阅读说明：本技术 一种基于常压dbd放电的碳纤维表面连续处理方法和装置 (Carbon fiber surface continuous treatment method and device based on normal-pressure DBD discharge ) 是由 罗思海 李榕凯 何卫锋 聂祥樊 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种基于常压DBD放电的碳纤维表面连续处理方法和装置,涉及等离子体表面工程技术领域。本发明提供的装置包括：包括供气系统、等离子体发生系统和碳纤维传送系统；供气系统包括气体源和混合气腔体,等离子体发生系统包括激励电源、高压电极、接地电极、绝缘介质以及半密闭腔体,碳纤维传送系统包括驱动装置、送/放装置。碳纤维等离子体表面连续处理方法是将碳纤维通过传动系统连续输送进入到预设的气氛环境介质下DBD放电等离子体工作腔,进行等离子体处理,实现碳纤维表面粗化,同时在表面产生活性基团,从而提高复合材料内部碳纤维与树脂基体的粘结强度。(The invention discloses a carbon fiber surface continuous treatment method and device based on normal-pressure DBD discharge, and relates to the technical field of plasma surface engineering. The device provided by the invention comprises: comprises a gas supply system, a plasma generation system and a carbon fiber conveying system; the gas supply system comprises a gas source and a mixed gas cavity, the plasma generation system comprises an excitation power supply, a high-voltage electrode, a grounding electrode, an insulating medium and a semi-closed cavity, and the carbon fiber conveying system comprises a driving device and a conveying/discharging device. The continuous treatment method of the carbon fiber plasma surface is characterized in that carbon fibers are continuously conveyed to enter a DBD discharge plasma working cavity in a preset atmosphere environment medium through a transmission system to be subjected to plasma treatment, the surface roughening of the carbon fibers is realized, and active groups are generated on the surface, so that the bonding strength of the carbon fibers and a resin matrix in the composite material is improved.)

1. A carbon fiber surface continuous treatment method based on normal-pressure DBD discharge is characterized by comprising the following steps:

opening gas cylinder valves of functional gas and inert gas according to a preset atmosphere environment, controlling the flow of corresponding gas cylinders, wherein the flow range is 0-50L/min, mixing the gas cylinders, filling the whole discharge cavity with mixed gas, ensuring that the discharge medium is in the preset atmosphere environment and the pressure is atmospheric pressure, and the functional gas can be oxygen, nitrogen dioxide and oxygen-containing gas; the inert gas is helium or argon;

step two, under the normal pressure atmosphere environment obtained in the step one, an electrode is connected with a high-frequency direct-current power supply, voltage is applied to two electrodes of a medium, the voltage is 10 kV-20 kV, a uniform and stable plasma area is formed, and mixed gas is adopted to purge the plasma area before the power supply is connected to generate plasma, so that the whole plasma is ensured to be filled with the mixed gas when the plasma is generated;

and step three, setting the motor speed according to the length of the discharge medium and the treatment time, and enabling the carbon fiber to continuously pass through the plasma zone obtained in the step two at the speed of 0.1-1.2m/min, thus finishing the treatment of the surface of the carbon fiber.

2. The method for continuously treating the surface of the carbon fiber based on the atmospheric-pressure DBD discharge as claimed in claim 1, wherein the predetermined atmosphere is determined according to the expected surface active groups of the carbon fiber after the continuous treatment.

3. The method for continuously processing the surface of the carbon fiber based on the atmospheric-pressure DBD discharge as claimed in claim 1, wherein the carbon fiber is subjected to a surface photoresist removing treatment before the processing in the step three.

