CN114086181B

CN114086181B - Etching solution and method for preparing aluminum alloy workpiece

Info

Publication number: CN114086181B
Application number: CN202111218244.3A
Authority: CN
Inventors: 张士浤; 袁稳芳; 李亮; 于龙; 李怡文; 宋茹茹
Original assignee: Fulian Yuzhan Technology Shenzhen Co Ltd
Current assignee: Fulian Yuzhan Technology Shenzhen Co Ltd
Priority date: 2021-10-19
Filing date: 2021-10-19
Publication date: 2023-11-10
Anticipated expiration: 2041-10-19
Also published as: CN114086181A

Abstract

An etching solution for etching aluminum alloy comprises water, organic acid and Fe which can be dissociated in the water ²⁺ And Cl ^‑ Is a substance of (a). The etching solution provided by the application is used for carrying out chemical corrosion on aluminum alloy in an organic environment, the organic environment system can provide a mild etching environment, the ion transmission rate is relatively low, and the uncontrollable reaction caused by the too high ion transmission rate is prevented. The application also provides a method for preparing the aluminum alloy workpiece.

Description

Etching solution and method for preparing aluminum alloy workpiece

Technical Field

The application relates to the field of metal materials, in particular to an etching solution and a method for preparing an aluminum alloy workpiece.

Background

Portable consumer electronics are becoming increasingly available in people's lives. Consumer demand for the appearance of electronic products and the performance of housings is also increasing. The aluminum alloy material has the advantages of high strength, small density, good mechanical property, good toughness, good corrosion resistance and the like, and is a good choice for being used as a shell substrate of electronic products.

Because of consumer demands for physical and chemical properties such as strength, appearance, density, etc. of materials for industrial products, these demands cannot be met by using aluminum alloys alone at present, so that the characteristics of aluminum alloy materials are generally maintained while the characteristics of other materials are introduced. In the related art, holes are generally formed in an aluminum alloy by electrochemical etching, and then other materials are molded in the holes to form an aluminum alloy workpiece. However, after electrochemical corrosion treatment, the density of holes on the aluminum alloy is low, the distribution of the holes is uneven, and insufficient bonding strength between the aluminum alloy and other materials can occur, so that the air tightness and water tightness performance of the aluminum alloy workpiece are poor.

Disclosure of Invention

In view of the foregoing, there is a need to provide an etching solution capable of forming holes in the surface of an aluminum alloy instead of electrochemical etching and a method for producing an aluminum alloy workpiece by etching with the etching solution, so as to solve the above-mentioned problems.

An etching solution for etching aluminum alloy comprises water, organic acid and Fe which can be dissociated in the water ²⁺ And Cl ^- Is a substance of (a).

Further, the organic acid is at least one selected from oxalic acid, tartaric acid, citric acid, glycolic acid, gluconic acid, glacial acetic acid, formic acid, benzoic acid, sulfamic acid and ethylenediamine tetraacetic acid.

Further, the water can dissociate Fe from the water ²⁺ And Cl ^- Is selected from the group consisting of ferrous salts selected from FeSO and chlorides ₄ And FeCl ₂ At least one of them.

Further, the chloride is selected from NaCl, KCl, caCl ₂ 、MgCl ₂ 、FeCl ₂ ZnCl ₂ At least one of them.

Further, fe of the ferrous salt in the etching solution ²⁺ The molar concentration of (C) is 0.05mol/L to 0.50mol/L.

Further, the chloride is Cl in the etching solution ^- The molar concentration of (C) is 0.5mol/L to 4.0mol/L.

Further, the molar concentration ratio of chloride ions to ferrous ions in the etching solution is 1:1-50:1.

Further, the etching solution further comprises a corrosion inhibitor, wherein the corrosion inhibitor can be at least one selected from sodium molybdate, sodium gluconate and ethylenediamine tetraacetic acid.

A method for preparing an aluminum alloy workpiece comprises the step of treating an aluminum alloy product by using the etching solution so as to form holes on the surface of the aluminum alloy product.

Further, the hole depth of the hole is in the range of 20 μm to 60 μm.

Further, the holes include a first hole and a second hole on a wall of the first hole, and the second hole and the first hole form a conical spike structure.

