Acid etching treatment method of aluminum alloy for anodic oxidation and aluminum alloy subjected to acid etching treatment

Abstract

The invention provides an acid etching treatment method of an aluminum alloy for anodic oxidation and the aluminum alloy subjected to acid etching treatment. The acid etching treatment method comprises the following steps: S1, carrying out dipping treatment on the aluminum alloy by adopting a surface treatment solution to obtain the dipped aluminum alloy; and S2, the aluminum alloy subjected to dipping treatment is washed, and acid etching treatment of the aluminum alloy for anodic oxidation is completed. The aluminum alloy is subjected to dipping treatment through the surface treatment liquid, a clean and uniform aluminum alloy surface is obtained, favorable conditions are created for continuous and uniform growth of a subsequent anodic oxidation film layer, and introduction of anodic oxidation defects is effectively reduced. Compared with a traditional alkali etching and bright dipping process, the acid etching treatment method for the aluminum alloy avoids the problems of large aluminum alloy loss and surface intergranular over-corrosion induced by alkali etching, the flatness and compactness of a subsequent anodic oxide film can be effectively improved, the anti-corrosion performance and surface quality of the aluminum alloy anodic oxide film layer are improved, and the service life of the aluminum alloy anodic oxide film layer is prolonged. And the production efficiency and the product quality are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of pre-treatment of aviation aluminum alloy anodization, and in particular to an acid etching method for an aluminum alloy for anodization and the aluminum alloy after the acid etching treatment. Background Art

[0002] Aviation aluminum materials (2xxx, 7xxx, Al-Li, etc.) are highly sensitive to local corrosion and are generally anodized to improve the corrosion resistance of the substrate and the bonding strength with subsequent coatings, thereby ensuring service safety. In the actual production process of aviation aluminum alloy parts, various defects are often inevitably introduced on the surface, such as natural oxide film, pollutants, scratches, etc. The presence of these defects will reduce the production quality of aluminum materials and greatly reduce the subsequent anodizing quality. Therefore, aluminum alloys must be pre-treated before anodizing.

[0003] Generally speaking, the pre-treatment technology of anodizing of aviation aluminum alloys mainly includes steps such as degreasing, alkaline etching, and polishing. Degreasing can remove oil stains on the surface of aluminum alloys. Alkaline etching can further remove the natural oxide film, pollutants, etc. on the surface of aluminum alloys, and eliminate surface defects such as scratches and indentations. Polishing treatment can neutralize the remaining alkali on the surface of aluminum alloys and remove certain attachments on the surface of aluminum. However, the time and temperature of alkaline etching have a more prominent effect on it. In actual industrial production, there are often problems such as large aluminum alloy loss and surface intergranular corrosion induced by alkaline etching, which in turn causes discontinuous growth of the anodized film and the introduction of defects, which brings great damage to the environmental adaptability and surface quality of the aviation aluminum alloy protection system.

[0004] In summary, it is urgent to develop an alkali-free anodizing pretreatment method for aviation aluminum alloys to improve production efficiency while ensuring the uniform and continuous growth of the subsequent anodized film. Summary of the invention

[0005] The main purpose of the present invention is to provide an acid etching method for anodizing aluminum alloy and the aluminum alloy after acid etching, so as to solve the problems in the prior art of alkaline etching treatment of aviation aluminum alloy before anodizing, such as large aluminum loss, surface intergranular corrosion, and influence on the surface quality and application performance of the oxide film.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided an acid etching treatment method for anodized aluminum alloy, the acid etching treatment method comprising: step S1, using a surface treatment liquid to immerse the aluminum alloy to obtain the immersion-treated aluminum alloy; step S2, rinsing the immersion-treated aluminum alloy to complete the acid etching treatment of the anodized aluminum alloy; wherein the surface treatment liquid comprises an acid solution and an additive, the acid solution comprises ammonium bifluoride, an inorganic acid and a solvent, the additive comprises an additive A and an additive B, the additive A comprises a corrosion inhibitor, and the additive B comprises a surfactant.

