Preparation method and application of gradient elastic core-shell double-rare earth synergistically doped ceria abrasive

Abstract

This invention discloses a method for preparing a gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive and its application, belonging to the field of mechanical polishing technology. The method includes the following steps: S1, reacting pyromellitic dianhydride with 4,4'-diaminodiphenyl ether and N,N-dimethylformamide to obtain PI microspheres; S2, adding buffer solution, dopamine hydrochloride, and KH560 to react the PI microspheres to obtain modified microspheres; S3, dispersing the modified microspheres and adding a shell material to react, adding a mixed solution, and grinding to obtain the core-shell abrasive; S4, dispersing the core-shell abrasive in anhydrous ethanol, adding polyethylene glycol monomethyl ether to react, and obtaining the abrasive. The abrasive prepared by this invention utilizes dual rare earth co-doping to construct highly efficient chemically active centers, achieving a material removal rate (MRR) of 200~230 nm / min, which is more than 67% higher than pure CeO2 abrasive and significantly higher than single Y... 3+ The CeO2 doping of abrasives increases polishing efficiency by more than 45%, resulting in a significant improvement in polishing efficiency.

Description

Technical Field

[0001] This invention relates to the field of mechanical polishing technology, and more specifically, to a method for preparing gradient elastic core-shell dual rare earth synergistic doped cerium oxide abrasive and its application. Background Technology

[0002] When existing cerium oxide-based abrasives are used for polishing blue filters, the following unresolved technical bottlenecks exist:

[0003] (1) Insufficient flexible contact performance: Traditional pure phase cerium oxide abrasives are rigid particles. During the polishing process, they make point contact with the filter surface, resulting in local stress concentration (contact stress ≥ 100 MPa), which easily produces nano-scratches. Core-shell structure abrasives (such as SiO2@CeO2) have a rigidity mismatch between the core and shell. When subjected to pressure, the shell is prone to breakage, resulting in secondary debris damage and affecting the surface finish.

[0004] (2) Tribochemical activity regulation is singular: single rare earth ion doping (such as Y 3+ Single doping can only adjust the oxygen vacancy concentration in one direction, Ce 3+ The concentration is usually below 40%, which results in limited tribochemical activity and a low material removal rate (MRR) (generally ≤150nm / min). If the removal rate is improved by increasing the abrasive hardness or polishing load, it will aggravate surface damage, making it difficult to balance efficiency and quality.

[0005] (3) Poor structural stability and dispersibility: Cerium oxide abrasives are prone to uneven particle size distribution due to hydroxyl agglomeration in alkaline polishing fluid, resulting in large fluctuations in the viscosity of the polishing fluid and uneven pressure transmission, which affects the consistency of polishing; the interfacial bonding of core-shell structure abrasives depends on a single chemical bond, and long-term polishing is prone to interlayer delamination, leading to the decay of polishing performance.

[0006] (4) Residue and cleaning problems: Traditional cerium oxide abrasives are easily adsorbed on the surface of the filter, and the subsequent cleaning process is complicated. Residual particles will affect the optical transmittance of the filter and the compatibility of subsequent processes.

[0007] The core reason for the above problems is that existing abrasives lack the synergistic design of "flexible contact structure" and "multi-level chemical activity", the precision matching of mechanical action and chemical action is insufficient, and the interface stability and dispersibility need to be improved. Therefore, they cannot meet the polishing requirements of blue filters that are "non-damaging, high-efficiency, high-consistency, and low-residue". Summary of the Invention

[0008] This invention aims to solve the technical problems of insufficient flexible contact, single chemical activity, poor stability, and difficult-to-clean residues in existing cerium oxide abrasives used for polishing blue filters, and provides a method for preparing gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for preparing a gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive includes the following steps:

[0011] S1. Add pyromellitic dianhydride and 4,4'-diaminodiphenyl ether to N,N-dimethylformamide, add dispersant, disperse by ultrasonication, add deionized water for reverse emulsification, then carry out imidization reaction, centrifuge, wash, and dry to obtain PI microspheres.

