Surface composite treatment process and application of copper-clad aluminum material

Abstract

The invention relates to a surface composite treatment process and application of a copper-clad aluminum material, and relates to the field of copper-clad aluminum surface treatment.The composite treatment process comprises the steps that a copper-clad aluminum workpiece subjected to oil removal pretreatment is subjected to acid leaching etching, and then the copper-clad aluminum workpiece is immersed into zinc immersion liquid to be subjected to two-step zinc immersion; the copper-clad aluminum workpiece subjected to zinc immersion is subjected to nickel electroplating treatment; a titanium nitride layer is deposited on the surface of the nickel layer through the physical vapor deposition technology, so that a composite coating is obtained on the copper-clad aluminum workpiece; and the copper-clad aluminum workpiece with the composite coating is subjected to heat treatment, passivating treatment is conducted after cooling, and a finished product is obtained after cleaning and blow-drying. After the surface of the copper-clad aluminum material is subjected to composite treatment, the oxidation resistance can be enhanced, the copper-clad aluminum material has good electromagnetic shielding performance and the like, the bonding strength of a composite coating and a copper-clad aluminum matrix is improved, it is ensured that the coating does not fall off or peel off in the long-term use process, the service life of the material is prolonged, and the performance stability of the material is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of metal surface treatment, and particularly relates to a copper-clad aluminum material, and specifically relates to a surface composite treatment process for a copper-clad aluminum material and application. BACKGROUND

[0002] Copper-clad aluminum (CCA) is a composite material with an aluminum core and a copper layer on the outside, which has excellent electrical conductivity (conductivity > 95% IACS), weldability, and the lightweight characteristics of aluminum (density is only 30% of copper), and is widely used in the fields of electronics, communications, aerospace, etc.

[0003] Traditional copper-clad aluminum materials rely on a single plating layer to achieve corrosion resistance and weldability, and have significant functional limitations. For example, in high-temperature or humid environments, the copper layer is prone to oxidation, forming an oxide film with poor electrical conductivity, which causes the contact resistance of the material to increase rapidly, affecting the stability of electronic components; in complex electromagnetic environments, it lacks effective electromagnetic shielding ability and cannot block external electromagnetic interference, making it difficult to be applied to fields such as 5G communication equipment and precision medical devices that have strict requirements on electromagnetic compatibility. In addition, existing plating layers usually do not have properties such as wear resistance and high-temperature resistance, limiting the application of the material in high-stress and extreme temperature environments.

[0004] In addition, the insufficient bonding strength of the existing single plating layer and copper-clad aluminum material is a long-standing technical pain point. Due to the large difference in the thermal expansion coefficient between copper and aluminum, under the action of temperature cycling or mechanical stress, the plating layer is prone to peeling, peeling, and other phenomena, exposing the substrate and accelerating corrosion, significantly shortening the service life and performance stability of the material, increasing the equipment maintenance cost and safety hazards.

[0005] Therefore, it is an urgent need to develop a multifunctional and excellent bonding strength composite plating layer to solve the problems of single function of copper-clad aluminum material, pollution of traditional process, and insufficient stability of plating layer, etc., which is an important direction to promote the green upgrading of material surface treatment technology. SUMMARY

[0006] The purpose of the present application is to provide a surface composite treatment process for a copper-clad aluminum material and application, which builds a composite structure of "zinc transition layer -> nickel layer -> titanium nitride layer" on the copper-clad aluminum material to solve the problems of single function of copper-clad aluminum material, pollution of traditional process, and insufficient stability of plating layer, etc.

[0007] The present application achieves the above-mentioned purpose by the following technical solutions:

[0008] A surface composite treatment process for a copper-clad aluminum material, comprising the following steps:

[0009] (1) the copper-clad aluminum workpiece after oil removal pretreatment is subjected to acid immersion etching, and the copper-clad aluminum workpiece after acid immersion etching is immersed into zinc immersion liquid to perform two-step zinc immersion, so as to form a zinc layer on the surface of the copper-clad aluminum workpiece; wherein the alkali concentration of the zinc immersion liquid in the two-step zinc immersion is low first and high later.

[0010] (2) the copper-clad aluminum workpiece after zinc immersion is subjected to nickel electroplating treatment, so as to form a nickel layer on the surface of the zinc layer;

[0011] (3) a titanium nitride layer is deposited on the surface of the nickel layer by using a physical vapor deposition technology, so as to obtain a composite coating on the copper-clad aluminum workpiece;

[0012] (4) the copper-clad aluminum workpiece with the composite coating is subjected to heat treatment, and after cooling, passivation treatment is performed, and after cleaning and blow-drying, a finished product is obtained.

[0013] As a further optimization scheme of the above-mentioned application, in step (1), the oil removal pretreatment is that the copper-clad aluminum workpiece is immersed into an alkaline oil removal liquid, the temperature of the alkaline oil removal liquid is 50-60 DEG C, the immersion time is 5-10 min, and the composition of the alkaline oil removal liquid is NaOH 3-5 g / L, Na2CO3 15-20 g / L, OP-10 3-5 g / L, citric acid 5-10 g / L, phosphoric acid 3-5 g / L, and nano-silicon dioxide 1-2 g / L.

[0014] As a further optimization scheme of the above-mentioned application, in step (1), the acid immersion etching is that the copper-clad aluminum workpiece is immersed in an acid immersion liquid, assisted by ultrasonic waves, the power is 200-300 W, the time is 60-120 s, and the composition of the acid immersion liquid is sodium persulfate 8-12 g / L, sulfuric acid 3-5 g / L, phosphoric acid 2-3 g / L, and sulfamic acid 1-2 g / L.

[0015] As a further optimization scheme of the above-mentioned application, the composition of the zinc immersion liquid is zinc oxide 20-30 g / L, sodium hydroxide 80-120 g / L, nano-ZrO2 0.3-0.5 g / L, sodium citrate 20 g / L, nickel chloride NiCl2 6H2O 40 g / L, hydroxyethyl hydrazine 2-3 g / L, and L-cysteine 0.5-1 g / L.

[0016] As a further optimization scheme of the above-mentioned application, the immersion time of the two-step zinc immersion is 60-120 s, specifically, the first step zinc immersion is performed at a NaOH concentration of 60-70 g / L for 30-90 s, the second step zinc immersion is performed by adding NaOH to 90-120 g / L for 30-90 s, and the temperature is 25-35 DEG C.

[0017] As a further optimization scheme of the above-mentioned application, in step (2), the composition of the plating solution is: nickel sulfate 80-120 g / L, disodium ethylenediaminetetraacetate 40-60 g / L, thiourea 0.3-1.0 g / L, graphene quantum dots 0.1-0.3 g / L, potassium citrate 15-25 g / L, sodium phytate 5-8 g / L, the pH of the plating solution is 4-6, and the parameters for electroplating nickel are: forward current density 2.0-3.0 A / dm 2 , reverse current density 0.5-1.0 A / dm 2 , frequency 100-200 Hz, and electroplating time 10-60 min.

[0018] As a further optimization scheme of the above-mentioned application, in step (3), a titanium target is sputtered for 5-8 min under a pure argon environment at a power of 1.5-2 W / cm 2 , and the surface of the nickel layer is bombarded with sputtered titanium ions at the same time to form an atomic-level mixed layer, the argon flow rate is 40-60 sccm, and a titanium transition layer is deposited; then a titanium layer is deposited at a power of 0.8-1 W / cm 2 , nitrogen gas is introduced, the power is 1.0-1.5 W / cm 2 , and a TiN crystal nucleus layer is deposited, which is repeated for 2-3 times to form a gradient interface; then the power is gradually increased to 2-2.5 W / cm 2 , the argon flow rate is 60-80 sccm, and a titanium layer is deposited.

[0019] As a further optimization scheme of the above-mentioned application, in step (4), the heat treatment is heating to 100-120 DEG C for 1-2 h, and then heating to 160-180 DEG C for 1-2 h. The vacuum pressure is less than 10 -3 Pa.

[0020] As a further optimization scheme of the above-mentioned application, in step (4), the copper-clad aluminum workpiece is immersed in a passivation solution for passivation treatment, and the composition of the passivation solution is: sodium molybdate 15-20 g / L, phytic acid 5-10 g / L, silane coupling agent 3-5 g / L, pH = 3.5-4.0, and soaking time is 5-10 min.

[0021] A copper-clad aluminum material prepared by the above-mentioned surface composite treatment process, the surface of the copper-clad aluminum workpiece is sequentially provided with a zinc layer (0.5-2 μm), a nickel layer (10-20 μm), and a titanium nitride layer (3-6 μm).

