Environment-friendly aluminum alloy reflector polishing solution and preparation method thereof

Abstract

The invention discloses an environment-friendly aluminum alloy reflector polishing solution and a preparation method thereof, and belongs to the technical field of general inhibition of corrosion or scale deposition of metal materials. The environment-friendly aluminum alloy reflector polishing solution is prepared from the following components: 2 to 4 weight percent of abrasive particles, 0.2 to 0.6 weight percent of glycine, 10 to 30 weight percent of water and the balance of polyethylene glycol and a pH regulator for regulating the pH value of the environment-friendly aluminum alloy reflector polishing solution to 10 to 11. The components are non-toxic and pollution-free, so that the damage to polishing equipment and the pollution to the environment are reduced. The environment-friendly aluminum alloy reflector polishing solution disclosed by the invention is mild in reaction, the risk of over-corrosion of the surface of aluminum alloy is reduced, and the aluminum alloy reflector polishing solution has excellent reflectivity after being polished; the preparation method is simple in steps and easy to operate, and has good applicability in an enlarged production environment. The method has wide application prospects in the fields of precise polishing of aluminum alloy and the like.

Description

Technical Field

[0001] This invention relates to the field of general technology for inhibiting corrosion or scale buildup in metallic materials, and particularly to an environmentally friendly polishing fluid for aluminum alloy mirrors and its preparation method. Background Technology

[0002] Chemical mechanical polishing (CMP) is one of the precision surface finishing technologies capable of achieving global planarization, playing an indispensable role in the manufacturing of integrated circuits, microelectromechanical systems (MEMS), and optical components. Aluminum alloys, due to their excellent mechanical properties and electrical and thermal conductivity, are widely used in these fields, making high-quality surface polishing crucial.

[0003] Studies have shown that the pH value of the polishing slurry has a significant impact on the removal rate of aluminum alloys. The pH range of 4.6 to 8.3 is the passivation zone for aluminum. In this region, aluminum is easily oxidized, forming a high-hardness, dense passivation film on the aluminum metal surface to prevent corrosion. This passivation film has a hardness much higher than that of the aluminum substrate, leading to reduced chemical activity and a decrease in aluminum removal rate. Currently, precision polishing of aluminum alloys mainly relies on acidic polishing slurry systems. However, during the polishing process using acidic polishing slurries, the acidic system directly corrodes the aluminum alloy substrate, especially materials containing copper, magnesium, and other alloying elements, easily leading to "over-corrosion," resulting in pitting, pinhole, or grain boundary corrosion on the surface, damaging the integrity of the metal structure. At the same time, acidic polishing slurries also corrode the polishing equipment itself, which is detrimental to the long-term maintenance of the equipment.

[0004] Based on the above-mentioned technical deficiencies, those skilled in the art have proposed a method for polishing aluminum alloys under alkaline conditions. In this technical approach, hydrogen peroxide (H2O2) is considered an ideal oxidant due to its strong oxidizing ability. It first oxidizes the aluminum alloy surface to form an oxide film, and then the alkaline components dissolve the oxide film to achieve polishing. For example, Chinese invention patent CN110172301A provides an environmentally friendly aluminum alloy polishing liquid and its preparation method. This environmentally friendly aluminum alloy polishing liquid is prepared from alumina (Al2O3) nanoparticles, hydrogen peroxide solution, chitosan oligosaccharide, water, and a pH adjuster; the concentration of alumina nanoparticles in the polishing liquid is 10~30 g / L, the concentration of hydrogen peroxide is 1 vol.%~1.5 vol.%, the concentration of chitosan oligosaccharide is 2~6 g / L, and the pH value is 11~12. However, the reaction rate of hydrogen peroxide and alkaline components is difficult to control precisely, and oxidation-dissolution imbalance is very likely to occur. More importantly, hydrogen peroxide is affected by temperature, pH fluctuations, and metal ions (Al2O3 produced by the dissolution of aluminum alloy). 3+ Cu 2+(Under the influence of catalytic decomposition, it will rapidly decompose into oxygen and water, causing a sharp drop in concentration and a drastic decrease in polishing effect (such as gloss and uniformity).

