Investigate the performance of functional coatings with physically modified boron nitride composite fillers

Abstract

Fillers play a pivotal role in endowing coatings with multifunctional properties. Hexagonal boron nitride (h-BN), a lamellar nanofiller, can significantly enhance the thermal conductivity, corrosion resistance, and mechanical properties of polymer resin-based coatings due to its unique structural features. However, the significant surface energy mismatch between h-BN (a low-polarity inorganic material) and polar organic polymers leads to poor interfacial wettability and phase separation tendencies. Simultaneously, the high specific surface area of BN nano/micro particles promotes agglomeration driven by hydrogen bonding, π-π stacking, or electrostatic forces (e.g., charged surfaces). This study employs an environmentally friendly physical encapsulation strategy to modify h-BN using silica sol, while leveraging the porous structure of dried silica sol to adsorb the corrosion inhibitor benzotriazole (BTA), thereby synergistically improving the corrosion resistance of the coating. FE-SEM observations confirm that silica sol successfully constructs a porous morphology on the surface of lamellar BN, effectively inhibiting filler agglomeration in the resin. The introduction of modified BN increases the coating hardness to 3H, with in-plane and through-thickness thermal conductivities improving by 1332 % and 342 %, respectively, compared to pure epoxy coatings. Electrochemical impedance spectroscopy (EIS) and salt spray tests demonstrate a remarkable enhancement in corrosion resistance. This research provides a novel approach for the application of h-BN in functional protective coatings.