Preparation method of CFRP surface textured electromagnetic shielding coating

Abstract

The invention discloses a preparation method of a CFRP surface texturing electromagnetic shielding coating. The preparation method is characterized in that the main preparation process comprises CFRP matrix pretreatment, reduction layer preparation, surface texturing treatment, conductive layer preparation and main electromagnetic shielding layer preparation. In the CFRP matrix pretreatment, a binding phase not exceeding 10 microns on the surface is removed by adopting a high-molecular polymer abrasive gas jet, a reduction layer is prepared into an ABS plastic layer with the coating thickness of 10-20 microns, and in the surface texturing treatment, periodically and densely arranged frustum-shaped surface textures are embossed on the surface of the reduction layer by adopting a metal embossing mold; the conductive layer is prepared by chemically plating a compact Cu-plated layer with the thickness not exceeding 5 microns on the surface of the frustum-shaped texture, and the main electromagnetic shielding layer is prepared by electroplating a compact Ni-plated layer with the thickness being more than 10 microns on the surface of the chemically-plated Cu-plated layer. The method is used for enhancing the electromagnetic protection performance of CFRP parts in electronic information equipment, the attenuation of X-band (8-12 GHz) wireless electromagnetic waves can reach 90 dB at most, and the method has wide application prospects in the fields of aerospace, robots and the like.

Description

Technical Field

[0001] The invention relates to a surface treatment technology, in particular to a surface textured coating technology, specifically to a preparation method of a CFRP surface textured electromagnetic shielding coating. Background Art

[0002] Carbon fiber has excellent properties such as fatigue resistance and strong stability. CFRP parts are widely used in aerospace, robotics and other fields. Due to the surge in the number of electronic information equipment, electromagnetic interference is becoming more and more frequent, and electromagnetic protection performance is particularly important. However, CFRP has low electrical conductivity and magnetic permeability, poor electromagnetic impedance matching, and cannot meet the needs of electromagnetic protection.

[0003] In order to enhance the electromagnetic shielding performance of CFRP parts, the current mainstream practice is to use machine grinding to pre-treat the surface and then plate a metal coating. Pre-treatment can eliminate adverse factors such as the surface passivation layer that affect the bonding performance, but it is difficult to control the grinding accuracy and it is easy to cause damage to the surface of the CFRP matrix. CFRP has poor compatibility with metal materials, the interface atoms cannot form strong chemical bonds, the intermolecular forces such as van der Waals forces are low, and there are loose and porous defects on the surface of the coating, which affects the bonding strength of the coating. At the same time, a single metal electromagnetic shielding coating system is affected by impedance matching and skin effect, and the attenuation of electromagnetic waves is limited. In summary, the metal electromagnetic shielding coating prepared by the existing method has poor bonding performance and electromagnetic loss performance, and cannot fundamentally solve the problem of electromagnetic interference of CFRP parts. Summary of the invention

[0004] The purpose of the present invention is to address the problems of poor surface conductivity of CFRP components on electronic information equipment and limited electromagnetic loss capacity of traditional metal coating structures, and to invent a method for preparing a CFRP surface textured electromagnetic shielding coating. This method changes the surface characteristics of CFRP by forming a metal layer with a specific microstructure on the CFRP surface, changes the reflection and absorption characteristics of electromagnetic waves on the metal surface, and thus enhances the electromagnetic shielding performance of CFRP.

[0005] The technical solution of the present invention is:

[0006] A method for preparing a CFRP surface textured electromagnetic shielding coating, characterized in that the main preparation process includes CFRP substrate pretreatment, reduction layer preparation, surface texturing treatment, conductive layer preparation, and main electromagnetic shielding layer preparation.

[0007] The CFRP substrate pretreatment first uses acetone ultrasonic cleaning to clean the attached pollutants on the substrate surface, and then uses a high molecular polymer abrasive air jet method under an air pressure of 0.3-0.5 MPa to remove the resin bonding phase on the surface that does not exceed 10 μm. The particle size of the polymer abrasive used is 50-100 mesh, and the Barcol hardness of the polymer abrasive is 35-55 HBa.