[0005] In summary, this paper presents an environmentally friendly polishing slurry for aluminum alloy mirrors using a novel technical approach and its preparation method. This solution addresses the aforementioned problems in existing polishing slurry systems and is of great significance for the precision machining of aluminum alloys. Summary of the Invention

[0006] In view of the above-mentioned defects of the prior art, the purpose of the present invention is to provide an environmentally friendly aluminum alloy mirror polishing slurry and its preparation method. It uses non-toxic components to reduce the pollution of the polishing slurry to the environment and the damage to the polishing equipment. Furthermore, it reduces the risk of over-corrosion of the aluminum alloy surface through group design, so that the polished surface has excellent reflectivity.

[0007] In a first aspect of the present invention, an environmentally friendly polishing fluid for aluminum alloy mirrors is provided, comprising the following components: Abrasive particles 2 wt.%~4 wt.%, glycine 0.2 wt.%~0.6 wt.%, water 10 wt.%~30 wt.%, balance being polyethylene glycol and a pH adjuster to adjust the pH of the environmentally friendly aluminum alloy mirror polishing slurry to 10~11.

[0008] Preferably, the abrasive particles include at least one of cerium oxide, aluminum oxide, and silicon oxide.

[0009] Preferably, the abrasive grains are hydrophilic abrasive grains.

[0010] Preferably, the particle size of the abrasive grains is 20~50 nm.

[0011] Preferably, the polyethylene glycol includes one or both of polyethylene glycol 200 and polyethylene glycol 400.

[0012] Compared to conventional polyethylene glycol (PEG) used in polishing slurries, PEG 200 and PEG 400 are low molecular weight liquid PEGs with low viscosity, good flowability, and excellent miscibility with water. They are easier to disperse uniformly in polishing slurry systems and less prone to forming localized viscous areas. Combined with the design concept of this invention, this facilitates the formation of a targeted dispersion medium with water, optimizes the dispersibility of abrasive particles, and thus optimizes polishing performance.

[0013] Preferably, the pH adjuster includes one or both of potassium hydroxide aqueous solution and citric acid.

[0014] In a second aspect of the present invention, a method for preparing the environmentally friendly aluminum alloy mirror polishing fluid of the first aspect of the present invention is provided, comprising the following steps: (1) Prepare raw materials according to the component ratio; add glycine to water and mix to obtain glycine solution; add abrasive particles to polyethylene glycol and mix to obtain dispersion; (2) Add glycine solution to dispersion, mix and then adjust the pH of the system to 10-11 with pH adjuster to obtain mixture; (3) The mixture is ultrasonically dispersed to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0015] Preferably, in step (3), the ultrasonic dispersion treatment time is 5 to 30 minutes.

[0016] In a third aspect of the invention, the application of the environmentally friendly aluminum alloy mirror polishing fluid of the first aspect of the invention is provided, including: using it as a polishing fluid for precision polishing of aluminum alloys.

[0017] Preferably, the reflectivity of the polished aluminum alloy is ≥95%.

