preface
Carbon fiber composite material is a material with excellent performance, with the characteristics of light weight, high strength, corrosion resistance, damping and so on.
With the rapid development of modern radio technology, the requirements for materials are getting higher and higher. Traditional metal materials are not only heavy, but also susceptible to corrosion and poor seismic performance, so they cannot meet the development needs of radio technology.
Starting from the basic structure, preparation method and electromagnetic characteristics of carbon fiber composites, this paper discusses the application of carbon fiber composites in the radio field.
The basic structure and preparation method of carbon fiber composite
Carbon fiber composite is a high-performance composite material composed of carbon fiber and matrix materials. Its basic structure consists of carbon fiber as the strength component, and the matrix material, which is the component that transmits the load and fixes the fiber.
Carbon fiber is usually made of high-strength, high-modulus polyacrylonitrile (PAN) fiber, which is carbonized at high temperature to make its mass fraction more than 90% pure carbon fiber.
Its preparation methods include hand-layering, automated manufacturing, prepreg preparation and spinning.
Among them, manual stacking is the most traditional and simplest method, but it is inefficient and is generally used for small batch production and research.
Automated manufacturing includes automatic cutting, automatic stacking, automatic molding and other processes, which can achieve efficient, stable and controllable production.
Prepreg preparation is the pre-coating of a layer of matrix resin on the fibers to make a semi-finished product, which is then heated and cured, and is often used in large-scale production.
Spinning is the direct production of carbon fiber materials into thread, which is then used for weaving or preparation into composite materials.
When preparing carbon fiber composites, a variety of factors need to be considered, such as fiber ratio, lamination method, resin type, heating conditions, etc. At the same time, it is also necessary to carry out subsequent processing and surface treatment of products, such as shearing, perforation, bonding, etc., to adapt to different application scenarios.
Electromagnetic wave transmission of carbon fiber composites
The electromagnetic wave transmission performance of carbon fiber composites refers to the ability of electromagnetic waves to transmit in the material. Under normal circumstances, carbon fiber composites have certain absorption and reflection capabilities for electromagnetic waves, while the transmission ability is weak, which makes carbon fiber composites have certain limitations in electromagnetic wave applications.
Carbon fiber in carbon fiber composites is itself a conductive material capable of absorbing and scattering electromagnetic waves.
Secondly, the structure of carbon fiber composites contains two different materials, fiber and matrix, and the interaction between them leads to the reflection and scattering of electromagnetic waves. Moreover, the thickness and fiber arrangement of carbon fiber composites will also affect the transmission performance of electromagnetic waves.
For the electromagnetic wave transmission problem of carbon fiber composites, the researchers proposed some solutions. For example, in the preparation of carbon fiber composites, multi-layer structures and carbon fibers arranged at different angles can be used to optimize their electromagnetic wave transmission performance.
At the same time, carbon fiber composites can also be coated or coated with electromagnetic wave shielding materials to enhance their electromagnetic wave shielding capabilities.
It should be noted that the electromagnetic wave transmission performance of carbon fiber composites behaves differently in different frequency ranges.
In practical applications, carbon fiber composites have stronger electromagnetic wave absorption and scattering capabilities in the higher frequency range, while their transmission capacity is relatively high in the lower frequency range.
The electromagnetic wave transmission performance of carbon fiber composites is a complex problem, which needs to comprehensively consider the structure, preparation process and application environment of the material, and adopt a variety of means to optimize and improve.
Electromagnetic shielding of carbon fiber composites
The electromagnetic shielding performance of carbon fiber composite materials refers to the absorption and scattering ability of the material to electromagnetic waves, and its main mechanism includes three ways: reflection, scattering and absorption. Carbon fiber composite material has excellent electromagnetic shielding performance and can be widely used in the field of electromagnetic shielding. The following will conduct an in-depth analysis of the electromagnetic shielding of carbon fiber composites from three aspects: material structure, preparation process and application scenarios.
