A polishing composition for surface fine polishing of an aluminum alloy, a polishing liquid, and use thereof

Abstract

The application discloses an aluminum alloy surface fine polishing polishing composition, polishing liquid and application thereof, and particularly belongs to the technical field of metal surface treatment. The polishing composition comprises the following components in mass fraction: 70-80 parts of silica sol, 1-4 parts of dispersing agent, 5-7 parts of surfactant, 5-10 parts of corrosion inhibitor, and 0.5-2 parts of water-retaining agent; and the surfactant is composed of perfluoropolyether, coconut oil alkylolamide and sodium dodecyl benzene sulfonate. The polishing composition provided by the application has high polishing efficiency, can reduce polishing cost, improve product quality, has low material surface roughness and few scratches after polishing treatment, effectively improves the polishing surface quality, improves the overall appearance and durability of the material, and the polishing liquid does not contain toxic substances such as chromium / phosphorus, and is environment-friendly.

Description

Technical Field

[0001] This invention belongs to the field of metal surface treatment technology, specifically, it relates to a polishing composition, polishing liquid and its application for fine polishing of aluminum alloy surfaces. Background Technology

[0002] Aluminum alloys are widely used in consumer electronics, automotive parts, aerospace, and high-end decorative industries due to their excellent strength-to-weight ratio, thermal conductivity, and machinability. In these applications, the high gloss, high reflectivity, and defect-free polishing of aluminum alloy surfaces are key requirements for improving the aesthetics, corrosion resistance, and functionality of products.

[0003] Currently, the industry mainly relies on the following two types of technologies for fine polishing of aluminum alloy surfaces:

[0004] I. Traditional Chemical / Electrochemical Polishing:

[0005] It employs a strong oxidizing acid system containing phosphoric acid, nitric acid, chromic acid, etc. Although it can achieve a bright surface, it poses serious environmental pollution (phosphorus / chromium wastewater), high corrosion risk (easily causing pitting corrosion and intergranular corrosion), and operational hazards, making it difficult to meet increasingly stringent environmental regulations.

[0006] II. Mechanical grinding and polishing fluids containing abrasives:

[0007] Using silica sol, alumina, and other abrasives, supplemented with additives, while improving environmental friendliness, existing polishing slurries still have significant drawbacks: Insufficient corrosion inhibition: In alkaline polishing environments (pH often > 10), aluminum alloy surfaces are prone to uneven corrosion, loss of gloss, and even black spots, especially for high-performance alloys containing copper and zinc; Poor abrasive dispersion stability: Nano-SiO2 particles are prone to agglomeration and sedimentation, resulting in a short polishing slurry shelf life and uneven abrasive distribution during polishing, leading to surface defects such as scratches and orange peel texture; Imbalanced surfactant compatibility: Single or simply compounded surfactants cannot simultaneously address wetting and penetration, oil emulsification, foam control, and abrasive dispersion synergy, causing fluctuations in polishing efficiency or residual stains.

[0008] In recent years, although some research has attempted to develop environmentally friendly polishing slurries, most studies have focused on optimizing single components and have not systematically addressed the multidimensional contradictions between abrasive dispersion stability, corrosion inhibition efficiency, and surface activity synergy. Especially in the high-end manufacturing sector, there is an urgent need for a polishing technology that can simultaneously achieve "zero corrosion damage, ultra-mirror gloss, and long-term stability." Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide a novel polishing composition and polishing fluid for fine polishing of aluminum alloys. Through multi-component functional coupling and innovative formulation, it solves problems such as insufficient corrosion inhibition performance and poor abrasive dispersion stability while reducing pollution.

[0010] To achieve the above objectives, the present invention discloses the following technical solutions:

[0011] In a first aspect, the present invention provides a polishing composition for fine polishing of aluminum alloy surfaces, wherein the composition comprises the following components in parts by mass:

[0012]

[0013] The surfactant is composed of perfluoropolyether, coconut oil alkyl alcohol amide, and sodium dodecylbenzene sulfonate.