[0008] The reduction layer is prepared by coating a layer of ABS plastic layer capable of reducing metal ions in the chemical plating solution on the surface of the pretreated CFRP substrate, and the thickness of the reduction layer is 10-20 μm.

[0009] The surface texturing treatment uses a metal stamping mold to stamp a frustum-shaped surface texture on the surface of the reduction layer. The stamping temperature is 130-150°C. The frustum texture is arranged in a periodic and close arrangement with equal spacing in the vertical and horizontal directions. The diameter of the frustum head at the surface end is Ds = (20-50) μm, the height of the frustum is h = (10-20) μm, and the relationship between the frustum taper T and the electromagnetic wave frequency ω attenuated by the shielding layer is:

[0010]

[0011] α is the electromagnetic wave penetration coefficient of the frustum texture surface, ranging from 0 to 0.707; ω is the electromagnetic wave frequency, Hz; γ is the electrical conductivity of the composite coating, S / m, and μ is the magnetic permeability of the composite coating, H / m.

[0012] The conductive layer is prepared by chemically plating a dense Cu layer with a thickness not exceeding 5 μm on the surface of the embossed cone. The main electromagnetic shielding layer is prepared by electroplating a dense Ni layer with a thickness of more than 10 μm on the surface of the chemically plated Cu layer on the surface of the cone. The chemical plating of Cu and the electroplating of Ni adopt existing process methods. When electroplating Ni, the anode needs to use a mesh Ni electrode and force the plating solution to flow.

[0013] The CFRP surface textured electromagnetic shielding coating has a shielding effectiveness of 70 to 90 dB for electromagnetic waves in the 8 to 12 GHz band.

[0014] The beneficial effects of the present invention are:

[0015] The preparation method of the CFRP surface textured electromagnetic shielding coating of the present invention comprises the following steps: pretreatment of the CFRP substrate can achieve lossless removal of the resin bonding phase on the surface of the carbon fiber, and effectively remove the passivation layer on the surface of the substrate; ABS plastic is used in the preparation of the reduction layer to solve the matching problem between the carbon fiber and the metal material, and improve the bonding performance of the coating; the surface texturing treatment effectively improves the reflection and absorption characteristics of electromagnetic waves on the metal surface; and the conductive layer and the main electromagnetic shielding layer improve the electromagnetic loss efficiency.

[0016] The present invention is used to enhance the electromagnetic protection performance of CFRP parts in electronic information equipment, and has a maximum attenuation of 90 dB for X-band (8-12 GHz) radio electromagnetic waves, and has broad application prospects in aerospace, robotics and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of the CFRP surface textured electromagnetic shielding coating prepared by the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] like Figure 1 shown.

[0020] A method for preparing a CFRP surface textured electromagnetic shielding coating mainly includes CFRP substrate pretreatment, reduction layer preparation, surface texturing treatment, conductive layer preparation and main electromagnetic shielding layer preparation. The structure obtained by the preparation is as follows Figure 1 As shown, it consists of a CFRP substrate, an ABS reducing layer, a Cu conductive layer and a Ni main shielding layer.

[0021] Example 1.

[0022] 1. Pretreatment, reduction layer preparation, surface texturing, conductive layer preparation, and main electromagnetic shielding layer preparation are performed on the CFRP substrate.

[0023] 2. Matrix pretreatment: First, use acetone ultrasonic cleaning for 5 minutes to remove the attached pollutants on the substrate surface, and then use the polymer abrasive air jet method under an air pressure of 0.3MPa to remove the resin bonding phase on the surface that does not exceed 10μm. The particle size of the polymer abrasive used is 50 mesh, and the Barcol hardness of the polymer abrasive is 35HBa.

[0024] 3. Preparation of reduction layer: A layer of ABS plastic that can reduce metal ions in the chemical plating solution is coated on the surface of the pretreated CFRP substrate, and the thickness of the reduction layer is 10 μm.

