▎ 摘　　要

NOVELTY - Graphene-coated alumina comprises graphene existing in the surface of alumina and/or aluminosilicate having a mean diameter of 1 mu m and amorphous structure. USE - Graphene-coated alumina is used for forming aggregates used for electromagnetic wave shields in dedicated short range communication and electronic toll collection systems, and for electronic materials (all claimed) used in electric wires, gas diffusion layers of batteries, capacitors, condensers, etc. Can also be used for semiconductor manufacturing apparatus, magnetic head manufacturing apparatus, inverters, servomotors, coating materials of electroconductive cables, etc. ADVANTAGE - The graphene-coated alumina has excellent electric field blocking capability even in low-frequency region (0.1 MHz to 26.8 GHz), surface hydrophobicity, electroconductivity, and mixing property with respect to resin, and low electrical resistance. The graphene-coated alumina is capable of blocking low-frequency electromagnetic wave of 125 kHz to 8 MHz. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) aggregate of graphene-coated alumina; and (2) surface hydrophobic treatment, which involves coating graphene on the surface of sheet-like material containing alumina and/or aluminosilicate.