[0014] Preferably, the silica sol contains 30-45% silica by mass.

[0015] More preferably, the silicon dioxide is silicon dioxide particles with a particle size of 50-100 nm.

[0016] Preferably, the dispersant is selected from at least one of polyethylene glycol, sodium polyacrylate, and polyvinylpyrrolidone.

[0017] Preferably, the surfactant is composed of perfluoropolyether, coconut oil alkanolamide, and sodium dodecylbenzenesulfonate in a mass ratio of 1:(1-2):(0.6-0.8).

[0018] Preferably, the corrosion inhibitor is composed of copolyvinylpyrrolidone and ammonium persulfate in a mass ratio of 1:(0.3-0.5).

[0019] More preferably, the method for preparing the corrosion inhibitor includes the following steps:

[0020] (1) Heat deionized water to 50±5℃, add copovidone powder at a solid-liquid mass ratio of 1:(8-10), stir at 200-300rpm for 30-40min, and after dissolution, cool the system to 25-30℃ to obtain copovidone solution.

[0021] (2) Dissolve ammonium persulfate in deionized water at 20-30℃ at a solid-liquid mass ratio of 1:(5-7), and stir at 100-150 rpm until a transparent solution is obtained to obtain an ammonium persulfate solution;

[0022] (3) Add the ammonium persulfate solution dropwise to the copovidone solution at a rate of 5 mL / min, maintain stirring at 300 rpm and a water bath at 30±2℃, and continue stirring for 60 min after the addition is complete to obtain the corrosion inhibitor. The amount added is calculated according to the mass ratio of copovidone to ammonium persulfate 1:(0.3-0.5).

[0023] Preferably, the water-retaining agent is at least one selected from butanediol, glycerol, and hexanediol.

[0024] Secondly, the present invention provides a polishing liquid for fine polishing of aluminum alloy surfaces, wherein the polishing liquid contains the polishing composition described in the first aspect.

[0025] Preferably, the polishing liquid also contains water.

[0026] More preferably, the polishing liquid contains the following components by weight:

[0027]

[0028] Thirdly, the present invention provides a method for preparing the polishing slurry described in the second aspect, the method comprising the following steps:

[0029] Step 1. Place the silica sol, surfactant, water-retaining agent and water in a mixing container and mix and stir until homogeneous to obtain mixture A;

[0030] Step 2. Stir mixture A at 200-300 r / min, adding dispersant and corrosion inhibitor while stirring. After stirring for 40-50 min, the polishing liquid is obtained.

[0031] Fourthly, the present invention provides the use of the polishing composition described in the first aspect in the preparation of polishing agents for aluminum alloys.

[0032] In this invention:

[0033] Surfactants can improve the wettability of polishing fluid on aluminum alloy surfaces, ensuring that the liquid can spread evenly to cover the entire polishing surface, avoiding uneven polishing. At the same time, they emulsify tiny oil stains or organic residues, preventing them from depositing on the surface and causing polishing defects, increasing scratches, pitting, etc. The surfactants provided by this invention can assist dispersants in stabilizing silica nanoparticles and preventing abrasive agglomeration and sedimentation. Perfluoropolyether, coconut oil alkanolamide, and sodium dodecylbenzenesulfonate together maintain wettability, emulsification, and dispersibility within the specific ratio range provided by this invention.

[0034] Copovidone, as a water-soluble polymer, has excellent adsorption and film-forming ability on metal surfaces. It can form a physical barrier film to isolate the corrosive medium from contact with the aluminum substrate, thereby achieving corrosion inhibition. At the same time, its molecular structure contains groups that can complex with metal ions, enhancing the protective effect and also playing a certain role in dispersion and stabilization.

