly, and simple to process, demonstrating excellent industrial application prospects.

[0008] Preferably, the phosphate-based surfactant is selected from potassium isotridecyl ether phosphate or C6-16 perfluoroalkyl ethanol phosphate ammonium salt.

[0009] Through the above technical solutions, both potassium isotridecyl ether phosphate and C6-16 perfluoroalkylethanol phosphate ammonium salt exhibit excellent metal oxide complexation and stripping capabilities as well as wetting and penetration properties, and show good compatibility with chelating agents and polyquaternary ammonium salts. Among them, potassium isotridecyl ether phosphate has better water solubility and is easier to prepare; the fluorocarbon chain of perfluoroalkylethanol phosphate ammonium salt gives it lower surface tension, enabling it to penetrate deep into nanoscale gaps to strip stubborn particles. Both are preferred solutions for phosphate-based surfactants and can be flexibly selected according to actual process requirements, both ensuring excellent cleaning results.

[0010] Preferably, the wetting agent is selected from one or more of the following: acetylenic diol modified surfactant FS-683, rhamnose ester Carfil BIO-RL1, fatty alcohol polyoxyethylene Ethylan 1005, FENTACARE F08, fluorocarbon surfactant, and organosilicon surfactant.

[0011] The above technical solutions can significantly reduce the surface tension of the cleaning solution, enhance its wetting and penetration ability on the surface of the Faraday rotating plate, and allow the cleaning solution to fully contact and penetrate into the nanoscale gaps and particle adhesion interface. Rhamnose ester is a bio-derived surfactant that combines excellent emulsifying and dispersing properties with environmental friendliness. The combination of the wetting agent and the phosphate ester-based surfactant synergistically reduces the solid-liquid interfacial tension, promotes the detachment and dispersion of peeled particles, and further improves cleaning efficiency and uniformity.

[0012] Preferably, the diol diether derivative is selected from one or more of diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol methyl propyl ether, and dipropylene glycol methyl ethyl ether.

[0013] Through the above technical solutions, the diol diether derivative is a high-boiling-point water-soluble organic solvent with a moderate evaporation rate and excellent dissolution and penetration ability. It can effectively dissolve the organic pollutants and waxes remaining during the polishing process, while also helping to reduce the surface tension of the cleaning solution and enhance the wetting and penetration effect.

[0014] Preferably, the green chelating agent is selected from one or more of the following: trisodium methylglycine diacetate, tetrasodium glutamate diacetate, iminodisuccinate, polyaspartate, polyepoxysuccinate, and polyaspartate.

[0015] The above-mentioned green chelating agents are all biodegradable and environmentally friendly, possessing strong chelating ability for metal ions such as Ca, Mg, Te, and Er. When combined with citric acid, they form a "synergistic chelation" system through the complementarity of their multidentate coordination structures, with MGDA and other main chelating agents efficiently chelating Mg. 2+With an equal amount of metal ions, citric acid provides additional carboxyl coordination sites, enhancing the chelation ability for high-valence metal ions. Together, they fully dissolve the stripped metal oxide particles into soluble ions, effectively preventing secondary deposition.

[0016] Preferably, the polyquaternary ammonium salt polymer is selected from one or more of polyquaternary ammonium salt-6, polyquaternary ammonium salt-7, polyquaternary ammonium salt-22 and polyquaternary ammonium salt-39.

[0017] Preferably, the mass ratio of the green chelating agent to citric acid is (1.8-3.2):1.

[0018] Through the above technical solutions, the green chelating agent and citric acid form an optimal synergistic coordination configuration at this ratio. The multidentate coordination structure of the green chelating agent efficiently chelates Mg. 2+ With an equal amount of main metal ions, citric acid provides three additional carboxyl coordination sites, enhancing the chelation ability for high-valence metal ions (such as Te and Er). Within this ratio range, the two form a complementary configuration of "main chelating agent + auxiliary ligand," maximizing chelation capacity and achieving the most stable coordination. This results in optimal dissolution and removal of metal oxide particles, effectively preventing secondary deposition while avoiding waste due to excessive chelating agent or decreased chelation ability due to imbalanced ratio, ensuring stable and reliable cleaning results.

