▎ 摘　　要

NOVELTY - Carbon steel material comprises carbon steel substrate, and reduced graphene oxide coating layer formed on the carbon steel substrate. USE - The carbon steel material is useful for heat sink in electrical and electronic devices e.g. wearable electrical and electronic devices. ADVANTAGE - The carbon steel material: has improved thermal diffusivity and thermal conductivity; and is lightweight. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for manufacturing a carbon steel material comprising immersing graphite in an acid solution, stirring, taking out graphite from the acid solution, washing, drying, expanding the interlayer distance of the graphite through a heat treatment process and synthesizing the dried graphite into expanded graphite, immersing the expanded graphite in a mixed solution of sulfuric acid and manganese potassium peroxide so that the expanded graphite is oxidized and exfoliated, washing the product of oxidation and exfoliation to remove acids and bases and obtaining graphene oxide, dispersing the graphene oxide in a solvent to prepare a light brown graphene oxide dispersion, coating the graphene oxide dispersion on a carbon steel substrate, and obtaining a carbon steel substrate coated with reduced graphene oxide by performing chemical reduction on the carbon steel substrate coated with the graphene oxide dispersion.