Chemical aluminum plating solution and chemical aluminum plating method

Abstract

The present invention discloses a chemical aluminum plating solution and a chemical aluminum plating method, which belong to the field of chemical metal plating. The chemical aluminum plating solution is composed of an aluminum hydride complex and a solvent, and is prepared by reacting LiAlH4 and the corresponding complex hydrochloride in a solvent under an anhydrous and oxygen-free atmosphere and then filtering. After the substrate is roughened and / or grafted, it is immersed in an activation solution containing organic titanium for activation, washed and dried, and then immersed in the chemical aluminum plating solution in an anhydrous and oxygen-free atmosphere for aluminum plating. After the reaction is completed, it is quenched, washed, and dried to obtain an aluminum-plated substrate. The preparation method of the chemical aluminum plating solution is simple and can be stably stored for a long time at room temperature. After simple roughening and activation steps, chemical aluminum plating can be achieved on different substrates, and there are no requirements for the morphology and properties of the substrate. The chemical aluminum plating solution and the aluminum plating method are suitable for substrates of various materials and shapes, and can effectively impart a lightweight and highly conductive metal aluminum coating to the surface or interior of the substrate, and have a wide range of application value.

Description

Technical Field

[0001] The present invention belongs to the field of chemical metal plating, and in particular relates to an aluminum plating solution based on an aluminum hydride tertiary amine complex and a preparation method thereof, as well as a chemical aluminum plating method comprising substrate pretreatment, aluminum plating reaction control and aluminum plating solution quenching. Background Art

[0002] Aluminum is a commonly used metal material with advantages such as high electrical conductivity, low density, and stability in air. In production and daily life, it is often necessary to coat aluminum layers onto materials to utilize their metallic properties. Common methods include vacuum evaporation, electroplating, and chemical plating. Vacuum evaporation is a process that uses a certain method to evaporate the coating material under vacuum conditions, causing the vaporized particles to fly to the surface of the substrate and condense into a film. The Chinese invention patent application "A Method for Vacuum Evaporation of Aluminum Film on Plastics" (CN105088148A) uses glow discharge to evaporate aluminum and deposit it on plastic. This method is relatively low in cost, but has certain requirements for the workpiece shape. It is mainly used for flat coating and is not suitable for substrates with concave surfaces or complex surface structures. Electroplating is a process that uses the principles of electrolysis to deposit a metal film on a substrate under the action of an external electric current. The Chinese invention patent application, "A Method for Uniformly Electroplating Aluminum on the Surface of a Mobile Phone Midframe" (CN115323446A), uses AlCl3-EMIC ionic liquid as the electroplating solution. The aluminum coating on the die-cast aluminum mobile phone midframe is uniform and high-quality. However, when electroplating complex-shaped workpieces, uneven electric field lines can lead to uneven coating and the formation of dendrites at the edges and corners.

[0003] Electroless plating is a coating process in which metal ions are reduced and deposited onto the surface of a substrate in the absence of an external current. The Chinese invention patent "Electroless Aluminum Plating Solution and Electroless Aluminum Plating Method" (CN101210319A) is based on an ionic liquid prepared from onium halide and aluminum chloride. It uses metal hydrides such as diisobutylaluminum hydride as a reducing agent to plate aluminum onto a SnCl2 / PdCl2-activated substrate. This method is suitable for a variety of conductive and non-conductive substrates, but the solvent requires a large amount of expensive AlCl3-EMIC ionic liquid that does not participate in the reaction, and multiple activation steps are required.

