Selective Stripping of Cadmium and Zinc-Nickel Coatings

Inorganic finishes such as Cadmium and Zinc-Nickel are commonly used on aircraft, support equipment, automotive, oil and gas industries and many other applications for corrosion protection. Occasionally the need arises to remove these coatings for inspection and reapplication of the coating. Maintainers use methods such as hand sanding, wet sanding, or abrasive blasting to abrade away the Cd or Zn-Ni layer. This method generates inhalation and exposure risks to the maintainer, as well as to the surrounding environment.For parts that are overhauled at the depot level (D-level), spent Cd or Zn-Ni coatings can be stripped by immersing the part in a chemical tank. After the coatings are stripped, the underlying metal can be inspected, repaired, and recoated with new Cd or Zn-Ni coatings. However, the tank chemical process is not feasible to perform at intermediate (I-level) or organizational (O-level) level maintenance facilities. Dozens of I-level and O-level facilities around the world perform touch-up repairs of Cd or Zn-Ni coatings on aircraft components.A thixotropic stripping solution that can stick to coatings has been developed to selectively strip areas of Cd or Zn-Ni coatings in preparation for inspection of the underlying surfaces.