According to the etching solution and the method for preparing the aluminum alloy workpiece, the aluminum alloy is subjected to chemical corrosion in the organic environment, a mild etching environment can be provided by an organic environment system, the ion transmission rate is relatively low, and the uncontrollable reaction caused by the too high ion transmission rate is prevented. On the one hand, the surface of the aluminum alloy has a dense oxide film (Al ₂ O ₃ ) Cl in etching solution ^- The oxide film on the surface of the aluminum alloy can be locally dissolved (namely, pitting corrosion), and the local dissolution is the basis for forming the hole morphology; on the other hand, fe ²⁺ Forming a primary cell with aluminum in the aluminum alloy on the basis of local dissolution of the oxide film so as to etch the aluminum, and enabling etching solution to continue etching along the hole direction so as to form honeycomb holes; in yet another aspect, fe ²⁺ Can complex with acid radical ions in organic acid, thereby dissociating H ⁺ Forming a weak acid environment, the proper acid environment is favorable for Cl ^- And Fe (Fe) ²⁺ Etching of aluminum alloys, due to the continuous dissociation of H ⁺ A stable etching environment can be continuously maintained.

Drawings

Fig. 1 is a flow chart of etching an aluminum alloy product by using an etching solution according to an embodiment of the present application.

Fig. 2 is a schematic structural diagram of an etching solution etching aluminum alloy product according to an embodiment of the present application.

Fig. 3 is a photograph of an aluminum alloy workpiece according to an embodiment of the present application.

Fig. 4 is a photograph of an aluminum alloy workpiece provided in accordance with another embodiment of the present application.

Fig. 5 is a photograph of an aluminum alloy workpiece provided in accordance with yet another embodiment of the present application.

Fig. 6 is a scanning electron microscope (Scanning Electron Microscope, SEM) test chart of an aluminum alloy workpiece having a second hole on the wall of the first hole according to an embodiment of the application.

FIG. 7 is a chart of a first hole depth test of a first hole according to an embodiment of the present application.

Description of the main reference signs

The application will be further described in the following detailed description in conjunction with the above-described figures.

Detailed Description

In order that the above-recited objects, features and advantages of the present application will be more clearly understood, a more particular description of the application will be rendered by reference to the appended drawings and appended detailed description. The embodiments of the present application and the features in the embodiments may be combined with each other without collision. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application, and the described embodiments are merely some, rather than all, embodiments of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes all and any combination of one or more of the associated listed items.

The embodiment of the application provides an etching solution, which is used for chemically etching aluminum alloy to form holes with a certain shape on the surface of the aluminum alloy.

The etching solution comprises water, organic acid and Fe which can be dissociated in the water ²⁺ And Cl ^- Is a substance of (a).

The aluminum alloy is chemically corroded in an organic environment, and the organic environment system can provide a mild etching environment, so that the ion transmission rate is relatively low, and the uncontrollable reaction caused by the too high ion transmission rate is prevented. On the one hand, the surface of the aluminum alloy has a dense oxide film (Al ₂ O ₃ ) Cl in etching solution ^- The oxide film on the surface of the aluminum alloy can be locally dissolved (namely, pitting corrosion), and the local dissolution is the basis for forming the hole morphology; on the other hand, fe ²⁺ Forming a primary cell with aluminum in the aluminum alloy on the basis of local dissolution of the oxide film so as to etch the aluminum, and enabling etching solution to continue etching along the hole direction so as to form honeycomb holes; in yet another aspect, fe ²⁺ Can be complexed with acid radical ions in organic acid to dissociate H ⁺ Forming a weak acid environment, the proper acid environment is favorable for Cl ^- And Fe (Fe) ²⁺ Etching of aluminum alloys, due to the continuous dissociation of H ⁺ A stable etching environment can be continuously maintained.

In the subsequent etching process, the oxide film on the surface of the aluminum alloy may be completely removed, for example, the etching time may be prolonged, as the reaction proceeds. When the aluminum alloy having the holes is taken out from the etching solution, the surface of the aluminum alloy may again form an oxide film due to contact of oxygen in the air with the surface of the aluminum alloy.

The water may be water added separately to the etching solution, including ordinary water or deionized water; water produced by adding a compound containing crystal water to the etching solution may be used. Water is used for dissociation and can dissociate Fe ²⁺ And Cl ^- Is a substance of (a).

