Metal with nano micropores in surface, preparation method, metal-resin composite containing metal and part

Abstract

The invention discloses a metal with nano micropores in the surface, a preparation method, a metal-resin composite containing the metal and a part. The metal with the nano micropores in the surface comprises a micropore layer arranged on the metal surface, the micropore layer is provided with a plurality of micropores, the thickness of the micropore layer is 200-500 nm, and the pore diameter of the micropores is 30-70 nm. The preparation method comprises the following steps of metal surface oil removal, primary alkali corrosion, primary neutralization, sanding, secondary alkali corrosion, secondary neutralization, electrolytic film forming and surface activation. According to the nano-microporous structure formed by the method, the contact area of metal and molten plastic can be remarkably increased, and meanwhile, the interface bonding force can be further improved through physical and chemical adsorption generated in nano-pores. In addition, the nano structure can also improve the surface wettability, promote plastic filling and reduce bubble defects.

Description

Technical Field

[0001] This invention relates to the field of alloy surface treatment technology, and in particular to a metal with nanopores on its surface, a preparation method thereof, a metal-resin composite containing the metal, and parts thereof. Background Art

[0002] In some manufacturing fields, the one-piece molding technology of metal and plastic is required. During the injection molding process of metal and plastic, the bonding strength of the metal-plastic interface directly affects the reliability and durability of the product. The process technology has a direct impact on the performance of the finished product. At present, the industry mostly uses bonding methods such as adhesives, sandblasting, chemical etching, and anodizing to achieve this.

[0003] However, traditional adhesive bonding methods suffer from increased costs and the tendency of organic adhesives to age under high temperature and humidity conditions. Mechanical treatment methods (such as sandblasting) produce finished products with poor control over surface roughness, making it difficult to form uniform nanoscale structures and easily introducing residual stress. Chemical treatment methods (such as pickling) cause significant pollution and are prone to excessive corrosion, thus affecting the properties of the substrate. Finished products produced by anodizing have limited mechanical interlocking between the porous alumina layer and the plastic, resulting in low bonding strength, and the process also consumes a lot of energy.

[0004] In conclusion, developing a new nanoscale surface treatment technology with high bonding strength has become an urgent need for the industry. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a metal with high bonding strength and a surface with nanopores, a preparation method, a metal-resin composite containing the metal, and a part.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A first aspect is provided: a metal with nanopores on its surface, comprising a microporous layer disposed on the metal surface, the microporous layer having a plurality of micropores, the thickness of the microporous layer being 200-500 nm, and the pore size of the micropores being 30-70 nm.

[0008] The aluminum alloy surface prepared by the method of the present invention forms a nanoporous layer with a thickness of about 200-500nm. The nanoporous layer has a large number of nanopores, with a pore size between 30-70nm, and is irregular in shape. It has a large specific surface area, which can facilitate the subsequent filling of more plastic, achieve better glue content, and have high bonding strength.

[0009] As an optional implementation, the thickness of the microporous layer is 280-330 nm, and the pore size of the micropores is 30-40 nm.

[0010] In a second aspect, the present invention provides a method for preparing a metal with nanopores on its surface as described in the first aspect, comprising the following steps: degreasing the metal surface, primary alkaline etching, primary neutralization, sandblasting, secondary alkaline etching, secondary neutralization, electrolytic film formation, and surface activation.

[0011] The present invention addresses the challenge of existing nanopore preparation processes failing to simultaneously achieve both high surface roughness and good resin content. The invention improves the nanopore preparation process, specifically modifying the sandblasting and secondary alkaline etching processes. The sandblasting process roughens the aluminum alloy surface, creating numerous micron-sized pores that can bond with plastic. The secondary alkaline etching process further enhances the sandblasting effect, resulting in even better micron-sized pores. This provides a better foundation for the subsequent electrolytic film formation and surface activation to create nanopores, thereby increasing the bonding area between the aluminum alloy and resin. This allows for a strong bond between the aluminum alloy and plastic, resulting in a tightly integrated aluminum alloy product with superior performance.

[0012] As an optional implementation, the sandblasting process uses a sand-forming agent comprising the following components at mass concentrations: 10 g / L-100 g / L ferric chloride, 10 g / L-100 g / L hydrochloric acid, 5 g / L-100 g / L ammonium bifluoride, and 10 g / L-100 g / L sulfuric acid. Utilizing the reducing, oxidizing, and pitting abilities of organic / inorganic acids (such as hydrogen fluoride / ferric chloride), uniform and dense corrosion points are formed on the aluminum alloy surface, resulting in a micron-level rough surface.

