Metal substrate surface treatment method and metal substrate after stripping

Abstract

The present application provides a method for treating the surface of a metal substrate, comprising: providing a metal substrate, the metal substrate comprising an aluminum substrate layer, a first oxide layer and a second oxide layer, the first oxide layer being connected between the second oxide layer and the aluminum substrate layer, the second oxide layer comprising a porous structure; placing the second oxide layer in a first solution to form a plurality of cracks in the porous structure to obtain an intermediate; placing the intermediate in a second solution to powderize the porous structure having the plurality of cracks, thereby forming a powderized layer on the side of the first oxide layer away from the substrate layer; and removing the powderized layer. The method for treating the surface of a metal substrate provided in the present application has the advantage of reducing the loss of the aluminum substrate layer. In addition, the present application also provides a metal substrate after stripping.

Description

Technical Field

[0001] The present application relates to the technical field of metal processing, and in particular to a surface treatment method for a metal substrate and a metal substrate after stripping. Background Art

[0002] During the processing of aluminum alloy, an anodic oxide film will be formed on the surface to improve the corrosion resistance, wear resistance and decorative properties of aluminum alloy. For an anodic oxide film that cannot meet the requirements, the surface of the aluminum alloy workpiece needs to be processed secondary anodic processing to remove the previously formed anodic oxide film. Currently, the use of strong alkali to remove the oxide film also causes greater corrosion to the aluminum substrate, resulting in an increase in the amount of aluminum substrate removed. Summary of the invention

[0003] The present application provides a metal substrate surface treatment method and a metal substrate after stripping to reduce the loss of an aluminum base layer.

[0004] In a first aspect, the present application provides a method for surface treatment of a metal substrate, comprising: providing a metal substrate, the metal substrate comprising an aluminum substrate layer, a first oxide layer and a second oxide layer, the first oxide layer being connected between the second oxide layer and the aluminum substrate layer, the second oxide layer comprising a porous structure; placing the second oxide layer in a first solution to form a plurality of cracks in the porous structure to obtain an intermediate; placing the intermediate in a second solution to powderize the porous structure having the plurality of cracks, thereby forming a powderized layer on the side of the first oxide layer away from the substrate layer; and removing the powderized layer.

[0005] In the first aspect, in some possible embodiments, the second oxide layer is aluminum oxide formed by anodization, the first solution includes an aluminum sulfate aqueous solution or an aminosulfonic acid aqueous solution, and the step of "placing the second oxide layer in the first solution" includes: placing the second oxide layer in an aluminum sulfate aqueous solution with a mass fraction of 15% to 25%, the reaction temperature is 75 to 85°C, and the reaction time is 50 to 80 minutes; or placing the second oxide layer in an aminosulfonic acid aqueous solution with a mass fraction of 10% to 15%, the reaction temperature is 75 to 85°C, and the reaction time is 50 to 80 minutes.

[0006] In the first aspect, in some possible implementations, the step of "placing the intermediate in a second solution" includes: setting the temperature of the second solution to 85-95° C. and the reaction time to not less than 90 minutes.

[0007] In the first aspect, in some possible embodiments, the second solution includes, by mass percentage: sodium acetate, 1-3%; triethanolamine, 3-7%; bis(2-hydroxyethyl)dimethylammonium chloride, 5-12%; and water, 75-77%.

[0008] In the first aspect, in some possible implementations, the second solution includes, by mass percentage: nickel acetate, 0.5-3%; alkyl polyglycoside, 1-5%; ammonia water, 5-10%; and water, 80-85%.

[0009] In the first aspect, in some possible embodiments, the metal substrate further includes a sealing layer, which covers the surface of the second oxide layer, and a portion of the sealing layer is filled into the porous structure. Before "placing the metal substrate in the first solution", it also includes: placing the metal substrate in a desealing solution to remove the sealing layer.