[0007] Furthermore, the additive A is selected from any one or more of organic nitrogen azoles, phosphoamines, sodium gluconate, sodium citrate, glycerol, inorganic trivalent cerium, inorganic molybdates and phosphates.

[0008] Furthermore, the additive B is selected from any one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, ferrous sulfate and dipropylene glycol.

[0009] Furthermore, the mass ratio of the additive A, additive B and acid solution is (0.5-5):(0.05-0.1):1000.

[0010] Furthermore, in the surface treatment liquid, the solvent is deionized water; and / or the mass concentration of ammonium bifluoride is 30 to 100 g / L.

[0011] Furthermore, in the surface treatment liquid, the mass concentration of the inorganic acid is 50-150 g / L, and the inorganic acid is nitric acid and / or sulfuric acid.

[0012] Furthermore, the type of the aluminum alloy is selected from any one or more of 2024, 7050, 7075 and 2060.

[0013] Furthermore, in the above step S1, the immersion treatment time is 20 to 80 seconds, and / or the immersion treatment temperature is 20 to 60°C.

[0014] Furthermore, in the above step S2, the rinsing solvent is deionized water, and / or the rinsing time is 10 to 200 seconds.

[0015] According to another aspect of the present invention, there is provided an acid-etched aluminum alloy, wherein the acid-etched aluminum alloy is obtained by the aforementioned acid-etching method for anodizing aluminum alloy.

[0016] Applying the technical solution of the present invention, the present application relates to an alkali-free aerospace aluminum alloy anodizing pretreatment method. The present application performs an immersion treatment on the aluminum alloy by the above-mentioned specific surface treatment liquid to obtain a clean and uniform aluminum alloy surface, which creates favorable conditions for the continuous and uniform growth of the subsequent anodized film layer and effectively reduces the introduction of anodizing defects. Specifically, by compounding ammonium bifluoride, inorganic acid and solvent to form an acid solution, the oxide film and impurities on the surface of the aluminum alloy are removed, providing a clean surface for subsequent anodizing treatment; in addition, by adding additive A to the acid solution, the reaction uniformity of the aluminum alloy surface during the acid treatment process is improved, thereby avoiding the occurrence of local excessive corrosion problems on the surface; at the same time, the introduction of surfactant additive B is conducive to enhancing the degreasing ability, inhibiting the heat loss of the solution and the volatilization of the bath liquid, while improving the stability of the bath liquid, and further improving the cleanliness of the aluminum alloy surface. Compared with traditional alkaline etching and polishing processes, the acid etching treatment method for aluminum alloy in the present application avoids the problems of large aluminum alloy loss and surface intergranular corrosion induced by alkaline etching, can effectively improve the flatness and density of the subsequent anodized film, improve the corrosion resistance and surface quality of the aluminum alloy anodized film layer, and greatly improve production efficiency and product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0018] Figure 1 The glow discharge energy spectrum results in the thickness direction of the aluminum alloy in Example 1 and Comparative Examples 1-2 of the present application are shown, wherein (a) represents Example 1; (b) represents Comparative Example 1; (c) represents Comparative Example 2;

[0019] Figure 2 The surface morphologies after anodizing treatment in Example 1 and Comparative Example 1 of the present application are shown, wherein (a) represents Example 1; (b) represents Comparative Example 1;

[0020] Figure 3 The statistical results of the porosity of the anodized films prepared in Examples 1 to 3 and Comparative Example 1 of the present application are shown. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] As analyzed in the background technology of this application, the prior art alkaline etching treatment of aviation aluminum alloys before anodizing has problems such as large aluminum loss, surface intergranular corrosion, and impact on the surface quality and application performance of the oxide film. In order to solve the above problems, this application provides an acid etching method for anodizing aluminum alloys and aluminum alloys after acid etching.