[0018] Based on the above technical solutions, the design concept and principle of this invention are as follows: This invention employs raw materials in a specific design ratio. Under selected components, polyethylene glycol and water are used to form a corresponding dispersion medium. The different dispersibility of abrasive particles within this medium affects polishing performance. Water provides the medium carrier for the chemical reaction in chemical mechanical polishing, while oxygen in the air participates in the reaction to generate alumina or aluminum hydroxide under alkaline conditions (pH=10~11). Glycine contains both amino and carboxyl groups and has a dual tendency to ionize into hydrogen ions or hydroxide ions. The purpose and function of using glycine in this invention is to control the weak ionization of glycine into anionic form (H2N-CH2-COO) under the designed ratio (0.2 wt.%~0.6 wt.%) and environmental conditions (pH=10~11). -The reaction proceeds in the direction of the aluminum alloy surface. During the dissolution of aluminum oxide on the aluminum alloy surface, the anions formed by the ionization of glycine recombine with the generated aluminum ions. The resulting composite product is carried away with the slurry, thus ensuring the reaction continues in the target direction. Finally, combined with abrasive removal of the oxide layer, the combined chemical and mechanical action produces a smooth aluminum alloy surface with minimal damage, significantly improving the reflectivity after polishing. Furthermore, strong acids, strong bases, or strong oxidants can easily cause over-corrosion of the base metal during polishing. This invention uses glycine, a weak acid and weak base with a pKa2 of 9.6, and designs a target pH environment to control its ionization and subsequent reactions. Under the selected environment, it selectively dissolves the oxide layer through specific coordination with aluminum ions, exhibiting a mild and controllable chemical polishing and cleaning effect. This environment also solves the problem of surface damage caused by conventional strong alkalis. These aspects are crucial for the precision polishing of aluminum alloys. The design of the above raw materials must be controlled within the designed proportion range. Too high a glycine content will lead to over-corrosion, while too low a content will affect the chemical reaction efficiency; too high an abrasive concentration will lead to increased scratches, while too low a concentration will result in insufficient removal rate.

[0019] It should be noted that there are polishing solutions in the art that use similar raw materials to those of this invention (such as CN115821266A and CN105970228A), but their purpose is to utilize the complexing agent to release hydroxide ions during the polishing process (in which glycine exists in the form of...). + The pH value of the recycled aluminum alloy polishing solution is continuously adjusted using H3N-CH2-COOH. In this invention, glycine is designed to release hydrogen ions and anions (H2N-CH2-COOH). - The process involves using similar raw materials to achieve the aforementioned polishing effect. However, the physicochemical changes involved in both processes differ fundamentally.

[0020] Compared with the prior art, the present invention has the following advantages and beneficial effects: This invention provides an environmentally friendly polishing slurry for aluminum alloy mirrors. Its components are all non-toxic and non-polluting, reducing damage to polishing equipment and reducing environmental pollution. In addition, the reaction is mild under the component design of this invention, reducing the risk of over-corrosion of the aluminum alloy surface and resulting in excellent reflectivity after polishing.

[0021] This invention provides a method for preparing an environmentally friendly polishing fluid for aluminum alloy mirrors. The steps are simple and easy to operate, and it has good applicability in a large-scale production environment.

[0022] This invention provides an application of an environmentally friendly aluminum alloy mirror polishing slurry, which has broad prospects in the fields of precision polishing of aluminum alloys. Attached Figure Description

[0023] Figure 1 This is a test schematic diagram of a four-axis pneumatic polishing machine; Figure 2 This is a reflectivity test chart of the environmentally friendly aluminum alloy mirror polishing fluid in Example 1 during application; Figure 3 This is a reflectivity test chart of the environmentally friendly aluminum alloy mirror polishing slurry in Example 2 during application; Figure 4 This is a reflectivity test chart of the environmentally friendly aluminum alloy mirror polishing slurry in Example 3 during application; Figure 5 This is a test graph showing the reflectivity of the environmentally friendly aluminum alloy mirror polishing fluid in Example 4 during application. Figure 6 This is a reflectivity test chart of the environmentally friendly aluminum alloy mirror polishing slurry in Example 5 during application; Figure 7 This is a reflectivity test chart of the environmentally friendly aluminum alloy mirror polishing slurry of Example 6 in application; Figure 8 The reflectance test diagram of the polishing slurry in Comparative Example 1 during application is shown. Figure 9 In the diagram, (a) shows the surface roughness of the aluminum alloy mirror before polishing with environmentally friendly aluminum alloy mirror polishing liquid, and (b) shows the surface roughness after polishing. Figure 10 In the figure, (a) shows the surface microstructure of the aluminum alloy mirror after polishing with environmentally friendly aluminum alloy mirror polishing liquid; (b) shows the surface microstructure of the aluminum alloy mirror after polishing with the polishing liquid of Comparative Example 1. Figure 11 In the image, (a) is a picture of an aluminum alloy mirror after it has been polished with an environmentally friendly aluminum alloy mirror polishing liquid; (b) is a picture of an aluminum alloy mirror after it has been polished with the polishing liquid of Comparative Example 1. Detailed Implementation

