▎ 摘　　要

NOVELTY - A composite material comprises 97.5-98.5 mass% nylon powder, 0.4-0.6 mass% graphene, 0.7-1.8 mass% flow aid, and 0.2-0.5 mass% antioxidant. USE - Composite material used in three-dimensional printing (claimed). ADVANTAGE - The composite material has high hardness, tensile strength and bending strength, and is environment-friendly. It has melting point of 180 degrees C, bending strength of 50-80 MPa, tensile strength of 50-80 MPa, and hardness of 80-90 HV. The preparation method of the composite material involves physical doping method to avoid damage to the material caused by chemical doping. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the composite material, comprising: (A) adding nylon raw material in a sealed high pressure container, adding water and heating, and drying the nylon material; (B) adding nylon material and solvent to a reaction kettle, stirring, introducing inert gas in the kettle at 1-2 MPa, heating to 130-180 degrees C, continuously stirring, then vacuumizing until the pressure is reduced to 0.1-0.2 MPa, then distilling the solution, removing water, controlling pressure to normal pressure and reducing temperature to 80-100 degrees C, then adding catalyst and activating agent, regulating pressure to 1-2 MPa and temperature to 130-180 degrees C, holding constant temperature and pressure for 1-1.5 hours, then reducing to normal temperature and normal pressure, separating out powder product, filtering the powder product, washing and drying to obtain nylon powder; and (C) adding flow aid, antioxidant, and nylon powder into a sealed stirrer, uniformly mixing, then adding graphene and high speed stirring to obtain the composite material.