Epoxy nanocomposites with dual filler system: Improving surface protection against wear and thermocyclic corrosion

This investigation explores the influence of dual nanofillers - multi-walled carbon nanotubes (MWCNT) and silicon nitride nanoparticles (SiN) - on the properties of epoxy (EP). Analyses of tribological characteristics show hybrid nanocomposite of 0.25/ 0.75 wt% of SiN/MWCNT filler system improves the wear resistance by 96 % compared to EP. Raman spectroscopy reveals a novel curing mechanism induced by SiN nanoparticles when incorporated into epoxy at room temperature, while DSC thermograms show SiN’s role in enhancing the crosslinking density. Creep studies indicate that EP/SiN nanocomposites at 0.5 wt% loading reduced the creep rate by 99 % compared to EP over a 10-min duration at 60 ◦C. Dynamic mechanical analysis (DMA) illustrates a significant increase in storage modulus and a 13 ◦C increment in the glass transition temperature (Tg) for 0.5 wt% EP/SiN nanocomposites. High-resolution transmission electron microscopy (HR-TEM) ascertained the homogeneous dispersion of nanofillers in hybrid nanocomposites, suggesting improved and uniform stress transfer. SiN-based composites are more effective than MWCNT-based composites in protecting mild steel from corrosion with a coating efficiency of 87 %. The potential of SiN to reduce free amine groups responsible for the corrosion process is presented, while physisorption tests are conducted to evaluate pore size and volume in the corroded samples. Field emission scanning electron microscopy (FE-SEM) is employed to analyze worn-out and corroded surfaces comprehensively. In EMI shielding, SiN reduces reflectivity without affecting the absorptive capacity of MWCNTs, making them suitable for coatings in stealth applications.