[0024] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0025] In the following embodiments: Four-axis pneumatic polishing machine, Wuxi Xibin Optoelectronic Equipment Co., Ltd. QJP25; White light interferometer, ZYGO NewView 9000; Hydrophilic silica: Beasley New Materials (Suzhou) Co., Ltd.; Hydrophilic alumina: Hebei Chengyue Metal Materials Co., Ltd.; Hydrophilic cerium oxide: Hebei Hangbei Metal Materials Co., Ltd.; The average particle size of the above abrasive grains is 50 nm.

[0026] Example 1 This embodiment provides an environmentally friendly polishing fluid for aluminum alloy mirrors, the preparation method of which is as follows: (1) Weigh 2 wt.% hydrophilic silica, 0.3 wt.% glycine, 20 wt.% deionized water, and the remainder is polyethylene glycol 400 and pH adjuster; under stirring conditions, mix glycine and deionized water evenly to obtain glycine solution; then add hydrophilic silica to polyethylene glycol 400 and stir to fully disperse the abrasive particles to obtain dispersion. (2) Add glycine solution to dispersion, stir, and then add potassium hydroxide aqueous solution dropwise to adjust the pH of the system to 10 to obtain a mixture; (3) The mixture is placed in an ultrasonic disperser and ultrasonically dispersed for 15 min to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0027] Example 2 This embodiment provides an environmentally friendly polishing fluid for aluminum alloy mirrors, the preparation method of which is as follows: (1) Weigh 2 wt.% hydrophilic silica, 0.3 wt.% glycine, 20 wt.% deionized water, and the remainder is polyethylene glycol 200 and pH adjuster; under stirring conditions, mix glycine and deionized water evenly to obtain glycine solution; then add hydrophilic silica to polyethylene glycol 200 and stir to fully disperse the abrasive particles to obtain dispersion. (2) Add glycine solution to dispersion, stir, and then add potassium hydroxide aqueous solution dropwise to adjust the pH of the system to 10 to obtain a mixture; (3) The mixture is placed in an ultrasonic disperser and ultrasonically dispersed for 15 min to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0028] Example 3 This embodiment provides an environmentally friendly polishing fluid for aluminum alloy mirrors, the preparation method of which is as follows: (1) Weigh 2 wt.% hydrophilic alumina, 0.3 wt.% glycine, 20 wt.% deionized water, and the remainder is polyethylene glycol 400 and pH adjuster; under stirring conditions, mix glycine and deionized water evenly to obtain glycine solution; then add hydrophilic alumina to polyethylene glycol 200 and stir to fully disperse the abrasive particles to obtain dispersion. (2) Add glycine solution to dispersion, stir, and then add potassium hydroxide aqueous solution dropwise to adjust the pH of the system to 10 to obtain a mixture; (3) The mixture is placed in an ultrasonic disperser and ultrasonically dispersed for 15 min to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0029] Example 4 This embodiment provides an environmentally friendly polishing fluid for aluminum alloy mirrors, the preparation method of which is as follows: (1) Weigh 2 wt.% hydrophilic alumina, 0.3 wt.% glycine, 20 wt.% deionized water, and the remainder is polyethylene glycol 200 and pH adjuster; under stirring conditions, mix glycine and deionized water evenly to obtain glycine solution; then add hydrophilic alumina to polyethylene glycol 200 and stir to fully disperse the abrasive particles to obtain dispersion. (2) Add glycine solution to dispersion, stir, and then add potassium hydroxide aqueous solution dropwise to adjust the pH of the system to 10 to obtain a mixture; (3) The mixture is placed in an ultrasonic disperser and ultrasonically dispersed for 15 min to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0030] Example 5 This embodiment provides an environmentally friendly polishing fluid for aluminum alloy mirrors, the preparation method of which is as follows: (1) Weigh 2 wt.% hydrophilic cerium oxide, 0.3 wt.% glycine, 20 wt.% deionized water, and the remainder is polyethylene glycol 400 and pH adjuster; under stirring conditions, mix glycine and deionized water evenly to obtain glycine solution; then add hydrophilic cerium oxide to polyethylene glycol 200 and stir to fully disperse the abrasive particles to obtain dispersion. (2) Add glycine solution to dispersion, stir, and then add potassium hydroxide aqueous solution dropwise to adjust the pH of the system to 10 to obtain a mixture; (3) The mixture is placed in an ultrasonic disperser and ultrasonically dispersed for 15 min to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0031] Example 6 This embodiment provides an environmentally friendly polishing fluid for aluminum alloy mirrors, the preparation method of which is as follows: (1) Weigh 2 wt.% hydrophilic cerium oxide, 0.3 wt.% glycine, 20 wt.% deionized water, and the remainder is polyethylene glycol 200 and pH adjuster; under stirring conditions, mix glycine and deionized water evenly to obtain glycine solution; then add hydrophilic cerium oxide to polyethylene glycol 200 and stir to fully disperse the abrasive particles to obtain dispersion. (2) Add glycine solution to dispersion, stir, and then add potassium hydroxide aqueous solution dropwise to adjust the pH of the system to 10 to obtain a mixture; (3) The mixture is placed in an ultrasonic disperser and ultrasonically dispersed for 15 min to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