[0004] Lee et al. prepared an electroless aluminum plating precursor solution by coordinating aluminum hydride with n-butyl ether. They then activated the substrate surface with titanium isopropoxide by fumigation, successfully producing an electroless aluminum thin film. This electroless plating method requires a certain temperature (90–100°C), and the instability of the n-butyl ether coordination makes the solution easily deteriorating and difficult to store for a long time. Furthermore, the activation method is crude, making it only suitable for flat substrates and requiring high temperature and closed conditions to achieve uniformity. In subsequent studies, they used trimethylamine to stabilize aluminum hydride to prepare AlH₃·NMe₃ solid powder and obtained metallic Al thin films through a solution stamping process. In another study, they used a method of coating titanium isopropoxide activation solution and infrared drying to prepare aluminum-coated thin film materials at 150°C by roll-to-roll printing. However, there are problems with activation uniformity and high reaction temperature, and the roll-to-roll process is only applicable to thin film materials that can be made into rolls (Advanced Material, 2011, 23, 46: 5524-5528; ACS Applied Materials&Interfaces, 2014, 6, 17, 15480-15487; RCS Advance, 2018: 36.). Shen et al. used AlH3·NEt3 precursor to react with N, N-dimethyloctylamine to generate AlH3·NMe2C8H 17 Active materials, catalytically decomposed at 105°C to form an Al film on a Pt-patterned nanocrystal substrate. However, this method requires expensive Pt nanocrystals, can only produce planar patterns, uses difficult-to-remove high-boiling-point amines to stabilize AlH₃, and requires relatively high temperatures (Journal of the American Chemical Society, 2012, 134, 19: 8034-8037). Douglas et al. reacted LiAlH₄ with various tertiary amine hydrochlorides in n-hexane at -78°C, followed by recrystallization to obtain a pure liquid form of aluminum hydride-tertiary amine complex. This complex was drop-cast onto various flat substrates at 100°C and thermally decomposed to form Al films. This method requires an ultra-low temperature, anhydrous, and oxygen-free environment, making the operation complex and tedious. Furthermore, the Al film formation process is a non-activating thermal decomposition process and is only applicable to flat substrates (ACS Applied Materials & Interfaces, 2020, 12, 23: 26193-26199).

[0005] Based on the above analysis, existing aluminum plating technologies all have certain limitations. There are restrictions on the shape of the substrate, making it difficult to aluminum-plate complex-shaped substrates. At the same time, there are also high requirements for the conductivity and other properties of the substrate. Furthermore, the existing chemical plating conditions are harsh, the process is complex, and the chemical plating solution is unstable, making it difficult to achieve large-scale production. Therefore, designing and preparing a chemical plating solution that can be stably stored at room temperature, and developing a plating process that is simple to operate, not restricted by the shape of the substrate, and widely applicable to various substrates, are of vital importance to the development of chemical aluminum plating technology. Summary of the Invention

[0006] In order to solve the above-mentioned existing technical problems, the present invention aims to provide a process for chemically plating aluminum on surfaces of various complex-shaped, conductive and non-conductive substrates to obtain controllable high-quality coatings.

[0007] To achieve the above technical objectives, the present invention provides a solution chemical aluminum plating process, including an aluminum hydride-amine complex chemical aluminum plating solution and its preparation method, a substrate pretreatment method, a method for controlling the aluminum plating reaction, and a method for quenching the aluminum plating solution.

[0008] Specifically, the present invention first provides a chemical aluminum plating solution, which is composed of an aluminum hydride complex and a solvent and is obtained by the following preparation method:

[0009] In an anhydrous and oxygen-free atmosphere, LiAlH4 is dispersed in a solvent, a Lewis base hydrochloride slightly less than the stoichiometric ratio is added to the dispersion, the mixture is stirred and reacted for a period of time, and LiCl and excess LiAlH4 precipitate produced by the reaction are removed by filtration to obtain the chemical aluminum plating solution.

[0010] The solvent includes, but is not limited to, ether, cyclic ether or hydrocarbon solvents such as n-butyl ether, diethyl ether, 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, n-hexane and cyclohexane.

[0011] The Lewis base hydrochloride is preferably a tertiary amine hydrochloride, including but not limited to trimethylamine hydrochloride, triethylamine hydrochloride, tripropylamine hydrochloride, and N,N-dimethyloctylamine hydrochloride. The aluminum hydride complex formed is an aluminum hydride-tertiary amine complex, including but not limited to one or a mixture of two or more of an aluminum hydride-triethylamine complex, an aluminum hydride-trimethylamine complex, an aluminum hydride-tripropylamine complex, and an aluminum hydride-N,N-dimethyloctylamine complex.

[0012] Preferably, each liter of the chemical aluminum plating solution contains 0.01 to 2 mol of aluminum hydride complex.

[0013] The present invention also provides a substrate pretreatment method suitable for the above-mentioned chemical aluminum plating solution, comprising roughening and / or grafting the substrate, and activating the substrate, wherein:

[0014] (1) Substrate roughening: Cut the substrate into a suitable size or shape, clean it, and soak it in a roughening liquid or roughening atmosphere. Roughen it at a temperature range of -15°C to 80°C for 0.5 to 24 hours. After the roughening is completed, take out the substrate and wash it with deionized water, ethanol and other solvents in sequence. After drying, obtain the roughened substrate sample.