[0019] Preferably, the environmentally friendly cleaning agent is composed of the following components in weight percentage: potassium isotridecyl ether phosphate 3.0-5.0 wt%, rhamnosyl ester Carfil BIO-RL1 1.0-2.5 wt%, dipropylene glycol methyl propyl ether 5.0-10.0 wt%, trisodium methylglycine diacetate 5.0-10.0 wt%, citric acid 2.5-4.5 wt%, polyquaternium-6 0.5-1.2 wt%, with the balance being deionized water; the pH value of the cleaning agent is 9.0-10.5.

[0020] The above technical solution achieves deep synergistic effects among the components. Specifically, potassium isotridecyl ether phosphate, as a preferred phosphate-based surfactant, exhibits strong complexing-exfoliation capabilities for metal oxide particles such as Mg, Te, and Er. Rhamnose ester, as a bio-derived wetting agent, effectively reduces the surface tension of the cleaning solution, enhances wetting and penetration, and is environmentally friendly. Dipropylene glycol methyl propyl ether, as a preferred diol ether, possesses excellent water solubility, dissolving power, and permeability, assisting in the dissolution of organic pollutants and improving system homogeneity. Trisodium methylglycine diacetate and citric acid form a synergistic chelating system in a preferred ratio, efficiently chelating metal ions. Polyquaternium-6 prevents particle back-adhesion through charge neutralization and steric hindrance. The synergistic effect of these components achieves highly efficient removal of nanoscale polishing particles from the surface of the Faraday rotation plate, with residual particles ≤3-5 / mm² and a back-adhesion rate <1-3%. Simultaneously, the weakly alkaline system (pH 9.0-10.5) does not corrode the substrate, protects magneto-optical properties, and demonstrates significant advantages such as excellent cleaning effect, safety, environmental friendliness, and stable performance.

[0021] Secondly, this application provides a cleaning method for bismuth-substituted terbium-iron garnet Faraday rotating plates, using the environmentally friendly cleaning agent described in the first aspect, and employing multi-band composite ultrasonic waves to clean the Faraday rotating plates, including the following steps: S1. A bismuth-substituted terbium-iron-garnet Faraday rotating plate is immersed in the environmentally friendly cleaning agent; S2. Use low-frequency ultrasonic waves for rough cleaning, with a low frequency of 20-35kHz, a cleaning temperature of 40-60℃, and a cleaning time of 2-5 minutes. S3. Use medium-frequency ultrasonic cleaning for fine cleaning, with a medium frequency of 60-80kHz, a cleaning temperature of 40-60℃, and a cleaning time of 2-5 minutes. S4. Use high-frequency ultrasonic cleaning for fine cleaning, with a high frequency of 130-140kHz, a cleaning temperature of 40-60℃, and a cleaning time of 2-5 minutes. S5. Rinse with deionized water and dry.

[0022] Preferably, in step S1, citric acid is first added to deionized water and stirred to dissolve, then a green chelating agent is added and stirred to dissolve, followed by the sequential addition of a glycol diether derivative, a phosphate ester surfactant, a wetting agent, and a polyquaternary ammonium salt polymer, and the pH value is adjusted after replenishing the deionized water.

[0023] Preferably, step S5 involves rinsing with deionized water. Specifically, first, high-pressure spray rinsing with deionized water is used, with a spray pressure of 0.3-0.6 MPa and a spray time of 60-120 s; then, four-stage countercurrent overflow rinsing with deionized water is performed, with each stage lasting 360 s and the rinsing temperature being 40-60℃; finally, the rinsed Faraday rotor is slowly lifted in deionized water at 70-80℃ and centrifuged to dry.