The organic acid may be at least one selected from oxalic acid, tartaric acid, citric acid, glycolic acid, gluconic acid, glacial acetic acid, formic acid, benzoic acid, sulfamic acid, and ethylenediamine tetraacetic acid. The organic acid can continuously dissociate H in water ⁺ Is Fe ²⁺ And Cl ^- The chemical reaction with the aluminum alloy provides a weakly acidic environment, thereby providing a mild etching environment and continuously maintaining a stable etching environment.

Said water being capable of dissociating Fe from said water ²⁺ And Cl ^- Is selected from the group consisting of ferrous salts and chlorides. The ferrous salt may be selected from FeSO ₄ And FeCl ₂ At least one of them. The chloride may be selected from NaCl, KCl, caCl ₂ 、MgCl ₂ 、FeCl ₂ ZnCl ₂ At least one of them. Wherein FeCl ₂ Can simultaneously dissociate Fe ²⁺ And Cl ^- Is a substance of (a).

Fe dissociated from the ferrous salt in the etching solution ²⁺ The molar concentration of (C) is 0.05mol/L to 0.50mol/L. Fe (Fe) ²⁺ The molar concentration of the catalyst is too low, the hole depth of the formed holes is shallow, and the morphology of the holes is irregular; fe (Fe) ²⁺ Is too high in molar concentration of Fe ²⁺ The complexing ability with acid radical ions is too strong, so that the acidity in the reaction process is too high, and honeycomb holes are not formed.

Cl dissociated from the chloride in the etching solution ^- The molar concentration of (C) is 0.5mol/L to 4.0mol/L. Cl ^- If the molar concentration is too low, the aluminum alloy cannot be locally dissolved on the surface of the aluminum alloy; cl ^- When the molar concentration of (c) is too high, the chemical balance of pitting corrosion is broken, and surface corrosion is likely to occur on the surface of the aluminum alloy.

Cl ^- With Fe ²⁺ The total molar concentration of (2) cannot be too low or too high. The total molar concentration is too low, the pitting corrosion capacity is poor, and the corrosion rate is low; if the total molar concentration is too high, the corrosion capacity is too high, and a good hole morphology cannot be obtained.

Cl in the etching solution ^- With Fe ²⁺ The molar concentration ratio of (2) is 1:1-50:1. Cl in etching solution ^- With Fe ²⁺ Has a large influence on the formation of pores. The molar concentration ratio is too low to be dissolved locally on the surface of the aluminum alloy, and Fe ²⁺ The complexing capacity with acid radical ions is too strong, so that the acidity is too high in the reaction process, and honeycomb holes are not formed; when the molar concentration ratio is too high, the chemical balance of pitting corrosion is destroyed, which is easy to lead to corrosion of the surface forming surface of the aluminum alloy, and the hole depth of the formed hole is shallowThe appearance is irregular.

The etching solution can further comprise a corrosion inhibitor, wherein the corrosion inhibitor can be at least one selected from sodium molybdate, sodium gluconate and ethylenediamine tetraacetic acid (EDTA). The corrosion inhibitor is used for slowing down the occurrence of chemical etching reaction, so that the etching reaction is milder, and the occurrence of surface corrosion is prevented.

In some embodiments, fe can be dissociated in the water ²⁺ And Cl ^- Does not include a substance capable of dissociating Fe in the water ³⁺ Is a substance of (a).

The inventors found that due to Fe ³⁺ Takes chemical reaction with aluminum in aluminum alloy, has stronger reaction activity and is larger than Fe ²⁺ The reactivity with aluminum results in uncontrollable chemical etching reactions, so that the etching solution does not include Fe which can dissociate in the water ³⁺ Is a substance of (a).

The etching solution cannot contain ions with strong oxidability so as to prevent the ions with strong oxidability from reacting with aluminum, so that the aluminum surface is corroded, pore forming on the surface of the aluminum alloy is not facilitated, even if the pore forming is performed, the pore is also a shallow pore, the morphology of the pore is irregular, and the subsequent forming material of the aluminum alloy product in the pore is not facilitated to form an industrially applicable composite material. Here, the relatively strong oxidizing ions such as perchlorate, hypochlorite, and the like.

Referring to fig. 1, the specific etching steps for etching the aluminum alloy article 20 to obtain the aluminum alloy workpiece 100 by using the etching solution may include:

step S1: an aluminum alloy article 20 is provided, the aluminum alloy article 20 having an oxide on a surface thereof.

