Study On The Relationship Between Micromechanics And Macroscopic Mechanical Properties Of Carbon Fiber Laser Graphitization

Carbon fiber reinforced polymer(CFRP)has many advantages,such as easy to form in large area,good specific strength,small weight of forming parts and so on.Many fields with high requirements for material properties,such as military weapons,sports,wind power,etc.,regard it as an irreplaceable material choice.And its high price hinders its further expansion of application fields and scope.Therefore,people are actively looking for new materials and technologies to reduce the cost of carbon fiber production and processing.In view of the shortcomings of low temperature rise limit,easy loss of furnace body and high energy consumption in the traditional graphitization process of carbon fiber,the laser graphitization device came into being.The carbon fiber was irradiated by laser,and the centralized heating of carbon fiber was realized by using the photo thermal conversion effect,which reduced the energy consumption and simplified the equipment.However,in practice,there are some problems in the operation of carbon fiber graphitization equipment,and the mechanism of graphitization process is different from that of traditional reaction furnace.Therefore,the relationship between microstructure and mechanical properties of carbon fiber during laser graphitization was studied.The main research contents are as follows:Firstly,the laser graphitization equipment was improved,the stable and continuous operation of carbon fiber laser graphitization tow was realized,and the continuous graphite fiber tow was prepared.The optimal power density condition for Shanghai Petrochemical's original polyacrylonitrile(Pan)T300 grade carbon fiber tow was 250 W/cm2,and the tensile modulus was increased by 8%.Secondly,based on the carbon fiber structure theory and microscopic characterization,such as electron microscope(SEM),X-ray diffraction(XRD)and small angle X-ray scattering(SAXS)experimental results,the three main components of microcrystalline,microporous and amorphous carbon in the carbon fiber were determined.The change of carbon fiber morphology in different power density,and the heating ability is better than that of traditional graphite furnace.The size orientation of microcrystalline is improved during the laser reaction,which is beneficial to enhance the modulus of carbon fiber.Finally,the surface treatment of the fiber before and after laser graphitization of T300 carbon fiber in Shanghai Petrochemical Company was carried out.Using SEM and XPS to analyzing the change of fiber's morphology and chemical structure.Finally,a protective argon recovery plasma generator was proposed to improve the utilization rate of argon.