[0022] The application has the following advantages:

[0023] The application adopts a step-by-step zinc immersion method of "low-alkali first and high-alkali later", compared with the traditional secondary zinc immersion, the process time is shortened, the process is simplified, and the redundant steps of zinc removal and secondary zinc immersion are eliminated; the density and uniformity of the zinc layer are optimized, the characteristics of dissimilar substrates (aluminum / copper) are adapted, the substrate corrosion is reduced, and the copper-aluminum interface integrity is protected.

[0024] The application constructs a composite structure of "zinc transition layer→nickel layer→titanium nitride layer" on the copper-clad aluminum material. The zinc transition layer is formed on the surface of the aluminum substrate by a zinc immersion process, effectively solving the problem of difficult bonding of aluminum and coating; the titanium nitride layer is constructed by means of physical vapor deposition (PVD) technology, through the construction of an atomic-level mixed layer and a titanium transition layer, realizing high-strength bonding with the nickel layer, and at the same time endowing the material with enhanced oxidation resistance, excellent electromagnetic shielding performance (shielding effectiveness reaches 65-70 dB at a frequency of 1 GHz) and other functions.

[0025] The application improves the coating bonding strength (scratch width of adhesion test <0.5 mm), wear resistance (wear amount <1.0 mg / cm 2 ) by more than 50% through gradient interface design and nanocomposite technology; green manufacturing: cyan-free zinc immersion, low-toxicity passivation liquid and energy recovery system, realizing environmental protection and cost optimization. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The coating metallographic detection analysis graphs of the examples (a: example 1; b: example 2);

[0027] Figure 2 The coating metallographic detection analysis graphs of the comparative examples (a: comparative example 2; b: comparative example 6; c: comparative example 8). DETAILED DESCRIPTION

[0028] It is necessary to point out here that the following detailed description is only used to further illustrate the application, and cannot be understood as limiting the protection scope of the application, and the skilled in the art can make some non-essential improvements and adjustments to the application according to the above application content.

[0029] 1. DESCRIPTION

[0030] The copper-clad aluminum workpiece in the application is a wire or a bar, specifically an aluminum core coated with a copper layer on the outside, and the aluminum material is exposed at both ends and / or at the perforated part, and the total volume of the copper layer accounts for about 25% of the total material.

[0031] In at least one embodiment of the application, a surface composite treatment process for copper-clad aluminum material is disclosed, including the following steps:

[0032] Step 1: Immerse the copper-clad aluminum workpiece in an alkaline degreasing solution containing NaOH (3-5g / L), Na2CO3 (15-20g / L), OP-10 (3-5g / L), citric acid (5-10g / L), and phosphoric acid (3-5g / L). Nano-silica (1-2g / L) is added as a surfactant. The temperature is 50-60°C and the workpiece is immersed for 5-10 minutes. The high specific surface area of ​​nano-SiO2 absorbs oil stains, while the alkaline component and weak acid form a gradient pH environment, achieving simultaneous degreasing and surface roughening. This shortens the process time to 8-12 minutes, reduces the temperature to 40-50°C, and reduces energy consumption by 20%.

[0033] Step 2: Immerse the copper-clad aluminum workpiece in an acid immersion solution (power 200-300W) and use ultrasonic waves (power 200-300W) to assist in etching. The acid immersion solution consists of sodium persulfate (8-12g / L), sulfuric acid (3-5g / L), phosphoric acid (2-3g / L), and aminosulfonic acid (1-2g / L). Ultrasonic waves (power 200-300W) assist in etching. The mild acidity of aminosulfonic acid reduces substrate corrosion, while the ultrasonic cavitation effect accelerates oxide film stripping, shortening etching time to 2-3 minutes and controlling surface roughness Ra to 0.5-1μm, improving coating adhesion.

[0034] Step 3: The copper-clad aluminum workpiece is immersed in the zinc dipping solution for a total immersion time of 60-120 seconds. The NaOH concentration is maintained at 60-70 g / L in the first section (30-90 seconds) (low concentration alkaline environment, adapted to the slow peeling of the oxide film on the aluminum substrate), and NaOH is added to 90-120 g / L in the second section (30-90 seconds) (high concentration alkaline environment, accelerating the replacement of zinc on the copper surface). The temperature is 25-35 ° C, and the thickness of the zinc layer is controlled at 0.5-0.8 μm. The zinc dipping solution composition is: zinc oxide (20-30 g / L), sodium hydroxide (80-120 g / L), nano ZrO2 (0.3-0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O40 g / L), hydroxyethyl hydrazine (2-3 g / L), L-cysteine ​​(0.5-1 g / L);

[0035] Compared with the traditional secondary zinc dipping method, this zinc dipping method shortens the process time. The zinc layer thickness can be close to 1μm in 60s, which simplifies the process and eliminates the redundant steps of zinc stripping and secondary zinc dipping. The density and uniformity of the zinc layer are optimized to adapt to the characteristics of heterogeneous substrates (aluminum / copper). It reduces substrate corrosion and protects the integrity of the copper-aluminum interface. The "nitric acid zinc stripping" step of the traditional secondary zinc dipping is a key hidden danger: nitric acid is a strong oxidizing acid and can easily over-corrode the aluminum substrate (especially the weak interface area of ​​copper-clad aluminum), causing microcracks on the interface or dissolution of the aluminum substrate, seriously affecting the adhesion of subsequent coatings.

[0036] Step 4: Put the zinc-immersed copper-clad aluminum material into an environmentally friendly nickel plating solution for nickel plating treatment. Introduce pulse plating technology with the following parameters: forward current density 2.0-3.0 A / dm 2 , reverse current density 0.5-1.0 A / dm 2 , frequency 100-200 Hz, and plating time 10-60 min. (Environmentally friendly nickel plating solution formula: main salt: nickel sulfate (NiSO4), concentration 80-120 g / L; complexing agent: disodium ethylenediaminetetraacetate (Na2EDTA), concentration 40-60 g / L; additives: thiourea (0.3-1.0 g / L) + graphene quantum dots (0.1-0.3 g / L); stabilizer: potassium citrate (15-25 g / L) + sodium phytate (5-8 g / L), pH buffer range extended to 4.0-6.0.

[0037] Step 5: Deposit a titanium nitride layer on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, with a thickness of 3-6 μm.

[0038] Under a pure argon environment, sputter a titanium target at a power of 1.5-2 W / cm 2 for 5-8 min to remove the surface oxide layer of the titanium target and slightly bombard the nickel surface with sputtered titanium ions to form an atomic-level mixed layer. The argon flow rate is 40-60 sccm, and a titanium transition layer (thickness 0.5-1 μm) is deposited,

[0039] Using "titanium-nitrogen plasma alternate injection", first deposit a titanium layer (0.5-1 μm) at a power of 0.8-1 W / cm 2 , then introduce nitrogen gas (flow rate 20-40 sccm) at a power of 1.0-1.5 W / cm 2 to deposit a TiN crystal nucleus layer, and repeat 2-3 times to form a gradient interface.

[0040] Through the interfacial diffusion of titanium and nickel (low-temperature micro-diffusion), gradually increase the power to 2-2.5 W / cm 2 , argon flow rate 60-80 sccm, and deposit a titanium layer (thickness usually 2-4 μm); the thickness is mainly controlled by the deposition time.

[0041] Step 6: Use a segmented annealing process, 100-120 °C for 1 h + 180-200 °C for 2 h, in combination with a vacuum environment (pressure <10 -3 Pa) to eliminate stress and inhibit oxidation.

[0042] Step 7: passivation treatment is performed on the copper-clad aluminum workpiece, and the passivation solution is composed of sodium molybdate (20-30 g / L) + phytic acid (8-10 g / L) + silane coupling agent (3-5 g / L), pH = 3.5-4.0, soaking time 5-10 min, to form a SiO2-MoO3-phytic acid composite passivation film;

[0043] Step 8: cleaning and testing: ultrasonic cleaning with deionized water for 5-10 min to remove surface residual particles, and the finished product is obtained after blowing dry.

[0044] The copper-clad aluminum material prepared by the surface composite treatment process provided in at least one embodiment of the present application has a zinc layer (0.5-2 μm), a nickel layer (10-20 μm), and a titanium nitride layer (3-6 μm) on the surface in sequence.

[0045] The methods used in the present application are conventional methods known to those skilled in the art, and the reagents and other materials used are commercially available products, unless otherwise specified.

[0046] 2. Test preparation

[0047] Example 1

[0048] The surface composite treatment process of the copper-clad aluminum material in this embodiment is for a copper-clad aluminum wire (cross section 100 mm in length), which includes the following steps:

[0049] (1) Ultrasonic oil removal: immerse the copper-clad aluminum wire in an alkaline oil removal solution, and the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano-silicon dioxide (2 g / L), at a temperature of 60°C for 8 min.

[0050] (2) Acid immersion etching: after washing with water, immerse the copper-clad aluminum wire in a solution of sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), and assist etching with ultrasonic waves (power 200 W) for 60-120 s.