[0025] 4. Surface texturing treatment. Use a metal stamping mold to stamp the surface of the reduction layer. Figure 1 The frustum-shaped surface texture shown in the figure has an imprinting temperature of 130°C. The frustum texture is arranged in a periodic and close arrangement with equal spacing in the vertical and horizontal directions. The diameter of the frustum head at the surface end is Ds=30μm, the height of the frustum is h=10μm, and the taper of the frustum is T:

[0026]

[0027] α is the electromagnetic wave penetration coefficient of the frustum texture surface, which is 0.5556; ω is the electromagnetic wave frequency, which is 10 GHz.

[0028] 5. Preparation of the conductive layer: A dense Cu layer with a thickness of no more than 5 μm is textured on the surface of the stamped frustum.

[0029] 6. Preparation of the main electromagnetic shielding layer: A dense Ni layer with a thickness of more than 10 μm is electroplated on the surface of the textured chemically plated Cu layer on the frustum surface. The chemically plated Cu and electroplated Ni adopt the existing process methods. When electroplating Ni, the anode needs to use a mesh Ni electrode and force the plating solution to flow.

[0030] 5. Coating shielding effect: The CFRP surface textured electromagnetic shielding coating has a shielding effectiveness of 70-90dB for electromagnetic waves in the 8-12GHz band.

[0031] Example 2.

[0032] 1. Pretreatment, reduction layer preparation, surface texturing, conductive layer preparation, and main electromagnetic shielding layer preparation are performed on the CFRP substrate.

[0033] 2. Matrix pretreatment: First, use acetone ultrasonic cleaning for 5 minutes to remove the attached pollutants on the substrate surface, and then use a polymer abrasive air jet method under an air pressure of 0.4MPa to remove the resin bonding phase on the surface that does not exceed 10μm. The particle size of the polymer abrasive used is 80 mesh, and the Barcol hardness of the polymer abrasive is 45HBa.

[0034] 3. Preparation of reduction layer: A layer of ABS plastic that can reduce metal ions in the chemical plating solution is coated on the surface of the pretreated CFRP substrate, and the thickness of the reduction layer is 15 μm.

[0035] 4. Surface texturing treatment. A metal stamping mold is used to stamp a frustum-shaped surface texture on the surface of the reduction layer. The stamping temperature is 140°C. The frustum texture is arranged in a periodic and close arrangement with equal spacing in the vertical and horizontal directions. The diameter of the frustum head at the surface end is Ds = 40 μm, the height of the frustum is h = 15 μm, and the taper of the frustum is T:

[0036]

[0037] α is the electromagnetic wave penetration coefficient of the frustum texture surface, which is 0.2475; ω is the electromagnetic wave frequency, which is 10 GHz.

[0038] 5. Preparation of the conductive layer: A dense Cu layer with a thickness of no more than 5 μm is textured on the surface of the stamped frustum.

[0039] 6. Preparation of the main electromagnetic shielding layer: A dense Ni layer with a thickness of more than 10 μm is electroplated on the surface of the textured chemically plated Cu layer on the frustum surface. The chemically plated Cu and electroplated Ni adopt the existing process methods. When electroplating Ni, the anode needs to use a mesh Ni electrode and force the plating solution to flow.

[0040] 6. Coating shielding effect: The CFRP surface textured electromagnetic shielding coating has a shielding effectiveness of 70-90dB for electromagnetic waves in the 8-12GHz band.

[0041] Example 3.

[0042] 1. Pretreatment, reduction layer preparation, surface texturing, conductive layer preparation, and main electromagnetic shielding layer preparation are performed on the CFRP substrate.

[0043] 2. Matrix pretreatment: First, use acetone ultrasonic cleaning for 5 minutes to remove the attached pollutants on the substrate surface, and then use the polymer abrasive air jet method under an air pressure of 0.5MPa to remove the resin bonding phase on the surface that does not exceed 10μm. The particle size of the polymer abrasive used is 100 mesh, and the Barcol hardness of the polymer abrasive is 55HBa.