[0024] The above technical solution utilizes strong cavitation energy in the low-frequency band (20-35kHz) to remove firmly attached large particles; dense and uniform cavitation bubbles in the mid-frequency band (60-80kHz) to remove submicron-sized particles; and gentle energy in the high-frequency band (130-140kHz) to remove nano-sized particles without damage and avoid cavitation corrosion. The three-stage ultrasonic waves, progressing from coarse to fine, work synergistically with the chemical stripping and chelating effects of the cleaning agent components to achieve dual physical and chemical cleaning. Rinsing employs a combination of high-pressure spraying and four-stage countercurrent overflow, along with slow lifting dehydration at 70-80℃ and centrifugal drying to ensure no residue or water stains on the surface. This synergistic combination of the above processes and the cleaning agent enables efficient removal of nano-sized polishing particles, ensuring a clean and damage-free optical surface, meeting the ultra-high cleanliness requirements before coating, and ensuring the process is safe, environmentally friendly, stable, and controllable.

[0025] In summary, this application has the following beneficial effects: 1. This application constructs a three-pronged cleaning mechanism of "targeted exfoliation—synergistic chelation—anti-redeposition" through a multi-component compounding of phosphate-based surfactants, a green chelating agent and a citric acid synergistic chelation system, and polyquaternary ammonium salt polymers. The phosphate-based surfactants exhibit strong complexing-exfoliation capabilities for metal oxide particles such as Mg, Te, and Er; the green chelating agent and citric acid synergistically chelate and dissolve metal ions; and the polyquaternary ammonium salt prevents particle re-adhesion through charge neutralization and steric hindrance. The synergistic effect of these three components achieves highly efficient removal of nanoscale polishing particles from the surface of Faraday rotation plates (residual particles ≤3-5 / mm). 2 With a removal rate of ≥99% and an anti-adhesion rate of <1-3%, the weakly alkaline system does not corrode the substrate, thus protecting the integrity of the optical surface and the magneto-optical properties.

[0026] 2. The multi-band composite ultrasonic cleaning method of this application uses low, medium and high ultrasonic waves to gradually transition from coarse to fine, which works in synergy with the chemical action of the cleaning agent to achieve an organic combination of physical stripping and chemical chelation. Combined with high-pressure spraying, four-stage countercurrent overflow rinsing, slow lifting dehydration and centrifugal drying, it ensures that there are no residues or water stains on the surface, meets the ultra-high cleanliness requirements before coating, and the process is safe, environmentally friendly, stable and controllable. Attached Figure Description

[0027] Figure 1 SEM image of the dirt to be cleaned on the surface of a bismuth-substituted terbium-iron-garnet Faraday rotation plate; Figure 2 This is a scanning electron microscope (SEM) image of the bismuth-substituted terbium-iron garnet Faraday rotation sheet after surface cleaning, as shown in Example 1. Figure 3 The image shows a microscopic comparison of the surface of the bismuth-substituted terbium-iron garnet Faraday rotation plate before and after cleaning, magnified 100 times. Detailed Implementation

[0028] The technical solution of this application is further illustrated by specific embodiments below. These specific embodiments do not represent a limitation on the scope of protection of this application. Any non-essential modifications and adjustments made by others based on the concept of this application still fall within the scope of protection of this application.

[0029] Unless otherwise specified, the experimental methods shown in the following examples are conventional methods. All reagents and materials shown are commercially available products.

[0030] Among them, polyquaternium-6, polydimethyldiallylammonium chloride, has a number average molecular weight Mn of 100,000-500,000 and is available in a 40% aqueous solution.