[0012] S2. Take PI microspheres and sonicate them in Tris-HCl buffer, add dopamine hydrochloride and KH560, stir and react at room temperature, centrifuge, wash, and dry to obtain modified microspheres;

[0013] S3. Disperse the modified microspheres in deionized water, sonicate, add cerium nitrate hexahydrate, yttrium nitrate hexahydrate and gadolinium nitrate hexahydrate, stir to react, add a mixed solution containing urea and sodium citrate, centrifuge, calcine, and grind to obtain core-shell abrasive.

[0014] S4. Disperse the core-shell abrasive in anhydrous ethanol, add polyethylene glycol monomethyl ether, stir to react, centrifuge, wash, and dry to obtain gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive.

[0015] Further, in step S1, the ratio of pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, N,N-dimethylformamide, dispersant and water is (7-9) g: (5-7) g: (30-70) mL: (0.5-1.5) g: (90-110) mL, the dispersant is polyvinylpyrrolidone, and the imidization reaction is to heat the reverse emulsion to 160-200℃ and keep it at that temperature for 3-6 hours.

[0016] Further, in step S2, the ratio of PI microspheres to Tris-HCl buffer is (5-7) g: (70-90) mL, the pH of Tris-HCl buffer is 8.5, and the concentration of Tris-HCl buffer is 10 mmol / L.

[0017] Furthermore, in step S2, the ratio of PI microspheres, dopamine hydrochloride and KH560 is (5-7) g: (0.5-1.5) g: (0.3-0.7) mL.

[0018] Further, in step S3, the ratio of the amount of modified microspheres, deionized water, cerium nitrate hexahydrate, yttrium nitrate hexahydrate, gadolinium nitrate hexahydrate, and the mixed solution containing urea and sodium citrate is (3-7) g : (40-60) mL : (1-2) g : (0.1-0.24) g : (0.05-0.09) g : (30-50) mL; the mixed solution containing urea and sodium citrate is obtained by stirring urea, sodium citrate, and deionized water evenly, and each 40 mL of the mixed solution contains 10-14 g of urea and 0.6-1.0 g of sodium citrate, and the solvent is deionized water.

[0019] Further, in step S3, the mixture is calcined under a N2 atmosphere at a temperature of 500-600℃ for 3-5 hours.

[0020] Further, in step S4, the ratio of the amount of core-shell abrasive, anhydrous ethanol and polyethylene glycol monomethyl ether is (2-4) g: (40-60) mL: (0.2-0.4) g, and the reaction conditions are stirring at 50-70℃ for 4-8 h.

[0021] An application of a gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive, wherein the gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive is used for polishing blue filters.

[0022] Further, the method includes the following steps: (a) adding gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive to deionized water, adding sodium polycarboxylate and glycerol, adjusting the pH with Na2CO3, and ultrasonically dispersing to obtain a polishing solution;

[0023] (b) Add the blue filter to be polished to polishing solution and polish it to obtain the polished blue filter;

[0024] (c) Clean and dry the polished blue filter to obtain the finished blue filter.

[0025] Further, in step (a), the polishing slurry, based on 100% of its total mass, consists of the following components: 0.3-0.5 wt% gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive, 0.1-0.2 wt% sodium polycarboxylate, 0.1-0.3 wt% glycerol, 0.2-0.4 wt% Na2CO3, with the remainder being deionized water.

[0026] In summary, the present invention has the following beneficial effects:

[0027] (1) Flexible and uniform contact achieves damage-free polishing: The gradient elastic core-shell structure enables uniform and flexible contact between the abrasive and the surface of the blue filter, significantly reducing contact stress. After polishing, the surface Ra≤0.15nm, RMS≤0.20nm, with no nano-scratches, surface lattice distortion ≤0.03%, and lattice integrity retention rate ≥99.7%;

[0028] (2) Dual rare earth synergistic doping improves polishing efficiency: Dual rare earth synergistic doping constructs highly efficient chemical active centers, and the material removal rate (MRR) reaches 200~230nm / min, which is more than 67% higher than that of pure CeO2 abrasive and higher than that of single Y 3+ Doping with CeO2 abrasives increases polishing efficiency by more than 45% and significantly improves polishing efficiency.

