Electromagnetic shielding coating on the surface of resin-based composite material and preparation method thereof

Abstract

An electromagnetic shielding coating and its preparation method are disclosed on the surface of a resin-based composite material (such as phenolic resin). The coating is prepared by using arc spraying and cold gas dynamic spraying (hereinafter referred to as cold spraying) to prepare an aluminum coating on the surface of the resin-based composite material, thereby giving it electromagnetic shielding properties. The coating raw materials are pure aluminum wire and plasma-spheroidized pure aluminum powder. The outer diameter of the aluminum wire is Φ3mm, and the particle size of the aluminum powder is 5-45μm. Arc spraying: spraying voltage 35-40V, spraying current 250-450A, spraying distance 180-240mm, robotic arm walking speed 300-500mm / s, translational step distance 4-6mm, coating thickness 0.05-0.1mm. Cold spraying: the carrier gas is nitrogen, spraying gas pressure 5-7MPa, spraying gas temperature 300-500℃, spraying distance 20-40mm, powder feed rate 30-50g / s, robotic arm walking speed 300-500mm / s, translational step distance 1-3mm, coating thickness 0.5-1mm. The prepared coating has a bonding strength ≥3MPa, porosity ≤3%, and coating resistivity ≤3.5×10⁻⁶. ‑8 Ωm.

Description

Technical Field

[0001] This project belongs to the field of surface engineering technology and relates to a method for preparing electromagnetic shielding coatings on resin-based composite materials (such as phenolic resin composites). Using this technology, electromagnetic shielding coatings can be prepared on resin-based composite heat shielding sleeves and other components. The substrate is minimally affected by the heat-affected zone during spraying, the coating deposition efficiency is high and fast, the coating thickness is controllable, and the deposited coating has high bonding strength with the substrate. Furthermore, it allows for subsequent grinding or machining. This is a new technology for preparing electromagnetic shielding coatings on resin-based composite materials such as heat shielding sleeves. It is expected to be widely applied in aerospace, aviation, and machinery fields to improve the shortcomings of existing thermal spraying technologies and enhance component reliability. Background Art

[0002] Resin-based composite materials have been widely used in recent years for hot-end components such as heat shields due to their excellent thermodynamic properties. However, this material itself is a wave-transmitting material and does not possess electromagnetic shielding properties. This project employs arc spraying and cold gas dynamic spraying technologies to prepare a metallic aluminum coating on the surface of the resin-based composite material, thereby endowing it with electromagnetic shielding properties to meet the electromagnetic shielding functional requirements of the component.

[0003] Arc spraying technology uses an electric arc to melt the spraying filament, and then uses a high-speed airflow to atomize and accelerate the molten spraying material onto the workpiece surface to form a coating. This technology is widely used in engineering fields such as corrosion protection and wear resistance. Cold air dynamics spraying technology (referred to as cold spraying technology) is a coating preparation technology based on the principles of aerodynamics and high-speed collision dynamics. The principle of this technology is to send spraying powder of a certain particle size into a preheated high-speed airflow, accelerate it, and impact the substrate at high speed in a completely solid state, producing large plastic deformation and depositing it on the substrate surface to form a coating.

[0004] Arc spraying technology, due to its high spraying temperature, can easily cause thermal damage to resin-based composite materials during prolonged spraying. Cold spraying technology, due to its high particle velocity, can easily cause erosion of the resin-based composite material, preventing coating formation. Therefore, this technology combines arc spraying and cold spraying techniques. First, an aluminum coating of approximately 0.1 mm thickness is prepared on the resin-based composite material using arc spraying technology, and then an aluminum coating of approximately 0.5 mm thickness is prepared using cold spraying technology. Using this coating preparation method, the temperature rise of the resin-based composite material substrate is low (not exceeding 80℃), the coating adhesion is high (greater than 3 MPa), the coating deposition efficiency is high and fast, the coating thickness is controllable, and subsequent grinding or machining is possible. This achieves the goal of rapidly depositing and preparing a metallic electromagnetic shielding coating on the surface of resin-based non-metallic composite components requiring electromagnetic shielding. Summary of the Invention