[0010] In the first aspect, in some possible embodiments, the sealing layer includes boehmite, the desealing solution includes a nitric acid solution or an oxalic acid solution, and the step of "placing the metal substrate in the desealing solution" includes: placing the sealing layer in a nitric acid solution with a mass fraction of 15-25%, a temperature of 25-35°C, and a reaction time of 10-20 minutes; or placing the sealing layer in an oxalic acid solution with a mass fraction of 15-20%, a temperature of 65-75°C, and a reaction time of 10-15 minutes.

[0011] In the first aspect, in some possible implementations, before the step of "placing the metal substrate in a desealing solution", the step also includes: placing the metal substrate in a cleaning agent to remove oil stains on the surface of the sealing layer, and the cleaning agent includes sodium phosphate, sodium pyrophosphate, sodium silicate and alkylphenol polyoxyethylene ether.

[0012] In the first aspect, in some possible embodiments, the step of "removing the powdered layer" includes: placing the powdered layer in a nitric acid solution with a mass fraction of 18-22%, a temperature of 25-30°C, and a reaction time of 3-5 minutes, or placing the powdered layer in a solution containing sulfuric acid with a mass fraction of 18-22% and a mass fraction of 3-7%, a temperature of 25-30°C, and a reaction time of 3-5 minutes.

[0013] In a second aspect, the present application provides a stripped metal substrate obtained by the above-mentioned metal substrate surface treatment method, wherein the metal substrate comprises a substrate layer and a first oxide layer, and the thickness of the first oxide layer is 0.3 to 0.5 microns.

[0014] The surface treatment method of a metal substrate provided in the present application first places a second oxide layer having a porous structure in a first solution to form a plurality of cracks, and then places it in a second solution to powderize it and remove it after forming a powderized layer. This step-by-step treatment method can accurately act on the anodized film (second oxide layer). By creating cracks in the porous structure and powderizing it, the excessive corrosion of the aluminum substrate layer can be effectively reduced compared to the traditional method of directly removing the oxide film. Because in the process of forming cracks and powderizing, the force is mainly concentrated on the structural changes of the oxide film itself, rather than the direct erosion of the aluminum substrate layer and the first oxide layer, thereby reducing the amount of aluminum substrate layer removed, and ensuring the integrity and mechanical properties of the metal substrate.

[0015] At the same time, this treatment method can more thoroughly remove the anodized film, so that the surface of the metal substrate can be subjected to more precise and high-quality subsequent treatment operations, such as re-anodization, electroplating, painting, etc., which is beneficial to improve the bonding strength between the subsequent coating and the metal substrate, thereby improving the overall performance of the entire metal product, such as corrosion resistance, wear resistance, etc., and expanding the application of metal substrates in more fields with higher surface quality requirements (such as high-end electronic product housings, precision mechanical parts, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a flow chart of a method for surface treatment of a composite metal substrate proposed in an embodiment of the present application.

[0017] Figure 2 A schematic cross-sectional view of a metal substrate proposed in an embodiment of the present application.

[0018] Figure 3 for Figure 2 The schematic cross-sectional view of the metal substrate after removing the sealing layer is shown.

[0019] Figure 4 for Figure 3 The schematic cross-sectional view of the porous structure of the metal substrate after cracks are formed is shown.

[0020] Figure 5 for Figure 4 The schematic cross-sectional view of the powdered layer formed after the porous structure is powdered is shown.

[0021] Figure 6 for Figure 5 The cross-sectional schematic diagram after the powdered layer is removed is shown.

[0022] Figure 7 A schematic cross-sectional view of a metal substrate after stripping provided in one embodiment of the present application.

[0023] Main component symbols Metal substrate 10 Aluminum base layer 11 The first oxide layer 12 The second oxide layer 13 Porous structure 131 Crack 132 Sealing layer 14 Intermediate 20 Powdered layer 30 The metal substrate 10' after stripping. DETAILED DESCRIPTION

[0024] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0025] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0026] The following is a detailed description of various embodiments of the present invention in conjunction with the accompanying drawings.

