▎ 摘　　要

NOVELTY - Preparation of nanocomposite heat dissipation film involves adding expanded graphite to ethanol, ultrasonically vibrating for 1-3 hours to obtain nano-graphite dispersion, reacting with fuming sulfuric acid and hydrogen peroxide for 30-50 minutes, reacting with ethylene glycol for 1-1.5 hour, filtering, cooling to obtain nano-graphene, adding boric acid and urea to deionized water to form uniform solution, stirring copper powder, feeding in carbon tube furnace, calcining, to obtain boron nitride-coated copper powder, adding nanographene to absolute ethanol to obtain dispersion liquid (A), adding boron nitride-coated copper powder to ionized water to form dispersion liquid (B), filtering dispersion liquid (A) to obtain bottom nanographene film, pouring the dispersion liquid (B) onto the bottom nanographene film, pumping to obtain nano-graphene film/boron nitride-coated copper powder film, pouring the remaining dispersion liquid (A), filtering, separating composite film and drying. USE - Preparation of nanocomposite heat dissipation film for electronic devices with high heat generation, light emitting diode lamps and liquid crystal display products. DETAILED DESCRIPTION - Preparation of nanocomposite heat dissipation film involves (1) adding expanded graphite to ethanol, dispersing by ultrasonically vibrating for 1-3 hours to obtain nano-graphite dispersion, adding fuming sulfuric acid and hydrogen peroxide to weaken the layer, reacting for 30-50 minutes, adding ethylene glycol, reacting for 1-1.5 hour, filtering out, washing to neutralize, transferring to muffle furnace at 400-500 degrees C for expansion (E2), transferring to atmosphere furnace under nitrogen protection, increasing the temperature to 800-900 degrees C, keeping warm for 4-5 hours, heating at 1100-1200 degrees C for 1-2 hour, cooling furnace to obtain nano-graphene, (2) adding boric acid and urea to deionized water to form uniform solution, adding copper powder, mechanically stirring at 800-1000 rpm for 1-3 minute, filtering out, feeding in carbon tube furnace under nitrogen protection, heating at 900-950 degrees C for 10-20 minutes, increasing the temperature to 1250-1300 degrees C for 1.5-2.5 hour for heat preservation, calcining, air cooling, washing with water, drying to obtain boron nitride-coated copper powder, (3) adding nanographene to certain amount of absolute ethanol to obtain dispersion liquid (A), adding boron nitride-coated copper powder to ionized water to form dispersion liquid (B), feeding half the volume of dispersion liquid (A) in alumina filter membrane, vacuum filtering by vacuum pump under the action of suction force, arranging the nanographene closely together to obtain the bottom nanographene film, pouring the dispersion liquid (B) onto the bottom nanographene film, pumping continues filtering to obtain nano-graphene film/boron nitride-coated copper powder film, pouring the remaining dispersion liquid (A), filtering for 5-8 hours to obtain nano-graphene film/boron nitride-coated copper powder film/nano graphite, separating the composite film of olefin film from the inorganic alumina filter membrane and drying at 35-38 degrees C.