[0015] (2) Substrate grafting: Soak the substrate in the grafting solution and graft for 0.25 to 6 hours at a temperature range of -15°C to 50°C. After the grafting is completed, take out the substrate and wash it with deionized water, ethanol and other solvents in turn. After drying, the grafted substrate sample is obtained.

[0016] (3) Substrate activation: The roughened and / or grafted substrate is immersed in the activation solution and activated at a temperature range of -15°C to 50°C for 0.25 to 24 h. After the activation is completed, the substrate is removed and washed with deionized water, ethanol and other solvents in sequence, and then dried to obtain the activated substrate sample.

[0017] In the above step (1), the substrate includes but is not limited to metal, paper, wood, glass, ceramic and polymer. The roughening liquid and roughening atmosphere are selected differently depending on the substrate. The roughening liquid includes but is not limited to a mixture of concentrated sulfuric acid and concentrated nitric acid, a mixture of hydrogen peroxide and concentrated sulfuric acid, a mixture of chromic acid and sulfuric acid, etc. The roughening atmosphere includes but is not limited to air plasma, oxygen plasma and ozone, etc.

[0018] In the above step (2), the substrate includes but is not limited to metal, paper, wood, glass, ceramic and polymer, and the grafting liquid is selected differently depending on the substrate. The grafting liquid includes but is not limited to water, ethanol and / or acetone solutions of 3-triethoxysilyl-1-propylamine (KH550) and / or 3-mercaptopropyltrimethoxysilane (KH590).

[0019] In the above step (3), the activation solution is preferably a solution containing an organic titanium compound, including but not limited to ethanol, methanol, isopropanol, acetone and / or n-hexane solutions of tetrabutyl titanate, tetraisopropyl titanate, isopropyl triisostearate titanate and / or bis(acetylacetonato) diisopropyl titanate.

[0020] The present invention further provides a method for controlling an electroless aluminum plating reaction and a method for quenching an electroless aluminum plating solution, comprising:

[0021] The activated substrate is immersed in an electroless aluminum plating solution in an anhydrous and oxygen-free atmosphere. The reaction is carried out at an appropriate temperature (e.g., -20°C to 80°C) for a period of time (e.g., 15 minutes to 30 days). The substrate is then removed and immersed in a quenching solution to quench the reaction. After the quenching reaction is complete, the substrate is removed, washed with a suitable solvent, and dried to obtain an aluminum-plated substrate.

[0022] In the above method, the quenching solution is selected differently depending on the substrate and the chemical aluminum plating solution. The quenching solution includes but is not limited to water, ethanol, methanol, acetone, n-butyl ether, dioxane, cyclohexane and mixtures thereof in different proportions.

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention provides an electroless aluminum plating solution, the raw materials and preparation steps of which are very simple. After a simple activation treatment, electroless aluminum plating can be achieved on various substrates. Compared with plating solutions for electroless plating of other metals, the aluminum plating solution is more stable and can be stored at room temperature for a long time without deterioration under anhydrous and oxygen-free conditions. Compared with other electroless aluminum plating solution systems, the aluminum plating solution is simple to prepare, low in cost, and stable in properties.

[0025] (2) The present invention also provides an aluminum plating and post-treatment process based on the above-mentioned plating solution, which is simple and easy to operate. Since the reaction is essentially a decomposition reaction under the action of an interfacial catalyst, compared to electroplating, this method has basically no requirements for the shape of the substrate. This method can also obtain high-quality aluminum coatings on substrates with complex shapes, concave surfaces, powders, and porous materials that are difficult to electroplate. This method also has low requirements for the properties of the substrate surface. It does not require the substrate surface to be conductive or have other special properties. It only requires the titanium material to be activated, and has universal applicability to the applicable surface of the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an optical photograph of the surface of the aluminum-coated PEN sheet of Experimental Example 1 of the present invention.

[0027] Figure 2 These are optical photographs of the surface and longitudinal cross-section of the aluminum-coated balsa wood of Experimental Example 2 of the present invention.

[0028] Figure 3 These are optical photographs of the surface (left) and longitudinal cross-section (right) of the homogeneous aluminum-plated PDMS elastomer of Experimental Example 3 of the present invention.

[0029] Figure 4 This is an optical photograph of the surface of the aluminum-coated filter paper of Experimental Example 5 of the present invention.

[0030] Figure 5 This is a surface SEM electron microscope photograph of the aluminum-plated filter paper of Experimental Example 5 of the present invention.

