Aluminum alloy polishing liquid and polishing method thereof

Abstract

The application discloses an aluminum alloy polishing liquid and a polishing method thereof, and raw materials contain the following components in mass parts: 30-40 parts of citric acid, 2-3 parts of phytic acid, 2-4 parts of sodium molybdate, 70-80 parts of an oxidizing agent, 50-60 parts of nano-SiO2 slurry, 3-5 parts of a non-ionic surfactant, 0.1-0.2 parts of a catalyst, and 7-8 parts of a pH buffer, wherein the solid content of the nano-SiO2 slurry is 10%; the citric acid mildly chelates aluminum ions and controls the dissolution rate; the phytic acid contains six phosphate groups and forms a dense and multi-tooth chelate film on the aluminum surface, but there are micropores in the film; after the molybdate is dissolved, MoO4 2- anions are generated and migrate to the pores or defects of the phytic acid film, thereby better playing a slow-release role and avoiding surface roughness caused by over-etching.

Description

Technical Field

[0001] This application relates to the field of metal surface treatment technology, and in particular to an aluminum alloy polishing liquid and a polishing method thereof. Background Technology

[0002] Aluminum alloy polishing slurries have gained widespread application and development in the industrial field due to their significant advantages. Compared with traditional mechanical polishing, their main advantages are: efficient processing of complex-shaped workpieces, achieving uniform polishing across the entire surface and improving production efficiency; the resulting surface has higher mirror brightness and consistency, greatly enhancing the appearance quality of products; and they are particularly suitable for automated operation in large-scale production lines, reducing labor costs. These advantages make them a key surface treatment technology in the production of architectural profiles, electronic product casings, decorative parts, and industrial products requiring high-gloss surfaces.

[0003] However, the polishing process using aluminum alloy polishing slurries also presents key challenges, the most significant of which is the phenomenon of "over-etching." Over-etching easily occurs when the concentration of the polishing slurry components is not properly controlled, the temperature deviates from the optimal range, or the processing time is too long. This not only destroys the expected bright surface, resulting in a hazy appearance, but also causes more serious structural problems: for example, localized over-etching can form pits or unevenness; uncontrollable out-of-tolerance losses can occur in critical dimensions of the workpiece, severely affecting the surface flatness of aluminum alloy parts. Summary of the Invention

[0004] To address the problem of over-etching in traditional aluminum alloy polishing slurries, which affects the surface smoothness of polished products, an aluminum alloy polishing slurry and its polishing method are provided.

[0005] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0006] An aluminum alloy polishing slurry, the raw materials of which contain the following components in parts by weight:

[0007] The mixture contains 30-40 parts citric acid, 2-3 parts phytic acid, 2-4 parts sodium molybdate, 70-80 parts oxidant, 50-60 parts nano-SiO2 slurry, 3-5 parts nonionic surfactant, 0.1-0.2 parts catalyst, and 7-8 parts pH buffer, wherein the solid content of the nano-SiO2 slurry is 10%.

[0008] Through the above technical solution, citric acid gently chelates aluminum ions, controlling the dissolution rate and avoiding H+ ions. + The phytic acid, containing six phosphate groups, forms a dense, multidentate chelate film on the aluminum surface through strong coordination. This film physically covers the surface of the aluminum alloy, but microscopically contains pores. After the molybdate dissolves, it forms MoO4. 2-Anions migrate to the pores or defects of the phytic acid film; nonionic surfactants are uncharged and unaffected by pH, ionic strength, or aluminum surface potential, thus maintaining adsorption stability; uniformly dispersed nano-SiO2 removes protrusions through low-damage rolling friction, reducing localized electrochemical corrosion points caused by mechanical scratches.

[0009] Optionally, the mass ratio of phytic acid to sodium molybdate in the raw materials is 1:(1.2 to 1.3).

[0010] The above technical solution enables the phytic acid to molybdate mass ratio of 1:(1.2-1.3) to fully fill the pores of the phytic acid membrane with molybdate, thereby further reducing over-etching.

[0011] Optionally, the raw materials may also include 0.02 to 0.03 parts by weight of benzotriazole.

