The U. S. Army and Navy have experienced significant corrosion problems with magnesium alloys that are used to fabricate aircraft components. The most severe of these are associated with large and expensive transmission and gearbox housings for rotorcraft, which have to be removed prematurely because of corrosion. Many of the parts cannot be reclaimed because there is not an existing technology that can restore them adequately for service. The U.S. Army Research Laboratory has developed a Cold Spray process to reclaim magnesium components that shows significant improvement over existing methods and is in the process of qualification for use on rotorcraft. The Cold Spray repair has been shown to have superior performance in the tests conducted to date, is inexpensive, can be incorporated into production, and has been modified for field repair, making it a feasible alternative over competing technologies. Cold Spray trials were performed using various Aluminum powders at different deposition conditions with both Helium and Nitrogen carrier gas. Evaluations of the resultant Cold Spray Aluminum coatings deposited on ZE-41A Magnesium Alloy substrates were conducted using microstructural analysis, hardness, bond strength and corrosion testing. The work presented here represents the first two years of a three year effort, which will result in the establishment of a demonstration Cold Spray facility at the Naval Air Depot, where the overhaul and repair of Navy rotorcraft is accomplished.
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