[0035] Ammonium persulfate, as an oxidizing salt, helps to form a dense, stable, and easily mechanically peelable soft passivation oxide film on the aluminum surface, significantly improving polishing efficiency and corrosion resistance. However, too little oxidant and excessive mechanical action can lead to scratches on the wafer surface, while too much oxidant can result in excessively high surface chemical potential, leading to corrosion pits and other defects. Therefore, this invention optimizes the polishing effect and surface quality of the formulation by controlling the concentration and ratio of copovidone and oxidant.

[0036] The beneficial effects of this invention are:

[0037] 1. This invention improves the fine polishing performance of aluminum alloys through an innovative synergistic system of surfactants and corrosion inhibitors. The surfactants, including perfluoropolyether, coconut oil alkanolamide, and sodium dodecylbenzenesulfonate, are compounded in a specific ratio to synergistically solve the problems of abrasive agglomeration, uneven wetting, and unstable dispersion. This reduces the surface roughness after polishing, decreases scratch defects, and prolongs suspension stability. The corrosion inhibitor forms a dynamic protective layer, improving polishing efficiency while achieving polishing uniformity and further reducing the surface roughness after polishing.

[0038] 2. The polishing liquid provided by this invention has high polishing efficiency, which can reduce polishing costs and improve product quality. The surface roughness of the material after polishing is low and the number of scratches is small, which effectively improves the surface quality of the polished material and enhances the overall aesthetics and durability of the material. Moreover, the polishing liquid does not contain toxic substances such as chromium / phosphorus, thus achieving environmental friendliness. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0040] To further illustrate the present invention, detailed descriptions are provided below through the following embodiments. The raw materials used in the following embodiments and comparative examples of the present invention are all commercially available products; the raw material companies listed below represent one of the ways to purchase the raw materials.

[0041] In this invention:

[0042] The silica sol, model JN60-40 / 1, has a particle size of 55-65nm and a solid content of 40±1%, and was purchased from Zhejiang Delixin Micro-Nano Technology Co., Ltd.

[0043] Preparation of corrosion inhibitors

[0044] (1) Add deionized water to the reactor, heat to 50°C, slowly add copovidone powder at a solid-liquid mass ratio of 1:9, maintain stirring at 300 rpm for 40 min, and after dissolution, cool the system to 30°C to obtain copovidone solution for later use.

[0045] (2) Dissolve ammonium persulfate in deionized water at 30°C at a solid-liquid mass ratio of 1:6, and stir at 150 rpm until a transparent solution is obtained to obtain an ammonium persulfate solution;

[0046] (3) Add the ammonium persulfate solution dropwise to the copovidone solution at a rate of 5 mL / min, maintain stirring at 300 rpm and a water bath at 30±2℃, and continue stirring for 60 min after the addition is complete to obtain the corrosion inhibitor. The amount added is calculated based on the mass ratio of copovidone to ammonium persulfate of 1:0.4.

[0047] Preparation of surfactants

[0048] After accurately weighing the raw materials according to the mass ratio in Table 1, mix them evenly to obtain the surfactant.

[0049] Table 1. Proportions of Surfactants

[0050] Raw material name Surfactant 1 Surfactant 2 Surfactant 3 Perfluoropolyether 1 1 1 Coconut oil alkanolamide 1 1.5 2 Sodium dodecylbenzenesulfonate 0.6 0.7 0.8 Raw material name Surfactant 4 Surfactant 5 Surfactant 6 Perfluoropolyether 1 1 / Coconut oil alkanolamide / 1.5 1.5 Sodium dodecylbenzenesulfonate 0.7 / 0.7

[0051] Preparation of Examples

[0052] Weigh the raw materials precisely according to the mass fractions in Table 2;

[0053] Step 1. Place the silica sol, surfactant, water-retaining agent and water in a mixing container and mix and stir until homogeneous to obtain mixture A;

[0054] Step 2. Stir mixture A at a speed of 200-300 r / min, adding dispersant and corrosion inhibitor while stirring. After stirring for 40-50 min, the polishing liquid of Examples 1-4 is obtained.

