Objective

Hexavalent chromium based conversion coatings are common surface finishing technology utilized in nearly all military depots and commercial facilities where out of the specification used aircraft magnesium cast components are overhauled for recertification. The practice of using chromate conversion coatings dates back to the 1940’s as these solutions were fully compatible with magnesium and the numerous ferrous metal inserts installed in magnesium cast aircraft components. The ability to form a paint adhesion promoting layer on magnesium while not damaging the ferrous steel inserts such as studs, helicoils and bearing liners has kept hexavalent chromium an irreplaceable process solution at depots and overhaul facilities despite its well documented health hazards and Department of Defense (DoD) efforts in limiting their uses. Traditionally, magnesium anodization techniques including Immersion Tagnite™ may not be used to coat mixed magnesium and ferrous metal components because the anodization process will attack the ferrous metals other than magnesium. Recently, Technology Applications Group has developed an innovative process to “mask off” or shield the mixed metals from the magnesium anodization electrolyte and integrated the process with the Immersion and Brush Tagnite™ technologies which enables the environmentally friendly deposition of a high quality durable anodize coating on mixed metal magnesium components fabrication as well as overhaul.

The objective of this project is to facilitate the alternate high performance magnesium mixed metals immersion surface finish manufacturing capabilities at fabrication and overhaul industrial base so that the toxic legacy hexavalent chromium coating technologies are phased out completely and replaced with the Immersion/Brush Tagnite™ magnesium mixed metal surface finish manufacturing technology through effective technology demonstration and successful capability validation at Corpus Christi Army Depot (CCAD).