[0032] Comparative Example 1 This comparative example provides a polishing fluid that does not use deionized water as a carrier, and its preparation method is as follows: Weigh out 2 wt.% hydrophilic silica, 0.3 wt.% glycine, and the remainder polyethylene glycol 400; under stirring conditions, thoroughly stir the glycine, hydrophilic silica and polyethylene glycol 400, and then place them in an ultrasonic disperser for ultrasonic dispersion for 15 min to obtain polishing liquid.

[0033] Test Example 1 The environmentally friendly aluminum alloy mirror polishing slurries of Examples 1-6 and the polishing slurry of Comparative Example 1 were used to test their application effects on a Φ40 mm 6061 aluminum alloy mirror. Figure 1 As shown, an aluminum alloy mirror was processed using a four-axis pneumatic polisher. The polishing pad was frosted leather; the spindle speed was 45 rpm; the oscillating axis speed was 20 rpm; and the processing time was 2 hours. After polishing, scratches and surface oxidation were observed, and reflectance was measured using a Taylor infrared spectrometer. In the reflectance test, the reflectance was the average value calculated using an aluminum-plated surface as the substrate at wavelengths of 1500–2200 nm. Test images for Examples 1–6 and Comparative Example 1 are shown below. Figures 2-8 As shown in Table 1, the test results for reflectivity are as follows.

[0034] Table 1: Reflectance Test Results of Examples and Comparative Examples

[0035] In this field, untreated aluminum alloys typically have a reflectivity of 60%–75%, exhibiting diffuse reflection characteristics. Traditional mechanical polishing can achieve a reflectivity of 80%–88%, but micro-scratches and oxide layer scattering remain on the surface; conventional chemical mechanical polishing can achieve a reflectivity of 90%–92%. The above test results indicate that the environmentally friendly aluminum alloy mirror polishing solution can achieve a reflectivity ≥95%, with a maximum of 98.27%, approaching the performance of mirrors coated with dielectric reinforcement films (99%), reaching the high-performance industrial and optical grade range. The environmentally friendly aluminum alloy mirror polishing solution of this invention has excellent polishing effects, resulting in high reflectivity after polishing, meeting the precision polishing requirements of aluminum alloys. The polyethylene glycol system in Comparative Example 1 does not contain deionized water, making it impossible to adjust the pH and dissolve glycine, resulting in only mechanical removal and failing to achieve high surface quality.

[0036] Test Example 2 The surface roughness of the samples before and after polishing as described in Example 1 was measured using a white light interferometer. The surface roughness was obtained by averaging the results from five randomly sampled points from the center to the edge. The results are as follows: Figure 9As shown. Figure 9 In the figure, (a) shows that the roughness Sa is 3.282 nm before polishing, and (b) shows that the roughness Sa is 1.956 nm after polishing; and the morphology is uniform after polishing.

