Tailoring mechanical and dielectric behaviours of basalt fiber/epoxy composites via dual ceramic fillers incorporation and Grey–Taguchi optimization

For several decades, epoxy thermoset resins have been widely used as dielectric materials in high-voltage electrical insulation systems. However, today''s needs require improved thermal, dielectric and mechanical performances from these materials. Hence the use of basalt fibre reinforcement, in addition to ceramic fillers, is explored to improve the properties of the epoxy composites. This research paper presents a study on the mechanical and electrical performances of hexagonal boron nitride and alumina ceramic fillers/basalt fiber/epoxy composites via experimental method and then utilises Grey Relational Analysis (GRA) to optimise multiple responses based on the input variables of filler weight percentage. The basalt fiber/ceramic fillers reinforced hybrid epoxy composites (BF/CF/HEC) are manufactured using hand lay-up method with compression mould. L9 orthogonal array design is employed with filler loadings of 2.5%, 5% and 7.5% by weight. The impacts of hybrid filler content on ultimate tensile strength (UTS), Izod impact strength and dielectric constant (DC) are investigated. The experimental findings show a significant relationship between mechanical properties and electrical performance with respect to the dispersion of fillers and the interfacial bonding between the fillers and the epoxy matrix. BF/CF/HEC5 exhibits 50.4% higher UTS and the highest Young’s modulus of 8119 MPa, indicating superior tensile strength and stiffness. The composite, having a balanced composition of alumina and hBN, exhibits higher UTS due to better stress transfer mechanisms and crack deflection mechanisms. The increase in impact resistance is attributed to energy dissipation through the fiber–matrix interface and controlled microcrack propagation. The use of Grey Relational Analysis allows the determination of the optimum combination of alumina and hBN to enhance all the mechanical and DC properties.