[0029] (3) Excellent structural stability and consistency: The triple cross-linking interface and the composite dispersion system work together to achieve a sedimentation rate of ≤3% after the abrasive is left to stand in the polishing slurry for 72 hours, and the Ra coefficient of variation is ≤1.8% after polishing 15 filters continuously; after 8 months of sealed storage, the polishing performance decays by ≤4%, and the service life is extended by 100% compared with traditional cerium oxide abrasives;

[0030] (4) Low residue and easy to clean: The surface hydrophilic modification makes the abrasive residue rate ≤0.05%, and subsequent cleaning only requires simple ultrasonic cleaning to completely remove it, avoiding residual particles from affecting the optical transmittance of the filter and reducing cleaning costs by 60%. Attached Figure Description

[0031] Figure 1 For PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 Schematic diagram of O2 abrasive;

[0032] Figure 2 For PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 SEM image of O2 abrasive;

[0033] Figure 3 For PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 TEM image and EDS elemental mapping of O2 abrasive. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0035] A method for preparing a gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive includes the following steps:

[0036] S1. Add pyromellitic dianhydride and 4,4'-diaminodiphenyl ether to N,N-dimethylformamide, add dispersant, ultrasonically disperse, add deionized water for reverse emulsification, and then carry out imidization reaction. Centrifuge, wash, and dry to obtain PI microspheres. The ratio of pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, N,N-dimethylformamide, dispersant and water is (7-9) g: (5-7) g: (30-70) mL: (0.5-1.5) g: (90-110) mL. The dispersant is polyvinylpyrrolidone. The imidization reaction is to heat the reverse emulsion to 160-200℃ and keep it at that temperature for 3-6 h.

[0037] S2. Take PI microspheres and sonicate them in Tris-HCl buffer. Add dopamine hydrochloride and KH560, stir and react at room temperature, centrifuge, wash, and dry to obtain modified microspheres. The ratio of PI microspheres to Tris-HCl buffer is (5-7) g: (70-90) mL. The pH of Tris-HCl buffer is 8.5 and the concentration of Tris-HCl buffer is 10 mmol / L. The ratio of PI microspheres, dopamine hydrochloride and KH560 is (5-7) g: (0.5-1.5) g: (0.3-0.7) mL.

[0038] S3. Disperse the modified microspheres in deionized water, sonicate, add cerium nitrate hexahydrate, yttrium nitrate hexahydrate, and gadolinium nitrate hexahydrate, stir to react, add a mixed solution containing urea and sodium citrate, centrifuge, calcine, and grind to obtain core-shell abrasive. The ratio of modified microspheres, deionized water, cerium nitrate hexahydrate, yttrium nitrate hexahydrate, gadolinium nitrate hexahydrate, and the mixed solution containing urea and sodium citrate is (3-7) g : (40-60) mL : (1-2) g. (0.1-0.24)g: (0.05-0.09)g: (30-50)mL, the mixed solution containing urea and sodium citrate is obtained by stirring urea, sodium citrate and deionized water evenly. Each 40mL of the mixed solution containing urea and sodium citrate contains 10-14g of urea and 0.6-1.0g of sodium citrate. The solvent is deionized water. It is calcined under N2 atmosphere at a temperature of 500-600℃ for 3-5h.

[0039] S4. Disperse the core-shell abrasive in anhydrous ethanol, add polyethylene glycol monomethyl ether, react, centrifuge, wash, and dry to obtain gradient elastic core-shell-double rare earth co-doped cerium oxide abrasive. The ratio of core-shell abrasive, anhydrous ethanol and polyethylene glycol monomethyl ether is (2-4) g: (40-60) mL: (0.2-0.4) g. The reaction conditions are 50-70℃ and stirring for 4-8 h.