[0031] Figure 6 XRD diffraction spectrum of the aluminized filter paper of Experimental Example 5 of the present invention.

[0032] Figure 7 This is a surface optical photograph of the patterned aluminum-coated filter paper of Experimental Example 7 of the present invention.

[0033] Figure 8 This is an optical photograph of the cross section of the aluminized balsa wood of Comparative Example 1 of the present invention.

[0034] Figure 9 This is an optical photograph of the cross section of the aluminized balsa wood of Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0035] The present invention is described in detail below by specific examples, but the present invention can be implemented by other methods and is not limited to the following examples. Therefore, the scope of protection of the present invention is not limited by the following examples. The experimental methods, reagents and materials described in the examples, unless otherwise specified, are all conventional methods or can be purchased through commercial channels. The experimental instruments and equipment involved in the examples, unless otherwise specified, are all parameters selected by the manufacturer.

[0036] The preparation of the chemical aluminum plating solution used in the following experimental examples and comparative examples is as follows:

[0037] Plating solution 1: In an argon glove box, add 2.27 g of LiAlH4 to 100 mL of n-butyl ether and stir to disperse. To the dispersion, add 8.00 g (slightly less than a 1:1 stoichiometric ratio) of triethylamine hydrochloride in batches. React at room temperature for 12 h and filter to obtain a ~0.5 mol / L AlH3·NEt3 / n-butyl ether solution, which is recorded as plating solution 1.

[0038] Bath 2: Reduce the amounts of LiAlH4 and triethylamine hydrochloride by half. Follow the same steps as Bath 1 to obtain a ~0.25 mol / L AlH3·NEt3 / n-butyl ether solution, designated Bath 2.

[0039] Bath 3: Replace n-butyl ether with 1,4-dioxane. Follow the same steps as Bath 1 to obtain a ~0.5 mol / L AlH3·NEt3 / 1,4-dioxane solution, designated Bath 3.

[0040] Bath 4: Replace n-butyl ether with tetraethylene glycol dimethyl ether. Follow the same steps as Bath 1 to obtain a ~0.5 mol / L AlH3·NEt3 / tetraethylene glycol dimethyl ether solution, designated Bath 4.

[0041] Bath 5: Replace n-butyl ether with n-hexane. Follow the same steps as Bath 1 to obtain a ~0.5 mol / L AlH3·NEt3 / n-hexane solution, designated Bath 5.

[0042] Bath 6: Replace triethylamine hydrochloride with trimethylamine hydrochloride to obtain a ~0.5 mol / L AlH3·NMe3 / n-butyl ether solution, denoted as Bath 6.

[0043] Bath 7: Replace triethylamine hydrochloride with tripropylamine hydrochloride to obtain a ~0.5 mol / L AlH3·N(n-Pr)3 / n-butyl ether solution, denoted as Bath 7.

[0044] Bath 8: Replace triethylamine hydrochloride with N,N-dimethyloctylamine hydrochloride to obtain a ~0.5 mol / L AlH3·NMe2(n-Oct)3 / n-butyl ether solution, denoted as Bath 8.

[0045] Experimental Example 1:

[0046] Commercially available PEN (polyethylene naphthalate) sheets were cut into 2 cm × 2 cm sizes, washed with deionized water and ethanol in sequence, dried, and roughened using air plasma treatment on both sides for 10 min each to obtain roughened PEN sheets.

[0047] The roughened PEN sheet was immersed in a 1% tetrabutyl titanate-ethanol solution and activated at room temperature for 30 min. The sheet was taken out, washed with ethanol, and dried to obtain an activated PEN sheet.

[0048] The activated PEN sheet was immersed in plating solution 1 and reacted at room temperature for 48 h in anhydrous and oxygen-free atmosphere. After the reaction was completed, the substrate was taken out and immersed in ethanol to quench the reaction. The substrate was washed with deionized water and ethanol in sequence and dried to obtain an aluminum-plated PEN sheet ( Figure 1 ).

[0049] Experimental Example 2:

[0050] Commercially available balsa wood (~0.1 g / cm 3 ) were cut into 1 cm × 1 cm × 1 cm sizes, immersed in 1% NaClO2 / acetate buffer, treated at 80℃ for 12 h, taken out, rinsed with deionized water, changed the water three times, taken out, and freeze-dried to obtain delignified balsa wood.

[0051] Delignified balsa wood was immersed in 1% tetrabutyl titanate-ethanol solution and activated at 50°C for 30 min. The wood was taken out and washed with ethanol, acetone and cyclohexane in sequence and freeze-dried to obtain activated balsa wood.