[0055] Table 2. Mass parts of raw materials in Examples 1-4

[0056]

[0057]

[0058] Note: " / " in the table indicates no addition.

[0059] Preparation of comparative examples

[0060] To verify the impact of each component in the formulation on the overall performance, the formulation of Example 3 was modified by removing and replacing components, as detailed below:

[0061] Comparative Example 1: Surfactant 2 was replaced with surfactant 4, and the rest was the same as in Example 3;

[0062] Comparative Example 2: Surfactant 2 was replaced with surfactant 5, and the rest was the same as in Example 3;

[0063] Comparative Example 3: Surfactant 2 was replaced with surfactant 6, and the rest was the same as in Example 3;

[0064] Comparative Example 4: No corrosion inhibitor was added; all other aspects were the same as in Example 3.

[0065] Comparative Example 5: The corrosion inhibitor was replaced with ammonium persulfate, and the rest was the same as in Example 3;

[0066] The comparative preparation method is as follows:

[0067] Weigh the raw materials precisely according to the mass fractions in Table 3;

[0068] Step 1. Place the silica sol, surfactant, water-retaining agent and water in a mixing container and mix and stir until homogeneous to obtain mixture A;

[0069] Step 2. Stir mixture A at 200-300 r / min, adding dispersant and corrosion inhibitor while stirring. After stirring for 40-50 min, the polishing liquid of Comparative Example 1-5 is obtained.

[0070] Table 3. Mass parts of raw materials for Comparative Examples 1-4

[0071]

[0072] Note: " / " in the table indicates no addition.

[0073] Performance testing

[0074] The performance of the polishing fluids for aluminum alloy materials prepared in Examples 1-4 and Comparative Examples 1-5 was tested. The test methods are as follows, and the test results are shown in Table 4 below.

[0075] The polishing fluids prepared in Examples 1-4 and Comparative Examples 1-5 were used to polish aluminum alloy materials. The aluminum alloy materials used were 6061 aluminum alloy test pieces of uniform specifications, with dimensions of 100mm×100mm×5mm. Before polishing, the materials were pre-ground to a surface roughness of 200nm. During the polishing process, the pressure was 200g / cm, the polishing disc rotation speed was 70r / min, the polishing fluid flow rate was 4±0.2mL / min, the temperature was 25±2℃, and the time was 60min.

[0076] (1) Polishing rate

[0077] Weigh the aluminum alloy sample before polishing and record it as M0. Perform the polishing operation according to the polishing process parameters mentioned above. After polishing, thoroughly clean and dry the aluminum alloy material, weigh it after polishing, and record it as M1. Calculate the polishing rate using the following formula:

[0078]

[0079] Where: M0—mass of aluminum alloy material before polishing, mg;

[0080] M1 — Mass of polished aluminum alloy material, mg;

[0081] ρ — Density of aluminum alloy, g / cm³ 3 ;

[0082] A – Polished area, cm 2 ;

[0083] T – Polishing time, h.

[0084] (2) Surface roughness

[0085] Five points were selected: the perimeter and center of the aluminum alloy test pieces polished with the polishing liquids of Examples 1-4 and Comparative Examples 1-5. The roughness of each of the five points was tested using a surface roughness meter, with each point measured three times. The average roughness was then taken.

[0086] (3) Suspension stability

[0087] The polishing solutions of Examples 1-4 and Comparative Examples 1-5 were stored at room temperature away from light, and the stratification of the polishing solutions was examined to investigate their suspension stability.

[0088] (4) Degree of scratch

[0089] The number of scratches was observed using a microscope at five times magnification. Five locations were selected for observation: the perimeter and the center of the polished aluminum alloy sample.