[0027] On the one hand, see Figure 1 The present application discloses a surface treatment method for a metal substrate 10, comprising the steps of: S1: Please see Figure 2 A metal substrate 10 is provided, and the metal substrate 10 includes an aluminum substrate layer 11, a first oxide layer 12, and a second oxide layer 13. The first oxide layer 12 is connected between the second oxide layer 13 and the aluminum substrate layer 11. The second oxide layer 13 includes a porous structure 131.

[0028] Among them, the metal substrate 10 is an aluminum alloy substrate after anodization, and the material of the aluminum base layer 11 includes common aluminum alloy series, such as 6061 aluminum alloy, whose main components are aluminum, magnesium, silicon and other elements. It has good mechanical properties, processing performance and certain corrosion resistance, and can provide basic structural support for the entire metal substrate 10.

[0029] The first oxide layer 12 is a relatively thin oxide layer with a dense structure formed in the early stage by natural oxidation or in a weak oxidation environment. Its thickness is usually between 0.1-0.3 microns. It mainly serves to initially isolate the aluminum substrate layer 11 from the external environment and provide a transition basis for the subsequent formation of the second oxide layer 13.

[0030] The second oxide layer 13 is aluminum oxide formed by anodization, and its thickness is thicker than the first oxide layer 12, generally between 10-50 microns. The porous structure 131 in the second oxide layer 13 is a large number of tiny and interconnected pores formed on the surface of the first oxide layer 12 during the anodization process when aluminum reacts with the electrolyte. The pores are randomly distributed, and their pore sizes are generally in the nanometer to micrometer level.

[0031] The difference between the first oxide layer 12 and the second oxide layer 13 is that the first oxide layer 12 has a relatively dense structure, a thin thickness, and a relatively simple formation process; while the second oxide layer 13 has a large thickness and a porous structure 131, which is formed under the conditions of anodizing process after a long reaction time, and has a higher specific surface area and chemical activity.

[0032] The metal substrate 10 further includes a sealing layer 14, which covers the surface of the second oxide layer 13, and a portion of the sealing layer 14 is filled into the porous structure 131. Specifically, the sealing layer 14 includes boehmite (AlOOH∙NiOH), nickel acetate, nickel hydroxide and other substances.

[0033] During the formation of the sealing layer 14, when the metal substrate 10 is placed in a solution containing nickel acetate after anodization, the nickel ions generated by the dissociation of nickel acetate will interact with the aluminum oxide in the porous structure 131 and the solution environment. Nickel ions will first be adsorbed on the surface of aluminum oxide, and due to the active sites and charge distribution characteristics of the aluminum oxide surface, nickel ions gradually aggregate. Subsequently, under suitable conditions such as temperature and pH value, nickel ions undergo complex oxidation-reduction and precipitation reactions with aluminum atoms in aluminum oxide and hydroxide ions in the solution to generate boehms, which gradually accumulate in the pores and extend to the surface, thereby sealing the porous structure 131. Nickel acetate that does not participate in the boehm reaction may remain in the sealing layer 14, and as time goes by and the environment changes, part of the nickel acetate will be hydrolyzed to generate nickel hydroxide.

[0034] Wherein, step S1 further includes: removing the sealing layer 14. Specifically, it includes: S11: See Figure 3, the metal substrate 10 is placed in a cleaning agent to remove the oil stains on the surface of the sealing layer 14. Among them, the cleaning agent includes sodium phosphate, sodium pyrophosphate, sodium silicate and alkylphenol polyoxyethylene ether. Sodium phosphate and sodium pyrophosphate belong to phosphate substances. Both can be hydrolyzed in an aqueous solution to produce an alkaline environment, which is conducive to the emulsification and dispersion of oil stains. Sodium silicate has good emulsification, dispersion and wetting properties, which can better separate the oil stains from the surface of the sealing layer 14. Alkylphenol polyoxyethylene ether, as a non-ionic surfactant, contains both hydrophilic groups and hydrophobic groups in its molecular structure. The hydrophilic groups can interact with water molecules, and the hydrophobic groups attract each other with the oil stain molecules, thereby reducing the interfacial tension between the oil stains and the sealing layer 14, making the oil stains easier to be removed under the action of the cleaning agent.