[0037] In the testing of the polished samples, no significant scratches or oxidation marks were observed in the samples treated in Examples 1-6. For comparison, Figure 10 The microstructures of Example 1 and Comparative Example 1 after polishing are presented. It can be seen that after treatment with the environmentally friendly aluminum alloy mirror polishing solution of the present invention, the surface structure is uniform and stable, without corrosion, scratches, or other phenomena; while in Comparative Example 1, surface damage caused by over-corrosion was observed. Furthermore, Figure 11 The paper also presents a photograph of the polished object; the comparison shows that the polishing liquid of the present invention has good reflectivity after treatment, exhibiting a mirror effect, which corresponds to the high reflectivity test results in Table 1; in contrast, the surface of Comparative Example 1 is dull and has a lot of scratches.

[0038] Within the component range designed in this invention, those skilled in the art can adjust the raw material ratio or parameters according to actual needs, and the resulting environmentally friendly aluminum alloy reflector polishing fluid can achieve the expected effects of this invention. When the raw material ratio is not within the designed range, it is difficult to achieve the purpose of this invention. For example, if the concentration is too high, the solution system will easily become viscous; if it is too low, the system viscosity will be low, the abrasive particles will easily settle, and they will not have good dispersibility, making them easy to embed into the substrate surface during the polishing process.

[0039] In summary, the environmentally friendly aluminum alloy mirror polishing slurry of the present invention has high reflectivity after polishing and reduces the oxidation of aluminum alloy. Moreover, its composition and preparation process are simple, environmentally friendly and pollution-free, and it has broad application prospects in the field of precision polishing of aluminum alloys.

[0040] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. An environmentally friendly polishing fluid for aluminum alloy mirrors, characterized in that, It includes the following components: abrasive particles 2 wt.%~4 wt.%, glycine 0.2 wt.%~0.6 wt.%, water 10 wt.%~30 wt.%, with the balance being polyethylene glycol and a pH adjuster to adjust the pH of the environmentally friendly aluminum alloy mirror polishing solution to 10~11.

2. The environmentally friendly aluminum alloy mirror polishing fluid according to claim 1, characterized in that: The abrasive particles include at least one of cerium oxide, aluminum oxide, and silicon oxide.

3. The environmentally friendly aluminum alloy mirror polishing fluid according to claim 1, characterized in that: The abrasive grains are hydrophilic.

4. The environmentally friendly aluminum alloy mirror polishing slurry according to claim 1, characterized in that: The abrasive grains have a particle size of 20~50 nm.

5. The environmentally friendly aluminum alloy mirror polishing fluid according to claim 1, characterized in that: The polyethylene glycol includes one or both of polyethylene glycol 200 and polyethylene glycol 400.

6. The environmentally friendly aluminum alloy mirror polishing fluid according to claim 1, characterized in that: The pH adjuster includes one or both of potassium hydroxide aqueous solution and citric acid.

7. A method for preparing an environmentally friendly aluminum alloy mirror polishing fluid as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Prepare raw materials according to the component ratio; add glycine to water and mix to obtain glycine solution; add abrasive particles to polyethylene glycol and mix to obtain dispersion; (2) Add glycine solution to dispersion, mix and then adjust the pH of the system to 10-11 with pH adjuster to obtain mixture; (3) The mixture is ultrasonically dispersed to obtain an environmentally friendly aluminum alloy mirror polishing liquid.

8. The method for preparing the environmentally friendly aluminum alloy mirror polishing fluid according to claim 7, characterized in that: In step (3), the ultrasonic dispersion treatment time is 5~30 min.

9. The application of an environmentally friendly aluminum alloy mirror polishing slurry as described in any one of claims 1 to 6, or an environmentally friendly aluminum alloy mirror polishing slurry prepared by the preparation method described in claim 7 or 8, characterized in that, include: It is used as a polishing slurry for the precision polishing of aluminum alloys.

10. The application of the environmentally friendly aluminum alloy mirror polishing slurry according to claim 9, characterized in that: The reflectivity of the polished aluminum alloy is ≥95%.

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