[0013] As an optional implementation, the reagents used in the electrolytic film formation process include at least one of phosphoric acid, sulfuric acid, or oxalic acid, wherein the concentration of phosphoric acid is 50 g / L-300 g / L; the concentration of sulfuric acid is 20 g / L-100 g / L; and the concentration of oxalic acid is 5 g / L-50 g / L.

[0014] As an optional implementation, the reagents used for surface activation include 50-200 g / L nitric acid, sodium carbonate, or a surface conditioning agent, wherein the surface conditioning agent is selected from sodium bicarbonate, sulfamic acid, sodium sulfate, or sodium acetate. Surface activation mainly functions to expand pores and generate a large number of active substances on the inner side of the pore walls. These active substances can generate intermolecular forces with metals and plastics, further improving the bonding strength.

[0015] As an optional implementation, the electrolysis conditions for the electrolytic film formation are as follows: using the metal to be treated as the positive electrode and the carbon rod as the negative electrode, applying a voltage of 15V-30V, controlling the temperature of the electrolyte at 15℃-25℃, and electrolyzing for 5min-30min.

[0016] As an optional implementation, the surface activation process involves immersing the electrolyzed metal film in the reagent and treating it at 20-40°C for 60-300 seconds.

[0017] As an optional implementation, the degreasing treatment specifically involves placing the metal workpiece in an acid, alkali, or organic solvent with a concentration of 100–300 g / L and subjecting it to ultrasonic treatment at 40°C–60°C for 3–8 minutes. The ultrasonic power is 1.0–2.6 KW. The main purpose is to remove oil, dust, and other contaminants from the workpiece surface, exposing a clean metal surface.

[0018] As an optional implementation, the primary alkaline etching process is to remove the oxide layer on the metal surface. Specifically, the process involves immersing the metal workpiece obtained from the degreasing treatment into a sodium hydroxide or potassium hydroxide solution at a temperature of 35℃~75℃ and a concentration of 40-60g / L for 10~100 seconds. The alkaline etching process mainly removes the natural oxide film on the aluminum alloy surface, exposing the active substrate.

[0019] As an optional implementation, the first neutralization involves neutralizing the alkaline solution on the metal surface, followed by water washing of the metal. Specifically, the metal after the first alkaline etching treatment is neutralized in a 100-300 g / L nitric acid or sulfuric acid aqueous solution at a temperature of 25-55°C for 5-60 seconds.

[0020] As an optional implementation, the secondary alkaline etching process specifically involves immersing the degreasing metal workpiece in a sodium hydroxide or potassium hydroxide solution at a temperature of 35℃~75℃ and a concentration of 40-60g / L for 10~100 seconds.

[0021] As an optional implementation, the secondary neutralization involves neutralizing the alkaline solution on the metal surface and then washing the metal with water. Specifically, the metal after the secondary alkaline etching treatment is neutralized in a 100-300 g / L nitric acid or sulfuric acid aqueous solution at a temperature of 25-55°C for 5-60 seconds.

[0022] In a third aspect, the present invention provides a metal-resin composite comprising a metal substrate and a resin, wherein the metal substrate is a metal with nanopores on its surface as described in claims 1-2, or a metal with nanopores on its surface prepared by any of the methods described in claims 3-8, wherein the particle size of the resin is smaller than the pore size of the nanopores, and the resin fills the pores of the metal with nanopores on its surface.

[0023] In a fourth aspect, the present invention provides a component for an electronic product, which is made of the metal-resin composite described in the third aspect.

[0024] The nanoporous structure formed by the method of this invention can significantly increase the contact area between the metal and the molten plastic, achieving a "mechanical anchoring effect." Simultaneously, the physicochemical adsorption that may occur within the nanopores can further enhance the interfacial bonding force. Furthermore, the nanostructure can improve surface wettability, promote plastic filling, and reduce bubble defects. The metal obtained by the surface treatment method of this invention has numerous irregular nanoporous pores on its surface, with pore sizes between 30-70 nm, resulting in a large specific surface area and good mechanical anchoring effect. Attached Figure Description

[0025] Figure 1 Electron microscope as an embodiment of this application Figure 1 ;

[0026] Figure 2 Electron microscope as an embodiment of this application Figure 2 ;

[0027] Figure 3 Electron microscope as an embodiment of this application Figure 3 . Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0029] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0030] Unless otherwise defined, 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 invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] Example 1

[0032] The aluminum alloy is surface treated using the following method:

[0033] 1) Degreasing: The aluminum alloy metal workpiece is placed in nitric acid with a concentration of 150g / L and ultrasonically cleaned under constant temperature conditions of 50℃ for 5 minutes. The ultrasonic power is 2KW. In this step, the ultrasonic treatment time is set to 5 minutes and the power is set to 2kW. Through the synergistic effect of oxidative decomposition of nitric acid and ultrasonic cavitation effect, the surface grease and oxides are efficiently removed. It is especially suitable for deep degreasing of workpieces with complex structures, while avoiding excessive corrosion of the substrate.