[0035] During the cleaning process, the metal substrate 10 is immersed in the above-mentioned cleaning agent solution, the solution temperature is controlled at 40-60°C, and the immersion time is about 15-30 minutes. At the same time, stirring or ultrasonic oscillation and other means are used to further enhance the cleaning effect, ensuring that the oil stains on the surface of the sealing layer 14 can be completely removed, providing good basic conditions for the subsequent removal of the sealing layer 14 and the second oxide layer 13, and reducing the adverse effects of residual oil stains on subsequent chemical reactions and treatment effects.

[0036] S12: Place the metal substrate 10 in a desealing solution to remove the sealing layer 14, thereby exposing the porous structure 131. Specifically, the sealing layer 14 is placed in a nitric acid solution with a mass fraction of 15-25%, a temperature of 25-35°C, and a reaction time of 10-20 minutes. Under this condition, nitric acid has strong oxidizing properties and can undergo an oxidation-reduction reaction with the boehmite in the sealing layer 14, destroying its chemical bonds and decomposing the hydrated alumina into soluble aluminum salts, so that the surface of the second oxide layer 13 and the sealing layer 14 that invades the porous structure 131 are dissolved. The chemical equation for the reaction of nitric acid with boehmite is roughly: AlOOH·NiOH+4HNO 3 →Al(NO 3 ) 3 +Ni(NO 3 ) 2 +2H 2 O; Alternatively, the sealing layer 14 is placed in an oxalic acid solution with a mass fraction of 15-20%, the temperature is 65-75°C, and the reaction time is 10-15 minutes. The oxalate ions in the oxalic acid solution have a strong complexing ability and can form a stable complex with the aluminum ions and nickel ions in the boehmite, so that the boehmite is dissolved in the solution, thereby achieving the removal of the sealing layer 14. The chemical reaction equation can be expressed as: AlOOH·NiOH+3H 2 C 2 O4 →Al(C 2 O 4 ) 3 +Ni(C 2 O 4 )+3H 2 O; The rich pore network and large specific surface area inside the exposed porous structure 131 can provide sufficient attachment sites and reaction sites for subsequent agents. When the subsequent agents come into contact with the porous structure 131, the agent molecules can diffuse rapidly along the pores and penetrate into the interior, reacting chemically with alumina and possibly exposed aluminum atoms, such as ion exchange, thereby achieving precise regulation and modification of the physical and chemical properties of the porous structure 131.

[0037] S2: See Figure 3 and Figure 4 , placing the second oxide layer 13 in the first solution to form a plurality of cracks 132 in the porous structure 131, and obtaining the intermediate 20. The cracks 132 are fine gaps generated by the chemical reaction between the first solution and the porous structure 131 of the second oxide layer 13, which results in a decrease in the local strength of the porous structure 131 and the internal stress, and these gaps extend along the weak parts of the porous structure 131, thereby destroying the integrity of the porous structure 131.