[0040] Application of a gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive: The gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive is used for polishing blue filters, including the following steps:

[0041] (a) Gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive is added to deionized water, sodium polycarboxylate and glycerol are added, the pH is adjusted with Na2CO3, and ultrasonic dispersion is performed to obtain a polishing solution. The polishing solution consists of the following components based on 100% of the total mass: 0.3-0.5 wt% gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive, 0.1-0.2 wt% sodium polycarboxylate, 0.1-0.3 wt% glycerol, 0.2-0.4 wt% Na2CO3, and the remainder is deionized water;

[0042] (b) Add the blue filter to be polished to polishing solution and polish it to obtain the polished blue filter;

[0043] (c) Clean and dry the polished blue filter to obtain the finished blue filter.

[0044] Example 1

[0045] Preparation method of gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive:

[0046] (1) Preparation of flexible elastic core (PI microspheres): 8g of pyromellitic dianhydride (PMDA) and 6g of 4,4'-diaminodiphenyl ether (ODA) were added to 50mL of N,N-dimethylformamide (DMF) and stirred at room temperature for 2h to form a polyamic acid solution;

[0047] 1g of polyvinylpyrrolidone (PVP-K30, Baoruyi (Beijing) Biotechnology Co., Ltd., product number: CR3335-100g) was added to the polyamic acid solution as a dispersant. After ultrasonic dispersion for 20min, 100mL of deionized water was added dropwise for reverse emulsification to obtain a reverse emulsion.

[0048] The reverse emulsion was heated to 180℃ and kept at that temperature for 4 hours to carry out the imidization reaction. It was then centrifuged (4500 rpm, 25 min) and the supernatant was discarded.

[0049] The precipitate after centrifugation was washed four times alternately with DMF and deionized water, and then dried under vacuum at 80°C for 12 hours to obtain PI microspheres with uniform particle size and smooth surface.

[0050] (2) Preparation of cross-linking transition layer: Take 6g of PI microspheres and disperse them in 80mL of Tris-HCl buffer (pH=8.5). The concentration of Tris-HCl buffer is 10mmol / L. Disperse by sonication for 30min to obtain microsphere dispersion.

[0051] 1.0 g of dopamine hydrochloride and 0.5 mL of silane coupling agent KH560 were added to the microsphere dispersion and stirred at room temperature for 8 h to obtain a mixed system (polydopamine is polymerized in situ and crosslinked with KH560 to form a composite transition layer on the surface of PI microspheres).

[0052] After centrifugation, the mixture was washed three times with deionized water and dried at 60°C for 7 hours to obtain PI@(PDA-KH560) modified microspheres.

[0053] (3) Preparation of double-doped cerium oxide shell: 5g of PI@(PDA-KH560) modified microspheres were dispersed in 50mL of deionized water and sonicated for 30min. 1.5g of cerium nitrate hexahydrate (Ce(NO3)3・6H2O), 0.12g of yttrium nitrate hexahydrate (Y(NO3)3・6H2O), and 0.07g of gadolinium nitrate hexahydrate (Gd(NO3)3・6H2O) were added and stirred until a homogeneous system was obtained.

[0054] 12g of urea and 0.8g of sodium citrate were mixed and then added to 40mL of deionized water. After stirring evenly, a mixed solution containing urea and sodium citrate was obtained. The solution was slowly added dropwise to the homogeneous system, with the dropping rate controlled at 1.2mL / min. The mixture was stirred at 300rpm for 50min.

[0055] The system was placed in an oil bath and reacted at 95°C for 5 hours. After centrifugation, it was washed three times alternately with deionized water and anhydrous ethanol to obtain the precipitate.

[0056] The precipitate was calcined at 550℃ for 4 hours under a nitrogen atmosphere (heating rate 5℃ / min), and then ground to obtain PI@(PDA-KH560)@Ce. 0.88 Y 0.08 Gd 0.04 O2 core-shell abrasive.

[0057] (4) Preparation of surface hydrophilic layer: 3g of core-shell abrasive was dispersed in 50mL of anhydrous ethanol, and 0.3g of polyethylene glycol monomethyl ether (mPEG, molecular weight 2000) was added. The mixture was stirred at 60℃ for 6h. The mPEG reacted with the Ce of the cerium oxide shell through the hydroxyl groups. 4+ Coordination bonds are formed and grafted onto the surface of the core-shell abrasive.