[0012] Through the above technical solution, benzotriazole is vertically adsorbed onto highly active over-etching points such as aluminum grain boundaries and dislocations via N-atom heterocycles, forming Cu... + -BTA polymer film blocks local micro-cell corrosion pathways; complementary to phytic acid passivation film: phytic acid covers planar areas, BTA targets and protects grain boundaries, inhibits selective over-etching in sensitive areas of aluminum alloy, and reduces surface corrosion pit density.

[0013] Optionally, the nano-SiO2 in the nano-SiO2 slurry is modified with methoxy polyethylene glycol acrylate.

[0014] Through the above technical solution, methoxy polyethylene glycol acrylate long chains are grafted onto the surface of SiO2 to form a steric hindrance layer, which prevents particle agglomeration. The hydrophilic polyethylene glycol chains improve the dispersion stability of particles, eliminate local mechanical over-wear caused by agglomerates, avoid secondary corrosion caused by mechanical damage, and improve the microscopic uniformity of the surface.

[0015] Optionally, the preparation method of nano-SiO2 slurry modified with methoxy polyethylene glycol acrylate includes the following steps: dispersing dried nano-SiO2 in water to obtain a SiO2 suspension, adding a methoxy polyethylene glycol acrylate solution dropwise into the SiO2 suspension, and simultaneously shearing at high speed to obtain the modified nano-SiO2 slurry.

[0016] The above technical solution uses non-polar solvent dispersion to avoid hydrolysis and aggregation of hydroxyl groups on the SiO2 surface, centrifugal washing to remove ungrafted MPEG, and prevents residual organic matter from carbonizing and adhering to the surface during polishing, forming corrosion cells, thus ensuring the stability of abrasive dispersion and reducing local over-etching caused by particle aggregation.

[0017] Optionally, pH buffers include sodium acetate and acetic acid.

[0018] The above technical solution can maintain pH = 4.0 ± 0.2 and avoid H+ ionization when pH < 3.5. + Erosion is accelerated when pH > 4.5, Al 3+ Hydrolysis and precipitation induce pitting corrosion, while acetate ions (CH3COO-) preferentially adsorb onto the surface, assisting in the formation of a phytic acid corrosion inhibitor film and reducing over-corrosion caused by uncontrolled dissolution due to acidity fluctuations.

[0019] Optionally, the nonionic surfactant may be fatty alcohol polyoxyethylene ether.

[0020] Through the above technical solution, the polyoxyethylene chains in fatty alcohol polyoxyethylene ether are protonated in an acidic environment, and encapsulate negatively charged polishing residues through electrostatic interaction to form micelles, preventing residue accumulation from forming oxygen concentration cells that would lead to localized over-etching.

[0021] The second objective of this invention is achieved through the following technical solution:

[0022] A polishing method for aluminum alloys using polishing slurry includes the following steps:

[0023] S1: Use a cleaning agent to clean the aluminum alloy parts until they are free of oil and dust;

[0024] S2: Spray any of the above polishing liquids evenly and dynamically onto the aluminum alloy parts, and polish the surface of the aluminum alloy parts using a polishing wheel;

[0025] S3: Use liquid nitrogen to rapidly cool the aluminum alloy surface and then clean it with water.

[0026] Through the above technical solutions, dynamic spraying continuously refreshes the polishing slurry, preventing component decomposition from causing corrosion inhibition failure, and liquid nitrogen rapid cooling instantly freezes the surface reaction, terminating over-etching caused by residual acid corrosion.

[0027] In summary, this application has at least the following beneficial effects:

[0028] (1) Citric acid gently chelates aluminum ions, and the dissolution rate is strictly controlled to avoid H+ ions. + Severe erosion;

[0029] (2) Phytic acid forms a dense, multidentate chelate film on the aluminum surface through strong coordination. This film physically covers the surface of the aluminum alloy part. After the molybdate dissolves, MoO4 is generated. 2- Anions migrate to the pores or defects of the phytic acid membrane;

[0030] (3) The uniform dispersion of nano-SiO2 removes protrusions through low-damage rolling friction, reducing local electrochemical corrosion points caused by mechanical scratches. Detailed Implementation

[0031] raw material

[0032] Citric acid, specifically anhydrous citric acid, was purchased from Shandong Lemon Biochemical Co., Ltd.

