Hierarchical Reduced Graphene Oxide Reinforcement in Basalt/Epoxy Composites: Interfacial Engineering, Fracture Mechanisms, and Multifunctional Performance

ABSTRACT This study presents a hierarchical reinforcement strategy utilizing reduced graphene oxide (rGO) that concurrently functionalizes basalt fiber surfaces and the epoxy matrix in a basalt/epoxy composite. Electrophoretic Deposition (EPD) provided uniform rGO fiber coating, while ultrasonication–high‐shear mixing enabled stable, exfoliated rGO dispersion in the matrix. This dual‐phase methodology creates continuous three‐dimensional reduced graphene oxide networks that connect fiber‐matrix interfaces and bulk resin regions. The composites' tensile strength improved by 23.5%, interlaminar shear strength by 22.1%, mode‐I fracture toughness by 86%, storage modulus by 44% (7800 MPa at 30°C), and glass transition temperature rose to 95°C. Due to stress wave dissipation and crack deflection at rGO‐modified surfaces, high‐speed ballistic tests show a 26.7% increase in energy absorption (131.4 J) and specific energy absorption (2577 J/kg) over unmodified basalt/epoxy. The interconnected hierarchical rGO structure provides a broadband electromagnetic interference shielding effectiveness of approximately 40 dB (8–18 GHz), primarily due to absorption (SEA = 29 dB) resulting from multiple internal reflections and improved electrical percolation. This synergistic dual‐phase graphene functionalization approach produces lightweight structural composites that exhibit an outstanding blend of mechanical strength, impact resistance, and electromagnetic properties, rendering them highly suitable for aerospace, defense, and electronic enclosure applications.