Non-Toxic Coating to Replace the Cadmium Coating Used on Naval Fasteners - Zinc-Based Coating Alloy Development Program

1The most important reason for reduction and subsequent elimiantion of cadmuim coating in fasteners is the high potential health hazard. Industry is eliminating this metal from usage where ever possible. A family of zinc based alloys has shown favor for replacement. Binary systems with several other elemental additions have been investigated by workers in the plating field and found to be credible alternatives to cadmium. However, opportunities exist for building on this work and providing even better coatings for cadmium replacement with longer life and improved mechanical properties. Corrosion resistance and mechanical properties of modified alloys will be examined and compared for a dtermination of the best coating. Three different processes are proposed for experimental work using zinc base complex coatings. Materials selected for this study are zinc nickel cobalt manganese, and zinc nickel cobalt with chromate film and with manganese phosphate film. These materials will be subjected to a series of corrosion and durability tests. Results are expected to be positive and lead to new coatings for industrial and defense applications.