[0038] Wherein, when the first solution is an aqueous solution of aluminum sulfate, step S2 specifically comprises: S21: placing the second oxide layer 13 in an aluminum sulfate aqueous solution with a mass fraction of 15% to 25%, the reaction temperature is 75 to 85°C, and the reaction time is 50 to 80 minutes. Under this condition, the aluminum ions and sulfate ions in the aluminum sulfate solution react chemically with the aluminum oxide in the porous structure 131. The sulfate ions may combine with the aluminum atoms in the aluminum oxide to change its crystal structure, generate internal stress, and promote the formation of cracks 132. The chemical reaction equation is roughly as follows: Al 2 O 3 +3H 2 SO 4 →2Al 2 (SO 4 ) 3 +3H 2 O; When the first solution is an aqueous solution of sulfamic acid, step S2 specifically includes: S22: placing the second oxide layer 13 in a 10% to 15% aqueous sulfamic acid solution at a reaction temperature of 75 to 85°C for 50 to 80 minutes. Under these conditions, when sulfamic acid reacts with alumina, the sulfamic acid molecules will corrode the lattice of alumina, causing the porous structure 131 to gradually lose its original stability, thereby generating cracks 132. The reaction equation is, for example: Al 2 O 3 +3NH 2 SO 3 H→2Al(NH 2 SO 3 ) 3 +3H 2 O; Among them, the aluminum sulfate aqueous solution or the aminosulfonic acid aqueous solution is a weak acid solution, and the first oxide layer 12 is thin and dense, and has stronger corrosion resistance than the second oxide layer 13 under such weak acid conditions. Due to its compact structure, the first oxide layer 12 is difficult for hydrogen ions to penetrate into its interior to react with the aluminum matrix, and its formation process makes the chemical bond energy on its surface relatively high, and it has a certain resistance to acid corrosion. The porous structure 131 of the second oxide layer 13 provides a large number of diffusion channels for hydrogen ions, so that it can penetrate into the interior of the oxide layer to react chemically with aluminum oxide and aluminum atoms, and the porous structure 131 itself also has more stress concentration points and active sites, which are more easily destroyed in an acidic environment. Therefore, in the treatment process of this stage, only the second oxide layer 13 is corroded, thereby realizing selective treatment of the second oxide layer 13, and on the basis of not affecting the integrity of the first oxide layer 12, it creates conditions for a series of operations such as forming cracks 132 and pulverization in the porous structure 131 of the second oxide layer 13. Wherein, step S2 further includes: S23: Use ultrasonic vibration. When ultrasonic waves propagate in the solution, a cavitation effect will be generated, that is, the tiny bubbles in the liquid will expand rapidly under the negative pressure cycle of the ultrasound, and will collapse sharply under the positive pressure cycle. This violent cavitation phenomenon will produce an instantaneous high temperature and high pressure environment and a strong mechanical impact force in the local area. Under the combined action of hydrogen ions and ultrasound, the porous structure 131 is chemically eroded by hydrogen ions in the aqueous solution of aluminum sulfate or aminosulfonic acid, so that its crystal structure is gradually destroyed; on the other hand, the mechanical force generated by ultrasonic cavitation will aggravate this destructive process, so that stress concentration points are generated inside the porous structure 131, thereby corroding the porous structure 131 to produce a large number of microcracks 132. Cracks 132 destroy the integrity of the porous structure 131, making it easier for corrosive media to penetrate into the oxide film and contact the aluminum matrix, which is beneficial to the further reaction of other solutions with the porous structure 131 in the subsequent steps.

[0039] S3: See Figure 4 and Figure 5 The intermediate 20 is placed in a second solution to powderize the porous structure 131 having a plurality of cracks 132, thereby forming a powderized layer 30 on the side of the first oxide layer 12 away from the substrate layer. Specifically, the powderization process is performed under high temperature and weak alkaline conditions, so that the porous structure 131 having cracks 132 is powdered to form a powderized layer 30.

