AQUEOUS PROTECTIVE AND ADHESION PROMOTING COMPOSITION

摘要

An aqueous composition for coating a metallic substrate that is prepared by mixing at least one silane (preferably at least two silanes), at least about 20 weight percent phosphoric acid based on the total weight of the composition, and water, wherein the composition is substantially free of an organic solvent and a chromium-containing compound. The pH of the composition must not be above 3. The composition can be coated on a metallic substrate, particularly an aluminum substrate, to provide a pre-treatment layer for adhering overcoats.