There exists a need for environmentally benign coatings to eliminate cadmium or chromate coatings on high-strength fasteners. These coatings would provide high-strength, corrosion resistant fasteners for use weapon systems. Traditionally, high-strength steels have been used with cadmium (Cd) electroplated coatings, followed by a hexavalent chromium (Cr⁶⁺) rinse. The environmental hazards associated with both cadmium and chromates are well established.
Alternatives to both processes have been pursued within the coatings industry with very promising results. Developments with combinations of coatings  may meet future DOD requirements. These systems are free of hazardous post-treatments (Cr⁶⁺ rinse) and avoid embrittlement phenomena.
The elimination of hazardous materials will improve the life cycle costs and environmental and occupational health issues associated with the manufacture and maintenance of DOD weapon systems. Cd and Cr  present personnel hazards, and environmental hazards. These approaches would impart high end sacrificial corrosion resistance properties without use of hazardous Cr or Cd and without hydrogen embrittlement of fasteners.
This presentation will propose a multi-layer approach to provide a protective coating system. These systems will include a sacrificial metal base coat and may also include an organic topcoat technology that will provide the best combination of corrosion resistance and torque tension control.