Low Hyrdrogen Embrittlement (LHE) Brush Plating Chemistries for Cadmium (Cd) Replacement

Electrolytic cadmium (Cd) coatings topped by a hexavalent chromium [Cr(VI)] conversion coating post-treatment are the standard method used to protect and repair critical aircraft components (like landing gear). Cadmium coatings have excellent properties and have been used for over 50 years. Unfortunately, cadmium is regulated by OSHA and EPA; health and environmental concerns (worker exposure, hazardous waste handling and disposal) has led the DoD to develop substitutes. Numerous electroplating facilities currently operate. Thus a drop-in replacement for selective (brush electroplated) low hydrogen-embrittlement (LHE) cadmium repair coatings that can provide a ductile, conductive, lubricious and corrosion-resistant coating, with the same or better performance than cadmium, and can be applied by trained personnel using existing facilities, but which does not use toxic plating solutions would be an attractive option.The new repair coating achieved Phase I performance objectives by passing military and ASTM standard tests for adhesion and hydrogen embrittlement, showing good corrosion resistance in electrochemical tests. In Phase II, we will optimize the coating formulation while working with a major coating system supplier to qualify it by meeting all MIL-PRF- requirements. We will work with end users to coat aircraft parts during field qualification tests for an in-service performance assessment.