Corrosion resistance properties of organic-inorganic hybrid coatings on 2024 aluminum alloy

Three kinds of organic-inorganic hybrid coatings modified by tetraethoxysilane (TEOS) were prepared using precursors of vinyltrimethoxysilane (VMS), [3-(methacryloxy)propyl] trimethoxysilane (MPMS) and (3-glycidoxyproyl) trimethoxysilane (GPMS). Properties of corrosion resistance were tested by potentiodynamic polarization curves. Salt spray test and SEM images were also employed to examine the ablitity of coatings to resist long-time corrosion. The results show that hybrid coatings are effective for inhibiting corrosion reaction. Corrosion currents of VMS coating and MPMS coating were 300 times smaller than that of bare sample. The corrosion current of hybrid coatings is smallest when TEOS content reaches 15-20%. It was found that VMS coatings have the strongest ability to resist salt spray corrosion.