[0005] The technical problem solved by this invention is to overcome the shortcomings of existing technologies and provide an electromagnetic shielding coating and its preparation method on the surface of a resin-based composite material. By employing arc spraying and cold gas dynamic spraying technologies, a metallic aluminum coating is prepared on the surface of the resin-based composite material, giving it electromagnetic shielding properties to meet the functional requirements of electromagnetic shielding components. The electromagnetic shielding coating prepared on the resin-based composite material using this technology exhibits minimal heat-affected zone of the substrate during spraying, high coating deposition efficiency and speed, controllable coating thickness, and high bonding strength between the deposited coating and the substrate. This meets the electromagnetic shielding performance requirements of resin-based non-metallic composite components, solving the problem that resin-based composite materials themselves do not possess electromagnetic shielding properties.

[0006] The technical solution of the present invention is:

[0007] A method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material, comprising:

[0008] An aluminum underlayer was arc-sprayed onto the surface of a resin-based composite material sample, and then a cold spraying process was used to spray aluminum cold spray powder onto the aluminum underlayer to obtain a cold spray layer; the aluminum underlayer and the cold spray layer form an electromagnetic shielding coating.

[0009] The cold spray powder is made from pure aluminum powder through plasma spheroidization and is suitable for cold spraying.

[0010] The pure aluminum powder has a purity of ≥99.9% and a particle size of 40-65μm. The cold spray powder prepared after plasma spheroidization has a purity of ≥99.9% and a particle size of 5-45μm.

[0011] The plasma spheroidization process parameters include: main gas flow rate of 80-100 scfh, auxiliary gas flow rate of 5-10 scfh, current of 600-750 A, and powder feeding rate of 40-50 g / min.

[0012] The resin-based composite material is a phenolic resin composite material; the thickness of the electromagnetic shielding coating is 0.5-1mm; the raw material for preparing the aluminum substrate is Φ3mm pure aluminum wire with a purity ≥99%.

[0013] The arc spraying process parameters include: spraying voltage 35-40V, spraying current 250-450A, spraying distance 180-240mm, robotic arm walking speed 300-500mm / s, and translation step distance 4-6mm.

[0014] The thickness of the aluminum substrate is 0.05-0.1 mm.

[0015] The cold spraying process parameters include: nitrogen as the carrier gas, spraying gas pressure of 5-7 MPa, spraying gas temperature of 300-500℃, spraying distance of 20-40 mm, powder feeding rate of 30-50 g / s, robotic arm walking speed of 300-500 mm / s, and translation step distance of 1-3 mm.

[0016] The coating thickness obtained by the cold spraying is 0.5-1 mm.

[0017] An electromagnetic shielding coating on the surface of a resin-based composite material is obtained according to any of the above-described methods for preparing an electromagnetic shielding coating on the surface of a resin-based composite material.

[0018] In summary, this application includes at least the following beneficial technical effects:

[0019] 1. By combining arc spraying and cold spraying processes, an electromagnetic shielding coating with a thickness of 0.5-1mm was prepared.

[0020] 2. By using arc spraying technology to prepare an underlayer of appropriate thickness on the surface of resin-based composite materials, it is ensured that the cold spraying process can spray a thick aluminum coating on the surface of resin-based composite materials, thereby achieving excellent electromagnetic shielding performance of the surface of resin-based composite materials.

[0021] 3. The electromagnetic shielding coating prepared in this application has high preparation efficiency, low coating porosity, and coating adhesion that is significantly better than traditional brushing of metal coatings and pasting of metal films. The coating prepared by spraying can be directly machined without cracking or falling off.

[0022] 4. This application solves the problem that the preparation of electromagnetic shielding coatings by simple arc spraying is prone to causing thermal damage to the surface of resin-based composite materials, and the industry problem that aluminum coatings cannot be prepared on the surface of resin-based composite materials by using cold spraying technology alone. It overcomes the technical problem of preparing high-performance electromagnetic shielding coatings on the surface of resin-based composite materials. Attached Figure Description

[0023] Figure 1 Example 1: Macroscopic morphology photos of the resin-based composite material before and after applying an electromagnetic shielding coating;

[0024] Figure 2 Example 1: Scanning electron microscope image of the cross-section of the electromagnetic shielding coating. Detailed Implementation

[0025] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0026] Example 1

[0027] Pure aluminum powder with a purity of ≥99.9% and a particle size of 5-45μm is plasma spheroidized to produce a powder suitable for cold spraying with a purity of ≥99.9% and a particle size of 5-45μm. The plasma spheroidization process parameters are: main gas flow rate of 80scfh, auxiliary gas flow rate of 5scfh, current of 600A, and powder feed rate of 40g / min.

