Development of Cad Plating Replacement with Alkaline Zinc-Nickel Electroplating for Threaded Fasteners/Components

ABSTRACT: Aircraft structure, engine, propeller and landing gear systems utilize high and low strength steel, cad-plated threaded components and fasteners throughout its structure. Threaded components and fasteners manufactured from these alloys require sacrificial protective coatings due to the corrosive environment. Cadmium has traditionally been the preferred coating for such threaded components and fasteners due to its many desirable functional qualities. In addition to corrosion protection, cadmium also provides excellent lubricity characteristics; however, cadmium is a toxic metal and known carcinogen that poses environmental and occupational safety and health risks throughout the life cycle of the plated parts. ES3 successfully completed the Phase I effort meeting its primary goal of demonstrating that IZ-C17+ with trivalent conversion coating IZ-264 performs as well as Low Hydrogen Embrittlement (LHE) Cad plate on threads for upfront screening tests. Phase II testing validates the Zn-Ni IZ-C17+ with IZ-264 post treatment process in comparison to LHE cad utilizing industry accepted requirements for threaded fasteners / components for process installation, corrosion, thickness, fatigue, adhesion, hydrogen embrittlement and resistance to paint strippers and fluids The Phase II.5 transition plan will focus on implementing a full scale alkaline Zn-Ni (IZ-C17+) process barrel and rack plating line for usage at WR-ALC, conducting field evaluations and updating the technical data to authorize the use of alkaline Zn-Ni on LSS and HSS threaded fasteners and components for aircraft structural, propeller, and landing gear components.. BENEFIT: Research conducted to evaluate the alkaline zinc-nickel as a cadmium alternate focuses on military applications at USAF"s aircraft component and propeller maintenance repair facility at Robins AFB, Georgia; however, benefits will be similar for all commercial & military aircraft, engine and landing gear usages where cadmium electroplating is applied. The following list benefits ES3 expects from the alkaline zinc-nickel process for electroplating of threaded fasteners and components based on both industry and in-house research: Drop in replacement for all cad plated, threaded components and fasteners on low and high strength steel components. Eliminate health exposure concerns of cad plating (including brush cad) and meet OSHA emission regulations. Replace all IVD aluminum process, gaining the following benefits: o Ability to plate Internal Diameters (ID) o Lower processing costs o Unlimited process size constraints (tank size is only limiting factor). IVD chambers are size limited. o Eliminate Hydrogen Re-Embrittlement risks after exposure to aqueous cleaners. o Increased lubricity factors over IVD. Fully implemented, the alkaline zinc-nickel process would free up an entire section of the Robins AFB aircraft component and propeller system facility currently dedicated to IVD operations.