The oxide includes aluminum oxide formed by reacting metallic aluminum with oxygen.

Step S2: degreasing treatment is performed on the aluminum alloy product 20 to remove impurities such as oil stains on the surface of the aluminum alloy product 20.

Step S3: the aluminum alloy article 20 is treated with nitric acid at room temperature.

Nitric acid is used to further remove oil stains, oxides and other impurities from the surface of the aluminum alloy article 20. Wherein, when the aluminum alloy article 20 is subjected to nitric acid treatment, the oxide is removed, and when the aluminum alloy article 20 is exposed to air, the oxide film 22 (i.e. aluminum oxide film layer) is generated in the aluminum alloy article by reacting with oxygen in the air again.

Step S4: the aluminum alloy product 20 having the oxide film 22 on the surface thereof after the above-described treatment step is immersed in the above-described etching solution to chemically etch the aluminum alloy product 20 to form pores.

The temperature at which the etching solution impregnates the aluminum alloy article 20 may be 45 deg.c to 80 deg.c. The soaking time can be set according to the pore diameter and the pore depth which are formed as required.

Referring to FIG. 2, cl in the etching solution during etching ^- Firstly, locally dissolving (namely, spot corrosion) an oxide film 22 on the surface of the aluminum alloy, wherein the local dissolution is the basis for forming the hole morphology; fe (Fe) ²⁺ Reacts with aluminum in the aluminum alloy on the basis of the local dissolution of the oxide film 22, so that the etching continues along the hole direction, fe ²⁺ Complexing with acid radical ion in organic acid to dissociate H ⁺ Forming a weak acid environment, the proper acid environment is favorable for Cl ^- And Fe (Fe) ²⁺ Etching the aluminum alloy to form honeycomb-shaped holes; wherein, as the reaction proceeds, the oxide film 22 may be entirely etched.

Step S5: the aluminum alloy product 20 after chemical corrosion is placed in alkali liquor for alkali biting, and larger burrs are removed.

Step S6: the aluminum alloy article 20 subjected to the alkali bite treatment is again placed in a nitric acid solution for treatment.

Step S7: ultrasonic, water washing and drying to obtain the aluminum alloy workpiece 100 comprising the aluminum alloy matrix 10 and the holes 30, wherein the holes 30 are positioned on the surface of the aluminum alloy matrix 10.

Referring to fig. 3, an embodiment of the present application further provides an aluminum alloy workpiece 100, where the aluminum alloy workpiece 100 includes an aluminum alloy substrate 10 and holes 30 on the surface of the aluminum alloy substrate 10, and the holes 30 are in a honeycomb structure.

The holes 30 include a first hole 32 and a second hole 34 in the wall of the first hole 32.

In some embodiments, referring to fig. 3-5, the first holes 32 have a pore size of 20 μm-100 μm. Referring to fig. 6, the second holes 34 have a diameter of 1 μm to 5 μm. The formation mechanism of the first hole 32 is chemical pitting corrosion, which is due to small radius of chloride ions and high electronegativity, has extremely strong permeability and film dissolving capability (namely dissolving the oxide film 22), and can quickly form dense pitting corrosion on the surface of the aluminum alloy in an acidic environment; the formation of the second holes 34 is due to the rapid sanding action of chloride ions, and further etching on the walls of the first holes 32 forms the second holes 34. Here, the process of forming the punctiform corrosion of the chloride ions on the aluminum alloy surface is that the chloride ions are firstly punctuated to corrode the oxide film 22 on the aluminum alloy surface, and then are punctuated to expose the aluminum alloy metal surface on the oxide film 22, so as to further corrode downwards, thereby forming the first holes 32 and the second holes 34.

Referring to fig. 7, the hole 30 has a hole depth ranging from 20 μm to 60 μm.

The hole depths, the hole diameters, and the hole shapes of the first holes 32 and the second holes 34 are related to factors such as the composition of the etching solution, the etching time, the etching temperature, and the like.