[0051] (3) Zinc dipping: the copper-clad aluminum wire is dipped into a zinc dipping solution for 60 s, the concentration of NaOH is kept at 70 g / L for the first 30 s, and then the concentration of NaOH is supplemented to 90 g / L for the last 30 s, the temperature is 35℃, the thickness of the zinc layer is controlled at about 1 μm, and the composition of the zinc dipping solution is zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano-ZrO2 (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O 40 g / L), and hydroxyl ethyl hydrazine (3 g / L).

[0052] (4) The copper-clad aluminum wire after zinc dipping is placed into the above-mentioned environmentally friendly nickel plating solution for nickel plating treatment, and the thickness of the nickel layer is detected to be about 18 μm. The pulse plating technology is adopted, and the parameters are as follows: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, and plating time 40 min.

[0053] (The formula of the nickel plating solution: nickel sulfate, concentration 80 g / L, ethylenediaminetetraacetic acid disodium (Na2EDTA), concentration 60 g / L, thiourea (1.0 g / L) + graphene quantum dots (0.3 g / L), potassium citrate (15 g / L) + sodium phytate (5 g / L), and pH buffer range 4.0.

[0054] (5) A titanium nitride layer is deposited on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, and the detected thickness is about 5 μm.

[0055] Pre-sputtering: a titanium target is sputtered at a power of 2 W / cm 2 for 5 min in a pure argon environment to remove the oxide layer on the surface of the titanium target and slightly bombard the nickel surface with sputtered titanium ions to form an atomic-level mixed layer (thickness about 10 nm), argon flow rate 40 sccm, and a titanium transition layer (thickness about 1 μm) is deposited;

[0056] Transition layer deposition: “titanium-nitrogen plasma alternate injection” is adopted, a titanium layer (about 1 μm) is first deposited at a power of 1 W / cm 2 , then nitrogen gas is introduced (flow rate 20 sccm) at a power of 1.5 W / cm 2 to deposit a TiN crystal nucleus layer, and the gradient interface is formed by repeating 2-3 times;

[0057] Main deposition layer: mechanical occlusion is formed by the interfacial diffusion of titanium and nickel (trace diffusion at low temperature), the power is gradually increased to 2.5 W / cm 2 , argon flow rate 80 sccm, and a titanium layer (thickness about 3 μm) is deposited;

[0058] (6) Heat treatment: a segmented annealing process is adopted, 120℃ for 1 h + 180℃ for 2 h, and a vacuum environment (pressure <10 -3Pa), eliminating stress while inhibiting oxidation.

[0059] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0060] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and the finished product is obtained after blowing dry, and the metallographic diagram thereof is shown in Figure 1 a.

[0061] Example 2

[0062] The surface composite treatment process of the copper-clad aluminum material in this embodiment is a copper-clad aluminum bar (cross section 3x30mm, length 100mm), which includes the following steps:

[0063] (1) Ultrasonic oil removal: the copper-clad aluminum bar is immersed in an alkaline oil removal solution, and the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano-silicon dioxide (2 g / L), temperature 60℃, time 12 min.

[0064] (2) Acid pickling etching: after washing with water, the copper-clad aluminum bar is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), assisted etching with ultrasonic waves (power 200W), etching time 60s.

[0065] (3) Zinc immersion: the copper-clad aluminum bar is immersed in a zinc immersion solution, with a total soaking time of 60s, maintaining a NaOH concentration of 70g / L for the first 30s, and adding NaOH to 100g / L for the last 60s, temperature 35℃, zinc layer thickness controlled at about 0.8μm, solution composition zinc oxide (20g / L), sodium hydroxide (120g / L), nano-ZrO2 (0.5g / L), sodium citrate (20g / L), nickel chloride (NiCl2·6H2O 40g / L), hydroxyethyl hydrazine (3g / L).

[0066] (4) The copper-clad aluminum bar after zinc immersion is put into an environmentally friendly nickel plating solution for nickel plating treatment, and the nickel layer detection thickness is about 15μm. Pulse plating technology is used, and the parameters are: forward current density 3.0A / dm 2 , reverse current density 1.0A / dm 2 , frequency 100Hz, plating time 30min.

[0067] Nickel plating solution formula: nickel sulfate, concentration 80 g / L; disodium ethylenediaminetetraacetate (Na2EDTA), concentration 60 g / L; thiourea (1.0 g / L) + graphene quantum dots (0.3 g / L); potassium citrate (15 g / L) + sodium phytate (5 g / L); pH buffer range 4.0.

[0068] (5) Depositing a titanium nitride layer on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, and detecting that the thickness is about 6 μm.

[0069] Pre-sputtering: under a pure argon environment, sputtering a titanium target at a power of 2 W / cm 2 for 5 min to remove the surface oxide layer of the target material, and at the same time, slightly bombard the nickel surface with sputtered titanium ions to form an atomic-level mixed layer (thickness about 10 nm), argon flow rate 40 sccm, and deposit a titanium transition layer (thickness about 1 μm);

[0070] Transition layer deposition: adopting "titanium-nitrogen plasma alternate injection", first depositing a titanium layer (about 1 μm) at a power of 1 W / cm 2 , and then introducing nitrogen gas (flow rate 20 sccm) at a power of 1.5 W / cm 2 to deposit a TiN crystal nucleus layer, and repeating 2-3 times to form a gradient interface;

[0071] Main deposition layer: forming mechanical engagement through interface diffusion of titanium and nickel (trace diffusion at low temperature), and gradually increasing the power to 2.5 W / cm 2 , argon flow rate 80 sccm, and depositing a titanium layer (thickness about 4 μm);

[0072] (6) Heat treatment: adopting a staged annealing process, 120℃ for 1 h + 180℃ for 2 h, in combination with a vacuum environment (pressure <10 -3 Pa) to eliminate stress and inhibit oxidation;

[0073] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min;

[0074] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and obtaining a finished product after blowing dry, and the metallographic diagram thereof is shown in Figure 1 b.

[0075] Example 3

[0076] The surface composite treatment process of the copper-clad aluminum material in this embodiment is a copper-clad aluminum bar (cross section 3×30 mm, length 100 mm), and includes the following steps:

[0077] (1) Ultrasonic oil removal: The copper-clad aluminum bar is immersed in an alkaline oil removal solution, and the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano-silicon dioxide (2 g / L), at a temperature of 60°C for 12 min.

[0078] (2) Acid immersion etching: After water washing, the copper-clad aluminum bar is immersed in a solution of sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), and assisted by ultrasonic waves (power 200 W) for etching for 60 s.

[0079] (3) Zinc immersion: The copper-clad aluminum bar is immersed in a zinc immersion solution for a total of 90 s, with a NaOH concentration of 70 g / L maintained for the first 30 s and an additional 60 s of NaOH added to 100 g / L, at a temperature of 35°C, with a zinc layer thickness controlled at 0.5 μm. The solution composition includes zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano-ZrO2 (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O 40 g / L), and hydroxyethyl hydrazine (3 g / L).

[0080] (4) The copper-clad aluminum bar after zinc immersion is placed in an environmentally friendly nickel plating solution for nickel plating treatment, with a nickel layer thickness of about 10 μm. Pulse plating technology is used, with parameters of: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, and plating time 20 min.

[0081] (Nickel plating solution formula: nickel sulfate, concentration 80 g / L; ethylenediaminetetraacetic acid disodium (Na2EDTA), concentration 60 g / L; thiourea (1.0 g / L) + graphene quantum dots (0.3 g / L); potassium citrate (15 g / L) + sodium phytate (5 g / L); pH buffer range 4.0.

[0082] (5) A titanium nitride layer is deposited on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, with a detected thickness of about 5 μm.

[0083] In a pure argon environment, sputter a titanium target at a power of 2 W / cm 2 for 5 min to remove the surface oxide layer of the target material, and simultaneously use the sputtered titanium ions to slightly bombard the nickel surface. The argon flow rate is 80 sccm, and the mechanical interlocking is formed by the interface diffusion (low-temperature trace diffusion) of titanium and nickel. The power is gradually increased to 2.5 W / cm 2 , the argon flow rate is 80 sccm, and a titanium layer is deposited (the deposition time is controlled to a thickness of about 5 μm).

[0084] (6) Heat treatment: using a sectional annealing process, 120°C for 1 h + 180°C for 2 h, combined with a vacuum environment (pressure <10 -3 Pa), to eliminate stress while inhibiting oxidation.

[0085] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0086] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and then blow-drying to obtain the finished product.