[0028] The aluminum base layer is coated by electric arc spraying. The raw material for the coating is Φ3mm pure aluminum wire with a purity of ≥99%. The electric arc spraying process parameters are: spraying voltage 35V, spraying current 250A, spraying distance 180mm, robot arm walking speed 300mm / s, translation step distance 4mm, and coating thickness 0.05mm.

[0029] An electromagnetic shielding coating is obtained by spraying the aforementioned powder suitable for cold spraying onto an aluminum substrate using a cold spraying process. The cold spraying process parameters are as follows: the carrier gas is nitrogen, the spraying gas pressure is 5MPa, the spraying gas temperature is 300℃, the spraying distance is 20mm, the powder feeding rate is 30g / s, the robot arm walking speed is 300mm / s, the translation step distance is 1mm, and the coating thickness is 0.5mm.

[0030] Coating performance test results: Coating bond strength 3.62 MPa, coating porosity 1.35%, coating resistivity 3.4 × 10⁻⁶. -8 Ωm.

[0031] Appendix Figure 1 Macroscopic morphology photos of the resin-based composite material surface before and after applying an electromagnetic shielding coating are attached. Figure 2 The attached image shows a scanning electron microscope (SEM) image of the cross-section of the electromagnetic shielding coating. As can be seen from the attached image, the surface of the resin-based composite electromagnetic shielding coating prepared in this application is intact and free of cracks. The cross-sectional structure of the coating is dense with no obvious pores, and the interface between the coating and the substrate is tightly bonded without obvious cracks.

[0032] Example 2

[0033] Pure aluminum powder with a purity ≥99.9% and a particle size of 5-45μm is plasma spheroidized to produce a powder suitable for cold spraying with a purity ≥99.9% and a particle size of 5-45μm. The plasma spheroidization process parameters are: main gas flow rate of 100scfh, auxiliary gas flow rate of 10scfh, current of 750A, and powder feeding rate of 50g / min.

[0034] The aluminum base layer is coated by electric arc spraying. The raw material for the coating is Φ3mm pure aluminum wire with a purity of ≥99%. The electric arc spraying process parameters are: spraying voltage 40V, spraying current 450A, spraying distance 240mm, robot walking speed 500mm / s, translation step distance 6mm, and coating thickness 0.1mm.

[0035] The aforementioned powder suitable for cold spraying is applied to an aluminum substrate using a cold spraying process to obtain an electromagnetic shielding coating. The cold spraying process parameters are as follows: the carrier gas is nitrogen, the spraying gas pressure is 7MPa, the spraying gas temperature is 500℃, the spraying distance is 40mm, the powder feeding rate is 50g / s, the robot arm walking speed is 500mm / s, the translation step distance is 3mm, and the coating thickness is 1mm.

[0036] Coating performance test results: Coating bond strength 4.19 MPa, coating porosity 0.93%, coating resistivity 3.2 × 10⁻⁶. -8 Ωm.

[0037] Examples 3-6

[0038] The thicknesses of the aluminum substrate in Examples 3-6 are 0.02 mm, 0.07 mm, 0.1 mm, and 0.15 mm, respectively.

[0039] All other preparation conditions are as follows: pure aluminum powder with a purity ≥99.9% and a particle size of 5-45μm is plasma spheroidized to produce a powder suitable for cold spraying with a purity ≥99.9% and a particle size of 5-45μm. The plasma spheroidization process parameters are: main gas flow rate of 80scfh, auxiliary gas flow rate of 5scfh, current of 600A, and powder feeding rate of 40g / min.