Referring to fig. 7 again, the second holes 34 and the first holes 32 form a tapered spike structure, and the plurality of second holes 34 are stacked on the surface of the hole wall of the first holes 32 to form an irregularly and convexly shaped structure with a large opening at one end and a small opening at the other end, specifically, the first holes 32 are in a substantially tapered shape, and the plurality of second holes 34 form a recessed spike structure on the side wall of the first holes 32. The first hole 32 and the second hole 34 of the conical spike structure can increase the difficulty in separating the aluminum alloy workpiece 100 from the material body formed on the surface of the aluminum alloy workpiece 100, so that the drawing force of the aluminum alloy workpiece 100 and the material body is increased, particularly, the first hole 32 is approximately conical, and the large-opening end is far away from the interior of the material, so that the material body is more suitable for filling the material body when being molded in the first hole 32, and the filling degree is increased; the spike structure formed by the plurality of second apertures 34 on the sidewall of the first apertures 32 may in turn increase the bonding strength of the material body.

The present application will be illustrated by the following specific examples and comparative examples. Before chemical etching, the aluminum alloy is subjected to a cleaning step to remove impurities such as oil stains and oxides of the aluminum alloy.

The specific cleaning steps comprise: placing the aluminum alloy product into a degreasing agent with the temperature of 55 ℃ for degreasing treatment, wherein the degreasing treatment time is 5min; the aluminum alloy article was then treated with a 30% HNO3 solution for 120 seconds.

Carrying out chemical etching on the cleaned aluminum alloy product, wherein the step of chemical etching comprises the following steps: the cleaned aluminum alloy product is placed in an etching solution for chemical etching to form holes 30 on the surface of the aluminum alloy product.

The aluminum alloy workpiece 100 formed after etching is subjected to a drawing force test, which includes forming a material body in the hole 30 of the aluminum alloy workpiece 100, and testing the magnitude of a pulling force required for separating the aluminum alloy base 10 from the material body, thereby detecting the drawing force of the aluminum alloy base 10 and the material body.

Example 1-1

The etching solution comprises water, organic acid, chloride, ferrous salt and inhibitor. Wherein the organic acid is glycolic acid, the chloride is sodium chloride (NaCl), and the ferrous salt is ferrous sulfate (FeSO) ₄ ) The inhibitor is sodium molybdate; cl ^- Molar concentration of 1.71mol/L, fe ²⁺ At a molar concentration of 0.22mol/L, cl ^- With Fe ²⁺ The molar concentration ratio was 7.8, and the molar concentration of sodium molybdate was 0.01mol/L. And (3) placing the aluminum alloy product in an etching solution at 60 ℃ for chemical etching to obtain the aluminum alloy workpiece. The drawing force test is carried out on the aluminum alloy workpiece.

Examples 1 to 2

Unlike example 1-1, the following were: the organic acid is oxalic acid.

Examples 1 to 3

Unlike example 1-1, the following were: the organic acid is citric acid.

Comparative examples 1 to 1

Unlike example 1-1, the following were: the etching solution does not contain ferrous salt.

Comparative examples 1 to 2

Unlike example 1-1, the following were: the etching solution does not contain chloride.

Comparative examples 1 to 3

Unlike example 1-1, the following were: the organic acid in the etching solution is replaced by inorganic acid, and the inorganic acid is phosphoric acid (H ₃ PO ₄ )。

Please refer to table 1, which shows the main differences between the examples 1-1 to 1-3 and the comparative examples 1-1 to 1-3 and the corresponding test results.

TABLE 1

Examples 1-1 to 1-3 each include water, an organic acid, a chloride, a ferrous salt, and an inhibitor, comparative example 1-1 does not include a ferrous salt, comparative example 1-2 does not include a chloride, and the organic acid in comparative example 1-3 is replaced with an inorganic acid. The drawing forces of examples 1-1 to 1-3 and comparative examples 1-1, comparative examples 1-2 and comparative examples 1-3 were all significantly higher than those of comparative examples 1-1 to 1-3, respectively, indicating that the etching solutions including ferrous salts, chlorides and inorganic acids, all contribute to the formation of holes, thereby improving the drawing force of aluminum alloy workpieces, wherein the etching solution having inorganic acids has a stronger etching ability than that of organic acids, and easily damages the integrity of holes, thereby reducing the drawing force. Comparative examples 1-1 to 1-3 show no significant difference in the drawing force test results, indicating that the different kinds of organic acids have little effect on the drawing force of the aluminum alloy workpieces. Although the drawing force test results of comparative examples 1 to 3 were good, the etching solution containing the inorganic acid was relatively intense compared to the etching solution containing the organic acid, the reaction controllability was poor, and the service life of the etching solution containing the inorganic acid was low compared to the etching solution containing the organic acid.