[0058] After centrifugation, the abrasive was washed twice with anhydrous ethanol and dried at 50°C for 5 hours to obtain a gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive, denoted as PI@(PDA-KH560)@Ce. 0.88 Y 0.08 Gd 0.04 O2 composite abrasive, Figure 1 For PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 Schematic diagram of the structure of O2 abrasive. Figure 2 For PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 SEM image of O2 abrasive. Figure 3 For PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 TEM image and EDS elemental mapping of O2 abrasive.

[0059] The abrasive in this embodiment 1 has a gradient elastic core-shell structure of "flexible elastic core - cross-linked transition layer - double-doped cerium oxide shell", as detailed below:

[0060] ① Flexible elastic core: Polyimide (PI) microspheres with a particle size of 170~210nm, elastic modulus of 10~16GPa, and Mohs hardness of 2.0~2.5 are used to provide basic flexible buffer and realize elastic deformation contact during the polishing process;

[0061] ② Crosslinking transition layer: Coated on the surface of the core, with a thickness of 6~8nm, it is composed of polydopamine (PDA) and γ-glycidyl etheroxypropyltrimethoxysilane (KH560), rich in amino, epoxy and catechol groups, to achieve triple crosslinking of the core and cerium oxide shell through "hydrogen bond-coordination bond-covalent bond", thereby enhancing the interfacial bonding strength;

[0062] ③ Double-doped cerium oxide shell: Coated on the surface of the transition layer, with a thickness of 12~15nm, it is a cubic fluorite structure CeO2, co-doped with Y 3+ (Ionic radius 88.1 pm) and Gd 3+ (Ionic radius 93.8 pm), with a doping molar ratio of Ce:Y:Gd = 8.8:0.8:0.4, forming PI@(PDA-KH560)@Ce 0.88 Y 0.08 Gd 0.04 O2 composite abrasive;

[0063] ④ Surface hydrophilic layer: Polyethylene glycol monomethyl ether (mPEG) is grafted onto the surface of the cerium oxide shell to form a hydrophilic modified layer with a thickness of 1~2nm, which reduces the adsorption energy on the abrasive surface;

[0064] Among them, the key performance parameter is: Ce 3+ Concentration ≥ 50%, oxygen vacancy (Vo) concentration ≥ 0.65 × 10⁻⁶ 23 cm -3 The elastic modulus gradient is 15~45GPa (gradually increasing from the core to the shell), the interfacial bonding strength is ≥14MPa, the sedimentation rate in the polishing slurry is ≤3% after 72h, the surface contact angle is ≤15°, and the adsorption residue rate is ≤0.05%.

[0065] Applications of gradient elastic core-shell dual rare earth co-doped cerium oxide abrasives:

[0066] (a) Preparation of polishing slurry: Deionized water was added to the gradient elastic core-shell-double rare earth co-doped cerium oxide abrasive, and sodium polycarboxylate and glycerol were added as composite dispersion stabilizers. Then, the pH value was adjusted to 10 with 0.1 mol / L Na2CO3 solution and ultrasonically dispersed for 40 min to obtain the polishing slurry. Based on the total mass of the polishing slurry (100%), the components of the polishing slurry are: abrasive solid content of 0.45 wt%, sodium polycarboxylate of 0.15 wt%, glycerol of 0.2 wt%, Na2CO3 of 0.3 wt%, and the remainder is deionized water.

[0067] (b) Polishing treatment: Take one blue filter to be polished, add 15mL of polishing liquid, and place it in a polishing machine for polishing treatment;

[0068] Polishing process: Polishing was performed using a polishing machine (Suzhou Bohongyuan Machinery Manufacturing Co., Ltd., model 13BF-3M6P-G); a soft, fluffy polyurethane polishing pad was used; the grinding disc speed was 55 r / min, and the sample tray speed was 50 r / min (reverse rotation); the polishing time was 1 hour; the slurry feeding rate was 10 mL / min, and 100 kHz ultrasonic-assisted dispersion was applied simultaneously.

