A composite material heating method with double-sided plasma discharge

Abstract

A method for heating composite materials using double-sided plasma discharge is characterized by placing the composite material between first and second electrode structures, applying an alternating electric field to the electrodes on both sides, causing simultaneous gas discharge between one surface of the composite material and the first electrode, and between the other surface and the second electrode, thus heating both sides of the composite material simultaneously. The temperature of both sides of the composite material is controlled by adjusting the type of gas on both sides, the height of the gas gap, or the frequency, amplitude, duty cycle, and discharge time of the alternating electric field, or a combination of the above control variables. This invention utilizes plasma to heat the composite material on both sides, reducing the temperature gradient during the heating process, improving heating uniformity, and enhancing the quality of the composite material's curing.

Description

Technical Field

[0001] This invention relates to the field of composite material heating technology, and in particular to a composite material heating method based on double-sided plasma discharge. Specifically, it is a double-sided heat source heating technology for composite materials, applicable to the heating, curing, and molding processes of composite materials. Background Technology

[0002] In recent years, the application of composite materials in aerospace and advanced manufacturing has been expanding, placing higher demands on the uniformity and controllability of the temperature field during molding and heating. However, traditional methods such as autoclaves and ovens suffer from low heating efficiency, high energy consumption, large temperature differences, and difficulty in temperature control. While newer heating and curing methods based on principles such as electric heating, radio frequency heating, and microwave heating offer better energy transfer directionality, their contact uniformity is poor, and electromagnetic energy is significantly affected by the shape of coils, antennas, waveguides, and cavities, resulting in uneven curing temperature fields. To address these shortcomings, cold plasma generated by dielectric barrier discharge has been increasingly introduced into material processing and heating. Utilizing cold plasma to excite Joule heating within composite materials enables directional, non-contact heating, demonstrating considerable application potential.

[0003] In existing technologies, dielectric barrier discharge (DBD) has been widely used in material processing and related heating fields, and its processing schemes mostly adopt a single-sided electrode configuration. For example, Chinese patent CN206674287U discloses a surface dielectric barrier discharge plasma material device, which generates plasma on the material surface through a single-sided electrode and dielectric layer structure. This technology is mainly used for single-sided plasma material surface treatment and does not involve effective heating of the material interior or thickness direction. US patent US20230405884A1 discloses a method for repairing composite materials using single-sided DBD plasma. It induces heat generation inside the carbon fiber composite material by applying plasma to one side of the damaged patch, thereby achieving local heating. However, this method essentially relies on the material's conductivity and still adopts a single-sided discharge structure. It is difficult to reach the curing temperature on the back of the thick plate, and it needs to rely on the bottom ground plane to form a circuit, resulting in uneven temperature distribution in the thickness direction and limiting the shape and size of the processed parts. In addition, US patent US20240140020A1 discloses a plasma-based material processing or heating scheme, which achieves energy input through single-sided or asymmetric discharge, but it also lacks the ability to coordinate heating of both sides of the material and independent temperature control.

[0004] Existing technologies all employ a method of placing the composite material between two electrode structures and making contact with one of them, resulting in an overall structure with only a single-sided air gap discharge. This method leads to the problem that only one side of the composite material can be heated. Through extensive experiments, the inventors discovered that when a certain gas gap exists between the composite material and the contacting electrode structure, discharge and plasma generation also occur within this gas gap. Therefore, the inventors conducted numerous double-sided discharge heating experiments. By adjusting parameters such as the height of the double-sided air gap, simultaneous discharge on both sides of the composite material was achieved, enabling precise control of the temperature field on both sides. Therefore, this patent protects a heating method for double-sided plasma discharge.

[0005] This invention aims to solve the problem of large temperature gradients in existing single-sided plasma heating methods for composite materials, and proposes a double-sided plasma heating method for composite materials. This double-sided plasma heating method introduces symmetrical heating into plasma heating technology, enabling symmetrical temperature distribution on both sides of the composite material, significantly reducing the temperature gradient along the thickness direction. Simultaneously, the introduction of vacuum bag pressure couples heating and pressurization, further improving the uniformity of the heating temperature of the composite material and achieving high-quality heat curing. Summary of the Invention

[0006] The purpose of this invention is to address the problems of single-sided heating and large temperature difference in existing plasma discharge heating methods for composite materials. This invention provides a double-sided plasma heating method for composite materials, overcoming the large temperature difference in the thickness direction and the lack of pressure application in existing plasma heating methods. It offers a double-sided plasma discharge heating method for composite materials to achieve simultaneous heating and temperature control on both sides. In a preferred embodiment, it achieves coordinated control of the heating and pressurization processes, thereby improving the temperature uniformity of the composite material.

