ESTCP 2019 Project of the Year Award for Weapons Systems and Platforms
All military aviation platforms have magnesium components; however, magnesium is a very electrochemically "active" metal that leads to moisture-induced corrosion and galvanic corrosion due to mating with dissimilar metals. During the overhaul phase, the protective inorganic coating, primer and topcoat paint on these aviation magnesium components are stripped off to allow visual and penetrant inspection of the casting. After passing the inspection, the magnesium castings are dipped in a chemical conversion coating such as DOW 7 or DOW 19 before being placed back into service. Both of these DOW coatings contain hexavalent chromium (Cr6+).
Historically, anodic coatings could not be used to coat fully assembled magnesium housings because the anodic process is an oxidation process and would rapidly convert the steel components to rust. Under his ESTCP project, Mr. Kyu Cho from the U.S. Army Combat Capabilities Development Command Army Research Laboratory, led the Tagnite Technical Working Group (TWG) in the development of an innovative technology to mask off dissimilar metals such as steel in completed magnesium components in order to apply the Tagnite coating to legacy components without harm to the dissimilar metals. More details on this effort can be accessed under the project web page.
The advantages of the Tagnite anodize coating are twofold:
1) The Tagnite electrolyte and anodic coating contain no hazardous materials, and
2) The Tagnite coating has better corrosion resistance than the currently used hexavalent chromium coatings, DOW 7 and DOW 19.
In this project, Kyu Cho and the Tagnite TWG obtained several UH-60 magnesium drive train components from the Storage, Analysis, Failure Evaluation and Reclamation (SAFR) program site at the Corpus Christi Army Depot (CCAD), developed the masking technology, and successfully demonstrated and validated the masking technology at the CCAD Plating Shop by installing a Tagnite production line in the Plating Shop. This successful immersion Tagnite technology transition project achieved the primary objective of eliminating the use of hexavalent chromium DOW 7 and DOW 19 tanks for the treatment of magnesium aviation components at the CCAD Plating Shop while providing the additional benefit of better corrosion resistance.
Through their efforts on the project titled Improved Magnesium Protection for DoD Aviation and Weapon Component Technology, Mr. Kyu Cho and the Tagnite TWG team have been awarded the 2019 ESTCP Project of the Year from the Weapons Systems and Platforms Program Area.