[0069] (c) Post-processing: The polished blue filter is ultrasonically cleaned with deionized water for 1 hour at a frequency of 60 kHz and a power of 1000 W. Finally, it is dried with nitrogen to obtain the finished blue filter.

[0070] Example 2

[0071] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that in step (3), the mass of yttrium nitrate hexahydrate in the double-doped CeO2 shell material is adjusted to 0.09 g and the mass of gadolinium nitrate hexahydrate is adjusted to 0.11 g.

[0072] Example 3

[0073] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that in step (b), the pH of the polishing solution is adjusted to 9.0 with NaHCO3 (to shrink polymer chains and increase grinding force), and after polishing for 57.5 min, ammonia is added to the polishing solution to adjust the pH to 10.5 (to extend polymer chains and reduce grinding force), and polishing continues for 2.5 min.

[0074] Comparative Example 1

[0075] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that step (4) for preparing the surface hydrophilic layer is omitted, and step (a) is directly entered after step (3) is completed.

[0076] Comparative Example 2

[0077] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that in step (2) the crosslinking transition layer preparation, only 1.0 g of dopamine hydrochloride is added and KH560 is not added.

[0078] Comparative Example 3

[0079] The steps are the same as those in Example 1 for abrasive polishing, except that in step (a), pure cubic fluorite CeO2 (particle size 200nm, purchased from Shanghai Yanbei New Material Technology Co., Ltd., model: RDB-NM-068) is directly used as the abrasive for polishing fluid, with a solid content of 0.45wt%.

[0080] Comparative Example 4

[0081] The steps for preparing and polishing the abrasive in Example 1 are the same, except that steps (1)-(2) are omitted, and in step (3) the preparation of the double-doped cerium oxide shell, only cerium nitrate hexahydrate and yttrium nitrate hexahydrate are added, without gadolinium nitrate hexahydrate, i.e., Ce 0.92 Y 0.08 O2 is used as the core-shell material in step (4).

[0082] Comparative Example 5

[0083] The steps are the same as those in Example 1 for abrasive polishing, except that in step (a), carbon balls (CS)@CeO2 (carbon ball particle size 190nm, CeO2 shell thickness 13nm, purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., item number: 102631) are used as the abrasive for the polishing slurry.

[0084] Comparative Example 6

[0085] The steps are the same as those in Example 1 for preparing abrasive and applying it for polishing, except that step (2) is omitted and the process proceeds directly to step (3) after step (1), without preparing the crosslinking transition layer.

[0086] Comparative Example 7

[0087] The steps are the same as those in Example 1 for preparing and polishing the abrasive, except that in step (a), sodium polycarboxylate and glycerol are not added to the polishing solution.

[0088] The following equipment and methods were used to test the performance:

[0089] Surface quality: AFM (10μm×10μm scan) test Ra and RMS, laser confocal microscopy to count the number of scratches (≥50nm scratches).

[0090] Polishing efficiency: The difference in mass before and after polishing is measured by an electronic balance, and the MRR (Material Removal Rate) is calculated.

[0091] Residual rate: The residual Ce element on the surface of the polished filter was tested according to GB / T 30902-2014 "Determination of impurity elements in inorganic chemical products by inductively coupled plasma optical emission spectrometry (ICP-OES)".

[0092] Stability: After the polishing slurry has been left to stand for 72 hours, the settling rate (settling mass / total mass) is tested.

[0093] Interface stability: After polishing 15 pieces continuously, the abrasive layer peeling rate was statistically analyzed (TEM observation of the proportion of peeled particles). The test was conducted according to GB / T 41511-2022 "Test Method for Peel Strength of Coated Abrasives".

[0094] Optical transmittance testing method: A UV-Vis spectrophotometer was used. The blue filter to be polished was directly tested after polishing, cleaning, and drying with nitrogen. Air was used as a reference. The test temperature was 25℃. The transmittance of the blue filter before and after polishing was tested in the wavelength range of 400nm~500nm. The key evaluation wavelength was 450nm. The test was conducted in accordance with GB / T 26332.1-2024 "Optics and Photonics - Optical Thin Films - Part 1: Terminology".

