Cross-linking and Silanization of Clay-based Multilayer Films for Improved Corrosion Protection of Steel

The potential for polymer–clay thin film composite coatings to replace environmentally-damaging phosphate conversion coatings on steel is demonstrated. Polyethylenimine and vermiculite clay are used in the layer-by-layer deposition of a 300 nm thick nanobrick wall thin film that hinders the diffusion of corrosive ions. The corrosion prevention performance of the coating is improved through cross-linking with glutaraldehyde and silanization of steel with aminopropyltriethoxysilane prior to film deposition. Finally, the nanobrick wall film is tested with an epoxy topcoat, to demonstrate the viability of the recipe as a primer. Epoxy with the cross-linked and silanized nanobrick wall primer coating outperforms a neat epoxy coating. This unique coating shows tremendous potential for use as an environmentally-benign primer for steel.