[0031] The present application will be further described in detail below with reference to embodiments and comparative examples. Example

[0032] Example 1 A method for cleaning bismuth-substituted terbium-iron garnet Faraday rotation plates is provided, using an environmentally friendly cleaning agent for bismuth-substituted terbium-iron garnet Faraday rotation plates, the composition and dosage of which are shown in Table 1; the Faraday rotation plates are cleaned using multi-band composite ultrasonic waves, including the following steps: S1. Prepare 10L of the environmentally friendly cleaning agent according to the dosage of each component; immerse the Faraday rotating plate in the environmentally friendly cleaning agent; S2. Use low-frequency ultrasonic waves for rough cleaning, with a low frequency of 28kHz, a cleaning temperature of 50℃, and a cleaning time of 3 minutes. S3. Use medium-frequency ultrasonic cleaning at 68kHz, with a cleaning temperature of 50℃ and a cleaning time of 3 minutes. S4. Use high-frequency ultrasonic cleaning at 132kHz, with a cleaning temperature of 50℃ and a cleaning time of 3 minutes. S5. Rinse with high-pressure spray of deionized water at a pressure of 0.5 MPa for 90 seconds; then rinse with deionized water in a four-stage countercurrent overflow rinse, each stage for 360 seconds, at a temperature of 50°C; after rinsing, slowly lift and pull the Faraday rotor in deionized water at 75°C, and centrifuge at 1000 rpm for 2 minutes.

[0033] In step S1, citric acid is first added to deionized water and stirred to dissolve. Then, a green chelating agent is added and stirred to dissolve. Next, glycol diether derivatives, phosphate ester surfactants, wetting agents, and polyquaternary ammonium salt polymers are added in sequence. After replenishing the deionized water, the pH value is adjusted.

[0034]

[0035] Examples 2-8 The difference from Example 1 is that the dosage of the bismuth-substituted terbium-iron-garnet Faraday rotating plate environmentally friendly cleaning agent is shown in Table 1.

[0036] Example 9 The difference from Example 1 lies in the different parameters used for cleaning the Faraday rotating plate with multi-band composite ultrasonic waves; wherein: Step S2. Use low-frequency ultrasonic waves for rough cleaning, with a low frequency of 20kHz, a cleaning temperature of 40℃, and a cleaning time of 5 minutes. Step S3. Use mid-frequency ultrasonic cleaning at 60kHz, cleaning temperature at 40℃, and cleaning time at 5min. Step S4. Use high-frequency ultrasonic waves for fine cleaning, with a high frequency of 130kHz, a cleaning temperature of 40℃, and a cleaning time of 2-5 minutes. Step S5. Rinse with deionized water at a spray pressure of 0.3 MPa for 120 seconds; then rinse with deionized water in a four-stage countercurrent overflow rinse, each stage for 360 seconds, at a temperature of 40°C; slowly lift the rinsed Faraday rotor in deionized water at 70°C and centrifuge to dry.

[0037] Example 10 The difference from Example 1 lies in the different parameters used for cleaning the Faraday rotating plate with multi-band composite ultrasonic waves; wherein: Step S2. Use low-frequency ultrasonic waves for rough cleaning, with a low frequency of 35kHz, a cleaning temperature of 50℃, and a cleaning time of 2 minutes. Step S3. Use mid-frequency ultrasonic cleaning at 80kHz, cleaning temperature at 60℃, and cleaning time at 2min. Step S4. Use high-frequency ultrasonic waves for fine cleaning, with a high frequency of 140kHz, a cleaning temperature of 60℃, and a cleaning time of 2 minutes. Step S5. Rinse with high-pressure spray of deionized water at a pressure of 0.6 MPa for 60 seconds; then rinse with deionized water in a four-stage countercurrent overflow rinse for 360 seconds per stage at a temperature of 60°C; finally, slowly lift the rinsed Faraday rotor in deionized water at 80°C and centrifuge to dry.

[0038] Comparative Example Comparative Example 1 The difference from Example 1 is that the neutral cleaning agent disclosed in CN 106238402 A is used instead of the environmentally friendly cleaning agent in Example 1. The cleaning steps are as follows: ultrasonic cleaning at 60℃ for 40 minutes, rinsing with deionized water, ultrasonic cleaning with 99% industrial alcohol for 3-5 minutes, baking with 200W infrared lamp for 20-30 minutes, silicone adhesive removal 1-2 times, alcohol cleaning again for 2-3 minutes, and baking with infrared lamp for 20-30 minutes; the remaining cleaning parameters (ultrasonic frequency, temperature, time, rinsing conditions, etc.) are the same as in Example 1.