[0052] The activated balsa wood was immersed in the plating solution 1 and reacted at room temperature for 24 h in an anhydrous and oxygen-free atmosphere. After the reaction was completed, the substrate was taken out and immersed in ethanol / n-butyl ether with a volume ratio of 1:9 to quench. The substrate was washed with ethanol, acetone, and cyclohexane in sequence and freeze-dried to obtain aluminum-coated balsa wood ( Figure 2 ).

[0053] Experimental Example 3:

[0054] Commercially available Dow Corning 184, curing agent, and tetrabutyl titanate were mixed in a mass ratio of 100:10:1, stirred evenly, and cured at 60°C for 12 h. The cured transparent elastomer was cut into 1 cm × 1 cm × 2 mm pieces to obtain an activated PDMS elastomer.

[0055] The activated PDMS elastomer was immersed in plating solution 1 and reacted at room temperature for 48 h in anhydrous and oxygen-free atmosphere. After the reaction was completed, the substrate was taken out and immersed in ethanol / n-butyl ether with a volume ratio of 1:9 to quench. It was then washed with ethanol / n-butyl ether mixed solvents of different ratios (the ethanol ratio was gradually increased) and dried to obtain a homogeneous aluminum-plated PDMS elastomer ( Figure 3 ).

[0056] Experimental Example 4:

[0057] The preparation of activated PDMS elastomer was the same as that in Experimental Example 3.

[0058] The activated PDMS elastomer was immersed in plating solution 3 and reacted at room temperature for 48 h in an anhydrous and oxygen-free atmosphere. After the reaction was completed, the substrate was removed and immersed in ethanol / 1, 4-dioxane with a volume ratio of 1:9 to quench. It was then washed in ethanol / 1, 4-dioxane mixed solvents of different ratios (with gradually increasing ethanol ratios) and dried to obtain a surface-aluminum-plated PDMS elastomer.

[0059] Experimental Example 5;

[0060] Commercially available qualitative filter paper was cut into 3 cm × 3 cm sizes, washed with deionized water and ethanol in sequence, dried, and roughened by treating both sides with air plasma for 10 min each to obtain roughened filter paper.

[0061] The roughened filter paper was immersed in a 1% tetrabutyl titanate-ethanol solution and activated at room temperature for 15 min. The roughened filter paper was taken out, washed with ethanol, and dried to obtain the activated filter paper.

[0062] The activated filter paper was immersed in plating solution 1 and reacted at 50 ° C for 6 h in anhydrous and oxygen-free atmosphere. After the reaction was completed, the substrate was taken out and immersed in ethanol to quench the reaction. It was washed with deionized water and ethanol in sequence and dried to obtain the aluminum-plated filter paper ( Figure 4 ). The surface SEM electron microscope photo of the aluminum-plated filter paper is as follows Figure 5 As shown in Figure 2, it can be seen that an aluminum metal layer is uniformly deposited on the microscopic fiber structure of the filter paper; the XRD diffraction spectrum of the aluminum-coated filter paper is shown in Figure 2. Figure 6 As shown, it can be seen that there are diffraction peaks at 38°, 45°, 65°, and 78° in the spectrum, which is consistent with the XRD standard spectrum of metallic aluminum, and there are no other impurity peaks, indicating that a relatively pure crystalline metallic aluminum coating is obtained on the filter paper.

[0063] Experimental Example 6:

[0064] Plating solution 1 was replaced by plating solution 6, and the other steps were the same as those in Experimental Example 5.

[0065] Experimental Example 7:

[0066] The other steps are the same as those in Experiment 5, except that the activation step is changed to writing a certain pattern on the activated filter paper by dipping a glass rod into a 1% tetrabutyl titanate-ethanol solution and drying it. Figure 7 ).

[0067] Comparative Example 1:

[0068] The other steps were the same as those in Experimental Example 2, except that the immersion in 1% NaClO2 / acetate buffer and the treatment at 80℃ for 12 h were not performed. Figure 8 As shown in the figure, the aluminum coating only exists on the surface of the wood, and no metal aluminum coating is deposited inside the wood.

[0069] Comparative Example 2:

[0070] The other steps are the same as those in Experimental Example 2, except that the activation time at 50°C for 30 min was changed to activation time at room temperature for 15 min. Figure 9 As shown in the figure, the aluminum coating only exists in the center of the wood, and no metal aluminum coating is deposited on the surface and the inner position near the surface of the wood.

