Novel Conversion Coatings for Magnesium and Zinc-Nickel based on Cr(III) and Silanes

We are proposing to develop a novel coating system for plated zinc-nickel fasteners and for cast magnesium alloys. The new system is based on the use of Cr(III) conversion coatings, but we will develop one from scratch. The system will come in three different versions, two of which contain silane in some form. Version I is the Cr(III) conversion coating with the silane added to the Cr(III) Bath. Version II is the Cr(III) conversion coating, but it has the silane as a sealer system. Version III is the silane by itself. Its corrosion protection performance is enhanced by adding a leachable inhibitor and a small amount of water-dispersed resin system.   BENEFIT: The proposed systems are environmentally attractive as they do not contain hexavalent chromium. Their corrosion protection performance will be as good as or better than that of Cr(VI) conversion coating. The paint adhesion will be excellent due to the silanes in the systems. The coatings are applied at rather low temperatures and will be fully removable. In addition to zinc-nickel and magnesium, other metals can be treated as well.