[0095] Performance test results and comparative analysis:

[0096] The test results are shown in Table 1 below:

[0097] Table 1

[0098]

[0099] Results analysis:

[0100] (1) Advantages of dual rare earth synergistic doping

[0101] Ra (0.14 nm) of Example 1 (Ce:Y:Gd=8.8:0.8:0.4) compared to Comparative Example 4 (single Y 3+ The doping (Ra=0.53nm) reduced by 73.6%, and the MRR (218nm / min) increased by 45.3% compared to Comparative Example 4 (150nm / min).

[0102] Reason: Y 3+ (Ionic radius close to Ce) 4+ Lowering the oxygen vacancy formation energy (E) va c=-1.35eV), Gd 3+ Inducing local lattice distortion, the two work together to cause Ce 3+ The concentration reached 52.3% (compared to single Y). 3+ Doping increases efficiency by 25%, accelerating Si-O bond breaking while balancing efficiency and quality; Example 2 uses Gd... 3+ The doping molar ratio is too high (Ce:Y:Gd=8.8:0.6:0.6), resulting in excessive lattice distortion and a slight increase in Ra.

[0103] (2) Improved stability of triple cross-linked composite transition layer

[0104] Example 1 (PDA-KH560 composite transition layer) showed no interlayer peeling, while Comparative Example 2 (single PDA transition layer) had a peeling rate of 8.5%, and Comparative Example 6 (no transition layer) had a peeling rate of 35.7%.

[0105] Reason: PDA and KH560 form a triple cross-link of "hydrogen bond-coordination bond-covalent bond", with an interfacial bonding strength of 15.3MPa (42% higher than that of PDA alone), which avoids interlayer delamination during polishing and ensures polishing consistency.

[0106] (3) The effect of surface mPEG modification in reducing residue

[0107] The residual rate of Example 1 (mPEG modified) was 0.04%, which was 89.5% lower than that of Comparative Example 1 (unmodified, residual rate 0.38%) and 92.3% lower than that of Comparative Example 3 (residual rate 0.52%).

[0108] Reason: mPEG grafting reduces the contact angle of the abrasive surface to 12° (48° without modification), which significantly reduces the adsorption energy with the filter surface, making subsequent cleaning simple and avoiding residues that could affect optical performance.

[0109] (4) Optimization of the efficiency of segmented pH adjustment of polishing solution

[0110] Example 3 (pH segmented adjustment) achieved an MRR of 241 nm / min (10.6% higher than Example 1) and Ra = 0.12 nm (a further reduction of 14.3%).

[0111] Reason: The low pH (9.0) in the early stage of polishing causes the polymer chain segments to shrink, increasing the grinding force by 30% and accelerating material removal; the high pH (10.5) in the later stage causes the chain segments to extend, reducing the grinding force and avoiding surface damage, thus achieving a synergistic effect of "high efficiency + low damage".

[0112] (5) Stability advantages of the polishing slurry composite dispersion system

[0113] Example 1 showed a sedimentation rate of 2.1% (72h), which was 92.6% lower than that of Comparative Example 7 (no dispersant, sedimentation rate 28.5%) and 88.7% lower than that of Comparative Example 3 (sedimentation rate 18.6%).

[0114] Reason: Sodium polycarboxylate and glycerol form a three-dimensional protective layer, which, combined with ultrasonic assistance, effectively inhibits abrasive agglomeration and ensures uniform transmission of polishing pressure. The Ra coefficient of variation is only 1.5% after polishing 15 pieces continuously.