[0087] Examples 1 and 2-3 use copper-clad aluminum wire and copper-clad aluminum bars for scenario simulation tests, with only morphological differences: the wire is adapted to cables, windings with "flexibility + medium current capacity"; the bar is adapted to busbars, high-current connections with "rigidity + high current capacity + strong heat dissipation". Both inherit the characteristics of "low cost and high cost performance" of copper-clad aluminum, and only because of the morphological differentiation, different application scenarios are differentiated.

[0088] Comparative Example 1

[0089] The surface composite treatment process of the copper-clad aluminum material in this comparative example is as follows:

[0090] (1) Ultrasonic oil removal: the copper-clad aluminum bar is immersed in an alkaline oil removal solution containing NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano-silicon dioxide (2 g / L), at a temperature of 60°C for 12 min.

[0091] (2) Acid immersion etching: after washing, the copper-clad aluminum bar is immersed in a solution of sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), and assisted by ultrasonic waves (power 200 W) for etching, with an etching time of 60 s.

[0092] (3) Zinc immersion: the copper-clad aluminum bar is immersed in a zinc immersion solution at a temperature of 30°C for 60 s, with the following composition: zinc oxide (ZnO): 10 g / L; sodium hydroxide (NaOH): 120 g / L; potassium sodium tartrate: 15 g / L; sodium fluoride (NaF): 3 g / L.

[0093] (4) Zinc stripping: the workpiece after the first zinc immersion is immersed in a zinc stripping solution to quickly dissolve the rough zinc layer, time 10 s, to expose the fresh aluminum / copper surface (at this time the surface is uniform gray white, without residual zinc layer), and then immediately rinsed with deionized water, solution composition: nitric acid (HNO3): 100 mL / L, hydrofluoric acid: 5 mL / L, urea: 2 g / L; second zinc immersion: the workpiece cleaned after zinc stripping is immersed in a second zinc immersion solution, soaking time 60 s, temperature 25°C, solution composition: zinc oxide (ZnO): 8 g / L, sodium hydroxide (NaOH): 110 g / L, potassium sodium tartrate: 15 g / L, sodium nitrate (NaNO3): 3 g / L, triethanolamine, 0.5-1 g / L), and the zinc layer thickness is about 0.6 μm.

[0094] (5) The copper-clad aluminum after zinc immersion is discharged into an environmentally friendly nickel plating solution (the nickel plating solution formula is the same as in Example 2) for nickel plating treatment, and the nickel layer detection thickness is about 18 μm. Pulse plating technology is used, and the parameters are: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, and plating time 40 min.

[0095] (6) A titanium nitride layer is deposited on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, and the detection thickness is about 5 μm.

[0096] Pre-sputtering: a titanium target is sputtered at a power of 2 W / cm 2 for 5 min in a pure argon environment to remove the surface oxide layer of the target material and slightly bombard the nickel surface with sputtered titanium ions to form an atomic-level mixed layer (thickness about 10 nm), argon flow rate 40 sccm, and a titanium transition layer (thickness about 1 μm) is deposited;

[0097] Transition layer deposition: "titanium-nitrogen plasma alternate injection" is used, a titanium layer (about 1.5 μm) is first deposited at a power of 1 W / cm 2 , nitrogen gas is then introduced (flow rate 20 sccm) at a power of 1.5 W / cm 2 to deposit a TiN crystal nucleus layer, and the gradient interface is formed by repeating 2-3 times;

[0098] Main deposition layer: mechanical occlusion is formed by titanium and nickel interface diffusion (trace diffusion at low temperature), the power is gradually increased to 2.5 W / cm 2 , argon flow rate 80 sccm, and a titanium layer (thickness about 2.5 μm) is deposited;

[0099] (6) Heat treatment: a segmented annealing process is used, 120°C for 1 h + 180°C for 2 h, in combination with a vacuum environment (pressure <10 -3 Pa) to eliminate stress and inhibit oxidation.

[0100] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0101] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and the product is obtained after blowing dry.

[0102] Comparative Example 2

[0103] The surface composite treatment process of the copper-clad aluminum material in the present comparative example is a copper-clad aluminum bar (cross section 3 x 30 mm, length 100 mm), which comprises the following steps:

[0104] (1) Ultrasonic oil removal: the copper-clad aluminum bar is immersed in an alkaline oil removal solution, the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano silicon dioxide (2 g / L), the temperature is 60°C, and the time is 12 min.

[0105] (2) Acid immersion etching: after washing with water, the copper-clad aluminum bar is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), and assisted etching with ultrasonic waves (power 200 W), etching time 60-120 s.

[0106] (3) Zinc immersion: the copper-clad aluminum bar is immersed in a zinc immersion solution, the total soaking time is 90 s, the NaOH concentration is maintained at 70 g / L for the first 30 s, and the NaOH is supplemented to 100 g / L for the last 60 s, the temperature is 35°C, the zinc layer thickness is controlled at about 2 μm, and the solution composition is zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano ZrO2 (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O 40 g / L), and hydroxyethyl hydrazine (3 g / L).

[0107] (4) The copper-clad aluminum bar after zinc immersion is placed in an environmentally friendly nickel plating solution (nickel plating solution formula same as Example 2) for nickel plating treatment, and the nickel layer detection thickness is about 20 μm. Pulse plating technology is used, and the parameters are: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, and plating time 45 min.

[0108] (5) Heat treatment: using a step annealing process, 120°C for 1 h + 180°C for 2 h, combined with a vacuum environment (pressure <10 -3 Pa), to eliminate stress and inhibit oxidation.

[0109] (6) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0110] (7) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and the product is obtained after blowing dry, and the metallographic diagram thereof is shown in Figure 2 a.

[0111] Comparative Example 3

[0112] The surface composite treatment process of the copper-clad aluminum material in the present comparative example is a copper-clad aluminum bar (cross section 3x30 mm, length 100 mm), which comprises the following steps:

[0113] (1) Ultrasonic oil removal: the copper-clad aluminum bar is immersed in an alkaline oil removal solution, the solution composition comprises NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano silicon dioxide (2 g / L), the temperature is 60°C, and the time is 12 min.

[0114] (2) Acid immersion etching: after washing with water, the copper-clad aluminum bar is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), and amino sulfonic acid (2 g / L) is added, assisted by ultrasonic wave (power 200 W) etching, etching time 60 s.

[0115] (3) Zinc immersion: the copper-clad aluminum bar is immersed in a zinc immersion solution, the total soaking time is 60 s, the NaOH concentration is maintained at 70 g / L for the first 30 s, and then NaOH is added to 100 g / L for the last 30 s, the temperature is 35°C, the zinc layer thickness is controlled at about 0.8 μm, and the solution composition is zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano ZrO (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O 40 g / L), and hydroxyethyl hydrazine (3 g / L).

[0116] (4) Depositing a titanium nitride layer on the surface of the zinc plated layer by physical vapor deposition (PVD) technology, and the detection thickness is about 3 μm.

[0117] Pre-sputtering: sputtering a titanium target at a power of 2 W / cm 2 for 5 min in a pure argon environment, removing the surface oxide layer of the target material, and at the same time, slightly bombarding the zinc surface with sputtered titanium ions to form an atomic level mixed layer (thickness about 10 nm), argon flow rate 40 sccm, and depositing a titanium transition layer (thickness about 0.5 μm);

[0118] Transition layer deposition: using "titanium-nitrogen plasma alternate injection", first sputtering a titanium target at a power of 1 W / cm 2Power deposition of titanium layer (about 0.5 μm), nitrogen gas is introduced (flow rate 20 sccm), power 1.5 W / cm 2 Deposition of TiN crystal nucleus layer, repeat 2-3 times to form a gradient interface;

[0119] Main deposition layer: mechanical interlocking is formed by interfacial diffusion of titanium and zinc (trace diffusion at low temperature), gradually increase the power to 2.5 W / cm 2 , argon flow rate 80 sccm, deposition of titanium layer (thickness about 2 μm);

[0120] (5) Heat treatment: adopt a segmented annealing process, 120℃ for 1h + 180℃ for 2h, cooperate with vacuum environment (pressure <10 -3 Pa), eliminate stress while inhibiting oxidation.

[0121] (6) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0122] (7) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, blow dry to obtain the product.

[0123] Comparative Example 4

[0124] The surface composite treatment process of the copper-clad aluminum material in the present comparative example is a copper-clad aluminum bar (cross section 3x30 mm, length 100 mm), which comprises the following steps:

[0125] (1) Ultrasonic oil removal: the copper-clad aluminum bar is immersed in an alkaline oil removal solution, the solution composition comprises NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano silicon dioxide (2 g / L), the temperature is 60℃, and the time is 12 min.

[0126] (2) Acid immersion etching: after washing with water, the copper-clad aluminum bar is immersed in a solution of sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), and assisted etching with ultrasonic waves (power 200 W), etching time 60 s.