[0007] The technical solution of this invention is:

[0008] A method for heating composite materials by double-sided plasma discharge includes the following steps: (1) placing the composite material between a first electrode structure and a second electrode structure; (2) applying an alternating electric field to the first electrode structure and the second electrode structure, so that the gas between one side surface of the composite material and the first electrode and the gas between the other side surface and the second electrode simultaneously discharge, thereby achieving synchronous heating of both sides of the composite material.

[0009] Furthermore, a dielectric barrier layer is provided on the surface of the first electrode structure and the second electrode structure, wherein the dielectric barrier layer is ceramic, quartz glass, fluoroplastic, polyimide or other insulating dielectric layer material.

[0010] Furthermore, the waveform of the alternating electric field is preferably a sine wave, a pulse, a square wave, or a combination of the above waveforms.

[0011] Furthermore, the gas is air, or an inert gas, or a reactive gas, or a combination of the above gases, with helium or argon being preferred inert gases.

[0012] Furthermore, the heating power is adjusted by regulating the types of gases on both sides, the gas gap height, the frequency, amplitude, duty cycle, and discharge time of the alternating electric field, or a combination of the above control variables to regulate the temperature on both sides of the composite material. An offline setting control scheme can be used, or an online control scheme based on monitoring feedback signals can be used. The online control scheme involves measuring the temperature value on one side of the composite material. When the measured temperature is higher than the target temperature, the gas gap height on that side is increased; conversely, the gas gap height is decreased. The other side uses the same online temperature control scheme, and the temperatures on both sides are regulated independently. When the temperatures on both sides need to be increased or decreased simultaneously, the amplitude of the alternating electric field can be increased or decreased to achieve this. The monitoring feedback signal is obtained through a contact or non-contact temperature sensor, preferably a fiber optic grating sensor that is insensitive to discharge. The sensor can be embedded in the interlayer of the composite material or placed on one side of the composite material surface.

[0013] Furthermore, during the heating process, a vacuum bag is used to vacuum seal the composite material, and the composite material is simultaneously pressurized under dual-sided heating conditions.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] Compared to plasma heating technology with single-sided discharge and no pressurization, this invention has the following advantages: 1. Symmetrical heating on both sides: Through a dual-sided synchronous discharge structure, symmetrical heating is formed on both sides of the composite material. Compared with the single-sided discharge method, the temperature gradient in the thickness direction of the composite material can be significantly reduced. Experimental verification shows that the reduction can reach up to 92%; 2. Strong temperature controllability: Fine temperature control can be achieved through multi-variable coupling and regulation of gas parameters, electric field parameters, and gas gap height; 3. Support for independent adjustment: The temperature on both sides of the composite material supports simultaneous dual-sided regulation and independent single-sided regulation, which is suitable for complex requirements; 4. Compatible with pressurized curing process: The dual-sided plasma heating method proposed in this invention can be combined with vacuum bag pressurization process to achieve synchronous heating and pressurization, thereby improving the heating effect of the composite material. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a specific embodiment of the present invention, which uses a double-sided plasma discharge and vacuum pressurization structure to heat a composite laminate.

[0017] The numbers in the diagram are explained as follows: 1. Upper electrode (high voltage electrode); 2. Lower electrode (grounding electrode); 3. Upper dielectric barrier layer; 4. Lower dielectric barrier layer; 5. Composite material; 6. Upper gas gap; 7. Lower gas gap; 8. Vacuum bag; 9. Support structure; 10. Vacuum nozzle; 11. Temperature sensor (preferably FBG). Detailed Implementation

[0018] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention. The invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Implementation, for example Figure 1 As shown.