Example 2-1

The differences from examples 1-3 are: the chloride and ferrous salt are ferrous chloride (FeCl) ₂ )，Cl ^- Molar concentration of (2)The degree is 0.94mol/L, fe ²⁺ At a molar concentration of 0.47mol/L, cl ^- With Fe ²⁺ The molar ratio was 2.

Example 2-2

The differences from examples 1-3 are: cl ^- Molar concentration of 0.68mol/L, fe ²⁺ At a molar concentration of 0.07mol/L, cl ^- With Fe ²⁺ The molar ratio was 9.7.

Examples 2 to 3

The differences from examples 1-3 are: cl ^- Molar concentration of 0.68mol/L, fe ²⁺ At a molar concentration of 0.22mol/L, cl ^- With Fe ²⁺ The molar concentration ratio was 3.1.

Examples 2 to 4

The differences from examples 1-3 are: cl ^- Molar concentration of 0.68mol/L, fe ²⁺ At a molar concentration of 0.36mol/L, cl ^- With Fe ²⁺ The molar ratio was 1.9.

Please refer to table 2, which is a main distinction condition and corresponding test result for examples 2-1 to 2-4.

TABLE 2

Examples 2-1 to 2-4 different kinds of ferrous salts were selected and different Cl's were formulated ^- With Fe ²⁺ The molar concentration ratio can form an aluminum alloy workpiece with larger drawing force.

Example 3-1

The differences from examples 1-3 are: fe (Fe) ²⁺ At a molar concentration of 0.07mol/L, cl ^- With Fe ²⁺ The molar ratio was 24.4.

Example 3-2

The differences from examples 1-3 are: fe (Fe) ²⁺ At a molar concentration of 0.36mol/L, cl ^- With Fe ²⁺ The molar ratio was 4.8.

Examples 3 to 3

The differences from examples 1-3 are: cl ^- Molar concentration of (2)The degree is 3.42mol/L, fe ²⁺ At a molar concentration of 0.07mol/L, cl ^- With Fe ²⁺ The molar ratio was 48.9.

Examples 3 to 4

The differences from examples 1-3 are: cl ^- At a molar concentration of 3.42mol/L, cl ^- With Fe ²⁺ The molar ratio was 15.5.

Examples 3 to 5

The differences from examples 1-3 are: cl ^- The molar concentration of (C) is 3.42mol/L, fe ²⁺ At a molar concentration of 0.36mol/L, cl ^- With Fe ²⁺ The molar ratio was 9.5.

Please refer to table 3, which is a main distinction condition and corresponding test result for examples 1-3 and examples 3-1 to 3-5.

TABLE 3 Table 3

Comparing examples 3-1 and 3-3, examples 1-3 and 3-4, and examples 3-2 and 3-5, respectively, in the same Fe ²⁺ At a molar concentration of relatively low Cl ^- The molar concentration is favorable for forming the aluminum alloy workpiece with larger drawing force. Comparative examples 3-1 to 3-2 and examples 1-3 and examples 3-3 to 3-5, in the same Cl ^- Molar concentrations, examples 1-3 and examples 3-4 gave aluminum alloy workpieces with maximum drawing forces. Description by controlling Fe ²⁺ Molar concentration of (C) Cl ^- The molar concentration of the aluminum alloy workpiece with larger drawing force can be regulated and controlled.

Example 4-1

The differences from examples 1-3 are: the chloride is KCl.

Example 4-2

The differences from examples 1-3 are: the chloride is CaCl ₂ 。

Examples 4 to 3

The differences from examples 1-3 are: the chloride being MgCl ₂ 。

Examples 4 to 4

The differences from examples 1-3 are: the chloride is ZnCl ₂ 。

Please refer to table 4, which is a main distinguishing condition for examples 4-1 to 4-4 and the corresponding test results.

TABLE 4 Table 4

Comparative examples 4-1 to 4-4 show no significant difference in the drawing force test results, indicating that the different kinds of chlorides have little effect on the drawing force of the aluminum alloy workpieces.

Example 5-1

The differences from examples 1-3 are: does not contain inhibitors.

Example 5-2

The differences from examples 1-3 are: the inhibitor is sodium gluconate.

Examples 5 to 3

The differences from examples 1-3 are: the inhibitor is EDTA.