[0023] In a typical embodiment of the present application, a method for acid etching of an aluminum alloy for anodizing is provided, and the method comprises: step S1, immersing the aluminum alloy with a surface treatment liquid to obtain the aluminum alloy after immersion treatment; step S2, rinsing the aluminum alloy after immersion treatment to complete the acid etching of the aluminum alloy for anodizing; wherein the surface treatment liquid comprises an acid solution and an additive, the acid solution comprises ammonium bifluoride, an inorganic acid and a solvent, the additive comprises additive A and additive B, additive A comprises a corrosion inhibitor, and additive B comprises a surfactant.

[0024] The present application relates to an alkali-free anode oxidation pretreatment method for aviation aluminum alloys. The aluminum alloy is immersed in the above-mentioned specific surface treatment liquid to obtain a clean and uniform aluminum alloy surface, which creates favorable conditions for the continuous and uniform growth of the subsequent anodized film layer and effectively reduces the introduction of anodizing defects. Specifically, by compounding ammonium bifluoride, inorganic acid and solvent to form an acid solution, the oxide film and impurities on the surface of the aluminum alloy are removed, providing a clean surface for subsequent anodizing treatment; in addition, the reaction uniformity of the aluminum alloy surface during the acid treatment is improved by adding additive A to the acid solution, thereby avoiding the occurrence of local excessive corrosion problems on the surface; at the same time, the introduction of surfactant additive B is conducive to enhancing the degreasing ability, inhibiting the heat loss of the solution and the volatilization of the bath liquid, while improving the stability of the bath liquid, and further improving the cleanliness of the aluminum alloy surface. Compared with traditional alkaline etching and polishing processes, the acid etching treatment method for aluminum alloy in the present application avoids the problems of large aluminum alloy loss and surface intergranular corrosion induced by alkaline etching, can effectively improve the flatness and density of the subsequent anodized film, improve the corrosion resistance and surface quality of the aluminum alloy anodized film layer, and greatly improve production efficiency and product quality.

[0025] In one embodiment of the present application, the additive A is selected from any one or more of organic nitrogen azoles, phosphoamines, sodium gluconate, sodium citrate, glycerol, inorganic trivalent cerium, inorganic molybdates and phosphates.

[0026] The present application controls the type of additive A within the above range, such as organic nitrogen azole corrosion inhibitors that can form an adsorption film on the surface of the aluminum alloy, which can effectively inhibit the corrosion reaction, prevent the aluminum alloy from excessive corrosion during the acid etching process, and protect the grain boundaries. Inorganic trivalent cerium, inorganic molybdate and phosphate corrosion inhibitors inhibit corrosion by forming a protective film on the surface of the aluminum alloy or adjusting the pH value of the solution, and may promote the formation of a more uniform oxide film. Sodium gluconate and sodium citrate can reduce the surface tension of the solution, improve the wettability of the solution to the surface of the aluminum alloy, help to more thoroughly remove pollutants and natural oxide films, and level the surface of the aluminum alloy. Glycerol can promote the microscopic leveling of the surface of the aluminum alloy, making the surface of the aluminum alloy more uniform, which is conducive to the uniform growth of the subsequent anodized film; their common goal is to form a protective adsorption layer on the surface of the aluminum alloy, inhibit corrosion, avoid the appearance of surface quality defects of the aluminum alloy during the treatment process, and promote the leveling and cleaning of the surface of the aluminum alloy by adjusting the characteristics of the solution, thereby improving the quality and stability of the subsequent anodized film layer of the aluminum alloy.

[0027] In one embodiment of the present application, the additive B is selected from any one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, ferrous sulfate and dipropylene glycol.

