ESTCP Project 201412: Cadmium-Free Alternatives for Brush Plating Repair Operations
By Christopher Venturella
Environmental Effect Engineer, University of Dayton Research Institute
Cadmium (Cd) has been widely used in the aerospace industry and the Department of Defense (DoD) due to its excellent corrosion resistance, adhesion, and lubricity characteristics. Cadmium brush electroplating is used to repair worn and corroded parts, in many cases while the components are still installed on the aircraft. However, Cd is a toxic metal and human carcinogen that is heavily regulated in the United States and the European Union. Traditional brush plating is an “open” process that leads to potential worker exposure and contamination of surrounding areas.
Due to Cd toxicity and waste generation during cadmium operations, there are many environmental, health and safety problems as well as logistical problems and disposal costs associated with the use of cadmium at DoD repair depots and field operations. DoD, Air Force, and the Occupational Safety and Health Administration (OSHA) policies require the Air Force to eliminate Cd uses and exposures. During the last few years, OSHA issued multiple citations against Air Force depots. Executive Order 13423 issued January 24, 2007, “Strengthening Federal Environmental, Energy, and Transportation Management”, requires government agencies to reduce use and dispose of toxic and hazardous materials, including Cd.
ESTCP Project Focus:
This joint U.S. Air Force-ESTCP project focuses on the elimination of toxic/carcinogenic cadmium material for brush plating repair operations, and the reduction of solid waste associated with traditional brush plating repair processes.
The Dalistick Station is a Commercial-off-the-Shelf (COTS) mobile electroplating system that enables selective electrochemical treatments without generating any leakage of electrolyte during the plating process. Residual brush plating solution is captured and recycled for re-use in a closed-loop system. The Station is designed to perform plating and surface finishing operations on steels or light alloys on site, at DoD repair depots, or in the field. These treatments can be performed on curved, horizontal, and/or vertical surfaces and edges without any leakage of electrolyte. The generation of solid waste is also reduced through this process.
The Zinidal Aero Zn-Ni Solution is also a COTS system and is a candidate to replace Cd brush plating on high strength steels. It is intended to be used for repair applications on weapon systems parts and components (landing gear, terminal assemblies, landing gear doors, bushings, etc.) The coating provides sacrificial corrosion protection to steels, and the process does not require the hydrogen embrittlement relief baking when plating on high strength steels.
The use of the Dalistick Station and Zinidal solution are expected to offer the following immediate and long- term cost, regulatory, and environmental, health, and safety benefits:
- Elimination of Cd brush plating in repair operations
- Reduction of occupational and environmental hazards associated with Cd brush plating
- Avoidance of compliance issues in military repair operations
- Cost savings due to recycle and reuse of plating solution in closed-loop process
- Reduction of solid waste that is generated from traditional brush plating
- Reduction of worker exposure to hazardous materials and to residual brush plating solutions
- Reduction of exposure monitoring, need for personal protective equipment, permitting, and record keeping
The Dalistick Station and Zinidal Aero Zn-Ni Solution are currently undergoing qualification testing. Following the positive results from the qualification testing, the system will be placed in the field at an Air Force Air Logistics Center to further evaluate the systems’ performance under field repair conditions.
Reviewed and approved for public release: 88ABW-2016-3433