Development and performance evaluation of hexagonal boron nitride (h-BN) nanocomposite coatings for corrosion resistance in marine environments

The durability of epoxy-based coatings in corrosive environments is often compromised by moisture and ion penetration. In this study, hexagonal boron nitride (h-BN) nanosheets were incorporated into an epoxy matrix to enhance corrosion protection, leveraging their two-dimensional barrier characteristics. Nanocomposite coatings were formulated with varying h-BN loadings (0, 1, 3, and 5 wt%) and applied to mild steel substrates. Electrochemical performance was evaluated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), while accelerated salt spray testing was used to assess long-term durability. Results revealed that the 3 wt% h-BN coating exhibited the lowest corrosion current density (0.5 μA/cm²) and the highest impedance (68.0 kΩ·cm²), indicating significant enhancement in protective behavior. Visual analysis after salt spray exposure confirmed minimal rust formation (~12%) for this formulation. However, performance declined at 5 wt% due to probable nanosheet agglomeration and micro-defect formation. These findings highlight the importance of optimal filler loading in nanocomposite coatings and suggest that 3 wt% h-BN offers a robust and scalable strategy for improving corrosion resistance in epoxy systems. This work provides valuable insights into the design of high-performance anti-corrosive coatings using 2D nanofillers and lays the groundwork for future research into hybrid or functionalized systems for broader industrial applications.