Corrosion protection by multifunctional stratified coatings

We have demonstrated a hybrid coating consisting of both a stratified layer that incorporates corrosion inhibiting ions and a silicate barrier layer. The stratified layer is applied to the aluminum alloy using the layer-by-layer assembly (or electrostatic self-assembly) method and comprises alternating layers of charged polyelectrolytes and nanometer-thickness clay platelets. These nanocomposite coatings can be doped with corrosion inhibiting ions and allow lateral diffusion of those ions through the coating to have high 'throwing power'. Over the LBL coating is applied an organic-inorganic hybrid coating of organically modified silicates (ORMOSILs) to provide additional barrier protection and bind to primers and paints. These types of hybrid coatings have electrochemically shown superior corrosion protection compared to hexavalent chromium coatings.