[0033] Phytic acid, 50-70 wt%, was purchased from Laiyang Wanjiwei Bioengineering Co., Ltd.

[0034] Molybdate, specifically sodium molybdate, with a sodium molybdate content ≥99.0 wt%, a Mo content ≥39.3%, and a pH of 7-10, was purchased from Tianjin Sifang Chemical Co., Ltd.

[0035] The oxidant was a hydrogen peroxide solution, 35 wt% by weight, purchased from Hangzhou Mingxin Hydrogen Peroxide Co., Ltd.

[0036] Nano-SiO2, with a purity >99wt% and a particle size of 20nm, was purchased from Beijing Bailingwei Technology Co., Ltd.

[0037] Methoxylated polyethylene glycol acrylate was purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.

[0038] Sodium acetate (purity > 99 wt%) and glacial acetic acid (purity > 99 wt%) were both sourced from commercially available sources.

[0039] Ammonium molybdate, with a molybdenum trioxide content ≥84.0 wt% and a Mo content ≥56.0 wt%, was purchased from Tianjin Sifang Chemical Co., Ltd.

[0040] Benzotriazole, purity ≥99.8wt%, purchased from Shandong Longhui Chemical Co., Ltd.

[0041] 3-Aminopropyltriethoxysilane, with a content ≥98.0 wt%, was purchased from Jiangxi Hongbai New Materials Co., Ltd.

[0042] Sodium dodecylbenzenesulfonate (purity ≥95wt%), tartaric acid (purity ≥95wt%), and sodium tartrate (purity ≥98wt%) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0043] Alkylphenol polyoxyethylene ether, purity ≥99wt%, purchased from Xingtai Xinlanxing Technology Co., Ltd.

[0044] Preparation Example 1

[0045] A nano-SiO2 slurry is prepared as follows:

[0046] 100g of nano-SiO2 was evenly spread on an oven tray and dried at 100℃ until the moisture content was ≤0.1% to obtain dried nano-SiO2. 1000mL of deionized water was added to a mixer, and the dried nano-SiO2 was added to the mixer in 5 batches with an interval of 90s between each batch. The mixture was mixed at 2000rpm for 10min, and then ultrasonically treated at 500W for 15min to obtain nano-SiO2 slurry.

[0047] Preparation Example 2

[0048] A modified nano-SiO2, its preparation method:

[0049] 100g of nano-SiO2 was evenly spread on an oven tray and dried at 100℃ until the moisture content was ≤0.1% to obtain dried nano-SiO2; 990mL of deionized water was added to a mixer, and the dried nano-SiO2 was added to a high-speed mixer in 5 batches with an interval of 90s between each batch. The mixture was dispersed at 1000rpm for 8min to obtain dispersed nano-SiO2.

[0050] 10 mL of methoxy polyethylene glycol acrylate solution was sprayed into the mixer at a rate of 1 L / min, and simultaneously sheared at a high speed of 2500 rpm for 10 min. The methoxy polyethylene glycol acrylate solution was an aqueous solution of methoxy polyethylene glycol acrylate in ethanol, with a methoxy polyethylene glycol acrylate content of 4.8 wt%, an ethanol content of 80 wt%, and the remainder being water.

[0051] After standing for 2 hours, the modified nano-SiO2 slurry was obtained.

[0052] Preparation Example 3

[0053] A modified nano-SiO2 slurry is prepared in a manner different from that in Preparation Example 2, except that a 3-aminopropyltriethoxysilane solution is used instead of a methoxy polyethylene glycol acrylate solution. The 3-aminopropyltriethoxysilane solution is an aqueous solution of 3-aminopropyltriethoxysilane in ethanol, with a 3-aminopropyltriethoxysilane content of 4.8 wt%, an ethanol content of 80 wt%, and the remainder being water. The other parts are the same as in Preparation Example 2.

