Carbon fiber has excellent mechanical, chemical and electrical properties. It is an indispensable strategic new material for national economy and national defense construction. It is known as “black gold”. In the 21st century, the carbon fiber production technology has matured. In the future, with the continuous development of carbon fiber composite molding technology, the downstream application field continues to develop, especially the strong growth of aviation, automobile and wind power blades, and its driving role, the development prospect of carbon fiber industry. broad.

Carbon fiber industry chain

The Carbon fiberindustry chain can be roughly divided into the upstream of the production of carbon fiber materials and the downstream of the production of carbon fiber application parts. Enterprises between the upstream and downstream can be considered as equipment suppliers in the carbon fiber production process.

According to our classification, the upstream of the carbon fiber industry chain includes the process from raw silk to carbon fiber, that is, the raw silk is processed by a process of oxidation furnace, carbonization furnace, graphitization furnace, surface treatment, sizing, etc. After carbonization and other processes, it becomes a carbon fiber mainly composed of a graphite fiber structure.

The upstream of the carbon fiber industry chain is the petrochemical industry, which mainly obtains acrylonitrile through processes such as crude oil refining, cracking, and ammonia oxidation; carbon fiber enterprises produce polyacrylonitrile by polymerizing acrylonitrile-based raw materials, and then obtain them by spinning. Polyacrylonitrile raw silk, pre-oxidation, carbonization and other processes to obtain carbon fiber, through the processing of carbon fiber and high-quality resin to obtain carbon fiber composite material to meet the application needs.

The production process of Carbon fiber mainly includes: drawing, drawing, stabilizing, carbonizing and graphitizing.

Drawing: This is the first step in the production process of carbon fiber. This process is a physical change, mainly the separation of raw materials into a fiber process. In this process, mass transfer and heat transfer between the spinning stream and the coagulating liquid. Balanced movement. A strand that causes PAN to precipitate to form a gel structure.

Drafting: Generally carried out at a temperature of 100-300 degrees, which is achieved according to the stretching effect of the knot oriented fibers. This process is also a key step in achieving high modulus, high strengthening, densification and refinement of PAN fibers.

Stable: It is also known as pre-softening. The thermoplastic PAN linear macromolecular chain is converted into a non-plastic heat-resistant trapezoidal structure by heating and oxidizing at 400 ° C, so that it does not melt and burn at high temperature, maintains the fiber morphology, and the thermodynamics is in a stable state.

Carbonization: It is carried out in the range of 1000-2000 degrees, and the non-carbon elements in the PAN are driven out, and finally carbon fibers having a chaotic layer graphite structure containing more than 90% of carbon are formed.

Graphitization: In the range of 2000-3000 degrees, the transformation of amorphous and chaotic carbonized materials into a three-dimensional graphitized structure is the main technical measure to improve the modulus of carbon fibers.

The PAN raw yarn produced by the raw silk production process is pre-drawn by the wet heat of the wire feeder, and then sent to the pre-oxidation furnace by the drafting mechanism, and is obtained through different gradient temperature fields of several pre-oxidation furnace groups. Pre-oxidized fiber (pre-oxidized wire); pre-oxidized wire successively enters medium-temperature carbonization furnace and high-temperature carbonization furnace to obtain carbon fiber; carbon fiber is subjected to final surface treatment, sizing, drying and other processes to obtain carbon fiber finished product. The whole process of continuous wire routing, precise control, some problems in any process will affect the quality of stable production and final carbon fiber products. The carbon fiber production process is long, the technical key points are high, and the production barriers are high. It is a multi-disciplinary and multi-technology integration.

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