[0039] Comparative Example 2 The difference from Example 1 is that no polyquaternary ammonium salt polymers are added to the cleaning agent formulation, while the remaining components and dosages are the same as in Example 1, and the cleaning method is the same as in Example 1.

[0040] Comparative Example 3 The difference from Example 1 is that citric acid is not added to the cleaning agent formulation, while the remaining components and dosages are the same as in Example 1, and the cleaning method is the same as in Example 1.

[0041] Comparative Example 4 The difference from Example 1 is that no phosphate ester surfactant is added to the cleaning agent formulation, while the remaining components and dosages are the same as in Example 1, and the cleaning method is the same as in Example 1.

[0042] Comparative Example 5 The difference from Example 1 is that only 68kHz single-band ultrasonic cleaning was used during the cleaning process, the cleaning temperature was 50℃, the total cleaning time was 9 minutes, and the other conditions were the same as in Example 1; the cleaning agent was the same as in Example 1.

[0043] Comparative Example 6 The difference from Example 1 is that in step S5, after the fourth-stage rinsing, there is no slow dehydration with deionized water; instead, the product is directly centrifuged and dried. The remaining cleaning agents, ultrasonic parameters, and rinsing conditions are the same as in Example 1. Performance testing

[0044] The following performance tests were performed on the test materials, Examples 1-10, and Comparative Examples 1-5, and the test methods are shown in Table 2:

[0045] The specific parameters of the Faraday rotatable sheet used in the experiment are as follows: bismuth-substituted terbium iron garnet (Bi:TIG) single crystal; diameter: Φ5mm, thickness: 1.0±0.05mm.

[0046] The surface of the bismuth-substituted terbium-iron garnet Faraday rotation plate was subjected to SEM+EDS elemental analysis of the contaminants to be cleaned. The results are as follows: Figure 1 As shown in Table 3, the main components of the dirt to be cleaned are particulate matter formed by elements such as C, O, Mg, and Tc.

[0047]

[0048] The results obtained from the above performance tests are shown in Table 4.

[0049]

[0050] Performance test results showed that before cleaning, a large number of polishing fluid residue particles remained on the surface of the Faraday rotation plate. EDS energy dispersive spectroscopy analysis confirmed that the main components of the contaminants were particles formed by elements such as C, O, Mg, and Tc, with approximately 500-800 residual particles per mm. 2 Under an optical microscope, obvious particulate matter is visible. This condition does not meet the requirements for optical surface cleanliness before coating; it must undergo precise cleaning before proceeding to the coating process.

[0051] Examples 1-10 describe environmentally friendly cleaning agents and methods used to clean bismuth-substituted terbium-iron garnet Faraday rotation plates. In all examples, the surface residual particles were reduced to ≤3-5 particles / mm. 2 The removal rate reaches over 99%; EDS only detects inherent elements of the substrate such as Fe / Tb / Bi / O, while the characteristic elements of pollutants are completely eliminated; the anti-adhesion rate is <1-3%; and the appearance is free of scratches, corrosion, or water stains. Its superior performance is reflected in: phosphate ester-based surfactants achieve targeted complexation and exfoliation of metal oxide particles such as Mg / Te / Er; green chelating agents and citric acid synergistically chelate and dissolve metal ions; polyquaternary ammonium salts prevent particle anti-adhesion through charge neutralization and steric hindrance; and the weakly alkaline system (pH 8.5-10.5) does not damage the substrate. Simultaneously, a three-stage gradient ultrasonic process (low-frequency coarse cleaning to remove large particles → medium-frequency removal of submicron particles → high-frequency gentle removal of nanoparticles) achieves full particle size coverage; a four-stage countercurrent overflow rinsing thoroughly removes residues; and slow-lift dehydration + centrifugal drying ensures a water-free surface. Through the synergistic combination of chemical cleaning and physical ultrasonication, it fully meets the ultra-high cleanliness requirements for optical surfaces before coating, and the process is safe, environmentally friendly, highly efficient, and controllable.