[0028] The present application controls the type of additive B within the above range, such as anionic surfactants of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate. Such surfactants can effectively reduce the surface tension of water and enhance the wettability and permeability of the solution to the metal surface due to the hydrophilic group containing negative charge, thereby improving the degreasing efficiency and removing surface oil. Nonionic surfactants of alkylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether, although such surfactants have no charge, can also reduce the surface tension through the polyoxyethylene group in its molecular structure, improve the degreasing ability and the stability of the solution, and reduce volatility. Ferrous sulfate can act as a catalyst in the solution to promote the cleaning reaction, and can also be used as an auxiliary component to help control the pH value of the solution or enhance the corrosion inhibition effect. Dipropylene glycol can be used as a solvent and has surface activity through its polar and non-polar groups, which helps to improve the thermal stability of the solution, reduce heat loss, and inhibit the volatilization of the tank liquid. Their common goal is to enhance the degreasing ability, inhibit the heat loss of the solution and the volatilization of the tank liquid, and improve the stability of the tank liquid, which is conducive to improving production efficiency and product quality.

[0029] In one embodiment of the present application, the mass ratio of the additive A, additive B and acid solution is (0.5-5):(0.05-0.1):1000.

[0030] It is preferred to control the mass ratio of additive A, additive B and acid solution within the above range. While ensuring efficient degreasing and acid etching effects, it can also effectively control the corrosion on the surface of the aluminum alloy, avoid intergranular corrosion, and promote the uniform growth of the oxide film on the surface of the aluminum alloy, thereby ensuring the continuity and uniformity of the subsequent anodized film layer, thereby improving the corrosion resistance of the aluminum alloy.

[0031] In one embodiment of the present application, in the surface treatment liquid, the solvent is water; and / or the mass concentration of ammonium bifluoride is 30-100 g / L.

[0032] It is preferred to control water as the solvent, which is beneficial to the environmental protection and economy of the solution. At the same time, by controlling the mass concentration of ammonium bifluoride within the above range, it is beneficial to control the speed and depth of the acid etching reaction, reduce the risk of excessive corrosion, and improve the quality of the acid etching treatment of the aluminum alloy surface.

[0033] In one embodiment of the present application, in the surface treatment liquid, the mass concentration of the inorganic acid is 50-150 g / L, and the inorganic acid is nitric acid and / or sulfuric acid.

[0034] It is preferred to control the mass concentration and type of the inorganic acid within the above range, which is beneficial to removing the natural oxide film and impurities on the surface of the aluminum alloy, thereby improving the cleanliness of the aluminum alloy surface and the subsequent growth quality of the oxide film.

[0035] In one embodiment of the present application, the type of the aluminum alloy is selected from any one or more of 2024, 7050, 7075 and 2060.

[0036] The aluminum alloy type is preferably controlled within the above range, which expands the types of aluminum alloys that the treatment method can be applied to, improves the versatility and applicability of the process, and also improves the formation quality and protective performance of the subsequent anodized film.

[0037] In one embodiment of the present application, in the above step S1, the immersion treatment time is 20 to 80 seconds, and / or the immersion treatment temperature is 20 to 60°C.

[0038] It is preferred to control the time and temperature of the immersion treatment within the above range, which is beneficial to improving the efficiency and effect of the acid etching treatment, while also avoiding surface damage due to excessive time or high temperature, thereby improving the acid etching quality of the aluminum alloy surface and the continuous and uniform growth of the subsequent oxide film.

[0039] In one embodiment of the present application, in the above step S2, the flushing solvent is deionized water, and / or the flushing time is 10 to 200 seconds.

[0040] It is preferred to control the type of rinsing solvent and the rinsing time within the above range, which is conducive to promoting the thorough removal of residues on the surface of the aluminum alloy and reducing the risk of contamination and defects in the subsequent oxide film formation process, thereby improving the surface quality of the aluminum alloy and the performance of the oxide film.

[0041] In another typical embodiment of the present application, an acid-etched aluminum alloy is provided. The acid-etched aluminum alloy is obtained by the aforementioned acid-etching method for anodizing aluminum alloy.

