Preparation method and application of metal corrosion-resistant composite interface layer

Abstract

The invention discloses a preparation method and application of a metal corrosion-resistant composite interface layer. The problem that an existing electrophoretic coating is insufficient in protection performance is solved. The composite interface layer takes epoxy acrylic cationic resin as a matrix, and contains graphene nanosheets loaded with metal organic framework (MOF) particles and the like; the electrophoresis solution comprises the following components in percentage by mass: 20-30% of resin, 10-20% of talcum powder, 3% of a defoaming agent, 3% of a dispersing agent, 1-10% of GO-MOF and the balance of deionized water. The preparation method comprises the following steps: metal pretreatment, electrophoresis at 60-120V for 0.5-3min, and curing at 160-180 DEG C for 20-30min. GO-MOF enhances the compactness of resin bonding and an interface layer and adsorbs a corrosive medium, Tafel tests show that the corrosion resistance is remarkably improved, and the GO-MOF composite material is suitable for corrosion prevention of a battery pack shell.

Description

Technical Field

[0001] This invention relates to the field of metal coating technology, and specifically to a method for preparing and applying a metal corrosion-resistant composite interface layer. Background Technology

[0002] For metals, especially reactive metals, corrosion resistance has a crucial impact on their performance and operational stability. In the field of new energy batteries, even higher requirements are placed on the corrosion resistance of battery casings. Electrophoresis, as a widely used surface protection technology, produces coatings with various excellent properties. However, most current electrophoretic coatings are resin coatings, and their protective performance still needs further improvement.

[0003] To enhance the corrosion resistance of coatings, the addition of inorganic nanomaterials as functional fillers to improve the density and corrosion protection of resins has been widely applied and studied. However, most talc powders have few surface functional groups and weak interactions with resins, limiting their effectiveness in coatings. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing and applying a metal corrosion-resistant composite interface layer, so as to solve the defects of insufficient protective performance of existing electrophoretic coatings and poor compatibility between inorganic fillers and resins.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A method for preparing a metal corrosion-resistant composite interface layer includes the following steps: Step 1: Place the metal to be treated in the electrophoresis solution for electrophoresis treatment; Step 2: After drying the metal treated in Step 1, perform a curing treatment; the electrophoretic solution is calculated by mass as follows: 20-30% epoxy acrylate cationic resin, 10-20% talc, 3% defoamer, 3% dispersant, 1-10% graphene nanosheets loaded with metal-organic framework particles, and the balance being deionized water.

[0006] In a further embodiment, the process parameters for the electrophoretic treatment are: DC voltage controlled at 60-120V, and deposition time at 0.5-3 minutes; the process parameters for the curing treatment are: curing temperature controlled at 160-180℃, and curing time at 20-30 minutes.

[0007] In a further embodiment, the method for preparing the graphene nanosheets loaded with metal-organic framework particles includes the following steps: S1: Graphene is ultrasonically dispersed in an aqueous solution, and a metal salt is added to dissolve it, resulting in solution A; S2: Dissolve the organic ligand in water to obtain solution B; S3: Quickly add solution B to solution A, stir for 2 hours, and then centrifuge to collect the precipitate; S4: After washing the precipitate, freeze-dry it to obtain graphene nanosheets loaded with metal-organic framework particles.

[0008] In a further embodiment, the graphene nanosheets loaded with metal-organic framework particles have a graphene mass percentage of 10%-30%.

[0009] In a further embodiment, the metal salt is one or more of zinc salt and cobalt salt.

[0010] In a further embodiment, the organic ligand is 2-methylimidazole.

[0011] A further proposed approach includes a pretreatment step for the metal to be treated before step one: the metal to be treated is degreased, pickled, washed with water and dried in sequence to remove surface oil and oxide layer.

[0012] In a further embodiment, the process parameters for "ultrasonically dispersing graphene in an aqueous solution" in step S1 are: ultrasonic power 200-400W, ultrasonic time 20-40min.

[0013] The present invention has the following beneficial effects: The abundant functional groups on the surface of metal-organic framework materials and graphene can generate good interactions with resins, promoting the tightness of the bonding between nanomaterials and resins, and helping to form a dense coating.

[0014] Meanwhile, graphene's excellent flexibility can enhance the toughness of the coating and prevent the formation of local cracks that could lead to corrosion channels.

[0015] Metal-organic framework nanoparticles contain abundant pores, which can adsorb and anchor ions in the coating. At the same time, the large specific surface area of ​​metal-organic framework nanoparticles and graphene can physically adsorb ions, preventing ions from moving towards the metal matrix and causing corrosion.

[0016] This technology is simple to operate and has the advantage of large-scale production applications. Attached Figure Description

[0017] Figure 1 This is an electron microscope image of the graphene nanosheets loaded with metal-organic framework particles in Example 1.

[0018] Figure 2 This is the Tafel curve from Example 1.

[0019] Figure 3 This is the Tafel curve in Example 2. Detailed Implementation

[0020] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0021] Example 1 A method for preparing a metal corrosion-resistant composite interface layer, comprising the following specific steps. (1) Preparation of two-dimensional nanosheets: 200 mg of graphene and 297 mg of zinc nitrate were dissolved in an aqueous solution as solution A, and 328 mg of 2-methylimidazole was dissolved in water as solution B. Solution B was quickly added to solution A, stirred for 2 hours, centrifuged, washed, and freeze-dried to obtain powder.