1. Material structure
The basic structure of carbon fiber composite materials includes two parts, carbon fiber and matrix, in which carbon fiber has conductive properties, and the matrix usually adopts non-conductive materials.
In electromagnetic shielding applications, the conductive nature of carbon fiber is the key to achieving shielding effect. During the preparation process, the electromagnetic shielding performance of the material can be adjusted by controlling factors such as the orientation and density of the carbon fiber, the choice of the matrix material, and the thickness of the material.
2. Preparation process
The preparation process of carbon fiber composite has a great influence on its electromagnetic shielding performance. The traditional preparation methods include manual lamination, prepreg method and hot pressing molding, etc., and the carbon fiber composites prepared by these methods have good electromagnetic shielding performance.
With the development of technology, new preparation methods such as self-assembly, electrochemical deposition and laser sintering have gradually been applied to the preparation of carbon fiber composites, which can control the structure and properties of materials more accurately.
3. Application scenarios
The electromagnetic shielding application scenarios of carbon fiber composite materials include electronic equipment, communication equipment, aerospace vehicles, automobiles and other fields. Among them, electronic equipment and communication equipment are the main application fields of carbon fiber composite electromagnetic shielding.
In these fields, carbon fiber composite materials are often used to make electromagnetic shielding boxes, electromagnetic shielding windows and other components to protect equipment from external electromagnetic wave interference.
For the improvement of the electromagnetic shielding performance of carbon fiber composites, it can also be improved by adding conductive fillers, surface coatings, etc.
For example, adding conductive powders (such as silver powder, copper powder, etc.) to the composite matrix can improve the conductivity and electromagnetic shielding performance of the material; Oxidation or metal-plated coating on the surface of carbon fiber can enhance the surface conductivity of carbon fiber, thereby improving the electromagnetic shielding performance of the material.
Electromagnetic properties of carbon fiber composites
Carbon fiber composites have a variety of excellent electromagnetic properties, including dielectric constant, magnetic permeability, conductivity, etc
1. Dielectric constant
The dielectric constant is the ratio of dielectric capacitance to vacuum capacitance, and is the ability of the dielectric to store charge. The dielectric constant of carbon fiber composites is lower than that of metal materials, about 2.5, while the dielectric constant of copper is about 18, so carbon fiber composites show better performance than metals in high-frequency electromagnetic fields.
2. Permeability
Permeability is the ability of a material to respond to a magnetic field, which is the ratio of magnetic induction strength to magnetic field strength. The magnetic permeability of carbon fiber composites is close to that of a vacuum, about 1, so it does not interfere with the magnetic field.
3. Conductivity
Conductivity is the ability of a material to respond to electric current, which is the ratio of current density to electric field strength. Carbon fiber composites have low conductivity, typically below 10-5 S/m, and therefore exhibit good insulation properties in high-frequency electromagnetic fields.
Application of carbon fiber composites in the field of radio
Carbon fiber composites have good electromagnetic properties and therefore have a wide range of applications in the field of radio.
1. Antenna
Carbon fiber composites are lightweight and strong, so lighter and stronger antennas can be made. In addition, the electromagnetic properties of carbon fiber composites can optimize the operating efficiency and frequency response of the antenna.
2. Radar
The application of carbon fiber composite materials in radar is mainly reflected in radomes and reflectors. Carbon fiber composite material has good electromagnetic transmittance and low radar reflection cross-section, which can improve the detection range and accuracy of radar.
3. Microwave absorption
The electromagnetic properties of carbon fiber composites can make them play an important role in microwave-absorbing materials. Using the electromagnetic properties of carbon fiber composites, composite materials with excellent wave absorption properties can be designed.
Factors affecting the electromagnetic properties of carbon fiber composites
Scientific research has found that there are many factors affecting the electromagnetic properties of carbon fiber composites, the main factors include:
Conductivity of carbon fiber: As an important component of composite materials, carbon fiber conductivity is one of the important factors affecting the electromagnetic properties of materials.
