▎ 摘　　要

NOVELTY - Improving tensile strength of carbon fiber comprises transmitting preoxidized and carbonized carbon fiber bundle into high-voltage corona discharge zone and subjecting to corona treatment under - 5 to - 30 kV, while controlling moving speed at 5-30 m/hour; preparing 10-60 g/L functionalized graphene, distilled water and 0.1-1 wt.% dispersant into stable homogenous suspension; electrostatically depositing graphene on surface defects of corona-treated carbon fiber by using the suspension, while controlling moving speed at 5-30 m/hour; and heating to 300-1600 degrees C under argon atmosphere. USE - Method for improving tensile strength of carbon fiber (claimed). ADVANTAGE - The method improves the tensile strength of carbon fiber by more than 130%. DETAILED DESCRIPTION - Improving tensile strength of carbon fiber comprises: (A) transmitting preoxidized and carbonized carbon fiber bundle into high-voltage corona discharge zone and subjecting to corona treatment under - 5 to - 30 kV, preferably - 20 to - 25 kV, while controlling moving speed at 5-30 m/hour, preferably 10-20 m/hour; (B) preparing 10-60 g/L functionalized graphene, distilled water and 0.1-1 wt.% dispersant into stable homogenous suspension; (C) transmitting corona-treated carbon fiber bundle into electrostatic deposition zone, connecting cathode of high-voltage power supply to multi-needle injector through wire and connecting anode to ground via wire, delivering the suspension through a conduit into multi-needle injector cavity located above the carbon fiber bundle, spreading carbon fiber bundle on conveyor above a ground electrode plate, and applying 20-50 kV electricity and electrostatically atomizing the suspension to deposit graphene on surface defects of carbon fiber, while controlling moving speed at 5-30 m/hour; and (D) heating to 300-1600 degrees C under argon atmosphere. The functionalized graphene is aminated graphene, sulfonated graphene, or hydroxylated graphene and has functional group content of 0.5-4 wt.%, preferably 3-4 wt.%. The dispersant is imidazole benzenesulfonate ionic liquid. The discharge distance, i.e. distance between discharge device tip and ground electrode plate is controlled at 1-5 cm, preferably 2-3 cm. The deposition distance, i.e. distance between multi-needle injector and carbon fiber bundle is controlled at 5-30 cm. The weight ratio of carbon fiber to graphene is 1000:0.1-4.