[0071] The above describes in detail the preferred embodiments of the present invention and their experimental verification. It should be understood that a person skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solution that can be derived by a person skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A chemical aluminum plating solution, characterized in that The chemical aluminum plating solution consists of an aluminum hydride complex and a solvent, and is obtained by the following preparation method: in an anhydrous and oxygen-free atmosphere, LiAlH4 is dispersed in a solvent, and then a Lewis base hydrochloride in an amount slightly less than the stoichiometric ratio is added to the dispersion, the mixture is stirred for a reaction period, and LiCl and excess LiAlH4 precipitate produced by the reaction are removed by filtration to obtain the chemical aluminum plating solution; wherein the Lewis base hydrochloride is a tertiary amine hydrochloride selected from one or more of trimethylamine hydrochloride, triethylamine hydrochloride, tripropylamine hydrochloride and N,N-dimethyloctylamine hydrochloride; the aluminum hydride complex is a mixture of one or more of an aluminum hydride-trimethylamine complex, an aluminum hydride-triethylamine complex, an aluminum hydride-tripropylamine complex and an aluminum hydride-N,N-dimethyloctylamine complex; and the solvent is an ether, a cyclic ether or a hydrocarbon solvent.

2. The chemical aluminum plating solution according to claim 1, characterized in that The solvent is selected from one or more of n-butyl ether, diethyl ether, 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, n-hexane and cyclohexane.

3. The chemical aluminum plating solution according to claim 1, characterized in that Each liter of the chemical aluminum plating solution contains 0.01 to 2 mol of aluminum hydride complex.

4. A chemical aluminum plating method, characterized in that: Using the chemical aluminum plating solution according to any one of claims 1 to 3 to chemically plate a substrate comprises the following steps: 1) roughening and / or grafting the substrate; 2) immersing the roughened and / or grafted substrate in an activation solution containing an organic titanium compound for activation; 3) immersing the activated substrate in the chemical aluminum plating solution to perform aluminum plating in an anhydrous and oxygen-free atmosphere; 4) Take out the substrate and immerse it in a quenching solution to quench the reaction, wash it, and dry it to obtain an aluminum-plated substrate.

5. The chemical aluminum plating method according to claim 4, characterized in that The organic titanium compound is selected from one or more of tetrabutyl titanate, tetraisopropyl titanate, isopropyl triisostearate titanate, and bis(acetylacetonato) diisopropyl titanate.

6. The chemical aluminum plating method according to claim 4, characterized in that The roughening in step 1) is to clean the substrate and then immerse it in a roughening solution or a roughening atmosphere, roughening it in a temperature range of -15°C to 80°C for 0.5 to 24 hours, then taking out the substrate, washing it, and drying it to obtain a roughened substrate; the grafting is to immerse the substrate in a grafting solution, grafting it in a temperature range of -15°C to 50°C for 0.25 to 6 hours, after the grafting is completed, taking out the substrate, washing it, and drying it to obtain a grafted substrate; step 2) immersing the roughened and / or grafted substrate in an activation solution, activating it in a temperature range of -15°C to 50°C for 0.25 to 24 hours, then taking out the substrate, washing it, and drying it to obtain an activated substrate.

7. The chemical aluminum plating method according to claim 6, characterized in that The roughening liquid is selected from a mixture of concentrated sulfuric acid and concentrated nitric acid, a mixture of hydrogen peroxide and concentrated sulfuric acid, or a mixture of chromic acid and sulfuric acid; the roughening atmosphere is air plasma, oxygen plasma, or ozone; the grafting liquid is selected from a water, ethanol, and / or acetone solution containing 3-triethoxysilyl-1-propylamine and / or 3-mercaptopropyltrimethoxysilane; and the activation liquid is selected from an ethanol, methanol, isopropanol, acetone, and / or n-hexane solution containing tetrabutyl titanate, tetraisopropyl titanate, isopropyl triisostearate titanate, and / or bis(acetylacetonato) diisopropyl titanate.

8. The chemical aluminum plating method according to claim 4, characterized in that Step 3) Immersing the activated substrate in the chemical aluminum plating solution and reacting at a constant temperature of -20°C to 80°C for 15 minutes to 30 days.

9. The chemical aluminum plating method according to claim 4, characterized in that The quenching solution is selected from a mixture of one or more of water, ethanol, methanol, acetone, n-butyl ether, 1,4-dioxane, n-hexane, and cyclohexane.

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