[0022] (2) Preparation of corrosion-resistant composite interface layer: An electrophoresis solution was prepared consisting of 25% epoxy-acrylic cationic resin, 15% talc, 3% defoamer, 3% dispersant, 8% graphene nanosheets loaded with metal-organic framework particles, and the remainder deionized water. Aluminum alloy sheets were placed in the electrophoretic coating for electrophoretic treatment under a DC current of 80V for 1 minute. After deposition, curing was performed at 170℃ for 20 minutes. A comparative example was a metal substrate without an interface layer.

[0023] Effect verification: In Example 1, the graphene exhibits a flexible and two-dimensional structure with metal-organic framework nanoparticles uniformly distributed on its surface. Tafel analysis shows that the self-corrosion potential of this example is -251 mV, significantly higher than the self-corrosion potential of the control sample (-848 V). Simultaneously, the self-corrosion current of this example is only 0.0106 μA / cm², far lower than the self-corrosion current of the control sample (29.04 μA / cm²).

[0024] Example 2 A method for preparing a metal corrosion-resistant composite interface layer, the specific steps of which are as follows: (1) Preparation of two-dimensional nanosheets: 100 mg of graphene and 297 mg of cobalt nitrate were dissolved in an aqueous solution as solution A, and 328 mg of 2-methylimidazole was dissolved in water as solution B. Solution B was quickly added to solution A, stirred for 2 hours, centrifuged, washed and freeze-dried to obtain powder.

[0025] (2) Preparation of composite coating: An electrophoresis solution was prepared consisting of 30% epoxy acrylate cationic resin, 10% talc, 3% defoamer, 3% dispersant, 1% graphene nanosheets loaded with metal-organic framework particles, and the balance deionized water. Aluminum alloy sheets were placed in the electrophoretic coating for electrophoretic treatment under a DC current of 90V for 3 minutes. After deposition, a curing process was performed at 170℃ for 20 minutes.

[0026] Effect verification: As can be seen from the Tafel test, the self-corrosion potential of the embodiment is -213mV, which is significantly improved compared to the self-corrosion potential of the control sample of -848mV. At the same time, the self-corrosion current of the embodiment is only 3.64μA / cm2, which is much lower than the self-corrosion current of the control sample of 29.04μA / cm2.

[0027] In both embodiments, GO-MOF was prepared using zinc salt and cobalt salt, respectively. By adjusting the electrophoresis voltage, time, and amount of GO-MOF added, composite interface layers were obtained through an "electrophoresis + curing" process. Tafel testing showed that the self-corrosion potential of the metals in both embodiments shifted significantly to the positive direction and the self-corrosion current decreased significantly, proving that the method of the present invention can stably improve the corrosion resistance of metals and adapt to different process parameter requirements.

[0028] The above comparison shows that metals with a corrosion-resistant interface layer applied by electrophoresis have significantly stronger corrosion resistance than the original metal material.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a metal corrosion-resistant composite interface layer, characterized in that, Includes the following steps: Step 1: Place the metal to be treated in the electrophoresis solution for electrophoresis treatment; Step 2: After drying the metal treated in Step 1, perform a curing treatment; the electrophoretic solution is calculated by mass as follows: 20-30% epoxy acrylate cationic resin, 10-20% talc, 3% defoamer, 3% dispersant, 1-10% graphene nanosheets loaded with metal-organic framework particles, and the balance being deionized water.

2. The method for preparing the metal corrosion-resistant composite interface layer according to claim 1, characterized in that, The electrophoretic treatment process parameters are: DC voltage controlled at 60-120V, deposition time at 0.5-3 minutes; the curing treatment process parameters are: curing temperature controlled at 160-180℃, curing time at 20-30 minutes.

3. The method for preparing the metal corrosion-resistant composite interface layer according to claim 1, characterized in that, The method for preparing the graphene nanosheets loaded with metal-organic framework particles includes the following steps: S1: Graphene is ultrasonically dispersed in an aqueous solution, and a metal salt is added to dissolve it, resulting in solution A; S2: Dissolve the organic ligand in water to obtain solution B; S3: Quickly add solution B to solution A, stir for 2 hours, and then centrifuge to collect the precipitate; S4: After washing the precipitate, freeze-dry it to obtain graphene nanosheets loaded with metal-organic framework particles.

4. The method for preparing the metal corrosion-resistant composite interface layer according to claim 3, characterized in that, In the graphene nanosheets loaded with metal-organic framework particles, the mass percentage of graphene is 10%-30%.

5. The method for preparing the metal corrosion-resistant composite interface layer according to claim 3, characterized in that, The metal salt is one or more of zinc salt and cobalt salt.

6. The method for preparing the metal corrosion-resistant composite interface layer according to claim 3, characterized in that, The organic ligand is 2-methylimidazole.

7. The method for preparing the metal corrosion-resistant composite interface layer according to claim 1, characterized in that, Before step one, there is a pretreatment step for the metal to be treated: the metal to be treated is degreased, pickled, washed with water and dried in sequence to remove surface oil and oxide layer.

8. The method for preparing the metal corrosion-resistant composite interface layer according to claim 3, characterized in that, The process parameters for "dispersing graphene in an aqueous solution by ultrasound" in step S1 are: ultrasound power 200-400W, ultrasound time 20-40min.

9. The application of a method for preparing a metal corrosion-resistant composite interface layer as described in any one of claims 1-8 in the field of battery pack casing corrosion protection.

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