[0034] 2) Primary Alkaline Etching: The aluminum alloy after degreasing in step 1) is placed in a 50 g / L sodium hydroxide solution and treated at a constant temperature of 50°C for 30 seconds. This process rapidly dissolves the weak aluminum oxide layer and the aluminum substrate through alkaline etching, forming a uniform activated surface. Strict time control is required during this step to avoid over-etching, which could lead to dimensional deviations in the workpiece.

[0035] 3) First neutralization: Place the aluminum alloy treated in step 2) in a 200 g / L nitric acid aqueous solution and treat it at a constant temperature of 35°C for 30 seconds. This process utilizes the properties of nitric acid to quickly remove the residual aluminum hydroxide residue from alkaline etching, while simultaneously passivating the surface to form a dense oxide film. This step requires strict control of the reaction time and temperature to avoid hydrogen embrittlement of the substrate due to hydrogen permeation, ensuring the cleanliness of the interface for subsequent treatments.

[0036] 4) Sandblasting: A sandblasting agent is prepared using ferric chloride and hydrochloric acid. The concentration of ferric chloride in the sandblasting agent is 200 g / L, and the concentration of hydrochloric acid is also 200 g / L. The aluminum alloy is sandblasted at 45°C for 100 seconds using this sandblasting agent. The aluminum alloy is then washed with water. This step employs a low-temperature, high-efficiency process; the sandblasting temperature (45°C) is significantly lower than the conventional sandblasting temperature. This process achieves surface roughening through the following synergistic mechanism:

[0037] Micro-etching nucleation: Ammonium bifluoride preferentially dissolves the grain boundaries of the aluminum matrix, forming micron-sized etch pits as nucleation sites;

[0038] Oxidative deposition: Ferric chloride hydrolyzes in an acidic environment to generate FeOOH colloidal particles, which are adsorbed onto the inner wall of the corrosion pit;

[0039] Ion activation: Hydrochloric acid maintains a strongly acidic environment (pH < 1), which accelerates the anodic dissolution of aluminum and inhibits excessive hydrogen evolution.

[0040] 5) Secondary Alkali Etching: The sandblasted aluminum alloy is immersed in a 50g / L sodium hydroxide solution and treated at a constant temperature of 50℃ for 50 seconds. This step further removes the residue from the previous sandblasting process through directional micro-etching with alkali, simultaneously eliminating uneven areas from the first alkaline etching and fully exposing the surface crystalline structure. During operation, the reaction time and bath agitation must be strictly controlled to prevent over-etching that leads to excessive dissolution of grain boundaries and reduces dimensional accuracy.

[0041] 6) Secondary Neutralization: The aluminum alloy treated in step 5) is placed in a 200 g / L nitric acid aqueous solution and treated at a constant temperature of 35°C for 60 seconds. This process completely dissolves the residual aluminum hydroxide and intermetallic compounds from the alkaline corrosion in an acidic environment, while simultaneously forming a dense passivation film on the surface, blocking the risk of continued corrosion of the substrate. Strict control of the treatment time can effectively inhibit hydrogen ion penetration and avoid hydrogen embrittlement leading to a decline in mechanical properties.

[0042] 7) Electrolytic film formation: Using 100 g / L sulfuric acid as the electrolyte, with the metal to be treated as the positive electrode and a carbon rod as the negative electrode, a 20V DC voltage is applied, and the temperature of the electrolyte is controlled at 20℃. Electrolysis is carried out for 15 minutes, and a dense oxide film is formed on the metal surface through an anodic oxidation reaction. This process requires strict control of the electrolyte concentration and temperature to suppress side reactions and ensure the uniformity and bonding strength of the film layer.

