▎ 摘　　要

NOVELTY - Polydopamine-graphene double-layer composite functional coating is a double-layer coating comprising a polydopamine coating and a graphene ultra-thin coating from inside to outside. USE - Polydopamine-graphene double-layer composite functional coating used for applying on surface of biomedical magnesium alloy for preparing medical implant e.g. tissue engineering scaffold, cardiovascular scaffold, medical catheter and orthopedic implant device (all claimed). ADVANTAGE - The polydopamine is transparent, and has excellent biocompatibility and resistance to chloride ion permeability, and good binding force with a magnesium substrate and graphene. The chemical inertness and impermeability to almost all molecules of the graphene coating can greatly improve the long-term corrosion resistance of the substrate. The polydopamine is a semiconductor, and the graphene coating has excellent electrical conductivity. The contact between the polydopamine and graphene coating produces a potential barrier, which is a high-resistance region that blocks the entry of low-energy electrons, and then double-effects synergistically inhibiting the degradation of magnesium alloys. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the polydopamine-graphene double-layer composite functional coating, which involves preprocessing magnesium alloy by carrying out fluorination treatment, alkalization treatment, phosphorylation treatment or micro-arc oxidation treatment to form an insulating conversion layer, preparing polydopamine coating by soaking magnesium alloy in a dopamine hydrochloride solution and polymerizing for 1-60 hours at 20-40℃, taking out, ultrasonically cleaning, nitrogen drying, vacuum drying, and depositing the graphene coating on the magnesium alloy sample with a polydopamine coating, by physical/chemical vapor deposition.