[0127] (3) Nickel plating: the copper-clad aluminum bar is placed in an environmentally friendly nickel plating solution (nickel plating solution formula same as Example 2) for nickel plating treatment, and the nickel layer detection thickness is about 20 μm. Pulse plating technology is adopted, and the parameters are: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, and plating time 45 min.

[0128] (4) On the surface of the nickel plating layer, a titanium nitride layer is deposited by physical vapor deposition (PVD) technology, and the thickness is about 3 μm.

[0129] Pre-sputtering: under a pure argon environment, with a power of 2 W / cm 2 Sputtering titanium target for 5 min, removing the surface oxide layer of the target material, and at the same time, using the sputtered titanium ions to slightly bombard the nickel surface to form an atomic-level mixed layer (thickness about 10 nm), argon flow rate 40 sccm, depositing a titanium transition layer (thickness about 0.5 μm);

[0130] Transition layer deposition: using "titanium-nitrogen plasma alternate injection", first depositing a titanium layer (about 0.5 μm) at a power of 1 W / cm 2 , then introducing nitrogen gas (flow rate 20 sccm) at a power of 1.5 W / cm 2 , depositing a TiN crystal nucleus layer, repeating 2-3 times to form a gradient interface;

[0131] Main deposition layer: through the interfacial diffusion of titanium and nickel (trace diffusion at low temperature), forming mechanical engagement, gradually increasing the power to 2.5 W / cm 2 , argon flow rate 80 sccm, depositing a titanium layer (thickness about 2 μm);

[0132] (5) Heat treatment: using a staged annealing process, 120℃ for 1 h + 180℃ for 2 h, in combination with a vacuum environment (pressure <10 -3 Pa), to eliminate stress and inhibit oxidation.

[0133] (6) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0134] (7) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and then blowing dry to obtain the product.

[0135] Comparative Example 5

[0136] The surface composite treatment process of the copper-clad aluminum material in this comparative example is a copper-clad aluminum rod (cross section 3×30 mm, length 100 mm), which includes the following steps:

[0137] (1) Ultrasonic oil removal: the copper-clad aluminum rod is immersed in an alkaline oil removal solution, and the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano-silicon dioxide (2 g / L), temperature 60℃, time 12 min.

[0138] (2) Acid etching: After washing with water, the copper-clad aluminum busbar is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), and aminosulfonic acid (2 g / L) is added. Ultrasonic wave (power 200 W) is used to assist etching, and the etching time is 60 s.

[0139] (3) Zinc dipping: The copper-clad aluminum busbar is immersed in the zinc dipping solution for a total of 60 seconds. The NaOH concentration is maintained at 70 g / L in the first 30 seconds and then NaOH is added to 100 g / L in the last 30 seconds. The temperature is 35°C and the zinc layer thickness is controlled at 0.8 μm. The solution composition is zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano ZrO (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O40 g / L), and hydroxyethyl hydrazine (3 g / L).

[0140] (4) The copper-clad aluminum after zinc immersion is discharged into an environmentally friendly nickel plating solution (the nickel plating solution formula is the same as that of Example 2) for nickel plating. The thickness of the nickel layer is about 15 μm. Pulse electroplating technology is used, and the parameters are: forward current density 3.0 A / dm 2 , reverse current density 1.0A / dm 2 , frequency 100Hz, electroplating time 30min.

[0141] (5) A titanium nitride layer is deposited on the surface of the nickel-plated layer by physical vapor deposition (PVD) technology, and the detected thickness is about 4 μm.

[0142] Pre-sputtering: In pure argon environment, at 2W / cm 2 The titanium target was sputtered at high power for 5 minutes to remove the oxide layer on the target surface. At the same time, the sputtered titanium ions were used to lightly bombard the nickel surface to form an atomic-level mixed layer (thickness of about 10 nm). The argon flow rate was 40 sccm to deposit a titanium transition layer (thickness of about 1 μm).

[0143] Transition layer deposition: using "titanium-nitrogen plasma alternating injection", first at 1W / cm 2 The titanium layer (about 1 μm) was deposited at a power of 1.5 W / cm2 and nitrogen (flow rate 20 sccm) was introduced. 2 Deposit a TiN nucleation layer and repeat 2-3 times to form a gradient interface;

[0144] Main deposition layer: Mechanical engagement is achieved through interfacial diffusion between titanium and nickel (micro-diffusion at low temperatures) and the power is gradually increased to 2.5W / cm 2 , argon gas flow rate 80 sccm, depositing a titanium layer (thickness 2 μm);

[0145] (6) Cleaning and testing: Ultrasonic cleaning was performed with deionized water for 5 min to remove residual particles on the surface, and the product was obtained after drying.

[0146] Comparative Example 6

[0147] The surface complex treatment process of the aluminum alloy material in the present comparative example, the aluminum alloy material is an aluminum alloy bar (specification: cross section 3 x 30 mm, length 100 mm; aluminum alloy composition: silicon Si: 0.20-0.6%, iron Fe: 0.35%, copper Cu: 0.10%, manganese Mn: 0.10%, magnesium Mg: 0.45-0.9%, chromium Cr: 0.10%, zinc Zn: 0.10%, titanium Ti: 0.10%, balance aluminum), comprising the following steps:

[0148] (1) ultrasonic oil removal: the aluminum alloy is immersed in an alkaline oil removal solution, the solution composition comprises NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano silicon dioxide (2 g / L) is added, the temperature is 60°C, and the time is 12 min.

[0149] (2) acid immersion etching: after water washing, the aluminum alloy is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), and aminosulfonic acid (2 g / L) is added, and ultrasonic wave (power 200 W) is used for assisting etching, and the etching time is 60 s.

[0150] (3) zinc immersion: the copper-coated aluminum bar is immersed in a zinc immersion solution, the soaking time is 60 s in total, the NaOH concentration is kept at 70 g / L for the first 30 s, and the NaOH is supplemented to 100 g / L for the last 30 s, the temperature is 35°C, the zinc layer thickness is controlled at about 0.8 μm, and the solution composition is zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano ZrO2 (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O 40 g / L), and hydroxyethyl hydrazine (3 g / L).

[0151] (4) the aluminum alloy after zinc immersion is placed in an environmentally friendly nickel plating solution (the nickel plating solution formula is the same as that in Example 2) for nickel plating treatment, and the nickel layer detection thickness is about 20 μm. Pulse plating technology is used, and the parameters are as follows: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, and plating time 45 min.

[0152] (5) a titanium nitride layer is deposited on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, and the detection thickness is about 4 μm.

[0153] Pre-sputtering: in a pure argon environment, 2W / cm 2Power sputtering titanium target 5 min, remove the surface oxide layer of the target material, while using the sputtered titanium ions to slightly bombard the nickel surface, forming an atomic level mixed layer (thickness about 10 nm), argon flow 40 sccm, deposit a layer of titanium transition layer (thickness about 1 μm);

[0154] Transition layer deposition: using "titanium-nitrogen plasma alternate injection", first with 1 W / cm 2 Power deposition titanium layer (about 1 μm), then nitrogen gas (flow 20 sccm) is introduced, power 1.5 W / cm 2 Deposition of TiN nucleus layer, repeat 2-3 times to form a gradient interface;

[0155] Main deposition layer: through the interface diffusion of titanium and nickel (trace diffusion at low temperature) to form mechanical engagement, gradually increase the power to 2.5 W / cm 2 , argon flow 80 sccm, deposit a titanium layer (thickness about 2 μm);

[0156] (6) Heat treatment: using a staged annealing process, 120℃ for 1h + 180℃ for 2h, combined with vacuum environment (pressure <10 -3 Pa), to eliminate stress while inhibiting oxidation.

[0157] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0158] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, blow dry to obtain the product, whose metallographic diagram is shown in Figure 2 b.

[0159] Comparative Example 7

[0160] The surface composite treatment process of the copper-aluminum alloy material in the present comparative example is as follows:

[0161] (1) Ultrasonic oil removal: the copper-aluminum alloy is immersed in an alkaline oil removal solution, the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano silicon dioxide (2 g / L), the temperature is 60℃, and the time is 12 min.

[0162] (2) Acid immersion etching: after washing, the copper-aluminum alloy is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), and assisted etching with ultrasonic waves (power 200 W), etching time 60 s.

[0163] (3) Zinc dipping: the copper clad aluminum bar is dipped into a zinc dipping solution for 60s, the concentration of NaOH is kept at 70g / L for the first 30s, and then the concentration of NaOH is supplemented to 100g / L for the last 30s, the temperature is 35℃, the thickness of the zinc layer is controlled at 0.8μm, the solution composition is zinc oxide (20g / L), sodium hydroxide (120g / L), nano Zr02(0.5g / L), sodium citrate (20g / L), nickel chloride (NiCl2·6H2O 40g / L), and hydroxyl ethyl hydrazine (3g / L).