[0040] In terms of weight percentage, the second solution includes the following components: sodium acetate, 1-3%; triethanolamine, 3-7%; bis(2-hydroxyethyl)dimethylammonium chloride (QOH, cas:38402-02-7), 5-12%; water, 75-77%. The temperature of the second solution is set to 85-95°C, and the reaction time is not less than 90 minutes. Among them, sodium acetate provides an ionic environment in the solution, triethanolamine can provide weak alkaline conditions and enhance the reaction activity, and bis(2-hydroxyethyl)dimethylammonium chloride dominates the corrosion of the porous structure 131. When the porous structure 131 with cracks 132 enters the second solution, various components in the solution react with the aluminum oxide of the porous structure 131 and the fresh aluminum atoms exposed at the cracks 132 in various chemical reactions. For example, bis(2-hydroxyethyl)dimethylammonium chloride corrodes the porous structure 131, causing the cracks 132 to gradually expand and eventually cause the entire porous structure 131 to pulverize. The chemical reaction equation is roughly as follows: Al 2 O 3 +6QOH→2Al(QO) 3 +3H 2 O; Alternatively, the second solution has the following components in weight percentage: nickel acetate, 0.5-3%; alkyl polysaccharide, 1-5%; ammonia water, 5-10%; water, 80-85%. The temperature of the second solution is set to 85-95°C, and the reaction time is not less than 90 minutes. Nickel acetate participates in the replacement or complexation reaction of metal ions, alkyl polysaccharide helps to improve the surface activity of the solution, ammonia water adjusts the pH of the solution and participates in chemical reactions related to aluminum, promoting the pulverization of the crack 132 porous structure 131. The chemical reaction process can be expressed as: Al 2 O 3 +6NH 3 +3Ni(CH 3 COO 2 →2Al(NH 3 ) 3 +3Ni(OH) 2 +6CH 3 COOH; S4: See Figure 5 and Figure 6, remove the powdered layer 30, and obtain the metal substrate 10' after stripping. Specifically, step S4 includes: placing the powdered layer 30 in a nitric acid solution with a mass fraction of 18-22%, a temperature of 25-30°C, and a reaction time of 3-5 minutes. Nitric acid has strong oxidizing properties and can quickly dissolve the aluminum and its oxides in the powdered layer 30. The reaction principle is that nitric acid undergoes an oxidation-reduction reaction with aluminum and aluminum oxide to generate soluble aluminum nitrate and other products. The reaction equation is roughly as follows: 2Al+6HNO 3 →2Al(NO 3 ) 3 +3H 2 ;Al 2 O 3 +6HNO 3 →2Al(NO 3 ) 3 +3H 2 O Alternatively, the powdered layer 30 is placed in a solution containing 18-22% sulfuric acid and 3-7% hydrogen fluoride at a temperature of 25-30°C for a reaction time of 3-5 minutes. Sulfuric acid and hydrogen fluoride work together, hydrogen fluoride can react with aluminum and aluminum oxide to form soluble fluoroaluminate, and sulfuric acid further promotes the reaction, thereby improving the removal efficiency of the powdered layer 30. The chemical reaction equation is, for example: Al 2 O 3 +6HF→2AlF 3 +3H 2 O; 2Al+6HF→2AlF 3 +3H 2 See also Figure 7 , through detection, the second oxide layer 13 of the metal substrate 10' after stripping is completely removed, and the thickness of the first oxide layer 12 is 0.3-0.5 microns. In this way, the second oxide layer 13 is effectively removed for subsequent secondary anodizing or other surface treatment processes, and the first oxide layer 12 of appropriate thickness is retained to provide good protection for the aluminum substrate layer 11, reducing the corrosion loss of the aluminum substrate layer 11 during the stripping process, and ensuring the structural integrity and basic performance of the metal substrate 10. In the subsequent processing, the metal substrate 10 can be further anodized, painted, electroplated, etc. according to actual needs to obtain a metal product with specific performance and appearance requirements. For example, in the production of metal frames of electronic equipment, the metal substrate 10' after stripping can better meet the requirements of high precision, high strength and good corrosion resistance, providing a strong guarantee for the long-term stable operation and appearance quality of electronic equipment.