[0044] 3. Preparation of reduction layer: A layer of ABS plastic that can reduce metal ions in the chemical plating solution is coated on the surface of the pretreated CFRP substrate, and the thickness of the reduction layer is 20 μm.

[0045] 4. Surface texturing treatment. A metal stamping mold is used to stamp a frustum-shaped surface texture on the surface of the reduction layer. The stamping temperature is 150°C. The frustum texture is arranged in a periodic and close arrangement with equal spacing in the vertical and horizontal directions. The diameter of the frustum head at the surface end is Ds = 20 μm, the height of the frustum is h = 20 μm, and the taper of the frustum is T:

[0046]

[0047] α is the electromagnetic wave penetration coefficient of the frustum texture surface, which is 0.1583; ω is the electromagnetic wave frequency, which is 10 GHz.

[0048] 5. Preparation of the conductive layer: A dense Cu layer with a thickness of 5 μm was textured on the surface of the stamped frustum.

[0049] 6. Preparation of the main electromagnetic shielding layer: A 10 μm dense Ni layer is electroplated on the surface of the textured chemically plated Cu layer on the frustum surface. The chemically plated Cu and electroplated Ni adopt the existing process methods. When electroplating Ni, the anode needs to use a mesh Ni electrode and force the plating solution to flow.

[0050] 7. Coating shielding effect: The CFRP surface textured electromagnetic shielding coating has a shielding effectiveness of 70-90dB for electromagnetic waves in the 8-12GHz band.

[0051] The pre-treatment, preparation process and post-treatment not involved in the present invention are the same as those in the prior art or can be implemented by using the prior art.

Claims

1. A method for preparing a CFRP surface textured electromagnetic shielding coating, characterized in that: The preparation process includes CFRP matrix pretreatment, reduction layer preparation, surface texturing treatment, conductive layer preparation and main electromagnetic shielding layer preparation.

2. The preparation method according to claim 1, characterized in that: The CFRP substrate pretreatment first cleans the attached pollutants on the substrate surface, and then uses a high molecular polymer abrasive air jet method to remove the bonding phase on the surface not exceeding 10 μm at an air pressure of 0.3 to 0.5 MPa. The particle size of the polymer abrasive used is 50 to 100 mesh, and the Barcol hardness of the polymer abrasive is 35 to 55 HBa.

3. The preparation method according to claim 1, characterized in that: The reduction layer is prepared by coating a layer of ABS plastic layer capable of reducing metal ions in the chemical plating solution on the surface of the pretreated CFRP substrate, and the thickness of the reduction layer is 10-20 μm.

4. The preparation method according to claim 1, characterized in that: The surface texturing treatment uses a metal stamping mold to stamp a frustum-shaped surface texture on the surface of the reduction layer. The stamping temperature is 130-150°C. The frustum texture is arranged in a periodic and close arrangement with equal spacing in the vertical and horizontal directions. The diameter of the frustum head at the surface end is Ds = (20-50) μm, the height of the frustum is h = (10-20) μm, and the relationship between the frustum taper T and the electromagnetic wave frequency ω attenuated by the shielding layer is: α is the electromagnetic wave penetration coefficient of the frustum texture surface, ranging from 0 to 0.707; ω is the electromagnetic wave frequency, Hz; γ is the electrical conductivity of the composite coating, S / m; μ is the magnetic permeability of the composite coating, H / m.

5. The preparation method according to claim 1, characterized in that: The conductive layer is prepared by chemically plating a dense Cu layer with a thickness not exceeding 5 μm on the surface of the stamped frustum. The main electromagnetic shielding layer is prepared by electroplating a dense Ni layer with a thickness of more than 10 μm on the surface of the chemically plated Cu layer on the surface of the frustum. When electroplating Ni, a mesh Ni electrode is required for the anode and the plating solution is forced to flow.

6. The preparation method according to claim 1, characterized in that: The CFRP surface textured electromagnetic shielding coating has a shielding effectiveness of 70 to 90 dB for electromagnetic waves in the 8 to 12 GHz band.

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