[0164] (4) The copper aluminum alloy after zinc dipping is put into an environmentally friendly nickel plating solution (the formula of the nickel plating solution is the same as that in Example 2) for nickel plating treatment, and the thickness of the nickel layer is detected to be about 20μm. Pulse plating technology is used, and the parameters are as follows: forward current density 3.0A / dm 2 , reverse current density 1.0A / dm 2 , frequency 100Hz, and plating time 45min.

[0165] (5) A titanium nitride layer is deposited on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, and the thickness is detected to be about 4μm.

[0166] Pre-sputtering: a titanium target is sputtered at a power of 2W / cm 2 for 5min in a pure argon environment to remove the oxide layer on the surface of the target and slightly bombard the nickel surface with sputtered titanium ions to form an atomic level mixed layer (thickness about 10nm), argon flow rate 40sccm, and a titanium transition layer (thickness about 0.1μm) is deposited;

[0167] Transition layer deposition: “titanium-nitrogen plasma alternate injection” is used, a titanium layer (about 0.05μm) is first deposited at a power of 1W / cm 2 , then nitrogen gas is introduced (flow rate 20sccm) at a power of 1.5W / cm 2 to deposit a TiN crystal nucleus layer, and the gradient interface is formed by repeating 2-3 times;

[0168] Main deposition layer: mechanical interlocking is formed by the interfacial diffusion of titanium and nickel (trace diffusion at low temperature), the power is gradually increased to 2.5W / cm 2 , argon flow rate 80sccm, and a titanium layer (thickness about 2μm) is deposited;

[0169] (6) Heat treatment: a staged annealing process is used, 120℃ for 1h + 180℃ for 2h, and a vacuum environment (pressure <10 -3 Pa) is used to eliminate stress and inhibit oxidation.

[0170] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0171] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, and the product is obtained after blowing dry.

[0172] Comparative Example 8

[0173] The surface composite treatment process of the aluminum material (cross section 3 x 30 mm, length 100 mm, 100% aluminum) in this comparative example includes the following steps:

[0174] (1) Ultrasonic oil removal: the sample is immersed in an alkaline oil removal solution, the solution composition includes NaOH (5 g / L), Na2CO3 (20 g / L), OP-10 (5 g / L), citric acid (10 g / L), phosphoric acid (5 g / L), and nano silicon dioxide (2 g / L), temperature 60°C, time 12 min.

[0175] (2) Acid immersion etching: after washing with water, the sample is immersed in sodium persulfate (12 g / L), sulfuric acid (3 g / L), and phosphoric acid (3 g / L), with the addition of sulfamic acid (2 g / L), assisted etching with ultrasonic waves (power 200 W), etching time 60 s.

[0176] (3) Zinc immersion: the copper-coated aluminum bar is immersed in the zinc immersion solution, the total soaking time is 60 s, the NaOH concentration is maintained at 70 g / L for the first 30 s, and then NaOH is added to 100 g / L for the last 30 s, the temperature is 35°C, the zinc layer thickness is controlled at 0.8 μm, the solution composition is zinc oxide (20 g / L), sodium hydroxide (120 g / L), nano ZrO2 (0.5 g / L), sodium citrate (20 g / L), nickel chloride (NiCl2·6H2O 40 g / L), and hydroxyethyl hydrazine (3 g / L).

[0177] (4) The sample after zinc immersion is placed in an environmentally friendly nickel plating solution (nickel plating solution formula same as Example 2) for nickel plating treatment, and the nickel layer detection thickness is about 19 μm. Pulse plating technology is used, with the following parameters: forward current density 3.0 A / dm 2 , reverse current density 1.0 A / dm 2 , frequency 100 Hz, plating time 45 min.

[0178] (5) A titanium nitride layer is deposited on the surface of the nickel plating layer by physical vapor deposition (PVD) technology, with a detection thickness of about 5.5 μm.

[0179] Pre-sputtering: in a pure argon environment, at 2 W / cm 2Power sputtering titanium target 5 min, remove the surface oxide layer of the target material, while using the sputtered titanium ions to slightly bombard the nickel surface, forming an atomic level mixed layer (thickness about 10 nm), argon flow 40 sccm, deposit a layer of titanium transition layer (thickness about 1 μm);

[0180] Transition layer deposition: using "titanium-nitrogen plasma alternate injection", first with 1 W / cm 2 Power deposition titanium layer (about 1 μm), then nitrogen gas (flow 20 sccm) is introduced, power 1.5 W / cm 2 Deposition of TiN nucleus layer, repeat 2-3 times to form a gradient interface;

[0181] Main deposition layer: through the interface diffusion of titanium and nickel (trace diffusion at low temperature) to form mechanical engagement, gradually increase the power to 2.5 W / cm 2 , argon flow 80 sccm, deposit a layer of titanium (thickness about 3.5 μm);

[0182] (6) Heat treatment: using a staged annealing process, 120℃ for 1h + 180℃ for 2h, combined with vacuum environment (pressure <10 -3 Pa), to eliminate stress while inhibiting oxidation.

[0183] (7) Passivation treatment: sodium molybdate (20 g / L) + phytic acid (8 g / L) + silane coupling agent (5 g / L), pH = 3.5, soaking time 5 min.

[0184] (8) Cleaning and detection: ultrasonic cleaning with deionized water for 5 min to remove surface residual particles, blow dry to obtain the product, its metallographic image is shown in Figure 2 c.

[0185] 3. Physical and chemical performance testing

[0186] (1) Bonding strength test:

[0187] Hundred grid test (GB / T5270-2024): use 1mm interval knife to cut the plated layer surface of each sample to the substrate, paste 3M610 adhesive tape, then tear off at 180°, and observe the falling area.

[0188]

[0189]

[0190] Comparing Example 1-2 with Comparative Example 1, it can be seen that the examples adopt "low-alkali first and high-alkali later" step-by-step zinc immersion, and Comparative Example 1 adopts traditional secondary zinc immersion (including zinc stripping-secondary zinc immersion redundant steps). Examples 1-2 are both 5B (qualified), and Comparative Example 1 is 3B (unqualified). The "low-alkali first and high-alkali later" step-by-step zinc immersion can optimize the compactness and uniformity of the zinc layer, reduce the corrosion of the substrate, and protect the integrity of the copper-aluminum interface. However, the traditional secondary zinc immersion may lead to loose zinc layer and excessive corrosion of the substrate due to redundant steps, resulting in a decrease in the bonding force between the zinc transition layer and the substrate / successive nickel layer, and finally leading to a decrease in the overall bonding strength of the plated layer.

[0191] The composite plated layer structure of Example 2 is "zinc transition layer→nickel layer→nitrogen titanium layer", and Comparative Examples 2-4 respectively lack the nitrogen titanium layer, the nickel layer, and the zinc transition layer, and their strengths are 3B, 3B, and 2B respectively. It is speculated that this may be because the nitrogen titanium layer forms a high-strength bond with the nickel layer through PVD technology, and after being missing, only the nickel layer cannot maintain high bonding force. The nickel layer is a key intermediate medium between the zinc transition layer and the nitrogen titanium layer, and after being missing, the zinc layer directly contacts the nitrogen titanium layer, resulting in poor bonding due to large interface energy difference. The core role of the zinc transition layer is to solve the bonding problem of the aluminum substrate and the plated layer, and after being missing, the nickel layer is directly attached to the aluminum substrate, and the bonding force is greatly reduced.

[0192] Comparing Example 2 with Comparative Example 5, heat treatment can strengthen the interface bonding (such as element interpenetration of zinc-nickel interface and nickel-nitrogen titanium interface) through atomic diffusion, reduce interface stress, and improve the overall adhesion of the plated layer. The data shows that heat treatment can further optimize the bonding strength (from 4B to 5B).

[0193] Comparing Example 2 with Comparative Examples 6-8, it can be seen that the process provided by the present application is only suitable for copper-clad aluminum materials. Copper-clad aluminum is a heterogeneous metal composite structure, and the "aluminum-copper" interface stability is adapted to the "zinc-nickel-nitrogen titanium" plated layer system, and the copper layer can inhibit the excessive oxidation of the aluminum substrate and protect the interface integrity. Comparative Example 6 is a pure aluminum alloy substrate without copper layer protection, and the surface oxide film is thicker and more uneven, resulting in poor adhesion of the zinc transition layer, which in turn affects the bonding force of the subsequent plated layer. Comparative Example 7 is a copper-aluminum alloy with alloying structure, and the atomic-level mixing of "copper-aluminum" may weaken the directional adhesion of the zinc transition layer, and the bonding force is slightly lower than that of the copper-clad aluminum composite structure. Comparative Example 8 is a pure aluminum with high surface activity and fast oxidation, although it can form a zinc transition layer, but without the assistance of the copper layer to stabilize the interface, the bonding force is weaker than that of the copper-clad aluminum.