[0054] Preparation Example 4

[0055] A modified nano-SiO2 slurry, its preparation method:

[0056] 100g of nano-SiO2 was evenly spread on an oven tray and dried at 100℃ until the moisture content was ≤0.1% to obtain dried nano-SiO2; 990mL of deionized water was added to a mixer, and the dried nano-SiO2 was added to a high-speed mixer in 5 batches with an interval of 90s between each batch. The mixture was dispersed at 1000rpm for 8min to obtain dispersed nano-SiO2.

[0057] 10 mL of methoxy polyethylene glycol acrylate solution was directly added to the mixer, and the mixture was sheared at a high speed of 2500 rpm for 10 min. The methoxy polyethylene glycol acrylate solution was an aqueous solution of methoxy polyethylene glycol acrylate in ethanol, with a methoxy polyethylene glycol acrylate content of 4.8 wt%, an ethanol content of 80 wt%, and the remainder being water.

[0058] After standing for 2 hours, the modified nano-SiO2 slurry was obtained.

[0059] Example 1

[0060] An aluminum alloy polishing slurry is prepared from the following raw materials by weight: 350g citric acid, 25g phytic acid, 25g sodium molybdate, 750g hydrogen peroxide solution, 550g nano-SiO2 slurry, 40g fatty alcohol polyoxyethylene ether, 75g pH buffer, and 1.5g ammonium molybdate. The nano-SiO2 slurry is derived from Preparation Example 1. The pH buffer is a sodium acetate-acetic acid system with a molar ratio of sodium acetate to acetic acid of 0.174:1 and a pH buffer concentration of 0.1 mol / L.

[0061] An aluminum alloy polishing slurry, the preparation method of which is as follows:

[0062] Add citric acid and 500 mL of deionized water to the reaction vessel, stir at 300 rpm for 10 min at 45 °C, add phytic acid at 2 mL / min at 40 °C while stirring at 200 rpm, and sprinkle sodium molybdate in batches of 10 g each, with an interval of 30 s.

[0063] Ammonium molybdate was added under light-protected conditions, while N2 was introduced for protection at a flow rate of 0.1 m / s. 3 / h;

[0064] SiO2 slurry was dripped into the reactor at a rate of 10 mL / min, while being sheared at 1200 rpm.

[0065] Add pH buffer to the reaction vessel to adjust the pH to 3.8–4.2;

[0066] Add fatty alcohol polyoxyethylene ether to the reactor and stir at 1500 rpm for 3 min;

[0067] Hydrogen peroxide solution was added dropwise at a rate of 1 mL / s under conditions of 5±1℃, while stirring at a rate of 300 rpm, to obtain an aluminum alloy polishing solution.

[0068] Its usage method is as follows:

[0069] The aluminum alloy parts are made of 4008 series aluminum alloy with dimensions of 50mm×50mm×2mm and are sourced from commercially available products.

[0070] At 60°C, the aluminum alloy was immersed in a 5 wt% sodium hydroxide solution for 3 minutes, and then the surface of the aluminum alloy was rinsed with deionized water until no sodium hydroxide solution remained.

[0071] At 25℃, the cleaned aluminum alloy parts were placed on a polishing wheel at a speed of 1200 rpm and a pressure of 0.2 MPa, while polishing liquid was sprayed in at a speed of 3 mL / s for 5 min.

[0072] -50℃ cryogenic liquid nitrogen spray cooling for 5 seconds.

[0073] Comparative Example 1

[0074] An aluminum alloy polishing liquid differs from Example 1 in that it does not contain sodium molybdate. After adding phytic acid and stirring, the sodium molybdate is not added. The rest of the liquid is the same as in Example 1.

[0075] Comparative Example 2

[0076] An aluminum alloy polishing liquid differs from Example 1 in that it does not contain phytic acid, and after the citric acid and deionized water are stirred, no phytic acid is added. The rest of the liquid is the same as that in Example 1.

[0077] Comparative Example 3

[0078] An aluminum alloy polishing liquid, which differs from Example 1 in that 40g of sodium dodecylbenzenesulfonate is used instead of 40g of fatty alcohol polyoxyethylene ether, while the rest is the same as in Example 1.

[0079] Example 2

[0080] An aluminum alloy polishing slurry differs from Example 1 in that it contains 31.25g of sodium molybdate, while the rest of the slurry is the same as in Example 1.