[0042] The aluminum alloy of the present application is prepared by the aforementioned acid etching method of the anodized aluminum alloy. Compared with the traditional process, its surface is cleaner and more uniform, the quality of the oxide film layer is higher, it has better corrosion resistance and environmental adaptability, and can meet the high quality requirements of aluminum alloy parts in actual production.

[0043] The beneficial effects of the present application will be further illustrated below in conjunction with embodiments.

[0044] Example 1

[0045] Ammonium bifluoride with a mass concentration of 70 g / L and nitric acid with a mass concentration of 60 g / L are mixed, and water is used as a solvent to prepare an acid solution. Additive A and additive B are added to the acid solution in sequence, and stirred until they are completely dissolved to obtain a surface treatment liquid; wherein the mass ratio of additive A, additive B and acid solution is 2:0.1:1000, additive A is composed of sodium phosphate with a mass concentration of 1 g / L and glycerol with a mass concentration of 1 g / L, and additive B is composed of sodium dodecyl sulfate with a mass concentration of 0.1 g / L.

[0046] The aluminum alloy parts with model number 7075 were placed in the above-mentioned surface treatment liquid for immersion treatment. The immersion treatment time was 30 seconds and the immersion treatment temperature was 60°C. The 7075 aluminum alloy parts after immersion treatment were taken out and the surface was rinsed with flowing deionized water for 10 seconds to finally obtain the 7075 aluminum alloy parts after acid etching.

[0047] Example 2

[0048] Ammonium bifluoride with a mass concentration of 60 g / L and nitric acid with a mass concentration of 40 g / L are mixed, and water is used as a solvent to prepare an acid solution. Additive A and additive B are added to the acid solution in sequence, and stirred until they are completely dissolved to obtain a surface treatment liquid; wherein the mass ratio of additive A, additive B and acid solution is 0.9:0.07:1000, additive A is composed of sodium phosphate with a mass concentration of 0.8 g / L and cerium nitrate with a mass concentration of 0.1 g / L, and additive B is composed of sodium dodecylbenzene sulfonate with a mass concentration of 0.07 g / L.

[0049] The 2024 aluminum alloy component was placed in the above-mentioned surface treatment solution for immersion treatment. The immersion treatment time was 60 seconds and the immersion treatment temperature was 40°C. The 2024 aluminum alloy component after immersion treatment was taken out and the surface was rinsed with flowing deionized water for 100 seconds to finally obtain the 2024 aluminum alloy component after acid etching.

[0050] Example 3

[0051] Ammonium bifluoride with a mass concentration of 80 g / L and sulfuric acid with a mass concentration of 50 g / L are mixed, and water is used as a solvent to prepare an acid solution. Additive A and additive B are added to the acid solution in sequence, and stirred until completely dissolved to obtain a surface treatment liquid; wherein the mass ratio of additive A, additive B and acid solution is 1:0.06:1000, additive A is composed of sodium citrate with a mass concentration of 1 g / L, and additive B is composed of fatty alcohol polyoxyethylene ether with a mass concentration of 0.06 g / L.

[0052] The 2060 aluminum alloy component was placed in the above-mentioned surface treatment solution for immersion treatment. The immersion treatment time was 50 seconds and the immersion treatment temperature was 60°C. The 2060 aluminum alloy component after immersion treatment was taken out and the surface was rinsed with flowing deionized water for 200 seconds to finally obtain the 2060 aluminum alloy component after acid etching.