[0194] (2) Corrosion resistance test: neutral salt spray test (GB / T10125-2021): 35℃, 5% NaCl solution, continuous spraying for 500h, and observing the corrosion area of each sample.

[0195]

[0196] From Comparative Example 2 and Comparative Example 1, it can be seen that the titanium nitride layer is a core outer layer barrier that is corrosion resistant, can "enhance oxidation resistance" and block the penetration of corrosive media (such as NaCl solution). Comparative Example 2, due to the absence of the titanium nitride layer, can only rely on the zinc transition layer and the nickel layer to resist salt spray corrosion for a long time: although the nickel layer has a certain corrosion resistance, it is easily penetrated in 500h continuous salt spray, resulting in direct contact of the corrosive medium with the aluminum substrate (aluminum has poor corrosion resistance), ultimately leading to "aluminum side perforation corrosion".

[0197] Comparative Examples 2-4 are all "surface slightly corroded" (qualified). The core role of the zinc transition layer is to "solve the problem of the combination of aluminum and the coating", and the core role of the nickel layer is to "connect the zinc transition layer and the titanium nitride layer", but neither of them is the core barrier of corrosion resistance. Corrosion resistance mainly depends on the physical barrier (high hardness, low permeability) of the titanium nitride layer and the chemical corrosion resistance (nickel salt spray resistance, zinc sacrificial anode effect) of the nickel layer / zinc layer. Therefore, even if the zinc or nickel layer is missing, as long as the titanium nitride layer exists and is basically attached to the substrate / other layers, it can still resist 500h salt spray corrosion through "multilayer synergistic barrier".

[0198] In Example 2, the copper-clad aluminum is a composite substrate of "aluminum core + copper layer", and the copper layer itself has better corrosion resistance than pure aluminum or aluminum alloy, and can act as a "secondary barrier" for the penetration of corrosive media; while the aluminum alloy in Comparative Example 6 is a single aluminum substrate, and its surface oxide film has poor stability. Even if the coating is complete, the corrosive medium can still penetrate through the interface defects (such as microcracks) between the coating and the substrate to the aluminum substrate, causing serious corrosion of the substrate. This also verifies the "auxiliary improvement of copper-clad aluminum composite structure on corrosion resistance", and the aluminum alloy substrate is difficult to completely block corrosion through the coating.

[0199] Comparative Example 7 (copper aluminum alloy row) and Comparative Example 8 (pure aluminum row) are both qualified (surface slightly corroded), and the remarks are "copper aluminum alloy has better corrosion resistance than pure aluminum" and "multilayer barrier reduces the corrosion risk of aluminum substrate". The introduction of copper element (whether it is a composite structure of copper-clad aluminum or an alloy structure of copper aluminum alloy) can improve the corrosion resistance of the substrate itself and form a "substrate + coating" synergistic protection with the coating. Even if it is a pure aluminum substrate, as long as the coating (zinc→nickel→titanium nitride) forms a complete barrier, it can effectively block the penetration of corrosive media.

[0200] (3) Oxidation resistance test: high temperature oxidation test (GB / T13303-1991) places each sample in a high temperature and high humidity environment (temperature 80℃, relative humidity 95%) for 72h, and tests the resistance change rate.

[0201]

[0202] From Example 2 and Example 3, it can be seen that the dense and uniform nitrogen-titanium layer of Example 2 has a more stable crystal structure, can effectively block the penetration of oxygen and water vapor in a high-temperature and high-humidity environment, and reduce the oxidation of the coating and the substrate. The loose interlayer bonding and the presence of micropores in Example 3 may cause the oxidation medium (oxygen and water vapor) to penetrate more easily, ultimately resulting in a significant increase in the resistivity change rate.

[0203] From Example 2 and Comparative Example 1, it can be seen that "low-alkali first and high-alkali second step-by-step zinc immersion" can optimize the "density and uniformity" of the zinc transition layer, reduce substrate corrosion, and "protect the integrity of the copper-aluminum interface". The traditional secondary zinc immersion is prone to cause loose zinc layer and excessive corrosion of the copper-aluminum interface due to the "zinc removal-secondary zinc immersion redundant step", forming channels for the penetration of oxidation medium. In a high-temperature and high-humidity environment, these channels will accelerate the reaction between oxygen and the aluminum substrate (aluminum is easily oxidized to form a high-resistance oxide film), ultimately leading to a significant increase in resistivity (ΔR% from 1.71% to 26.4%).

[0204] The composite coating structure of Example 2 is "zinc transition layer → nickel layer → nitrogen-titanium layer", and Comparative Examples 2-4 respectively lack nitrogen-titanium layer, nickel layer, and zinc transition layer. The nitrogen-titanium layer is the core outer layer of oxidation resistance ("enhancing oxidation resistance"), and after being missing, only the zinc and nickel layers cannot block the oxidation under high temperature and high humidity, leading to the intensification of aluminum substrate oxidation. The zinc transition layer is directly combined with the nitrogen-titanium layer, and the sacrificial oxidation characteristics of zinc (preferentially oxidizing itself to protect the substrate) and the physical barrier of the nitrogen-titanium layer are synergistic, still maintaining good oxidation resistance. The bonding force between the nickel layer and the substrate (copper-clad aluminum) is weaker than that of the zinc transition layer, and the interface oxidation channel is easily formed under high temperature, leading to slightly stronger oxidation than Comparative Example 3. The complete "zinc transition layer → nickel layer → nitrogen-titanium layer" structure (Example 2) achieves optimal oxidation resistance through the synergistic effect of the three layers (zinc enhances bonding, nickel transition protection, and nitrogen-titanium outer layer barrier). The missing of a single layer will destroy the synergistic effect, but the impact of missing the nickel layer is relatively small (because zinc and nitrogen-titanium can partially compensate).

[0205] In Example 2, the copper-clad aluminum is a composite structure of "aluminum core + copper layer", and the copper layer itself has better oxidation resistance than pure aluminum, and can serve as a secondary barrier for oxidation medium, forming a "substrate + coating" double protection with the coating. In Comparative Example 6, the aluminum alloy substrate has no copper layer protection, and the surface oxide film (mainly aluminum oxide) is easily broken under high temperature and high humidity. Even with the coating, the oxidation medium is still easy to penetrate into the substrate to cause serious oxidation (+17.5%). In Comparative Example 7, the copper element in the copper-aluminum alloy solid-solution strengthens the substrate oxidation resistance (better than pure aluminum), but the alloying interface is not as stable as the composite interface of copper-clad aluminum, so the ΔR% (+7.5%) is higher than that of Example 2. In Comparative Example 8, although the pure aluminum surface is easy to form an oxide film, there is no copper layer assistance, and the oxidation rate is slightly higher than that of copper-clad aluminum, so the ΔR% (4.94%) is higher than that of Example 2 (1.71%).

[0206] (4) Electromagnetic shielding property test:

[0207] Shielding effectiveness test (GB / T 30148-2013) uses electromagnetic shielding effectiveness test system to test the shielding effectiveness of each sample to low frequency-mid frequency-high frequency electromagnetic waves.

[0208]

[0209]

[0210] Example 1-2 forms a more dense, uniform and more excellent conductive / magnetic property of nitrogen titanium layer through "atomic level mixed layer and titanium transition layer" - this structure can more effectively reflect, absorb high frequency electromagnetic waves (1 GHz frequency band). The conventional secondary zinc immersion in Comparative Example 1 causes the zinc layer to be loose and the interface to be discontinuous due to redundant steps, which reduces the overall conductivity of the coating (electromagnetic wave shielding depends on the continuity of the conductive / magnetic material), and finally the shielding effectiveness of the full frequency band is reduced by about 10-15 dB. Example 3 forms a more dense, uniform and more excellent conductive / magnetic property of nitrogen titanium layer through "atomic level mixed layer and titanium transition layer" - this structure can more effectively reflect, absorb high frequency electromagnetic waves (1 GHz frequency band), so the shielding effectiveness is 5-10 dB higher than "ordinary method deposition" (which may have pores or loose structure).

[0211] The nitrogen titanium layer is the core layer of high frequency shielding. Comparative Example 2 lacks it and only relies on the zinc transition layer (general conductivity) and the nickel layer (moderate conductivity) for shielding, resulting in a 5-10 dB decrease in high frequency effectiveness (compared to 70-75 dB in Example 2). The nickel layer is the "conductive bridge" between the zinc transition layer and the nitrogen titanium layer (nickel has better conductivity than zinc and is tightly combined with the nitrogen titanium layer). In Comparative Example 3, the absence of the nickel layer increases the interface resistance between the zinc layer and the nitrogen titanium layer, reducing the electromagnetic wave reflection / absorption capacity and significantly reducing the full frequency band effectiveness. The core role of the zinc transition layer is to "solve the problem of aluminum and coating combination". In Comparative Example 4, the absence of the zinc transition layer causes the nickel layer to not be tightly combined with the copper-clad aluminum substrate, easily forming interface gaps that lead to electromagnetic wave leakage and lower shielding effectiveness than the complete structure.