4. The utility model provides a carbon fiber surface continuous processing device based on ordinary pressure DBD discharges which characterized in that: the device comprises a gas supply system, a plasma generation system and a carbon fiber conveying system, wherein the gas supply system comprises a gas source (1) and a mixed gas cavity (2), the gas source (1) comprises different types of inert gases, oxygen-containing gases or other gases, and each gas source comprises a switch regulating valve (11), a pressure gauge (12) and a flow meter (13); the gas mixture chamber (2) should contain a plurality of gas inlets, at least four, for mixing different types of gases into the chamber (2). The plasma generating system comprises an excitation power supply (4), a high-voltage electrode (14), a grounding electrode (15), an insulating medium (16) and a semi-closed cavity (17), wherein the first four of the high-voltage electrode and the grounding electrode form a Dielectric Barrier Discharge (DBD) device, the carbon fiber conveying system comprises a driving device (6), a take-up machine (7), a wire pressing wheel (8) and a paying-off machine (9), at least four wire pressing wheels are needed, two wire pressing wheels are arranged at two ends of the plasma and used for fixing the position of the carbon fiber (10) and ensuring that the carbon fiber can smoothly pass through a plasma reaction chamber (18); the other two wire pressing wheels are used for controlling the trend of carbon fibers, the carbon fibers discharged by the pay-off machine (9) pass through the wire pressing wheels (8), pass through the plasma reaction chamber (18), and are withdrawn by the take-up machine (7) after passing through the wire pressing wheels (8), wherein the take-up machine (7) is driven by the driving device (6), the driving device (6) works to drive the take-up machine (7) to work, the pay-off machine (9) is driven to pay off, and the automation of the whole process of carbon fiber plasma processing is realized.

5. The device for continuously treating the surface of the carbon fiber based on the atmospheric pressure DBD discharge, according to claim 4, is characterized in that: the gas source (1) is a gas cylinder filled with different gases, and each gas cylinder is provided with a switch regulating valve (11), a pressure gauge (12) and a gas flowmeter (13).

6. The device for continuously treating the surface of the carbon fiber based on the atmospheric pressure DBD discharge, according to claim 4, is characterized in that: the semi-closed cavity (17) is made of an insulating material, the cavity on the left side is designed into different external dimensions according to requirements, the wire pressing wheel can be conveniently installed, the front side and the rear side are transparent and visible at least, the left side is hermetically connected with the mixed gas cavity (2) through the gas inlet (3), and the right side of the cavity completely contains the whole DBD device; in addition, it only needs to ensure that the carbon fiber is led out to form a small hole on the left side of the cavity, the position of the small hole is flush with the position of the carbon fiber (10), and the carbon fiber is ensured to penetrate out of the small hole.

7. The device for continuously treating the surface of the carbon fiber based on the atmospheric pressure DBD discharge, according to claim 4, is characterized in that: the two wire pressing wheels (8) are not limited by size, but are positioned on two sides of the plasma reaction chamber (18), and the installation positions of the two wire pressing wheels (8) ensure that the carbon fiber (10) passing through the plasma area is positioned at the zero potential position of the center of the plasma area, so that the carbon fiber is prevented from being ablated on the conductive surface; other creasing rollers have no definite position limitation, but have the function of keeping the carbon fibers in a tense state all the time in the processing process.

8. The device for continuously treating the surface of the carbon fiber based on the atmospheric pressure DBD discharge, according to claim 4, is characterized in that: the material of the wire pressing wheel, the material of the wire rewinding machine, the material of the wire unwinding machine and the material of the shaft wheel are all conductive materials.

9. The device for continuously treating the surface of the carbon fiber based on the atmospheric pressure DBD discharge, according to claim 4, is characterized in that: the driving device (6) comprises a programmable automatic controller and a stepping/servo motor, and the controller is programmed according to the requirement of the movement rate to realize the accurate control of the stepping/servo motor.

Technical Field

The invention belongs to the field of surface engineering, and relates to a carbon fiber surface continuous treatment method and device based on normal-pressure DBD discharge. More particularly, it relates to a method for modifying the surface of reinforced fiber in composite material to improve the binding force between the reinforced fiber and matrix and improve the strength of the composite material.

Background

The composite material has the obvious advantages of high specific strength, high specific rigidity, good corrosion resistance and the like, and has been widely applied in various fields of aerospace, automobiles, energy power and the like. In the aerospace field, the composite material is one of four major structural materials, the dosage of the composite material is gradually increased in military and civil aviation, and the dosage of the composite material represents the advanced level of an airplane to a certain extent.

Carbon fibers have attracted much attention in the field of composite materials because they have excellent tensile strength, fatigue strength, etc. and are lightweight as reinforcing fibers. The interface between the carbon fiber and the matrix is an important stress transfer surface of the composite material, and the property of the interface is directly related to the performance of the composite material. The carbon fiber has smooth surface, and like the resin and other matrixes, the surface is chemically inert, so that the bonding force between the carbon fiber and the matrix is insufficient, even the problems of 'Kiss bond' (the Kiss bond, which only contacts but has no defects, geometrically meets the requirements but can not transfer load), Weak bonding (the Weak bond bonding strength is Weak and is less than 20% of the normal bonding strength) and the like occur, the overall performance of the composite material is finally influenced, and the use safety of the component is seriously threatened. Therefore, the development of a carbon fiber surface treatment technology is urgently needed, the surface hydrophilicity and the chemical activity of the carbon fiber are improved, the surface is roughened, the contact area between the carbon fiber and a matrix is increased, the bonding force between the carbon fiber and the matrix is improved, and the safe use of the composite material is ensured.

