Study On High Temperature Laser Graphitization Process And Continuous Production Equipment Of Pan-based Carbon Fibers

Carbon fiber,a high-performance material,has broad application prospects in aerospace,automotive industry,new energy and leisure products.At present,the domestic industries of carbon fibers are developing rapidly,but the preparation of high performance carbon fibers still cannot meet the requirements of the state and related industries,and the technical problems of high temperature graphitization of carbon fibers need to be solved.However,ultra high temperature graphitization furnace and ultra high temperature heat treatment technology are the key technical difficulties in the preparation of high-performance carbon fiber.In this project,laser induced graphitization of carbon fiber method is used to prepare high performance carbon fibers based on laser graphitization technology.The relationship between the microstructure and the macro property and process of laser graphitization is explored,which provides a reference for the preparation of high performance carbon fiber by laser graphitization at ultra high temperature.The main contents of this paper are as follows:(1)The method of laser induced graphitization of carbon fiber is explored and verified,and the feasibility of the principle is confirmed.Then the related experimental platform was designed for experimental exploration based on the principle.A series of carbon fiber specimens under different conditions were prepared via the experimental platform.The chemical structure and microstructure of carbon fibers were studied by Raman spectroscopy and XRD ray diffraction.The change of carbon fiber surface after laser treatment was studied by scanning electron microscope.(2)Based on the preliminary experimental exploration and the design and the improvement of experimental platforms,ultra-high temperature graphitization equipment of carbon fiber via laser was further designed and manufactured according to the equipment parameters and technological parameters summarized by the experiments.The equipment realized the continuous graphitization process of carbon fiber via laser at ultra high temperature,and provided a platform support for the further experimental research.(3)The experimental results show that the graphitization degree of carbon fiber after laser graphitization is significantly increased,and with the increase of laser power,the order of microstructure and graphitization degree of carbon fiber are gradually increased in a certain power range.Meanwhile,the size of graphite microcrystalline Lc and La increase,the spacing of graphite microcrystalline layer decreases,and the number of stacking layers increases.The increase of drafting force can also promote the improvement of laser graphitization to a certain extent,and the carbon fibers are forced to choose the preferred orientation along the fiber axis.The extension of lase graphitization time can also increase the graphitization degree.Some cracks happened on the surface of carbon fibers after laser treatment,and the strength decreased,however the modulus increased.