[0053] Example 4

[0054] The difference from Example 1 is that the mass ratio of additive A, additive B and acid solution is 0.5:0.05:1000, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0055] Example 5

[0056] The difference from Example 1 is that the mass ratio of additive A, additive B and acid solution is 5:0.1:1000, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0057] Example 6

[0058] The difference from Example 1 is that the mass ratio of additive A, additive B and acid solution is 8:0.3:1000, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0059] Example 7

[0060] The difference from Example 1 is that the mass concentration of ammonium bifluoride is 30 g / L, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0061] Example 8

[0062] The difference from Example 1 is that the mass concentration of ammonium bifluoride is 100 g / L, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0063] Example 9

[0064] The difference from Example 1 is that the mass concentration of ammonium bifluoride is 130 g / L, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0065] Example 10

[0066] The difference from Example 1 is that the mass concentration of nitric acid is 50 g / L, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0067] Embodiment 11

[0068] The difference from Example 1 is that the mass concentration of nitric acid is 150 g / L, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0069] Example 12

[0070] The difference from Example 1 is that the mass concentration of nitric acid is 200 g / L, and finally a 7075 aluminum alloy component after acid etching is obtained.

[0071] Embodiment 13

[0072] The difference from Example 1 is that the immersion treatment time is 100 s, the immersion treatment temperature is 80° C., and finally a 7075 aluminum alloy component after acid etching is obtained.

[0073] Comparative Example 1

[0074] The difference from Example 1 is that the aluminum alloy component of model 7075 is degreased in a mixed solution of sodium hydroxide, sodium phosphate and sodium carbonate; the 7075 aluminum alloy component after degreasing is alkaline-etched with a 50g / L sodium hydroxide solution at a temperature of 57°C and a treatment time of 90s; the 7075 aluminum alloy component after alkaline etching is polished with a 180g / L sulfuric acid solution at a temperature of 25°C and a treatment time of 300s; and finally the treated 7075 aluminum alloy component is obtained.

[0075] Comparative Example 2

[0076] The difference from Example 1 is that the aluminum alloy component with model number 7075 is not subjected to any treatment.

[0077] Performance Testing

[0078] The aluminum alloy parts obtained in the above examples and comparative examples were anodized, and the structural density and corrosion resistance of the obtained anodized aluminum alloy film layer were evaluated. The specific method and evaluation results are as follows:

[0079] 1. Evaluation of oxide film / impurity layer thickness after pre-treatment:

[0080] The composition of the surface layer of each embodiment and comparative example was analyzed by glow discharge spectroscopy. The O content of 10 wt% was used as the boundary between the oxide layer / impurity layer and the aluminum alloy substrate. The oxide film / impurity layer of each component tested was listed in Table 1.

[0081] 2. Anodizing treatment:

[0082] The cleaned aluminum alloy was anodized with a mixed solution of sulfuric acid and boric acid for 20 min at a current density of 1.5 A / dm 2 , the temperature is 25°C, the mass percentage of sulfuric acid is 5%, and the mass percentage of boric acid is 0.8%.

[0083] 3. Evaluation of the compactness of anodized structure:

[0084] The surface morphology photos of Example 1 and Comparative Example 1 are as follows Figure 2 As shown, (a) represents Example 1; (b) represents Comparative Example 1. Figure 2 It can be seen that the anodized surface of Example 1 is smoother and more uniform, and the pore size is smaller. The scanning electron microscope image is imported into the image processing software, and the hole features are extracted by adjusting the threshold, and finally the area percentage occupied by the holes, that is, the porosity of the anodized film, is calculated. The results are shown in Table 1.

[0085] 4. Evaluation of corrosion resistance of anodized aluminum alloy:

[0086] The above examples and comparative examples were subjected to boiling water sealing: the anodized aluminum alloy was immersed in 95°C deionized water for 20 minutes, and then naturally air-dried. The corrosion resistance of each component was tested by an acid salt spray test (GB T 24195-2009), and the appearance time of the corrosion point is listed in Table 1.

[0087] The porosity and acid salt spray resistance time of the aluminum alloy parts obtained in the above examples and comparative examples are listed in Table 1.

[0088] Table 1

[0089]

[0090] Among them, the glow discharge spectrum results in the thickness direction of the aluminum alloy in Example 1 and Comparative Examples 1-2 of the present application are as follows: Figure 1 As shown, (a) represents Example 1; (b) represents Comparative Example 1; (c) represents Comparative Example 2.