[0052] Using the method described in Example 1, the surface contaminants to be cleaned from the cleaned bismuth-substituted terbium-iron garnet Faraday rotation sheet were analyzed by SEM+EDS elemental analysis. The results are as follows: Figure 2 As shown in Table 5, the effects before and after cleaning were compared using a microscope at 100x magnification. The comparison photos are as follows. Figure 3 As shown, the left side is before cleaning, where a large number of polishing particles are visible on the surface, and the color is dull; the right side is after cleaning, where the surface is clean and bright, with no visible contaminants, scratches, corrosion, or water stains, fully meeting the ultra-high cleanliness requirements for optical surfaces before coating.

[0053]

[0054] Comparative Example 1: Using a neutral cleaning agent (CN 106238402 A), although the ultrasonic conditions were the same as in Example 1, the neutral cleaning agent lacked the ability to complex and peel off Mg / Tc oxide particles. EDS still detected residual C / Mg / Tc elements, with residual particles >200 / mm. 2 The removal rate is only about 60-75%, the anti-adhesion rate is as high as 30-50%, and scratches and corrosion appear on the surface. This indicates that the key to the weakly alkaline compound cleaning agent formulation of this invention lies in the phosphate ester complexation and exfoliation, and the synergistic chelation of MGDA and citric acid.

[0055] Comparative Example 2: Lacking the steric hindrance and charge neutralization effect of polyquaternium salt, EDS detected trace amounts of residual Mg, with the residual particles increasing significantly to 50-80 particles / mm. 2 The anti-adhesion rate was 10-15%, which verified that the anti-redeposition and antistatic adsorption effects of polyquaternary ammonium salts are indispensable.

[0056] Comparative Example 3: Lacking the synergistic chelation effect between citric acid and MGDA, trace amounts of residual Mg were detected by EDS, with 40-60 residual particles / mm. 2 The anti-adhesion rate of 5-8% proves that the synergistic chelation system of MGDA and citric acid is crucial for the complete removal of Mg.

[0057] Comparative Example 4: Lack of specific complexation and exfoliation of metal oxide particles; EDS detected trace amounts of residual Mg, with 35-45 residual particles / mm. 2 The anti-adhesion rate of 6-10% indicates that the phosphate ester surfactant is the core component in the cleaning agent that achieves "strong peeling" of Mg / Tc particles.

[0058] Comparative Example 5: Using only 68kHz single-band ultrasound, lacking the gradient combination of low-frequency coarse cleaning to remove large particles and high-frequency fine cleaning to remove nano-sized particles and protect the surface, leaving 25-35 residual particles / mm. 2 The anti-adhesion rate was 8-12%. This verified the synergistic effect of multi-band composite ultrasound in the "coarse washing-medium washing-fine washing" gradient cleaning process.

[0059] Comparative Example 6: Lacking the slow-lifting dehydration step, the cleaning effect was comparable to Example 1, with residual particles ≤8 / mm. 2 EDS detected only Fe / Tb / Bi / O, but slight water stains appeared on the surface, indicating that slow lifting is crucial for uniformly removing the water film using surface tension and preventing water stains from remaining.

[0060] The above experimental results show that the environmentally friendly cleaning agent prepared in this application, combined with a multi-band composite ultrasonic cleaning method, effectively reduced the number of residual particles on the surface of bismuth-substituted terbium-iron garnet Faraday rotating plates from approximately 500 particles / mm before cleaning. 2Reduced to ≤3-6 per mm 2 The removal rate is over 99%; EDS testing shows that the characteristic elements of pollutants C, Mg, Te, and Er have completely disappeared, leaving only the inherent elements of the substrate, Fe / Tb / Bi / O; the anti-adhesion rate is <1-3%, and the appearance is free of scratches, corrosion, or water stains, fully meeting the ultra-high cleanliness requirements for optical surfaces before coating.

[0061] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the present invention, they are protected by patent law.