The surface modification method of the carbon fiber mainly comprises a physical method and a chemical method. The chemical modification is to introduce active groups such as amino, carboxyl, hydroxyl and the like on the surface of the fiber through chemical reaction so as to improve the bonding strength between the fiber and a matrix; the physical modification is to etch the surface of the fiber by using physical technologies such as plasma, electron beams and the like, introduce active groups such as hydroxyl, carbonyl and the like through breaking and recombination of chemical bonds, and simultaneously change the surface appearance characteristics of the fiber, thereby realizing the improvement of the bonding strength. Plasma surface treatment belongs to one of physical modification methods.

At present, there are many plasma generating methods, and DBD discharge, glow discharge, radio frequency induction coupling discharge, and the like are used in many aspects of fiber surface treatment. Because the carbon fiber is a conductive material, plasma treatment is carried out in an air environment, surface ablation is easy to occur, most of the existing plasma treatment is carried out in a vacuum or closed cavity to obtain a good surface state, the requirement on equipment is high, and large-scale automatic treatment is difficult to realize.

The invention provides a method and a device for continuously treating the surface of carbon fiber based on normal-pressure DBD discharge, aiming at reinforced carbon fiber for composite material, which can realize DBD discharge plasma treatment of the carbon fiber in atmospheric environment. The application of the invention can greatly improve the bonding strength of the carbon fiber and the matrix, further improve the service life of the composite material, and has important military value and obvious economic benefit.

Disclosure of Invention

The invention aims to provide a method and a device for continuously treating the surface of carbon fiber based on normal-pressure DBD discharge, which are used for solving the problems that the prior art lacks equipment for treating the surface of the carbon fiber, has low efficiency, can only be carried out in a vacuum or sub-vacuum environment, is not economical and the like.

In order to achieve the above object, the present invention provides a method for continuously treating a carbon fiber surface based on a normal pressure DBD discharge, the method comprising:

controlling the flow of each gas cylinder according to a preset atmosphere environment, opening a corresponding gas cylinder valve to mix the gas cylinders and enable the whole discharge cavity to be filled with mixed gas, and ensuring that the discharge medium is in the preset atmosphere environment and the pressure is atmospheric pressure.

And step two, under the normal-pressure atmosphere environment obtained in the step one, the electrode is connected with a high-frequency direct-current power supply, voltage is applied to two electrodes of the medium to form uniform and stable plasma, and the density of the plasma at the center of the generated plasma area is tested through the probe.

And step three, setting the motor speed according to the length of the discharge medium and the treatment time, and enabling the carbon fiber to continuously pass through the plasma zone obtained in the step two at a certain speed, namely finishing the treatment of the surface of the carbon fiber.

The atmosphere in the first step is a mixed gas containing a functional gas and an inert gas, wherein the functional gas may be oxygen, nitrogen dioxide, an oxygen-containing gas, and the like, and the inert gas is generally helium, argon, and the like. The selection and flow control of the functional gas are determined by the predetermined atmosphere, that is, by the surface active groups after the intended continuous treatment of the fiber surface.

Before the power supply is switched on to generate plasma, the plasma area is purged by adopting mixed gas, so that the whole plasma area is full of the mixed gas when the plasma is generated; the voltage applied during plasma treatment is 10-20 kV. The probe is used for monitoring and measuring the plasma density at the center of the plasma area under different discharge parameters.

And (3) carrying out surface photoresist removing treatment on the carbon fibers before treatment, wherein the passing speed of the carbon fibers in a plasma area is adjustable within the range of 0-0.1 m/s during treatment.