[0081] Example 3

[0082] An aluminum alloy polishing slurry differs from Example 2 in that 0.25g of benzotriazole is added. The benzotriazole is added after sodium molybdate and before ammonium molybdate. After adding the benzotriazole, the mixture is stirred at 200rpm for 30s. The rest of the process is the same as in Example 2.

[0083] Example 4

[0084] An aluminum alloy polishing slurry, which differs from Example 3 in that the nano-SiO2 slurry is derived from Preparation Example 2, while the rest is the same as Example 3.

[0085] Example 5

[0086] An aluminum alloy polishing slurry, which differs from Example 4 in that the nano-SiO2 slurry is derived from Preparation Example 3, while the rest is the same as Example 4.

[0087] Example 6

[0088] An aluminum alloy polishing slurry, which differs from Example 4 in that the nano-SiO2 slurry is derived from Example 4, while the rest is the same as Example 4.

[0089] Example 7

[0090] An aluminum alloy polishing liquid differs from Example 4 in that the pH buffer is tartaric acid-sodium tartrate, tartaric acid is used instead of acetic acid, and sodium tartrate is used instead of sodium acetate; the rest is the same as in Example 4.

[0091] Example 8

[0092] An aluminum alloy polishing liquid differs from Example 4 in that it uses alkylphenol polyoxyethylene ether instead of fatty alcohol polyoxyethylene ether, while the rest is the same as Example 4.

[0093] Comparative Example 4

[0094] An aluminum alloy polishing slurry differs from Example 4 in that it does not involve liquid nitrogen spray cooling in its application method; otherwise, it is the same as Example 4.

[0095] Example 9

[0096] An aluminum alloy polishing slurry differs from Example 4 in that it contains 300g of citric acid, 20g of phytic acid, 20g of sodium molybdate, 700g of hydrogen peroxide solution, 30g of fatty alcohol polyoxyethylene ether, 1g of ammonium molybdate, 0.2g of benzotriazole, 500g of modified nano-SiO2, and 70g of pH buffer, while the rest of the ingredients are the same as in Example 4.

[0097] Example 10

[0098] An aluminum alloy polishing slurry differs from Example 4 in that it contains 400g of citric acid, 30g of phytic acid, 40g of sodium molybdate, 800g of hydrogen peroxide solution, 50g of fatty alcohol polyoxyethylene ether, 2g of ammonium molybdate, 0.3g of benzotriazole, 600g of modified nano-SiO2, and 80g of pH buffer, while the rest of the ingredients are the same as in Example 4.

[0099] The surface roughness of the aluminum alloy parts used in Examples 1-10 and Comparative Examples 1-4 was tested. According to GB / T1031-2009 "Geometric Specifications for Products (GPS) Surface Structure Profilometry Parameters and Values", the profile curve of the non-repair area (centered on the indentation) was extracted in the scanning path of the profilometer. The filter cutoff wavelength λc = 0.8 mm and the evaluation length 3.5 mm were used. The arithmetic mean deviation was calculated to obtain the surface roughness (Ra) of the non-repair area, as shown in Table 1.

[0100] Table 1 Surface roughness test results

[0101] Non-repair region Ra (μm) Example 1 0.28 Comparative Example 1 0.85 Comparative Example 2 0.72 Comparative Example 3 0.61 Example 2 0.22 Example 3 0.16 Example 4 0.13 Example 5 0.18 Example 6 0.19 Comparative Example 4 1.05 Example 7 0.21 Example 8 0.23 Example 9 0.15 Example 10 0.22

[0102] Referring to Table 1,

[0103] Compared with Example 1, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 1 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Comparative Example 1.

[0104] The difference between Comparative Example 1 and Example 1 is that sodium molybdate was added in Example 1, and the molybdate dissolved to form MoO4. 2- Anions migrate to the pores or defects of the phytic acid film, enhancing its corrosion inhibition effect, thus the addition of sodium molybdate is necessary.

[0105] Compared with Example 1 and Comparative Example 2, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 1 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Comparative Example 2.