[0040] The aluminum underlayer is obtained by arc spraying: the raw material for spraying is Φ3mm pure aluminum wire with a purity of ≥99%, and the process parameters for arc spraying are: spraying voltage 35V, spraying current 250A, spraying distance 180mm, robot arm walking speed 300mm / s, and translation step distance 4mm.

[0041] An electromagnetic shielding coating is obtained by spraying the aforementioned powder suitable for cold spraying onto an aluminum substrate using a cold spraying process. The cold spraying process parameters are as follows: the carrier gas is nitrogen, the spraying gas pressure is 5MPa, the spraying gas temperature is 300℃, the spraying distance is 20mm, the powder feeding rate is 30g / s, the robot arm walking speed is 300mm / s, the translation step distance is 1mm, and the coating thickness is 0.5mm.

[0042] The coating performance test results are shown in Table 1.

[0043] Table 1: Test results of electromagnetic shielding coatings on aluminum substrates of different thicknesses

[0044]

[0045] Examples 7-9

[0046] Examples 7-9 differ only in the plasma spheroidization process parameters.

[0047] The plasma spheroidization process parameters in Example 7 are: main gas flow rate of 60 scfh, auxiliary gas flow rate of 4 scfh, current of 500 A, and powder feeding rate of 30 g / min.

[0048] The plasma spheroidization process parameters in Example 8 are as follows: main gas flow rate is 90 scfh, auxiliary gas flow rate is 8 scfh, current is 675 A, and powder feed rate is 45 g / min.

[0049] The plasma spheroidization process parameters for Example 9 are: main gas flow rate of 100 scfh, auxiliary gas flow rate of 10 scfh, current of 750 A, and powder feeding rate of 50 g / min.

[0050] All other preparation conditions were the same as in Example 1.

[0051] The coating performance test results are shown in Table 2.

[0052] Table 2: Detection results of electromagnetic shielding coatings with different plasma spheroidization process parameters

[0053] Coating adhesion strength / MPa Coating porosity / % Coating resistivity / Ωm Remark Example 7 2.43 3.07 <![CDATA[4.6×10 -8 ]]> Example 8 3.44 1.17 <![CDATA[3.3×10 -8 ]]> Example 9 3.59 1.19 <![CDATA[3.3×10 -8 ]]>

[0054] Examples 10-12

[0055] Examples 10-12 differ only in the arc spraying process parameters.

[0056] The arc spraying process parameters for Example 10 are: spraying voltage 32V, spraying current 200A, spraying distance 160mm, robotic arm walking speed 200mm / s, and translation step distance 3mm.

[0057] The arc spraying process parameters for Example 11 are: spraying voltage 38V, spraying current 350A, spraying distance 210mm, robotic arm walking speed 400mm / s, and translation step distance 5mm.

[0058] The arc spraying process parameters for Example 12 are: spraying voltage 40V, spraying current 450A, spraying distance 240mm, robot arm walking speed 500mm / s, and translation step distance 6mm.

[0059] All other preparation conditions were the same as in Example 1.

[0060] The coating performance test results are shown in Table 3.

[0061] Table 3: Test results of electromagnetic shielding coatings with different arc spraying process parameters

[0062]

[0063] Examples 13-15

[0064] Examples 13-15 differ only in the cold spraying process parameters.

[0065] The cold spraying process parameters for Example 13 are as follows: the carrier gas is nitrogen, the spraying gas pressure is 4MPa, the spraying gas temperature is 200℃, the spraying distance is 15mm, the powder feeding rate is 20g / s, the robot arm walking speed is 200mm / s, and the translation step distance is 0.5mm.

[0066] The cold spraying process parameters for Example 14 are as follows: the carrier gas is nitrogen, the spraying gas pressure is 6MPa, the spraying gas temperature is 400℃, the spraying distance is 30mm, the powder feeding rate is 40g / s, the robot arm walking speed is 400mm / s, and the translation step distance is 2mm.

[0067] The cold spraying process parameters for Example 15 are as follows: the carrier gas is nitrogen, the spraying gas pressure is 7MPa, the spraying gas temperature is 500℃, the spraying distance is 40mm, the powder feeding rate is 50g / s, the robot arm walking speed is 500mm / s, and the translation step distance is 3mm.

