Preparation process of carbon fiber composite materials

Overview of Carbon-Carbon Composite Materials

Carbon/carbon (C/C) composite material [https://www.vet-china.com/cc-composite-cfc/] is a carbon fiber reinforced composite material with a series of excellent properties such as high strength and modulus, light specific gravity, small thermal expansion coefficient, corrosion resistance, thermal shock resistance, good friction resistance, and good chemical stability. It is a new type of ultra-high temperature composite material.

C/C composite material [https://www.vet-china.com/custom-high-strength-high-temperature-resistant-cc-composite-material-carbon-fiber-felt.html/] is an excellent thermal structure-functional integrated engineering material. Like other high-performance composite materials, it is a composite structure composed of a fiber-reinforced phase and a basic phase. The difference is that both the reinforced phase and the basic phase are composed of pure carbon with special properties.

Carbon/carbon composite materials [https://www.vet-china.com/carbon-fiber-composites-cc.html/] are mainly made of carbon felt, carbon cloth, carbon fiber as reinforcement, and vapor deposited carbon as matrix, but it only has one element, which is carbon. In order to increase the density, the carbon generated by carbonization is impregnated with carbon or impregnated with resin (or asphalt), that is, carbon/carbon composite materials are made of three carbon materials.

Image: https://www.vet-china.com/uploads/Carbon-carbon-composites-6.jpg

Manufacturing process of carbon-carbon composite materials

1) Choice of carbon fiber

The selection of carbon fiber bundles and the structural design of fiber fabrics are the basis for manufacturing C/C composite [https://www.vet-china.com/custom-high-temperature-thermal-field-carbon-fiber-composite-cfc.html/]. The mechanical properties and thermophysical properties of C/C composites can be determined by rationally selecting fiber types and fabric weaving parameters, such as yarn bundle arrangement orientation, yarn bundle spacing, yarn bundle volume content, etc.

2) Preparation of carbon fiber preform

Carbon fiber preform refers to a blank that is formed into the required structural shape of the fiber according to the product shape and performance requirements in order to carry out the densification process. There are three main processing methods for preformed structural parts: soft weaving, hard weaving and soft and hard mixed weaving. The main weaving processes are: dry yarn weaving, pre-impregnated rod group arrangement, fine weaving puncture, fiber winding and three-dimensional multi-directional overall weaving. At present, the main weaving process used in C composite materials is three-dimensional overall multi-directional weaving. During the weaving process, all woven fibers are arranged in a certain direction. Each fiber is offset at a certain angle along its own direction and interwoven with each other to form a fabric. Its characteristic is that it can form a three-dimensional multi-directional overall fabric, which can effectively control the volume content of fibers in each direction of the C/C composite material, so that the C/C composite material can exert reasonable mechanical properties in all directions.

3) C/C densification process

The degree and efficiency of densification are mainly affected by the fabric structure and the process parameters of the base material. The process methods currently used include impregnation carbonization, chemical vapor deposition (CVD), chemical vapor infiltration (CVI), chemical liquid deposition, pyrolysis and other methods. There are two main types of process methods: impregnation carbonization process and chemical vapor infiltration process.

Image: https://www.vet-china.com/uploads/Carbon-carbon-composites-1.jpg

Liquid phase impregnation-carbonization

Liquid phase impregnation method is relatively simple in equipment and has wide applicability, so liquid phase impregnation method is an important method for preparing C/C composite materials. It is to immerse the preform made of carbon fiber into the liquid impregnant, and make the impregnant fully penetrate into the voids of the preform by pressurization, and then through a series of processes such as curing, carbonization, and graphitization, finally obtain C/C composite materials [https://www.vet-china.com/custom-high-strength-friction-cc-composites-cfc.html/]. Its disadvantage is that it takes repeated impregnation and carbonization cycles to achieve the density requirements. The composition and structure of the impregnant in the liquid phase impregnation method are very important. It not only affects the densification efficiency, but also affects the mechanical and physical properties of the product. Improving the carbonization yield of the impregnant and reducing the viscosity of the impregnant have always been one of the key issues to be solved in the preparation of C/C composite materials by liquid phase impregnation method.

The high viscosity and low carbonization yield of the impregnant are one of the important reasons for the high cost of C/C composite materials. Improving the performance of the impregnant can not only improve the production efficiency of C/C composite materials and reduce their cost, but also improve the various properties of C/C composite materials. Anti-oxidation treatment of C/C composite materials Carbon fiber begins to oxidize at 360 degrees C in the air. Graphite fiber is slightly better than carbon fiber, and its oxidation temperature begins to oxidize at 420 degrees C. The oxidation temperature of C/C composite materials is about 450 degrees C. C/C composite materials are very easy to oxidize in a high-temperature oxidative atmosphere, and the oxidation rate increases rapidly with the increase of temperature. If there are no anti-oxidation measures, the long-term use of C/C composite materials in a high-temperature oxidative environment will inevitably cause catastrophic consequences. Therefore, the anti-oxidation treatment of C/C composite materials has become an indispensable part of its preparation process. From the perspective of anti-oxidation technology, it can be divided into internal anti-oxidation technology and anti-oxidation coating technology.

Chemical Vapor Phase

Chemical vapor deposition (CVD or CVI) is to deposit carbon directly in the pores of the blank to achieve the purpose of filling the pores and increasing the density. The deposited carbon is easy to graphitize, and has good physical compatibility with the fiber. It will not shrink during re-carbonization like the impregnation method, and the physical and mechanical properties of this method are better. However, during the CVD process, if carbon is deposited on the surface of the blank, it will prevent the gas from diffusing into the internal pores. The carbon deposited on the surface should be removed mechanically and then a new round of deposition should be carried out. For thick products, the CVD method also has certain difficulties, and the cycle of this method is also very long.

Image: https://www.vet-china.com/uploads/Carbon-carbon-composites-3.jpg

Media Contact
Company Name: Ningbo VET Energy Technology Co., Ltd
Email:Send Email [https://www.abnewswire.com/email_contact_us.php?pr=preparation-process-of-carbon-fiber-composite-materials]
Country: China
Website: https://www.vet-china.com/



This release was published on openPR.