Please refer to table 5, which shows the main distinguishing conditions and the corresponding test results for examples 5-1 to 5-3 and examples 1-3.

TABLE 5

The aluminum alloy workpieces obtained by the etching solutions of examples 5-1 to 5-3 and examples 1-3 all had a large drawing force. Among them, the etching solutions of comparative examples 5-1 (no inhibitor added) and examples 5-2 to 5-3 and examples 1-3, with the addition of the inhibitor, were able to further improve the drawing force of the aluminum alloy workpiece.

Example 6-1

The differences from examples 1-3 are: the temperature of the chemical etching was 50 ℃.

Example 6-2

The differences from examples 1-3 are: the temperature of the chemical etching was 75 ℃.

Please refer to table 6, which is a main distinction condition and corresponding test result for examples 6-1 to 6-2 and examples 1-3.

TABLE 6

The aluminum alloy to the product is treated by etching liquid at different temperatures, so that the aluminum alloy workpiece with larger drawing force can be obtained.

The etching solution provided by the application is used for carrying out chemical corrosion on aluminum alloy in an organic environment, the organic environment system can provide a mild etching environment, the ion transmission rate is relatively low, and the uncontrollable reaction caused by the too high ion transmission rate is prevented. On the one hand, the surface of the aluminum alloy has a dense oxide film (Al ₂ O ₃ ) Cl in etching solution ^- The oxide film on the surface of the aluminum alloy can be locally dissolved (namely, pitting corrosion), and the local dissolution is the basis for forming the hole morphology; on the other hand, fe ²⁺ Forming a primary cell with aluminum in the aluminum alloy on the basis of local dissolution of the oxide film so as to etch the aluminum, and continuing etching the corrosion along the hole direction so as to form honeycomb holes; in yet another aspect, fe ²⁺ Can be complexed with acid radical ions in organic acid to dissociate H ⁺ Forming a weak acid environment, the proper acid environment is favorable for Cl ^- And Fe (Fe) ²⁺ Etching of aluminum alloys, due to the continuous dissociation of H ⁺ A stable etching environment can be continuously maintained.

The above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the above preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present application.

Claims

1. An etching solution for chemically etching aluminum alloy, which comprises the following substances:

water;

an organic acid;

can dissociate Fe in the water ²⁺ And Cl ^- Is a substance of (a); and

a corrosion inhibitor;

wherein the Fe is ²⁺ Complexing with the acid radical ion in the organic acid to dissociate the organic acid into H ⁺ To form a weak acid environment, the etching liquid does not comprise Fe which can be dissociated in the water ³⁺ Is a substance of (a); said water being capable of dissociating Fe from said water ²⁺ And Cl ^- Is selected from the group consisting of ferrous salts and chlorides; fe of the ferrous salt in the etching solution ²⁺ The molar concentration of (C) is 0.05mol/L to 0.50mol/L; cl of the chloride in the etching solution ^- The molar concentration of (C) is 0.5mol/L-4.0mol/L; the molar concentration ratio of chloride ions to ferrous ions in the etching solution is 1:1-50:1.

2. The etching solution according to claim 1, wherein the organic acid is at least one selected from oxalic acid, tartaric acid, citric acid, glycolic acid, gluconic acid, glacial acetic acid, formic acid, benzoic acid, sulfamic acid, and ethylenediamine tetraacetic acid.

3. The etching solution according to claim 1, wherein the ferrous salt is selected from FeSO ₄ And FeCl ₂ At least one of them.

4. The etching solution according to claim 1, wherein the chloride is selected from NaCl, KCl, caCl ₂ 、MgCl ₂ 、FeCl ₂ ZnCl ₂ At least one of them.

5. The etching solution according to claim 1, wherein the corrosion inhibitor is at least one selected from sodium molybdate, sodium gluconate and ethylenediamine tetraacetic acid.

6. A method for preparing an aluminum alloy workpiece comprises

Treating the aluminum alloy product with an etching solution to form holes on the surface of the aluminum alloy product; wherein the etching solution is the etching solution according to any one of claims 1 to 5.

7. The method of claim 6, wherein the pores have a pore depth in the range of 20 μm to 60 μm.

8. The method of claim 6, wherein the pores comprise a first pore and a second pore on a wall of the first pore, the second pore forming a tapered spike structure with the first pore.