[0106] The difference between Comparative Example 2 and Example 1 is that phytic acid was added in Example 1. Phytic acid contains 6 phosphate groups and forms a dense multidentate chelate film on the aluminum surface through strong coordination. This film physically covers the surface of the aluminum alloy part and plays a role in corrosion inhibition. It can be seen that the addition of phytic acid is necessary.

[0107] Compared with Example 1 and Comparative Example 3, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 1 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Comparative Example 3.

[0108] The difference between Comparative Example 3 and Example 1 is that in Example 1, sodium dodecylbenzenesulfonate, an ionic activator, was selected instead of a nonionic activator in the raw materials and preparation method. Nonionic surfactants are uncharged and are not affected by pH, ionic strength or aluminum surface potential, thus maintaining adsorption stability. It can be seen that the use of a nonionic activator is necessary.

[0109] Comparing Example 1 and Example 2, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 2 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 1.

[0110] The difference between Example 2 and Example 1 is that the mass ratio of phytic acid to sodium molybdate in the raw materials of Example 2 is 1:1.25. The mass ratio of phytic acid to molybdate of 1:1.25 can enable molybdate to fill the pores of the phytic acid membrane in sufficient quantity. It can be seen that the mass ratio of phytic acid to sodium molybdate of 1:1.25 is better.

[0111] Comparing Examples 2 and 3, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 3 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 2.

[0112] The difference between Example 3 and Example 2 is that benzotriazole was added to the raw materials in Example 3. Benzotriazole blocks the corrosion path of local micro-cells, complements the phytic acid passivation film, and inhibits selective over-corrosion in sensitive areas of aluminum alloy. It can be seen that adding benzotriazole is better.

[0113] Comparing Examples 3 and 4, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 3.

[0114] The difference between Example 4 and Example 3 is that the raw material nano-SiO2 slurry in Example 4 has been modified. Modification of nano-SiO2 can improve the dispersion stability of nano-SiO2 particles, avoid secondary corrosion caused by mechanical damage, and improve surface uniformity. Therefore, the modification of nano-SiO2 is superior.

[0115] Comparing Examples 4 and 5, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 5.

[0116] The difference between Example 5 and Example 4 is that Example 5 uses 3-aminopropyltriethoxysilane instead of methoxy polyethylene glycol acrylate to modify nano-SiO2. The long links of methoxy polyethylene glycol acrylate are grafted onto the surface of SiO2 to form a steric hindrance layer, preventing particle agglomeration. The hydrophilic polyethylene glycol chains improve the dispersion stability of particles and eliminate local mechanical over-wear caused by agglomerates. It can be seen that using methoxy polyethylene glycol acrylate to modify nano-SiO2 is superior.

[0117] Comparing Examples 4 and 6, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 6.

[0118] The difference between Example 6 and Example 4 is that in Example 6, the methoxy polyethylene glycol acrylate solution was directly added to the mixer during the preparation of modified nano-SiO2, instead of being sprayed into the mixer at a rate of 1 L / min while being sheared at high speed. The methoxy polyethylene glycol acrylate monomer solution was slowly dripped into the SiO2 suspension to ensure that the monomer molecules were in full contact with the SiO2 surface. The shearing force was synchronized with the dripping, avoiding heterogeneous coating caused by monomer self-polymerization or excessively high local concentration, thus improving interfacial compatibility and dispersion stability. It can be seen that spraying the methoxy polyethylene glycol acrylate solution into the mixer at a rate of 1 L / min while being sheared at high speed during the preparation of modified nano-SiO2 is superior.

[0119] Comparing Examples 4 and 7, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 7.

[0120] The difference between Example 7 and Example 4 is that in Example 7, the pH buffer is tartaric acid-sodium tartrate, while in Example 4, the pH buffer is acetate-sodium acetate. Acetate ions (CH3COO-) preferentially adsorb onto the surface, assisting in the formation of the phytic acid corrosion inhibitor film and reducing the over-etching caused by uncontrolled dissolution due to acidity fluctuations. It can be seen that the choice of acetate-sodium acetate as the pH buffer is better.

[0121] Comparing Examples 4 and 8, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 8.

