▎ 摘　　要

NOVELTY - Composite coating comprises an alcohol surface coating, an alcohol-based graphene coating and an alcohol chloride coating. The alcohol-type graphene coating comprises sodium nitrate and graphene, and the alcohol-base chloride coating comprises manganese chloride. USE - The composite coating is useful for precision sand casting core in precise sand casting mold core, preferably missile shell, oil cabin shell, engine accessory machine box, engine oil pipeline and automobile engine cylinder body. ADVANTAGE - The composite coating has uniform thickness, compact coating structure, and effectively reduces the burning loss of the light elements e.g. magnesium and lithium, reduces the subcutaneous needle hole of the casting, air hole defect, short production period, small pollution to the environment, and can realize the military equipment and new energy automobile complex structure precise aluminum alloy casting short period low cost green casting, economic benefit is obvious. DETAILED DESCRIPTION - AN INDEPENDENT CLAIM is also included for a preparation method of precise sand casting core. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic structural diagram of the surface of the precise sand casting core after the composite coating. 1Sand casting core base body 2Alcohol surface coating 3Alcohol-based graphene coating 4Alcohol chloride coating