▎ 摘　　要

NOVELTY - Slurry with medium and small diameters comprises graphene oxide with a sheet diameter of 1-50 mu m and water, where solid content of the graphene oxide is 10-80 g/l. USE - The slurry is useful for preparing a graphene oxide film with medium and small diameters (claimed). ADVANTAGE - The slurry ensures low viscosity and high solid content of graphene oxide; and improves higher density and good heat conducting performance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) preparing slurry comprising dispersing the graphene oxide in water after synthesizing graphene oxide with small and medium-sized graphite or crushing the medium-sized graphene oxide dispersed in water; (2) graphene oxide film with medium and small diameters comprising diameter of the graphene oxide is 1-50 mu m, preferably 3-30 mu m and the thickness of the graphene oxide film is 12-100 mu m; (3) preparing a graphene oxide film with medium and small diameters comprising preparing a graphene oxide slurry of medium and small diameters, coating the graphene oxide slurry on the substrate to form a wet graphene oxide slurry film, heating and drying the wet graphene oxide slurry film and peeling off to obtain a graphene oxide film, where the coating method includes blade coating, spray coating or roll coating, the drying temperature is 60-90 degrees C and the drying time is 30 minutes-2 hours; (4) high-density graphene thermally conductive film comprising density of the graphene thermally conductive film is 1.9-2.1 g/cm3, where the thickness of the graphene thermally conductive film is 12-200 mu m, the tensile strength of the graphene thermally conductive film is greater than 20 MPa, the 180 degrees bending resistance is greater than 50,000 times when the bending radius of the graphene thermal conductive film is 1 mm, the graphene thermally conductive film with a film thickness of 12-40 mu m can withstand 180 degrees bending more than 100000 times when the bending radius is 1 mm, the thermal conductivity of the graphene thermally conductive film is 1000-1900 W/mx K, the thermal conductivity of the graphene thermally conductive film is 1600-1900 W/mx K when the film thickness is 12-25 mu m, the thermal conductivity is 1400-1700W/mx K, When the thickness of the graphene thermally conductive film is 25-40 mu m and the thermal conductivity is 1000-1500W/mx K when the thickness of the graphene thermally conductive film is 40-100 mu m; and (5) preparing high-density graphene thermal conductive film comprising adopting graphene oxide film with small and medium diameters, reducing the graphene oxide film to obtain a graphene film, pressing the graphene film to obtain a high-density graphene thermal conductive film, where the reduction treatment method includes a thermal reduction method or a chemical reduction method, preferably a thermal reduction method, the thermal reduction method includes performing low-temperature treatment, medium-temperature treatment and high-temperature treatment on the graphene oxide film, where the low-temperature treatment method includes heating to 200-500 degrees C at a rate of 0.05-1 degrees C/minutes, the low-temperature treatment environment is air, nitrogen or inert gas atmosphere, preferably an inert gas atmosphere, preferably, the low-temperature treatment time is 5-7 hours, preferably 6 hours, the method for the intermediate temperature treatment includes heating to 1000-1500 degrees C at a rate of 1-5 degrees C/minute, preferably, an atmosphere of an inert gas in the environment of the intermediate temperature treatment, the time for the medium temperature treatment is 2-6 hours, preferably 4 hours, the high-temperature treatment method includes heating to 2500-3000 degrees C at a rate of 5-10 degrees C/minutes, the inert gas atmosphere of the high-temperature treatment environment, the high temperature treatment time is 1-3 hours, preferably 2 hours, the chemical reduction method includes chemically reducing the graphene oxide film by immersion or fumigation to remove residual reducing agent, the reducing agent includes hydrazine hydrate, amine organics, ascorbic acid and/or hydrogen iodide, the method for removing the residual reducing agent includes using pure water soaking, fumigation or heat treatment, the pressing pressure is 50-200 MPa, preferably, the pressing time is 2-24 hours.