Tailoring Thermal, Mechanical, and Magnetic Properties of Composites by Cobalt Ferrite‐Based Bimetallic Nanofillers

ABSTRACT Embedding magnetically permeable materials in polymer matrices allows composites to respond appropriately to magnetic fields, suitable for uses such as electromagnetic interference (EMI) shielding, sensors, actuators, inductors, and magnetic shielding for electronics or other purposes. Optimal magnetic performance is essential in most cases, but is usually achieved by high filler loadings, which in turn degrade mechanical integrity. This research investigates the contribution of annealing temperature to the tuning of the grain size and magnetic permeability of CoFe 2 O 4 nanoparticles with the aim of creating lightweight, responsive composites with enhanced multifunctionality. The nanoparticles were dispersed in an epoxy matrix at multiple weight fractions, and their structural and functional attributes were rigorously assessed. Findings show that well‐controlled grain development via annealing has a strong impact on magnetic response, particle dispersion, and composite integrity. Moreover, the existence of CoFe 2 O 4 increases the overall thermal conductivity of the matrix. The novelty of this study lies in a uniquely integrated approach, where annealing‐driven microstructural tuning of CoFe 2 O 4 nanoparticles enables simultaneous improvements in both thermal stability and anticorrosive performance of epoxy coatings, thereby providing multifunctional advantages over conventional epoxy/ferrite systems.