Organosilicon–KDS hybrid waterborne epoxy coatings for corrosion protection

Waterborne epoxy coatings offer environmental advantages over solvent-based coatings, but their application under marine conditions is limited by water sensitivity, insufficient flexibility, and poor compatibility with inorganic fillers. In this study, a self-emulsifying organosilicon-modified curing agent was combined with amino-functionalized hydrophobic silica nanoparticles (KDS) to prepare hybrid waterborne epoxy coatings. The effects of KDS loading on emulsion stability, surface morphology, wettability, mechanical properties, and corrosion resistance were investigated. Among the evaluated formulations, WHEC-20 exhibited favorable combined properties, including a water contact angle of 139° ± 3°, an elongation at break of approximately 102%, and a 5B adhesion rating after salt-spray exposure. After 1000 h of immersion in 3.5 wt.% sodium chloride (NaCl) solution, its fitted charge-transfer resistance was 8.864 × 108 Ω·cm2, approximately one order of magnitude higher than that of WHEC-0. Salt-spray and sodium chloride-solution immersion tests indicated improved laboratory corrosion protection following KDS incorporation. This improvement may be associated with changes in surface wettability and roughness, interfacial interactions, and coating-barrier properties. These findings demonstrate the potential of organosilicon–KDS hybrid waterborne epoxy coatings for corrosion protection under laboratory-simulated marine conditions.