In order to achieve the purpose, the invention also provides a carbon fiber surface continuous treatment device based on normal-pressure DBD discharge, which comprises an air supply system, a plasma generation system, a plasma testing system and a carbon fiber conveying system. Wherein the gas supply system comprises two parts of a gas source and a mixed gas cavity, wherein the gas source comprises different types of inert gases, oxygen-containing gases or other gases, and each gas source comprises a switch regulating valve, a pressure gauge and a flow meter; the gas mixing cavity should contain a plurality of gas inlets, at least four, for mixing different types of gases into the gas mixing cavity. The plasma generating system comprises an excitation power supply, a high-voltage electrode, a grounding electrode, an insulating medium and a semi-closed cavity, wherein the first four of the high-voltage electrode, the grounding electrode, the insulating medium and the semi-closed cavity form a Dielectric Barrier Discharge (DBD) device. The carbon fiber conveying system comprises a driving device, a take-up machine, wire pressing wheels and a pay-off machine, wherein the number of the wire pressing wheels is at least four, and the two wire pressing wheels are arranged at two ends of the plasma and used for fixing the position of the carbon fiber and ensuring that the carbon fiber can smoothly pass through the plasma reaction chamber; the other two wire pressing wheels are used for controlling the trend of the carbon fiber. Carbon fiber emitted by the pay-off machine passes through the plasma reaction chamber through the wire pressing wheel and is withdrawn by the take-up machine after passing through the wire pressing wheel, wherein the take-up machine is driven by the driving device, the driving device drives the take-up machine to work to drive the pay-off machine to pay off, and the automation of the whole process of carbon fiber plasma treatment is realized.

Furthermore, in the carbon fiber surface continuous treatment device based on the normal-pressure DBD discharge, the gas source is a gas cylinder filled with different gases, and each gas cylinder is provided with a switch regulating valve, a pressure gauge and a gas flowmeter.

Furthermore, the semi-closed cavity is made of an insulating material, the cavity on the left side is designed into different external dimensions according to requirements, so that the wire pressing wheel can be conveniently installed, the front side and the rear side are at least transparent and visible, the left side is hermetically connected with the mixed gas cavity through the gas inlet, and the right side of the cavity completely contains the whole DBD device; in addition, it only needs to ensure to lead out the carbon fiber to be the aperture to open at the cavity left side, and aperture position and carbon fiber position parallel and level ensure that the carbon fiber is worn out from this aperture.

Furthermore, the two wire pressing wheels are not limited by size, but are arranged at the two sides of the plasma reaction chamber, and the installation positions of the two wire pressing wheels ensure that carbon fibers passing through the plasma region are positioned at the zero potential position at the center, so that the carbon fibers are prevented from being ablated on the conductive surface; other creasing rollers have no definite position limitation, but have the function of keeping the carbon fibers in a tense state all the time in the processing process.

Furthermore, in the carbon fiber surface continuous treatment device based on normal-pressure DBD discharge, the material of the wire pressing wheel, the material of the wire rewinding machine, the material of the wire unwinding machine and the material of the shaft wheel are all conductive materials.

Furthermore, in the carbon fiber surface continuous treatment device based on the normal-pressure DBD discharge, the driving device (6) comprises a programmable automatic controller and a stepping/servo motor, and the controller is programmed according to the requirement of the movement rate to realize the accurate control of the stepping/servo motor.

Compared with the prior art, the invention has the following beneficial effects: the DBD discharge can be in a preset atmosphere environment by arranging the air supply system, and the DBD discharge can be carried out in the air environment; a fiber conveying system is arranged, so that automatic large-scale processing of the carbon fibers can be realized; in addition, the surface of the carbon fiber is treated by using a DBD discharge plasma treatment device, the surface of the carbon fiber is etched by plasma, active groups are generated on the surface while the surface is roughened, the bonding strength between the carbon fiber and a matrix is enhanced, and the performance of the composite material is improved. The carbon fiber surface continuous treatment device provided by the invention solves the problem that the DBD discharge plasma treatment of the carbon fiber can only be carried out in a vacuum or sub-vacuum environment.

Drawings

FIG. 1 is a carbon fiber surface plasma continuous treatment device based on atmospheric pressure DBD discharge;

FIG. 2 shows a DBD discharge plasma generation device of a carbon fiber surface plasma continuous processing device based on atmospheric pressure DBD discharge.