[0068] All other preparation conditions were the same as in Example 1.

[0069] The coating performance test results are shown in Table 4.

[0070] Table 4: Test results of electromagnetic shielding coatings with different cold spraying process parameters

[0071]

[0072] Comparative Example 1

[0073] The difference from Example 1 is that only arc spraying is used to prepare an electromagnetic shielding coating with a thickness of 0.55 mm.

[0074] The specific steps are as follows: use electric arc spraying to apply an aluminum coating, wherein the raw material for spraying is Φ3mm pure aluminum wire with a purity of ≥99%, and the electric arc spraying process parameters are: spraying voltage 35V, spraying current 250A, spraying distance 180mm, robotic arm walking speed 300mm / s, translation step distance 4mm, and coating thickness 0.55mm.

[0075] During this process, the surface of the resin-based composite material suffers severe thermal damage due to arc spraying, causing the coating to crack and peel off, making it impossible to prepare an electromagnetic shielding coating of the required thickness.

[0076] Comparative Example 2

[0077] The difference from Example 1 is that only cold spraying is used to prepare an electromagnetic shielding coating with a thickness of 0.55 mm.

[0078] The specific steps are as follows: The cold spraying process is used to spray the powder suitable for cold spraying prepared by the plasma spheroidization process in Example 1 onto the resin-based composite material. The cold spraying process parameters are as follows: the carrier gas is nitrogen, the spraying gas pressure is 5MPa, the spraying gas temperature is 300℃, the spraying distance is 20mm, the powder feeding rate is 30g / s, the robot arm walking speed is 300mm / s, the translation step distance is 1mm, and the coating thickness is 0.55mm.

[0079] During the cold spraying process, the resin-based composite material gradually thins due to erosion, making it impossible to prepare an electromagnetic shielding coating.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that the cold spraying powder used in the cold spraying process has not undergone plasma spheroidization, that is, the cold spraying powder is a commercially available powder with an irregular morphology.

[0082] Coating performance test results: Coating bond strength 2.43 MPa, coating porosity 5.61%, coating resistivity 5.53 × 10⁻⁶. -8 Ωm.

[0083] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material, characterized in that, include: An aluminum underlayer was arc-sprayed onto the surface of a resin-based composite material sample, and then a cold spraying process was used to spray aluminum cold spray powder onto the aluminum underlayer to obtain an electromagnetic shielding coating. The resin-based composite material is a phenolic resin composite material; The cold spray powder is made from pure aluminum powder through plasma spheroidization and is suitable for cold spraying. The cold spraying process parameters include: the carrier gas is nitrogen, the spraying gas pressure is 5-7MPa, the spraying gas temperature is 300-500℃, the spraying distance is 20-40mm, the powder feeding amount is 30-50g / s, the robot arm walking speed is 300-500mm / s, and the translation step distance is 1-3mm. The electric arc spraying process parameters include: spraying voltage 35-40V, spraying current 250-450A, spraying distance 180-240mm, robotic arm walking speed 300-500mm / s, and translation step distance 4-6mm. The thickness of the aluminum substrate is 0.05-0.1 mm.

2. The method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material according to claim 1, characterized in that: The pure aluminum powder has a purity of ≥99.9% and a particle size of 40-65μm. The cold spray powder prepared after plasma spheroidization has a purity of ≥99.9% and a particle size of 5-45μm.

3. The method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material according to claim 1, characterized in that: The plasma spheroidization process parameters include: main gas flow rate of 80-100 scfh, auxiliary gas flow rate of 5-10 scfh, current of 600-750 A, and powder feeding rate of 40-50 g / min.

4. The method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material according to claim 1, characterized in that: The thickness of the electromagnetic shielding coating is 0.5-1mm; The raw material for preparing the aluminum substrate is Φ3mm pure aluminum wire with a purity of ≥99%.

5. The method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material according to claim 1, characterized in that: The coating thickness obtained by the cold spraying is 0.5-1 mm.

6. An electromagnetic shielding coating on the surface of a resin-based composite material, characterized in that: The method for preparing an electromagnetic shielding coating on the surface of a resin-based composite material according to any one of claims 1-5 is as follows.

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