▎ 摘　　要

NOVELTY - Preparing graphene-coated polycrystalline mullite fiber composite conductive material comprises e.g. (i) soaking and cleaning polycrystalline mullite fiber in ethanol and acetone, introducing polycrystalline mullite fiber into strong oxidizing solution, and (ii) adding hydroxylated polycrystalline mullite fiber into distilled water, then adding epichlorohydrin, dimethylamine and triethylenetetramine, adding graphene oxide into distilled water, adding pH-adjusted graphene oxide dispersion into polyepichlorohydrin dimethylamine cation modified polycrystalline mullite fiber, and drying. USE - The method is useful for preparing graphene-coated polycrystalline mullite fiber composite conductive material (claimed). ADVANTAGE - The conductive material has excellent mechanical performance, high conductivity, excellent high temperature resistance, excellent thermal shock resistance, excellent corrosion resistance and low thermal conductivity. DETAILED DESCRIPTION - Preparing graphene-coated polycrystalline mullite fiber composite conductive material comprises (i) soaking and cleaning polycrystalline mullite fiber in mixed solution of ethanol and acetone and other volumes in a solid-liquid ratio 1:70-90 for 1-2 hours, removing and then drying in a solid ratio of 1:80-100, introducing polycrystalline mullite fiber into strong oxidizing solution, heating in water bath at 70-90 degrees C and speed of 2000-4000 revolutions/minute, stirring for 3-5 hours, performing ultrasonic treatment at 300-500 W power for 1-3 hours, suction filtering, washing residue with distilled water until neutral, drying at 80-90 degrees C for 8-14 hours to obtain hydroxylated polycrystalline mullite fiber, and (ii) adding hydroxylated polycrystalline mullite fiber into distilled water in a solid-liquid ratio 1:50-60, stirring at speed of 1500-3000 revolutions/minute, dispersing for 1-2 hours, then adding epichlorohydrin, stirring at 1000-2000 revolutions/minute, dispersing at rotation speed for 0.5-1.5 hours, adding dimethylamine and triethylenetetramine, heating in water bath at 60-70 degrees C, stirring at speed of 500-1000 revolutions/minute for 5-8 hours, then performing microwave treatment at 200-400 W power for 1-3 hours, suction filtering, washing residue with distilled water to the filtrate does not contain chloride ions, drying at 60-70 degrees C for 12-24 hours and then activating at 110-120 degrees C for 1-2 hours to obtain polyepichlorohydrin dimethylamine cation modified polycrystalline mullite fiber, adding graphene oxide into distilled water and ultrasonic stirring to obtain graphene oxide dispersion with mass fraction of 1-2%, then adjusting the pH value of graphene oxide dispersion to be 3-4 using hydrochloric acid solution with mass fraction of 15% in a mass ratio of 1:40-50, then adding pH-adjusted graphene oxide dispersion into polyepichlorohydrin dimethylamine cation modified polycrystalline mullite fiber, allowing to stand for 30-40 minutes, pulling 2-3 times during the period, then irradiating under ultravoilet light lamp for 2-3 hours, washing with distilled water to neutral, drying at 60-70 degrees C for 12-24 hours to obtain final product.