Detailed Description

The implementation is explained in detail with reference to fig. 1-2. According to the preset plasma discharge atmosphere environment and pressure, starting a corresponding gas source, and adjusting a switch adjusting valve 11 according to a pressure gauge 12 and a flowmeter 13 to enable the gas components and content to meet the preset atmosphere environment requirement; the opened gas enters the mixed gas cavity 2 to be mixed and is sent into the semi-closed cavity 17 through the gas inlet 3, and the mixed gas is ionized through DBD discharge in the plasma reaction chamber 18 to generate plasma; the carbon fiber 10 passes through the plasma reaction chamber 18 under the driving of the wire feeding/transmitting system, and is treated in the plasma generated by the DBD discharge for a certain time, so that the surface of the carbon fiber 10 is roughened, and meanwhile, a large number of active groups are introduced, so that the bonding strength between the carbon fiber and the matrix is improved, and further, the performance of the carbon fiber composite material is improved.

The plasma treatment process of the carbon fiber comprises the following steps:

step 1, removing glue and cleaning carbon fibers 10, and drying for later use; the specific cleaning process comprises the following steps: the carbon fiber is washed by deionized water, then is soaked in acetone or alcohol solution for 24 hours, is taken out and washed by the deionized water, and is dried.

And 2, sequentially penetrating carbon fibers 10 through a semi-closed cavity 17 and a plasma reaction chamber 18, sequentially placing the carbon fibers on a wire pressing wheel 8 in sequence, fixing the initial fiber/tow on a driving wire winding machine 7, placing a carbon fiber bundle on a wire releasing machine 9, and manually adjusting the wire winding machine to keep the carbon fibers in a tight state.

And 3, adjusting the positions of the wire pressing wheels 8 on two sides of the semi-closed cavity 17 to keep the wire pressing wheels at the same horizontal position, and simultaneously enabling the carbon fiber 10 arranged on the wire pressing wheels to be positioned at the center of the plasma reaction chamber 18.

And 4, opening the corresponding switch regulating valve 11 of the gas source 1 according to the preset discharge atmosphere environment, and regulating the size of the gas released by the switch regulating valve 11 according to the monitoring of the pressure gauge 12 and the flowmeter 13 to obtain the mixed gas meeting the preset atmosphere environment requirement.

The mixed gas contains functional gas and inert gas, wherein the functional gas is selected according to requirements, if active groups such as C-O, O-C-O, C-N are generated on the surface of the fiber, the corresponding gas source switch regulating valve 11 is opened to introduce corresponding elements, and the content of the elements is controlled by considering the requirements of the active groups expected to be formed on the surface of the fiber and considering the requirements of a DBD discharge atmosphere environment. When no new elements need to be introduced, the inert gas is directly selected. To avoid filament discharge or other ribbon discharge that may damage the carbon fibers 10, the content of the functional gas in the mixture should not be too high.

And step 5, switching on the direct current power supply 4 to enable the atmosphere environment between the electrodes to be broken down, and further ionizing the mixed gas in the plasma reaction chamber 18 to generate plasma. In the discharge starting stage, the plasma related parameters are monitored through the plasma testing system 5, and then the input voltage and the frequency of the power supply 4 are adjusted to obtain the preset plasma processing parameters.

And 6, starting the driving device 6, driving the take-up machine 7 to work, driving the pay-off machine 9 to prevent wires, and controlling the carbon fiber conveying direction by the wire pressing wheel 8, so that the carbon fibers 10 finally penetrate through the plasma reaction chamber 18 at a certain speed.

The speed of the carbon fiber is realized by adjusting the driving device 6, the speed value is determined according to the length of the electrode 15 and the preset carbon fiber processing time, the carbon fiber processing time is ensured to be met, and the processing time is from tens of seconds to tens of minutes. In the discharging process, the plasma testing system 5 also needs to monitor relevant parameters of the plasma in real time to ensure that the plasma environment for processing the carbon fibers is kept consistent, and if fluctuation occurs, the input parameters of the power supply 4 are adjusted in time.

In conclusion, the plasma acts on the carbon fiber passing through the plasma reaction chamber, on one hand, the surface of the fiber is etched to roughen the surface of the fiber, on the other hand, a large number of charged particles in the plasma generated by discharge irradiate the surface of the fiber to recombine chemical bonds on the surface of the fiber to form a new compound, a large number of active groups are introduced to improve the surface energy of the carbon fiber, and the two aspects jointly act to improve the bonding force between the carbon fiber and the matrix. The device for carbon fiber surface treatment based on atmospheric DBD discharge is simple, overcomes the defect that carbon fiber DBD surface treatment is carried out in a vacuum or low-pressure environment, and solves the problem that the industry lacks the device for carbon fiber surface treatment based on atmospheric DBD discharge.