Carbon Fiber Materials: Detailed Explanation of Characteristics and Production Processes

Carbon fiber materials have many characteristics, and their production processes are also relatively complex.

**I. Characteristics of carbon fiber materials**

1. High strength and high modulus: Several times stronger than steel. When subjected to force, it has high rigidity and plays an outstanding role in fields such as aerospace and racing.

2. Low density: Much lower than metal materials, making products lightweight. Suitable for fields such as aerospace and sporting goods that pursue weight reduction.

3. Strong corrosion resistance: Stable performance in harsh environments, no rust or corrosion, prolonging service life and reducing maintenance costs.

4. Good thermal stability: Can maintain performance at relatively high temperatures and can be used in high-temperature environments.

5. Good electrical conductivity: Conductivity can be adjusted through treatment to meet different needs.

6. Strong designability: The weaving structure and layup angle can be selected according to needs to achieve the best mechanical properties.

**II. Production process of carbon fiber materials**

1. Preparation of precursor:

• - Polymerization reaction: Using PAN, asphalt or rayon as raw materials. For example, in PAN-based carbon fiber, acrylonitrile monomers are polymerized through free radical addition reaction. One-step or two-step methods can be used to prepare polymerization solutions.

• - Spinning: There are wet spinning and dry-jet wet spinning. Wet spinning is simple to operate but the quality of precursor is low. Dry-jet wet spinning can produce high-performance precursor but has high requirements.

2. Pre-oxidation treatment: In air at 200 - 300°C, the linear molecular chains of the precursor are transformed into heat-resistant trapezoidal structures to improve thermal stability and oxidation resistance.

3. Carbonization stage: Under the protection of inert gas, it is heated to 1000 - 1500°C for high-temperature carbonization to remove non-carbon atoms and form carbon fiber with high carbon content.

4. Graphitization treatment: At a higher temperature, the crystallinity and orientation degree are further improved to enhance performance.

5. Surface treatment: Give the fiber chemical activity to better combine with resins and others. 6. Sizing treatment: Protect the fiber and improve affinity with resin. 7. Winding and packaging: Form product output.