Zinc Nickel as an Environmentally Preferred Alternative to Cad Plating
Low Hydrogen Embrittlement (LHE) Cadmium (Cd) Plating per MIL-STD-870 is currently used as a sacrificial protective coating on high strength steel (HSS) aircraft landing gear components to prevent corrosion. The Environmental Protection Agency (EPA) and DoD strictly regulate Cd waste streams and personnel exposure. Aircraft manufacturers and overhaul facilities have received waivers to continue use of Cd because there has not been a technically feasible 100% substitute for Cd plating. High strength steels used in landing gear pose unique challenges due to their sensitivity to Hydrogen Embrittlement (HE) and Environmentally-Assisted Cracking (EAC).
ES3 has developed, qualified, and implemented LHE alkaline Zinc-Nickel (Zn-Ni) Dipsol IZ-C17+ plating on high strength steels which meet Cd plate baseline corrosion prevention, fatigue, and HE objectives. This LHE Zn-Ni process enables aerospace manufacturing to meet environmental restrictions by eliminating Cd waste streams. Zn-Ni is a cyanide free plating process that meets the requirements for a non-embrittling process per ASTM F519. The LHE Zn-Ni process has excellent throwing power in both plating and corrosion protection. The coating consists of a uniform zinc alloy containing 12-18% nickel. LHE Zn-Ni is applicable to aircraft major structural components, such as pistons, cylinders, truck beams, torque arms, and axles as well as consumables such as pins, bearings, bushings, and bolts.