[0090] Table 4. Performance Tests of Various Polishing Fluids

[0091]

[0092]

[0093] Results analysis:

[0094] As shown in Table 4, the polishing fluids of Examples 1-4 have high polishing efficiency, good fine polishing effect, good dispersibility, and the particles are not easy to agglomerate. They are not easy to settle after long-term storage, which effectively extends the service life of the polishing fluid, reduces the waste and replacement frequency of the polishing fluid, and has excellent overall performance, meeting the requirements of fine polishing of aluminum alloys.

[0095] Comparative Examples 1-3 lacked coconut oil alkanolamide, sodium dodecylbenzene sulfonate, and perfluoropolyether, respectively, which led to a significant decrease in the dispersion stability of abrasives in the polishing slurry and a deterioration in processing performance. This proves that the surfactant provided by the present invention has a synergistic effect in promoting dispersion and improving polishing effect in the polishing slurry system.

[0096] The lack of corrosion inhibitor in Comparative Example 4 resulted in reduced polishing efficiency and poor polishing effect, proving that the corrosion inhibitor provided by this invention can weaken the bonding force between atoms on the material surface, making the material easier to remove and achieving efficient and uniform polishing.

[0097] The lack of copovidone in Comparative Example 5 resulted in increased surface roughness, more scratches, and poorer stability of the polishing slurry, demonstrating that the corrosion inhibitor provided by this invention effectively slows down corrosion compared to the traditional method of directly adding oxidants, while also playing a role in dispersion and stabilization.

[0098] In summary, the polishing slurries prepared in Examples 1-4 have high polishing efficiency, can reduce polishing costs, improve product quality, and result in materials with low surface roughness and fewer scratches after polishing. This effectively improves the surface quality of the polished material, enhances its overall aesthetics and durability, and makes the polishing slurries environmentally friendly as they do not contain toxic substances such as chromium / phosphorus.

[0099] Finally, it should be noted that the above embodiments and comparative examples are only used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polishing composition for fine polishing of aluminum alloy surfaces, characterized in that, The composition comprises the following components in parts by weight: 70-80 parts of silica sol; 1-4 parts dispersant; 5-7 parts surfactant; 5-10 parts corrosion inhibitor; Water-retaining agent 0.5-2 parts; The dispersant is selected from at least one of polyethylene glycol, sodium polyacrylate, and polyvinylpyrrolidone; The surfactant is composed of perfluoropolyether, coconut oil alkyl alcohol amide, and sodium dodecylbenzene sulfonate in a mass ratio of 1:(1-2):(0.6-0.8); The corrosion inhibitor is composed of copolyvinylpyrrolidone and ammonium persulfate in a mass ratio of 1:(0.3-0.5); The water-retaining agent is at least one of butanediol, glycerol, and hexanediol.

2. The polishing composition according to claim 1, characterized in that, The silica sol contains 30-45% silica by mass.

3. The polishing composition according to claim 2, characterized in that, The silica is silica particles with a particle size of 50-100 nm.

4. A polishing liquid for fine polishing of aluminum alloy surfaces, characterized in that, The polishing liquid contains any one of the polishing compositions according to claims 1-3.

5. The polishing slurry according to claim 4, characterized in that, The polishing fluid also contains water.

6. The polishing slurry according to claim 5, characterized in that, The polishing liquid contains the following components by weight: 70-80 parts of silica sol; 1-4 parts dispersant; 5-7 parts surfactant; 5-10 parts corrosion inhibitor; Water-retaining agent 0.5-2 parts; 10-15 parts water.

7. The method for preparing the polishing slurry according to claim 5 or 6, characterized in that, The preparation method includes the following steps: Step 1. Place the silica sol, surfactant, water-retaining agent and water in a mixing container and mix and stir until homogeneous to obtain mixture A; Step 2. Stir mixture A at 200-300 r / min, adding dispersant and corrosion inhibitor while stirring. After stirring for 40-50 min, the polishing liquid is obtained.

8. The use of the polishing composition according to any one of claims 1-3 in the preparation of polishing agents for aluminum alloys.

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