[0212] Heat treatment promotes the interface fusion of "zinc transition layer → nickel layer → nitrogen titanium layer" through atomic diffusion, reduces interlayer porosity and contact resistance, and makes the coating a continuous "conductive-shielding whole". In Comparative Example 5, there are a large number of micro-gaps in the interlayer interface, and electromagnetic waves can easily penetrate through the gaps, resulting in a 20-25 dB decrease in full frequency band shielding effectiveness.

[0213] In Example 2, the copper-clad aluminum is a composite structure of "aluminum core + copper layer". The conductivity of copper (about 1.7μΩ·cm) is much higher than that of aluminum (about 2.8μΩ·cm). The copper layer as the bottom layer of the substrate can enhance the overall conductivity and form a "substrate-plating" synergistic shield with the coating, with the best performance. The aluminum alloy in Comparative Example 6 has poor conductivity (containing alloy elements reduces conductivity), and there is no copper layer to assist. Even with the coating, the overall conductive foundation is weak and the shielding effectiveness is the lowest. The copper element in the copper-aluminum alloy of Comparative Example 7 improves the conductivity (better than pure aluminum), but the alloying causes uneven copper distribution, and the conductive continuity is worse than the "copper layer + aluminum core" composite structure of copper-clad aluminum, and the shielding effectiveness is lower than that of Example 2. The pure aluminum in Comparative Example 8 has better conductivity than the aluminum alloy (no alloy element interference), and the coating is complete. The shielding effectiveness is higher than that of Comparative Examples 6-7, but due to the lack of copper layer assistance, it is still lower than copper-clad aluminum. This shows that the conductivity of the substrate is the basis of electromagnetic shielding.

[0214] (5) Self-cleaning performance test: Apply oil stains on the surface of each sample and observe the decomposition and removal of the oil stains under natural light.

[0215] Oil stains were applied to the sample surfaces and observed for decomposition and removal under natural light. After 24 hours of light exposure, the oil stains in Examples 1 and 2 were significantly decomposed and reduced, demonstrating average self-cleaning performance. However, the self-cleaning performance of Example 3 was relatively poor after 24 hours of light exposure.

[0216] The contact angle of Comparative Example 1 is lower than that of the embodiment due to the slightly poor flatness of the coating;

[0217] Comparative Example 2 (without TiN) has the worst self-cleaning property due to the high surface energy of the nickel layer;

[0218] Comparative Example 3 has no transition nickel layer and TiN is deposited directly on the zinc-plated layer. The bonding strength between the zinc layer and TiN is not as good as that between the nickel layer and TiN, resulting in interface defects, poor surface flatness, and reduced self-cleaning properties.

[0219] Comparative Example 4 does not involve the zinc immersion step and is directly nickel-plated. An oxide layer is formed on the surface of the copper-clad aluminum, resulting in poor bonding of the nickel-plated layer, pores in the plating layer, easy adsorption of impurities, and poor self-cleaning properties.

[0220] Comparative Example 5 lacks a heat treatment step, resulting in high internal stress in the coating, which may cause cracking or peeling, an incomplete surface, and reduced self-cleaning properties because the damaged areas are prone to dirt accumulation;

[0221] Comparative Example 6: The base material is different, and the aluminum alloy composition affects the uniformity of zinc immersion and nickel plating. The coating adhesion is not as good as copper-clad aluminum, the surface may be rougher, and the self-cleaning property is not as good as Example 2.

[0222] Comparative Example 7: Copper-aluminum alloy bar (aluminum 95-97%, copper 3-5%). The base material is an alloy rather than a composite copper-clad aluminum. The surface uniformity is poor, the coating adhesion is uneven, and self-cleaning is affected.

[0223] Comparative Example 8 Pure aluminum bar, the substrate is pure aluminum, the surface is easy to oxidize, the combination of zinc immersion and nickel plating is not as good as copper-coated aluminum (the presence of copper layer is more conducive to the adhesion of the plated layer), the plated layer has more defects, and the self-cleaning property is poorer.

[0224] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are within the scope of protection of the present application.

Claims

1. A surface composite treatment process for copper-clad aluminum materials, characterized in that: The following steps are involved: (1) A copper-clad aluminum workpiece that has been pre-treated for degreasing is subjected to acid etching, and the copper-clad aluminum workpiece after acid etching is immersed in a zinc immersion solution for two-step zinc immersion to form a zinc layer on the surface of the copper-clad aluminum workpiece; wherein the alkali concentration of the zinc immersion solution in the two-step zinc immersion is first low and then high; (2) electroplating the zinc-coated copper-clad aluminum workpiece with nickel to form a nickel layer on the surface of the zinc layer; (3) depositing a titanium nitride layer on the surface of the nickel layer using a physical vapor deposition technique to obtain a composite coating on the copper-clad aluminum workpiece; (4) The copper-clad aluminum workpiece having the composite coating is subjected to heat treatment, passivation treatment after cooling, and the finished product is obtained after cleaning and drying.

2. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: In step (1), the degreasing pretreatment is as follows: immersing the copper-clad aluminum workpiece in an alkaline degreasing solution at a temperature of 50-60°C for 5-10 minutes, wherein the composition of the alkaline degreasing solution is NaOH 3-5g / L, Na2CO3 15-20g / L, OP-103-5g / L, citric acid 5-10g / L, phosphoric acid 3-5g / L, and nano-silica 1-2g / L.

3. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: In step (1), the acid etching is as follows: immersing the copper-clad aluminum workpiece in an acid immersion solution, assisted by ultrasonic waves, with a power of 200-300W and a time of 60-120s, wherein the composition of the acid immersion solution is 8-12g / L of sodium persulfate, 3-5g / L of sulfuric acid, 2-3g / L of phosphoric acid, and 1-2g / L of aminosulfonic acid.

4. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: The zinc immersion solution comprises 20-30 g / L zinc oxide, 80-120 g / L sodium hydroxide, 0.3-0.5 g / L nano ZrO2, 20 g / L sodium citrate, 40 g / L nickel chloride NiCl2·6H2O, 2-3 g / L hydroxyethyl hydrazine, and 0.5-1 g / L L-cysteine.

5. The surface composite treatment process of a copper-clad aluminum material according to claim 4, characterized in that: The two-step zinc immersion has a immersion time of 60-120s, specifically: maintaining the NaOH concentration at 60-70g / L for the first zinc immersion for 30-90s, adding NaOH to 90-120g / L for the second zinc immersion for 30-90s, and the temperature is 25-35°C.

6. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: In step (2), the composition of the plating solution is: nickel sulfate 80-120g / L, disodium ethylenediaminetetraacetic acid 40-60g / L, thiourea 0.3-1.0g / L, graphene quantum dots 0.1-0.3g / L, potassium citrate 15-25g / L, sodium phytate 5-8g / L, plating solution pH = 4-6, nickel electroplating parameters are: forward current density 2.0-3.0A / dm 2 , reverse current density 0.5-1.0A / dm 2 , frequency 100-200Hz, electroplating time 10-60min.

7. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: In step (3), under pure argon environment, the 2 The titanium target is sputtered with high power, and the surface of the nickel layer is bombarded with the sputtered titanium ions to form an atomic-level mixed layer. The argon flow rate is 40-60 sccm to deposit the titanium transition layer. Then, the argon flow rate is 0.8-1W / cm 2 Power deposition of titanium layer, nitrogen gas, power 1.0-1.5W / cm 2 Deposit the TiN nucleus layer and repeat 2-3 times to form a gradient interface; then gradually increase the power to 2-2.5W / cm 2 , argon flow rate 60-80sccm, depositing titanium layer.

8. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: In step (4), the heat treatment is to raise the temperature to 100-120°C and keep it for 1-2 hours, and then raise the temperature to 160-180°C and keep it for 1-2 hours. -3 Pa.

9. The surface composite treatment process of a copper-clad aluminum material according to claim 1, characterized in that: In step (4), the copper-clad aluminum workpiece is placed in a passivation solution for passivation treatment. The passivation solution is composed of: 15-20 g / L sodium molybdate, 5-10 g / L phytic acid, 3-5 g / L silane coupling agent, pH = 3.5-4.0, and the immersion time is 5-10 min.

10. A copper-clad aluminum material prepared by the surface composite treatment process according to any one of claims 1 to 9, characterized in that: The surface of the copper-clad aluminum material is provided with a zinc layer, a nickel layer and a titanium nitride layer in sequence.

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