Cadmium Plating Alternative
Cadmium Plating Alternative
Safer Alternative to Cadmium Plating. Extensive testing since 1995 by USAF, NAVAIR, ARL and others has clearly shown that the best replacement for cadmium plating is electrodeposited Al plating using the commercially available AlumiPlate.
Electrodeposited Al greatly exceeds the performance of Cd plate in:
- prevention of catastrophic corrosion-related failures, and
- compatibility with the numerous Al and Mg components used in most aerospace programs and weapons platforms.
Al has no identified Environment, Safety and Occupational Health (ESOH) issues, while other materials that have been considered in replacement of cadmium such as zinc/nickel (ZnNi) are now coming under regulatory pressure in Europe and the US.
Side-by-side environmental exposure testing of steel coupons plated with 0.0003” cadmium plus chromate versus 0.0003” aluminum plus chromate. Coupons were sprayed for 10 minutes every hour with seawater (Florida test facility). Photo taken after 1,176 hours.
Why and Where Cadmium Plating Was Used
Most weapons systems are heavily dependent on the use of steels, especially high strength steels, to provide adequate mechanical strength in a limited envelope. Unfortunately, these alloys are highly susceptible to corrosion and to catastrophic corrosion-related failures resulting from stress-corrosion cracking, environmental cracking and corrosion fatigue. Cadmium (Cd) plating has been the coating of choice since World War II to prevent corrosion. Galvanic corrosion of more electronegative alloys, such as Al, in contact with more noble materials, such as steel or titanium, is also a critical issue and, up to now, has only been controlled by Cd-plating the steel.
Cd-plating is a requirement throughout all DoD systems.
Its major uses include:
- Fasteners of all kinds in aircraft, vehicles and ships — thousands of rivets, bolts, etc. per system
- High strength steel hydraulic actuators for aircraft and vehicles (typically hundreds per aircraft)
- Electrical connector shells for all military systems (hundreds to thousands per system)
- Aircraft landing gear (fixed wing and rotary wing)
- Connectors for hydraulic and pneumatic lines
- Stainless steel sensors and actuators attached to aluminum frames.
These components are typically cadmium plated by the OEM. Any item requiring overhaul (essentially everything but fasteners and connectors) must be continually touched-up and frequently replated for corrosion control throughout the life cycle of the system at either the OEM or another authorized maintenance facility.