[0043] 8) Surface activation: Using a 100 g / L nitric acid solution, immerse the metal treated in step 7) in the solution and treat it at a constant temperature of 30°C for 200 seconds. This process dissolves the residual oxide passivation layer on the metal surface through the oxidizing properties of nitric acid, simultaneously forming a microporous structure in the substrate and improving surface homogenization. Strict control of temperature and time can avoid over-corrosion and ensure a highly active and homogenized surface state.

[0044] 9) Cleaning: The aluminum alloy treated in step 8) is cleaned using ultrasound in a constant temperature cleaning bath at 60℃. Ultrasonic waves remove residues from the membrane pores, allowing for more complete resin filling. The microjets generated by ultrasonic cavitation penetrate deep into the membrane pores, thoroughly removing residual chemicals and particles, creating an activated surface on the micropore walls. This process significantly improves the resin filling rate, providing a contamination-free substrate for subsequent impregnation processes.

[0045] 10) Drying: Dry the aluminum alloy after cleaning in step 9) to obtain a surface-treated aluminum alloy with nanopores. Of course, in other embodiments, natural drying can also be used, that is, there is no need to use a separate drying step.

[0046] The prepared aluminum alloy was observed under an electron microscope, and the scanning electron microscope image is shown below. Figures 1-3 As shown in the results, the aluminum alloy surface prepared by the method of Example 1 forms a microporous layer with nanopores and a thickness of about 280-330 nm. The microporous layer has a large number of nanopores, a porosity of 55%, and pores between 30-40 nm. The pores are irregular in shape and have a large specific surface area.

[0047] The roughness of the metal was measured using a stylus tracing method. The stylus was ensured to be correctly in contact with the measurement surface, and the roughness meter was confirmed to be parallel to the measurement surface. The Ra value of the surface roughness was measured by gently tracing the stylus across the surface being measured. The results showed that the metal roughness obtained in this embodiment was between 3 and 7 μm, indicating that the treated aluminum alloy had high surface roughness, large surface area of ​​micron-sized pores, and better bonding with resin. Furthermore, the amount of metal removed from the aluminum alloy substrate was minimized, keeping the removal amount less than 20 μm, thus avoiding glue overflow at the aluminum-plastic joint after injection molding.

[0048] In this embodiment, aluminum alloy and resin are composited, with the resin composition of the resin layer filling the pores of the surface-treated metal to form a metal-resin composite, hereinafter referred to as a metal test piece. The tensile strength of the metal test piece prepared in this embodiment was tested, and the average tensile strength was greater than 680N. The thrust strength was tested, and the result was greater than 480N. This indicates that the overall strength of the test piece is good. The metal and resin prepared in this embodiment were overlapped and bonded on a product manufacturing mold, and the tensile strength and superimposed force of the test piece were tested. The results showed that the average tensile strength was 680N, and the average superimposed force was 1800N. The residual adhesive content of the product was tested, and the results showed that after the prepared metal was bonded to the resin, the bond was tight, the residual adhesive content reached more than 90%, and the resin penetration depth was 110-120nm (SEM cross-section test), showing excellent filling effect and high bonding strength.

[0049] This metal-resin composite can be used in the manufacturing of electronic product components, improving the overall performance of the products.

[0050] Example 2

[0051] The difference from Example 1 is that step 1) uses a weakly alkaline degreasing agent (commercially available product, no special brand requirements) for degreasing treatment; step 4) uses ammonium bifluoride and sulfuric acid as sand-forming agents, wherein the concentration of ammonium bifluoride in the sand-forming agent is 30 g / L and the concentration of sulfuric acid is 100 g / L; step 7) electrolytic film formation: using 120 g / L phosphoric acid as electrolyte, with the metal to be treated as the positive electrode and the carbon rod as the negative electrode, an 18V DC voltage is applied, the temperature of the electrolyte is controlled at 17.5℃, and electrolysis is performed for 9 minutes.

[0052] The aluminum alloy prepared in Example 2 was subjected to structural characterization tests and performance verification tests. The results showed that the aluminum alloy prepared in this example formed a microporous layer with nanopores and a thickness of about 202-218 nm on its surface. The microporous layer had a large number of nanopores, a porosity of 48%, and pores between 30-34 nm. The pores were irregular in shape and had a large specific surface area.

[0053] The metal and resin prepared in this embodiment were bonded together, and the tensile and superimposed forces of the bonded specimens were tested. The results showed that the average tensile force was 635 N and the average superimposed force was 1200 N. The resin penetration depth of the product (SEM cross-section test) was tested, and the results showed that the depth was 100-110 nm, indicating excellent filling effect and high bonding strength.