Carbon fiber with good electrical conductivity can effectively resist the interference and radiation of electromagnetic waves, thereby improving the electromagnetic shielding performance of the material.
Fiber orientation and number of layers: Carbon fiber composites are usually made of multiple layers of fibers, and the interaction between the fiber layers in different orientations affects the electromagnetic properties of the material.
Directing the fiber perpendicular to the direction of electromagnetic wave propagation can effectively suppress the penetration of electromagnetic waves.
Fiber content and distribution: Both fiber content and distribution affect the electromagnetic properties of carbon fiber composites. The higher the fiber content, the better the conductivity of the material and the improved electromagnetic shielding performance.
The distribution and arrangement of fibers will also affect the electromagnetic shielding performance of the material, for example, the smaller the layer spacing of the fiber, the stronger the electromagnetic wave reflection and absorption capacity of the material.
Thickness and shape of the material: The thickness and shape of a carbon fiber composite also affect its electromagnetic properties. In general, the greater the thickness, the weaker the penetration ability of electromagnetic waves, so materials with larger thicknesses are more suitable for electromagnetic shielding fields.
But the shape of the material also affects the reflection and absorption capacity of electromagnetic waves, for example, materials with a tapered or curved shape can effectively suppress the reflection and leakage of electromagnetic waves.
External environment and operating frequency: The external environment and operating frequency also affect the electromagnetic properties of carbon fiber composites. For example, the electromagnetic properties of materials may change at high temperatures or humidity. At the same time, electromagnetic waves of different frequencies propagate differently in the material, so the specific operating frequency needs to be considered when selecting the material.
In addition, there are other factors that also affect the electromagnetic properties of carbon fiber composites, such as the coefficient of thermal expansion of the material, the surface treatment of the fiber, and the composition of the resin matrix.
The influence of carbon fiber composites on the development of modern radio
The application of carbon fiber composite materials has promoted the development of modern radio technology, which is reflected in the following aspects:
1. Improved performance of radio equipment
The lightweight, high strength and corrosion resistance of carbon fiber composite materials make radio equipment lighter and stronger, and have better anti-interference performance and frequency response.
2. Expanded the field of radio applications
The electromagnetic properties of carbon fiber composites expand the field of radio applications, such as radar, communication, microwave absorption, etc., which provide more possibilities for the development of radio technology.
3. Promote the development of manufacturing technology of radio equipment
The application of carbon fiber composites in the radio field requires high precision and high reliability of the manufacturing process, which promotes the continuous development and advancement of radio equipment manufacturing technology.
The author's opinion
Carbon fiber composites have excellent electromagnetic properties and are widely used in the radio field. The application of carbon fiber composite materials has promoted the development of radio technology, improved the performance of radio equipment, expanded the field of radio applications, and also promoted the development of radio equipment manufacturing technology.
With the continuous advancement of science and technology, the application of carbon fiber composite materials in the field of radio will become more and more extensive, and its performance and application will be continuously optimized and improved. Therefore, the research and development of carbon fiber composites is of great significance.
bibliography
1. Wen Bo. Study on electromagnetic characteristics of carbon nanomaterials[D]. Beijing Institute of Technology, 2015
2. WANG Xiaohong,LIU Junneng. Study on microwave reflection characteristics of carbon fiber composites[J].Functional Materials,1999(04)
3. Zhu Zhengyang. Mechanical Engineering Materials,2001(11)
4. SUN Liping, ZHANG Pengtao. Electromagnetic shielding characteristics of carbon fiber composites[J]. Forestry Machinery and Woodworking Equipment, 2005(03)
5. Zhang Guixue; SUN Shuchun. Development of civil carbon fiber composites in mainland China in recent years[J]. Fiber Composites, 1985(03)