Demonstration and Validation of LHE Zn-Ni Plating Process
Hill AFB Hill AFB United States
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Cadmium Cd plating is used as a coating on High Strength Steel HSS landing gear alloys to prevent corrosion. The cadmium plating process uses three chemicals currently listed as hazardous materials by the EPA, OSHA, and ATSDR cadmium, sodium cyanide, and hexavalent chrome. Cd is a known human carcinogen and a toxic heavy metal that can easily be leached, therefore it poses both environmental and health concerns. Due to these concerns and other limitations of Cd plating, Low Hydrogen Embrittlement Zinc-Nickel LHE Zn-Ni has been tested and qualified for use as a sacrificial coating to prevent corrosion to HSS alloys. LHE Zn-Ni is applied through an electroplating process similar to that of Cd plating, except LHE Zn-Ni does not use sodium cyanide as a chelator in the process, or hexavalent chrome conversion coat, reducing the use of hazardous chemicals and waste. The main objective of this project was to implement a full scale prototype LHE Zn-Ni plating line and demonstrate and validate that LHE Zn-Ni plating performs as good or better than Cd plating in corrosion prevention, resulting from environmental conditions and operational use. The objectives of the project were met by installation of the full scale plating line at Hill AFB and validation of the performance of LHE Zn-Ni. After qualifying the plating tanks, landing gear were plated to perform a Performance Tracking Program PTP where LHE Zn-Ni plated components were installed and tested on aircrafts at select bases around the country. Bases were selected with corrosive environmental conditions, to simulate the most aggressive natural environment that would be experienced at any location worldwide. The selected bases include McEntire JNG, Barbers Point US Coast Guard, New Orleans NAS Louisiana, and Hickam AFB.
- Coatings, Colorants and Finishes