[0054] In this embodiment, aluminum alloy and resin are combined to fill the pores of the surface-treated metal with a resin composition in the resin layer, thereby forming a metal-resin composite. This metal-resin composite can be used in the manufacturing of electronic product components to improve the overall performance of the product.

[0055] Example 3

[0056] The difference from Example 1 is that in step 7) electrolytic film formation: 180 g / L phosphoric acid is used as the electrolyte, the metal to be treated is used as the positive electrode and the carbon rod is used as the negative electrode, a DC voltage of 19.5V is applied, the temperature of the electrolyte is controlled at 19°C, and electrolysis is performed for 15 minutes.

[0057] The aluminum alloy prepared in Example 3 was subjected to structural characterization tests and performance verification tests. The results showed that the aluminum alloy prepared in this example formed a microporous layer with nanopores and a thickness of about 478-498 nm on its surface. The microporous layer had a large number of nanopores, a porosity of 62%, and pores between 40-50 nm. The pores were irregular in shape and had a large specific surface area.

[0058] The metal and resin prepared in this embodiment were bonded together, and the tensile and superimposed forces of the bonded specimens were tested. The results showed that the average tensile force was 715 N and the average superimposed force was 1700 N. The resin penetration depth (SEM cross-section test) was tested, and the results showed a depth of 178-193 nm, indicating excellent filling effect and high bonding strength.

[0059] In this embodiment, aluminum alloy and resin are combined to fill the pores of the surface-treated metal with a resin composition in the resin layer, thereby forming a metal-resin composite. This metal-resin composite can be used in the manufacturing of electronic product components to improve the overall performance of the product.

[0060] The above embodiments merely illustrate preferred implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention should be determined by the appended claims.

Claims

1. A metal with nanopores on its surface, characterized in that, It includes a microporous layer disposed on a metal surface, the microporous layer having multiple micropores, the thickness of the microporous layer being 200-500 nm, and the pore size of the micropores being 30-70 nm.

2. The metal with nanopores on its surface as described in claim 1, characterized in that, The thickness of the microporous layer is 280-330 nm, and the pore size of the micropores is 30-40 nm.

3. A method for preparing a metal with nanopores on its surface as described in any one of claims 1-2, characterized in that, The process includes the following steps: degreasing the metal surface, primary alkaline etching, primary neutralization, sandblasting, secondary alkaline etching, secondary neutralization, electrolytic film formation, and surface activation.

4. The method for preparing a metal with nanopores on its surface as described in claim 3, characterized in that, The sand-forming agent used in the sand-making process includes the following components at mass concentrations: 10g / L-100g / L ferric chloride, 10g / L-100g / L hydrochloric acid, 5g / L-100g / L ammonium bifluoride, and 10g / L-100g / L sulfuric acid.

5. The method for preparing a metal with nanopores on its surface as described in claim 3, characterized in that, The reagents used in the electrolytic film formation process include at least one of phosphoric acid, sulfuric acid, or oxalic acid, wherein the concentration of phosphoric acid is 50 g / L-300 g / L; the concentration of sulfuric acid is 20 g / L-100 g / L; and the concentration of oxalic acid is 5 g / L-50 g / L.

6. The method for preparing a metal with nanopores on its surface as described in claim 3, characterized in that, The reagents used for surface activation include 50-200 g / L nitric acid, sodium carbonate, or a surface conditioner, wherein the surface conditioner is selected from sodium bicarbonate, aminosulfonic acid, sodium sulfate, or sodium acetate.

7. The method for preparing a metal with nanopores on its surface as described in claim 3, characterized in that, The electrolytic film formation conditions are as follows: the metal to be treated is used as the positive electrode and the carbon rod is used as the negative electrode. A voltage of 15V-30V is applied, the temperature of the electrolyte is controlled at 15℃-25℃, and the electrolysis time is 5min-30min.

8. The method for preparing a metal with nanopores on its surface as described in claim 6, characterized in that, The surface activation process involves immersing the electrolyzed metal film into the reagent and treating it at 20-40°C for 60-300 seconds.

9. A metal-resin composite, characterized in that, The invention comprises a metal substrate and a resin, wherein the metal substrate is the metal with nanopores on its surface as described in claims 1-2, or the metal with nanopores on its surface prepared by any of the methods described in claims 3-8, wherein the particle size of the resin is smaller than the pore size of the nanopores, and the resin fills the pores of the metal with nanopores on its surface.

10. A component for use in electronic products, characterized in that, It is prepared using the metal-resin composite as described in claim 9.

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