Claims

1. An environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates, characterized in that, It consists of the following components by weight percentage: Phosphate ester-based surfactants: 1.0-5.0 wt%; Wetting agent 0.5-3.0 wt%; Diol diether derivatives 3.0-10.0 wt%; Green chelating agent 4.0-15.0 wt%; Citric acid 2.0-5.0 wt%; Polyquaternary ammonium salt polymers 0.5-1.5 wt%; The remainder is deionized water; The pH value of the cleaning agent is 8.5-10.5; The phosphate-based surfactant is selected from one or more of alkyl phosphate salts and alkyl polyoxyethylene ether phosphate salts.

2. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The phosphate-based surfactant is selected from potassium isotridecyl ether phosphate or C6-16 perfluoroalkyl ethanol phosphate ammonium salt.

3. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The wetting agent is selected from one or more of the following: acetylenic diol modified surfactant FS-683, rhamnose ester Carfil BIO-RL1, fatty alcohol polyoxyethylene Ethylan 1005, FENTACARE F08, fluorocarbon surfactant, and organosilicon surfactant.

4. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The diol diether derivative is selected from one or more of diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol methyl propyl ether, and dipropylene glycol methyl ethyl ether.

5. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The green chelating agent is selected from one or more of the following: trisodium methylglycine diacetate, tetrasodium glutamate diacetate, iminodisuccinate, polyaspartate, polyepoxysuccinate, and polyaspartate.

6. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The polyquaternary ammonium salt polymer is selected from one or more of polyquaternary ammonium salt-6, polyquaternary ammonium salt-7, polyquaternary ammonium salt-22, and polyquaternary ammonium salt-39.

7. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The mass ratio of the green chelating agent to citric acid is (1.8-3.2):

1.

8. The environmentally friendly cleaning agent for bismuth-substituted terbium-iron-garnet Faraday rotating plates according to claim 1, characterized in that, The environmentally friendly cleaning agent is composed of the following components by weight percentage: potassium isotridecyl ether phosphate 3.0-5.0 wt%, rhamnosyl ester Carfil BIO-RL1 1.0-2.5 wt%, dipropylene glycol methyl propyl ether 5.0-10.0 wt%, trisodium methylglycine diacetate 5.0-10.0 wt%, citric acid 2.5-4.5 wt%, polyquaternium-6 0.5-1.2 wt%, with the balance being deionized water; the pH value of the cleaning agent is 9.0-10.

5.

9. A cleaning method for bismuth-substituted terbium-iron garnet Faraday rotation plates, characterized in that, Using the environmentally friendly cleaning agent as described in any one of claims 1-8, and employing multi-band composite ultrasonic waves to clean the Faraday rotating plate, the process includes the following steps: S1. A bismuth-substituted terbium-iron-garnet Faraday rotating plate is immersed in the environmentally friendly cleaning agent; S2. Use low-frequency ultrasonic waves for rough cleaning, with a low frequency of 20-35kHz, a cleaning temperature of 40-60℃, and a cleaning time of 2-5 minutes. S3. Use medium-frequency ultrasonic cleaning for fine cleaning, with a medium frequency of 60-80kHz, a cleaning temperature of 40-60℃, and a cleaning time of 2-5 minutes. S4. Use high-frequency ultrasonic cleaning for fine cleaning, with a high frequency of 130-140kHz, a cleaning temperature of 40-60℃, and a cleaning time of 2-5 minutes. S5. Rinse with deionized water and dry.

10. A cleaning method for a bismuth-substituted terbium-iron garnet Faraday rotating plate as described in claim 9, characterized in that, In step S5, the Faraday rotor is rinsed with deionized water. Specifically, it is first rinsed by high-pressure spraying of deionized water at a pressure of 0.3-0.6 MPa for 60-120 seconds; then it is rinsed by four-stage countercurrent overflow rinsing with deionized water for 360 seconds per stage at a temperature of 40-60°C; the rinsed Faraday rotor is then slowly lifted and centrifuged in deionized water at 70-80°C for drying.

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