[0020] Figure 1 The image shows a composite laminate component. The laminate is made of carbon fiber reinforced resin matrix composite material, and the layup structure is [0°]. 30 A total of 30 layers of prepreg, each 3 mm thick, are used. The component is heated and cured using the double-sided plasma heating method of this invention. The specific steps are as follows:

[0021] Step 1: Prepare the prepreg and lay it up uniformly at 0°. Simultaneously, a temperature sensor 11 is installed inside the composite material 5 to monitor and control the temperature during the heating process. The temperature sensor 11 and the composite material 5 are integrated as a whole, fixed to support structures 9 on both sides, and placed inside a vacuum bag 8. A sealing structure is used to seal the bag, and a negative pressure environment is created through a vacuum nozzle 10, allowing pressurization under external pressure.

[0022] Step 2: Place the vacuum-evacuated composite material 5 between the upper electrode 1 (i.e., the first electrode, usually a high-voltage electrode) and the lower electrode 2 (i.e., the second electrode, usually a ground electrode), and respectively set an upper dielectric barrier layer 3 and a lower dielectric barrier layer 4 on the surfaces of the upper electrode 1 and the lower electrode 2. An upper gas gap 6 and a lower gas gap 7 are formed between the composite material 5 and the dielectric barrier layers. The gases on the upper and lower sides can be the same gas or different gases, and their discharge parameters can be adjusted according to process requirements to optimize the dual-sided heating effect.

[0023] Step 3: An alternating electric field is applied to the electrode structure using power supply V, causing discharge between the upper gas gap 6 and the lower gas gap 7, generating plasma and thus achieving double-sided heating. During the heating process, the temperature of the composite material 5 can be monitored and controlled in real time by adjusting the gas gap or alternating electric field parameters based on the temperature feedback from the pre-embedded temperature sensor 11.

[0024] The above description is merely one specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art can make various modifications or substitutions to the above embodiments without departing from the spirit and substance of the present invention, and all such modifications and substitutions should fall within the scope of protection of the present invention. Furthermore, the structural forms, material types, and process parameters involved in this embodiment are merely illustrative examples and do not constitute a limitation on the scope of protection of the present invention. Parts not covered in this invention are implemented using existing technologies.

Claims

1. A method for heating composite materials using double-sided plasma discharge, characterized in that, The method includes the following steps: (1) placing the composite material between the first and second electrode structures; (2) applying an alternating electric field to the electrodes on both sides, so that the gas between one side surface of the composite material and the first electrode and the other side surface and the second electrode discharge simultaneously, thereby heating both sides of the composite material.

2. The method according to claim 1, characterized in that: The first and second electrode structures have a dielectric barrier layer on their surfaces, which is made of ceramic, quartz glass, fluoroplastic, polyimide or other insulating dielectric layer.

3. The method according to claim 1, characterized in that: The waveform of the alternating electric field is a sine wave, a pulse, a square wave, or a combination of the above waveforms.

4. The method according to claim 1, characterized in that: The gas is in the form of air, an inert gas, a reactive gas, or a combination thereof.

5. The method according to claim 4, characterized in that: The inert gases are helium and argon.

6. The method according to claim 1, characterized in that: The heating power is controlled by adjusting the types of gases on both sides, the gas gap height, the frequency, amplitude, duty cycle, discharge time of the alternating electric field, or a combination of the above control variables to regulate the temperature on both sides of the composite material. An offline control scheme or an online control scheme based on monitoring feedback signals is used. The online control scheme measures the temperature on one side of the composite material; if the measured temperature is higher than the target temperature, the gas gap height on that side is increased, and vice versa. The other side uses the same online temperature control scheme, and the temperatures on both sides are controlled independently. When both sides need to be adjusted simultaneously, the amplitude of the alternating electric field is increased or decreased. The monitoring feedback signal is obtained through a contact or non-contact temperature sensor. The sensor can be embedded in the interlayer of the composite material or placed on one side of the composite material surface.

7. The method according to claim 6, characterized in that: The temperature sensor is a fiber Bragg grating sensor that is insensitive to discharge.

8. The method according to claim 1, characterized in that: During the heating process, the composite material is vacuum-sealed using a vacuum bag, and pressure is applied to the composite material simultaneously under dual-sided heating conditions.

Images