Corrosion-Resistant Zeolite Silicalite-1 Coatings Synthesized by Seeded Growth

It has been proved that zeolite MFI coatings synthesized by in situ hydrothermal synthesis is corrosion-resistant. Pure silica zeolite MFI (silicalite-1) coatings on aluminum alloy 1060 plates seeded by brush-coating a seed paste and leveling the seed layer with fingers have been synthesized by the seeded growth method in this study. The seed paste is composed of seeds, silica sol, and water. The effects of the seed/sol ratio and the seed crystal size on the properties of silicalite-1 coatings are investigated in detail. The corrosion protection performance of the silicalite-1 coatings on aluminum alloy plates is determined by a direct current polarization technique. The silicalite-1 coatings (similar to 3 mu m thick) obtained by the seeded growth method at 150 degrees C for 3 h are found to be highly b-oriented and corrosion-resistant in severely corrosive acidic aqueous solution (0.5 M H2SO4) and sodium chloride aqueous solution (0.5 M) exposed to air at room temperature. The optimum seed/sol ratio and the seed crystal size in the seed paste are 6.0 and 500 nm, respectively.