A kind of graphite fiber with laminated cross-section structure and its melt spinning method

Abstract

The invention provides a graphite fiber with a laminated cross-section structure and a melt spinning method thereof, comprising the following steps: step 1, using mesophase pitch for melt spinning to obtain fiber precursors; the spinneret hole cross section used for melt spinning It is rectangular, and the outlet chamfer is provided on the long side of the spinneret outlet, and the inner surface of the spinneret is coated with a layer of nickel, silver or platinum metal coating; step 2, the fiber precursors are sequentially subjected to non-melting carbonization and graphitization After processing, graphite fibers with a laminated cross-sectional structure are obtained. The present invention prepares fiber precursors with elliptical cross-sections. After non-melting carbonization and graphitization, the graphite sheets are approximately parallel to the direction of the long side of the fiber cross-section, so that La and Lc of graphite microcrystals can be fully developed. The graphite flakes are less wrinkled and dense, and the thermal conductivity of the final graphite fiber can reach 800-1100W / (m·K).

Description

technical field [0001] The invention belongs to the technical field of polymer fiber materials, and in particular relates to a graphite fiber with a laminated section structure and a melt spinning method thereof. Background technique [0002] Carbon fiber is a fibrous carbon material with a lower density than metal aluminum, but higher strength than steel, and has the characteristics of corrosion resistance and high modulus. Graphite fiber generally refers to carbon fiber with a carbon content of more than 99%. Compared with carbon fiber, graphite fiber not only has a high carbon content, but also has a high tensile modulus, and also has a small thermal expansion coefficient, good thermal stability, and stable dimensions. Excellent performance, so it is used to manufacture rigid, thin and dimensionally stable composite components, which are widely used in spacecraft and aerospace fields. The outstanding characteristics of mesophase pitch-based graphite fibers are their extr...

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Problems solved by technology

At present, the cross-section of pitch-based carbon fiber with high thermal conductivity is generally approximately circular, and the graphite microcrystalline structure of the cross-section is radial, onion-skin-like, laminated, composite or random-layered, etc. The laminated structure is conducive to the improvement of thermal conductivity. However, in the current carbon fibers with approximately circular cross-sections, the graphite sheets in the laminated structure are distributed perpendicular to the long side of the fiber cross-section, which restricts the growth of the microcrystalline structure, which in turn restricts the improvement of the thermal conductivity of carbon fibers.

Some scholars proposed a melt-spinning method with rectangular spinneret holes, and ribbon fibers were obtained by adjusting the aspect ratio of the holes, but the graphite sheets in the microcrystalline structure of the cross-section still showed a structure arranged perpendicular to the long side of the fiber cross-section , which restricts the growth of microcrystalline structure and the improvement of carbon fiber thermal conductivity to a certain extent, and the ribbon fiber is also not conducive to the subsequent application of composite materials.

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