[0122] The difference between Example 8 and Example 4 is that in Example 8, alkylphenol polyoxyethylene ether is used instead of fatty alcohol polyoxyethylene ether in the raw materials. In fatty alcohol polyoxyethylene ether, the polyoxyethylene chains are protonated in an acidic environment and encapsulate negatively charged polishing residue through electrostatic interaction to form micelles, preventing residue accumulation from forming oxygen concentration cells that cause local over-etching. It can be seen that fatty alcohol polyoxyethylene ether is superior.

[0123] Compared with Example 4, the surface roughness of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy part polished by the polishing liquid and polishing method of Comparative Example 4.

[0124] The difference between Comparative Example 4 and Example 4 is that the aluminum alloy polishing slurry application method in Comparative Example 4 does not involve liquid nitrogen spray cooling. Liquid nitrogen rapidly freezes the surface reaction and terminates the corrosion of residual acid. It can be seen that the use of liquid nitrogen spray cooling in the polishing method of polishing slurry is necessary.

[0125] Comparing Examples 4 and 9-10, the surface roughness of the non-repaired area of ​​the aluminum alloy parts polished by the polishing liquid and polishing method of Example 4 is less than that of the non-repaired area of ​​the aluminum alloy parts polished by the polishing liquid and polishing method of Example 9-10.

[0126] The difference between Example 9 and Example 4 is that the mass ratio of citric acid, phytic acid, sodium molybdate, hydrogen peroxide solution, fatty alcohol polyoxyethylene ether, ammonium molybdate, benzotriazole, nano-SiO2 slurry, and pH buffer in the raw materials of Example 9 is 300:20:20:700:30:1:0.2:500:70.

[0127] The difference between Example 10 and Example 4 is that in Example 10, the mass ratio of citric acid, phytic acid, sodium molybdate, hydrogen peroxide solution, fatty alcohol polyoxyethylene ether, ammonium molybdate, benzotriazole, nano-SiO2 slurry, and pH buffer in the raw materials is 400:30:40:800:50:2:0.3:600:80.

[0128] It can be seen that the optimal mass ratio of citric acid, phytic acid, sodium molybdate, hydrogen peroxide solution, fatty alcohol polyoxyethylene ether, ammonium molybdate, benzotriazole, nano-SiO2 slurry, and pH buffer is 350:25:31.25:750:40:1.5:0.25:550:75.

[0129] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present 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 protection claimed by the present invention, they are protected by patent law.

Claims

1. An aluminum alloy polishing slurry, characterized in that, The raw material contains the following components in parts by weight: The mixture contains 30-40 parts citric acid, 2-3 parts phytic acid, 2-4 parts sodium molybdate, 70-80 parts oxidant, 50-60 parts nano-SiO2 slurry, 3-5 parts nonionic surfactant, 0.1-0.2 parts catalyst, and 7-8 parts pH buffer, wherein the solid content of the nano-SiO2 slurry is 10%. The mass ratio of phytic acid to sodium molybdate in the raw materials is 1:(1.2~1.3); The raw materials also include 0.02 to 0.03 parts by weight of benzotriazole; Nano-SiO2 in nano-SiO2 slurry is modified with methoxy polyethylene glycol acrylate; The preparation method of the nano-SiO2 slurry modified with methoxy polyethylene glycol acrylate includes the following steps: Dry nano-SiO2 is dispersed in water to obtain a SiO2 suspension. A methoxy polyethylene glycol acrylate solution is added dropwise to the SiO2 suspension and simultaneously sheared at high speed to obtain a nano-SiO2 slurry. The pH buffer includes sodium acetate and acetic acid; The nonionic surfactant selected is fatty alcohol polyoxyethylene ether.

2. A polishing process for an aluminum alloy polishing slurry, characterized in that, Includes the following steps: S1: Use a cleaning agent to clean the aluminum alloy parts until they are free of oil and dust; S2: The polishing liquid described in claim 1 is uniformly and dynamically sprayed onto the aluminum alloy part, and the surface of the aluminum alloy part is polished using a polishing wheel; S3: Use liquid nitrogen to rapidly cool the aluminum alloy surface and then clean it with water.