Novel Room Temperature Method for Rapid In-Situ Removal of Oxide Layers from Superalloy Surfaces

Both failure analysis and reconditioning of nickel superalloy gas turbine and rocket engine components are plagued by a major problem: the thin oxide films that form on unprotected fracture surfaces during field operation obscure the surfaces intended foranalysis and interfere with repair procedures. Such oxide films mask the fracture surfaces and make them very difficult, if not impossible, to analyze and/or repair. Inhibited chemical etchants have been developed to remove oxide films from steels topreserve the base metal during pickling in the manufacturing processes. No similar process is required during nickel superalloy production, and no such inhibitor has been developed to date. In Phase I, Ultramet demonstrated the feasibility of utilizingultraviolet- and microwave-assisted chemical vapor deposition processes using activated atomic hydrogen gas near room temperature to rapidly remove the oxide films from superalloy fracture surfaces, producing clean nickel alloy component fracture surfacessuitable for failure analysis, repair, and/or joining (brazing). In Phase II, Ultramet will work with Williams International, a well-known small turbine manufacturer, to optimize and scale up the oxide removal technology and define specific brazingapproaches for nickel-based superalloys, specifically including MAR-M-247 and Waspaloy superalloys. Additionally, a mobile, ultraviolet-based oxide removal apparatus will be constructed to demonstrate the versatility, simplicity, and environmentalfriendliness of the process, including suitability for laboratory-scale analysis and field repair.