▎ 摘　　要

NOVELTY - Preparing graphene material comprises e.g. (i) pre-oxidizing the graphene, placing phosphorus pentoxide, potassium persulfate and concentrated sulfuric acid in container for sealing, heating in a water bath, stirring, adding graphene, keeping the temperature, washing with deionized water to neutrality, drying, dissolving pre-oxidized graphene solution in water to obtain graphene solution, adding dispersant and polymer and stirring to obtain graphene dispersion, (ii) adding acrylamide monomer and crosslinking agent into graphene dispersion liquid, mixing and pre-heating to obtain pre-heating solution, (iii) continuously heating mixture obtained in step (ii), adding initiator, coagulation accelerator and silane coupling agent, evaporating the organic solvent, heating, stirring and granulating to obtain graphite composite material coated with high molecular polymer on the surface and cooling, and carrying out conventional carbonization treatment. USE - The graphene material is useful for cold spraying (claimed). ADVANTAGE - The method: ensures that the polymer is completely coated on the surface of the graphite and the coating quantity of each time is the same. DETAILED DESCRIPTION - Preparing graphene material comprises (i) pre-oxidizing the graphene, placing phosphorus pentoxide, potassium persulfate and concentrated sulfuric acid in the container for sealing, and heating in a water bath at 75-85 degrees C, stirring in a water bath until all the raw materials are dissolved, slowly adding graphene many times in a small amount, keeping the temperature for 4-8 hours, after the reaction is completed, washing with deionized water to neutrality, and drying at 40-60 degrees C for 20-28 hours, dissolving the pre-oxidized graphene solution in water to obtain graphene solution, then adding dispersant and polymer, and mixing and stirring to obtain graphene dispersion, where the addition amount of dispersant is 0.05-0.2 wt.% of the mass of the graphene solution and the weight ratio between phosphorus pentoxide, potassium persulfate, concentrated sulfuric acid and graphite powder is 8:2:30:15, (ii) adding acrylamide monomer and crosslinking agent into graphene dispersion liquid, mixing and stirring and pre-heating to obtain pre-heating solution, where the dosage of acrylamide monomer is 5-7 wt.% of the mass of graphene dispersion liquid and the molar ratio between crosslinking agent and acrylamide monomer is 1:18-22, (iii) continuously heating the mixture obtained in step (ii), adding initiator, coagulation accelerator and silane coupling agent, evaporating the organic solvent, heating to completely solidify the high molecular polymer, fully stirring and granulating during the heating process to obtain graphite composite material coated with high molecular polymer on the surface and cooling to room temperature, the initiator is persulfate initiator, the accelerator is tetramethylethylenediamine, the addition amount of initiator is 1-2 wt.% of the total mass of acrylamide monomer and crosslinking agent, the addition amount of coagulant is 0.05% of the volume of the pre-heated solution, the mass ratio between graphene dispersion and boric acid is 100:2, and (iv) subjecting graphite composite material coated with high molecular polymer on the surface after cooling in step (iii) to conventional carbonization treatment to obtain final product.