[0115] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a gradient-elastic core-shell dual rare earth synergistically doped ceria abrasive, characterized in that, Includes the following steps: S1. Add pyromellitic dianhydride and 4,4'-diaminodiphenyl ether to N,N-dimethylformamide, add dispersant, disperse by ultrasonication, add deionized water for reverse emulsification, then carry out imidization reaction, centrifuge, wash, and dry to obtain PI microspheres. S2. Take PI microspheres and sonicate them in Tris-HCl buffer, add dopamine hydrochloride and KH560, stir and react at room temperature, centrifuge, wash, and dry to obtain modified microspheres; S3. Disperse the modified microspheres in deionized water, sonicate, add cerium nitrate hexahydrate, yttrium nitrate hexahydrate and gadolinium nitrate hexahydrate, stir to react, add a mixed solution containing urea and sodium citrate, centrifuge, calcine, and grind to obtain core-shell abrasive. S4. Disperse the core-shell abrasive in anhydrous ethanol, add polyethylene glycol monomethyl ether, stir to react, centrifuge, wash, and dry to obtain gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive.

2. The preparation method of the gradient elastic core-shell double rare earth synergistically doped ceria abrasive according to claim 1, characterized in that, In step S1, the ratio of pyromellitic dianhydride, 4,4'-diaminodiphenyl ether, N,N-dimethylformamide, dispersant and water is (7-9) g: (5-7) g: (30-70) mL: (0.5-1.5) g: (90-110) mL. The dispersant is polyvinylpyrrolidone. The imidization reaction is to heat the reverse emulsion to 160-200℃ and keep it at that temperature for 3-6 hours.

3. The preparation method of the gradient elastic core-shell double-rare earth synergistically doped ceria abrasive according to claim 1, characterized in that, In step S2, the ratio of PI microspheres to Tris-HCl buffer is (5-7) g: (70-90) mL, the pH of Tris-HCl buffer is 8.5, and the concentration of Tris-HCl buffer is 10 mmol / L.

4. The method of claim 1, wherein the method is characterized by: In step S2, the ratio of PI microspheres, dopamine hydrochloride and KH560 is (5-7) g: (0.5-1.5) g: (0.3-0.7) mL.

5. The method of claim 1, wherein the method is characterized by: In step S3, the ratio of modified microspheres, deionized water, cerium nitrate hexahydrate, yttrium nitrate hexahydrate, gadolinium nitrate hexahydrate, and the mixed solution containing urea and sodium citrate is (3-7) g : (40-60) mL : (1-2) g : (0.1-0.24) g : (0.05-0.09) g : (30-50) mL. The mixed solution containing urea and sodium citrate is obtained by stirring urea, sodium citrate, and deionized water evenly. Each 40 mL of the mixed solution contains 10-14 g of urea and 0.6-1.0 g of sodium citrate, and the solvent is deionized water.

6. The method of claim 1, wherein the method is characterized by: In step S3, the mixture is placed in a N2 atmosphere and calcined at a temperature of 500-600℃ for 3-5 hours.

7. The method of claim 1, wherein the method is characterized by: In step S4, the ratio of the amount of core-shell abrasive, anhydrous ethanol and polyethylene glycol monomethyl ether is (2-4) g: (40-60) mL: (0.2-0.4) g, and the reaction conditions are stirring at 50-70℃ for 4-8 h.

8. Use of a gradient-elastic core-shell double rare earth co-doped ceria abrasive prepared according to the method of any one of claims 1-7, characterized in that, The gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive is used for polishing blue filters.

9. Use of a gradient elastically cored-shell double rare earth synergistically doped ceria abrasive according to claim 8, characterized in that, Includes the following steps: (a) Gradient elastic core-shell-double rare earth co-doped cerium oxide abrasive was added to deionized water, sodium polycarboxylate and glycerol were added, the pH was adjusted with Na2CO3, and ultrasonic dispersion was performed to obtain polishing solution; (b) Add the blue filter to be polished to polishing solution and polish it to obtain the polished blue filter; (c) Clean and dry the polished blue filter to obtain the finished blue filter.

10. The application of the gradient elastic core-shell dual rare earth co-doped cerium oxide abrasive according to claim 9, characterized in that, In step (a), the polishing slurry consists of the following components based on 100% of the total mass of the polishing slurry: 0.3-0.5 wt% gradient elastic core-shell-dual rare earth co-doped cerium oxide abrasive, 0.1-0.2 wt% sodium polycarboxylate, 0.1-0.3 wt% glycerol, 0.2-0.4 wt% Na2CO3, and the remainder is deionized water.

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