Silica‐Coated Graphene Nanosheets for the Synergistic Optimization of Thermal Conductivity and Corrosion Protection in Epoxy Coatings

Graphene nanoplatelets (GNPs) hold great promise as functional fillers in polymer composites; however, their practical application is limited by poor dispersibility and interfacial compatibility within polymer matrices. In this study, GNPs were surface‐modified via a tetraethyl orthosilicate (TEOS)/3‐aminopropyltriethoxysilane (KH‐550) sol–gel method to construct uniform silica‐coated graphene nanosheets with a core–shell structure (GNP@SiO 2 ). The resulting core–shell particles were incorporated into epoxy resin at 6, 12, and 18 wt% to prepare composite coatings. The 18 wt% GNP@SiO 2 coating exhibited a thermal conductivity of 0.38 W m −1 K −1 , an 81% increase over pure epoxy (0.21 W m −1 K −1 ), and showed improved heat‐dissipation behavior, as evidenced by infrared thermal imaging and surface temperature evolution under identical heating conditions. In corrosion protection, the 12 wt% coating showed optimal performance, achieving a low‐frequency impedance modulus of 2.1 × 10 11 Ω cm 2 and a corrosion rate one order of magnitude lower than pure epoxy. Excessive filler (18 wt%) induced agglomeration and localized corrosion. This work demonstrates that GNP@SiO 2 content can be tailored to separately optimize thermal and anticorrosion properties, which represents a novel filler‐content‐based design strategy that avoids complex multicomponent systems. This approach offers practical relevance for developing multifunctional epoxy coatings with customizable performance profiles for applications such as electronic device heat dissipation and marine corrosion protection.