Thick ion-vapor-deposited aluminum coatings for irregularly shaped aircraft and spacecraft parts

Ion vapor deposition (IVD) is the same as the familiar physical vapor deposition (PVD) with one major difference—the substrate is held at a high negative potential with respect to the vapor source. This potential when applied at the proper system pressure improves adhesion and uniformity of the plating. Because the IVD process is not confined to line-of-sight deposition, parts with very complex shapes can be plated with a reasonably uniform coating. The deposit readily extends into the recesses and holes of the part due to the excellent throwing power of the process. Although IVD has been found superior to PVD, industry has not used IVD extensively in production applications. Recently McDonnell Aircraft Company has concentrated on applying IVD techniques to meet protective coating requirements of aircraft and spacecraft components. This technique has been used for applying coatings for corrosion prevention, aluminum coatings to replace cadmium coatings in contact with titanium to eliminate galvanic corrosion, and coatings for braze wettability. It is the purpose of this paper to present successful applications of the IVD process in coating production parts.