[0041] See also Figure 6 and Figure 7 In a second aspect, the present application provides a stripped metal substrate 10' obtained by the above-mentioned treatment method. The stripped metal substrate 10' comprises an aluminum base layer 10 and a first oxide layer 12. The thickness of the first oxide layer 12 is 0.3-0.5 micrometers.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A method for treating a metal substrate surface, characterized in that: include: Providing a metal substrate, the metal substrate comprising an aluminum substrate layer, a first oxide layer and a second oxide layer, the first oxide layer is connected between the second oxide layer and the aluminum substrate layer, and the second oxide layer comprises a porous structure; placing the second oxide layer in a first solution to form a plurality of cracks in the porous structure to obtain an intermediate; placing the intermediate in a second solution to powderize the porous structure having the plurality of cracks, thereby forming a powderized layer on a side of the first oxide layer facing away from the substrate layer; The powdered layer is removed.

2. The method for treating the surface of a metal substrate according to claim 1, wherein: The second oxide layer is aluminum oxide formed by anodic oxidation, the first solution includes an aluminum sulfate aqueous solution or an aminosulfonic acid aqueous solution, and the step of "placing the second oxide layer in the first solution" includes: The second oxide layer is placed in an aqueous solution of aluminum sulfate with a mass fraction of 15% to 25%, the reaction temperature is 75 to 85° C., and the reaction time is 50 to 80 minutes; or The second oxide layer is placed in an aqueous solution of aminosulfonic acid with a mass fraction of 10% to 15%, the reaction temperature is 75 to 85° C., and the reaction time is 50 to 80 minutes.

3. The surface treatment method according to claim 2, characterized in that: The step of "placing the intermediate in a second solution" comprises: The temperature of the second solution is set to 85-95° C., and the reaction time is not less than 90 minutes.

4. The method for treating the surface of a metal substrate according to claim 3, wherein: In terms of mass percentage, the second solution includes: sodium acetate, 1-3%; triethanolamine, 3-7%; bis(2-hydroxyethyl)dimethylammonium chloride, 5-12%; and water, 75-77%.

5. The method for treating the surface of a metal substrate according to claim 3, wherein: In terms of mass percentage, the second solution includes: nickel acetate, 0.5-3%; alkyl polyglycoside, 1-5%; ammonia water, 5-10%; and water, 80-85%.

6. The method for treating the surface of a metal substrate according to claim 1, wherein: The metal substrate further includes a sealing layer, the sealing layer covers the surface of the second oxide layer, and a portion of the sealing layer is filled into the porous structure. Before "placing the metal substrate in the first solution", the process further includes: The metal substrate is placed in a desealing solution to remove the sealing layer.

7. The method for treating the surface of a metal substrate according to claim 6, wherein: The sealing layer includes boehmite, the desealing solution includes a nitric acid solution or an oxalic acid solution, and the step of "placing the metal substrate in the desealing solution" includes: The sealing layer is placed in a nitric acid solution with a mass fraction of 15-25%, a temperature of 25-35° C., and a reaction time of 10-20 minutes; or The sealing layer is placed in an oxalic acid solution with a mass fraction of 15-20%, the temperature is 65-75° C., and the reaction time is 10-15 minutes.

8. The method for treating the surface of a metal substrate according to claim 7, wherein: Before the step of "placing the metal substrate with a desealing solution", the step further comprises: The metal substrate is placed in a cleaning agent to remove oil stains on the surface of the sealing layer. The cleaning agent includes sodium phosphate, sodium pyrophosphate, sodium silicate and alkylphenol polyoxyethylene ether.

9. The method for treating the surface of a metal substrate according to claim 1, wherein: The step of "removing the powdered layer" comprises: The powdered layer is placed in a nitric acid solution with a mass fraction of 18-22%, a temperature of 25-30°C, and a reaction time of 3-5 minutes, or, The powdered layer is placed in a solution containing 18-22% by mass of sulfuric acid and 3-7% by mass of hydrogen at a temperature of 25-30° C. for a reaction time of 3-5 minutes.

10. A stripped metal substrate obtained by the metal substrate surface treatment method according to any one of claims 1 to 9, characterized in that: The metal substrate includes a substrate layer and a first oxide layer, and the thickness of the first oxide layer is 0.3-0.5 micrometers.

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