Enhancement in Fracture Toughness and Tribological Stability of Epoxy Facilitated by Heterogeneous 0D-0D Nanofiller Networks: An Experimental and Analytical Evaluation

This work explores high-performance epoxy (EP) nanocomposites reinforced with silicon nitride (SiN) and tungsten carbide (WC) 0D-0D nanoparticles to overcome the intrinsic brittleness and weak wear resistance of EP. Both single-filler and dual-filler systems were developed and evaluated for their mechanical, fracture, and tribological behaviour. Among hybrid nanocomposites, ESW2 (0.25wt% SiN and 0.5wt% WC) exhibited the best overall performance, showing a remarkable increase in tensile strength, elastic modulus and strain by 130 %, 248 %, and 74 %, respectively, over EP. These improvements are attributed to SiN-induced crosslinking within the matrix and WC’s anchoring and nanopolishing effects, offering a unique combination of stiffness, strength, and ductility. Tribological tests demonstrated that WC-filled and hybrid nanocomposites achieved a sharp reduction in wear rate and maintained stable COF under high loads, attributed to various wear mechanisms. Analysis of fracture behaviour revealed that Irwin’s Linear Elastic Fracture Mechanics and the Huang-Kinloch models adequately described toughening in SiN-based systems through mechanisms such as plastic void growth and energy dissipation. However, WC-filled composites and hybrid nanocomposites exceeded theoretical predictions, revealing synergism. Wear and friction modelling further showed a reduction in frictional energy at higher loads, particularly for WC-based samples. Fleisher’s model, surface roughness, and 3D surface plots confirmed WC’s role in nanopolishing and transfer film formation, while SiN imparted thermal stabilization and micro-cutting resistance. In essence, this dual-filler epoxy system demonstrates a synergy by coupling toughness and wear resistance, making it ideal for engineering applications where mechanical integrity and abrasion resistance are demanded.