[0091] The statistical results of the porosity of the anodized films prepared in Examples 1 to 3 and Comparative Example 1 of the present application are as follows: Figure 3 shown.

[0092] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0093] The present application relates to an alkali-free anode oxidation pretreatment method for aviation aluminum alloys. The aluminum alloy is immersed in the above-mentioned specific surface treatment liquid to obtain a clean and uniform aluminum alloy surface, which creates favorable conditions for the continuous and uniform growth of the subsequent anodized film layer and effectively reduces the introduction of anodizing defects. Specifically, by compounding ammonium bifluoride, inorganic acid and solvent to form an acid solution, the oxide film and impurities on the surface of the aluminum alloy are removed, providing a clean surface for subsequent anodizing treatment; in addition, the reaction uniformity of the aluminum alloy surface during the acid treatment is improved by adding additive A to the acid solution, thereby avoiding the occurrence of local excessive corrosion problems on the surface; at the same time, the introduction of surfactant additive B is conducive to enhancing the degreasing ability, inhibiting the heat loss of the solution and the volatilization of the bath liquid, while improving the stability of the bath liquid, and further improving the cleanliness of the aluminum alloy surface. Compared with traditional alkaline etching and polishing processes, the acid etching treatment method for aluminum alloy in the present application avoids the problems of large aluminum alloy loss and surface intergranular corrosion induced by alkaline etching, can effectively improve the flatness and density of the subsequent anodized film, improve the corrosion resistance and surface quality of the aluminum alloy anodized film layer, and greatly improve production efficiency and product quality.

[0094] The above are only embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for acid etching of anodized aluminum alloy, characterized in that: The acid etching method comprises: Step S1, performing an immersion treatment on the aluminum alloy using a surface treatment liquid to obtain an immersion-treated aluminum alloy; Step S2, rinsing the aluminum alloy after the immersion treatment to complete the acid etching treatment of the aluminum alloy for anodizing; The surface treatment liquid comprises an acid solution and an additive, wherein the acid solution comprises ammonium bifluoride, an inorganic acid and a solvent, the additive comprises an additive A and an additive B, the additive A comprises a corrosion inhibitor, and the additive B comprises a surfactant.

2. The acid etching method according to claim 1, characterized in that: The additive A is selected from any one or more of organic nitrogen azoles, phosphate amines, sodium gluconate, sodium citrate, glycerol, inorganic trivalent cerium, inorganic molybdates and phosphates.

3. The acid etching method according to claim 1 or 2, characterized in that: The additive B is selected from any one or more of sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, alkylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether, ferrous sulfate and dipropylene glycol.

4. The acid etching method according to any one of claims 1 to 3, characterized in that: The mass ratio of the additive A, the additive B and the acid solution is (0.5-5):(0.05-0.1):1000.

5. The acid etching method according to any one of claims 1 to 4, characterized in that: In the surface treatment liquid, the solvent is deionized water; and / or the mass concentration of the ammonium bifluoride is 30 to 100 g / L.

6. The acid etching method according to any one of claims 1 to 5, characterized in that: In the surface treatment liquid, the mass concentration of the inorganic acid is 50-150 g / L, and the inorganic acid is nitric acid and / or sulfuric acid.

7. The acid etching method according to any one of claims 1 to 6, characterized in that: The type of the aluminum alloy is selected from any one or more of 2024, 7050, 7075 and 2060.

8. The acid etching method according to any one of claims 1 to 7, characterized in that: In the step S1, the immersion treatment time is 20 to 80 seconds, and / or the immersion treatment temperature is 20 to 60°C.

9. The acid etching method according to claim 1, characterized in that: In the step S2, the rinsing solvent is deionized water, and / or the rinsing time is 10 to 200 seconds.

10. An acid-etched aluminum alloy, characterized in that: The acid-etched aluminum alloy is obtained by the acid-etching method for anodizing aluminum alloy according to any one of claims 1 to 9.

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