INTERN MPAPS G-22 PDF

This specification covers the Corporation’s requirements for hex-chrome-free zinc-nickel plating on steel substrates.

APPLICATION

Zinc-nickel plating is used primarily for corrosion resistance of ferrous metal parts (fasteners, fittings, clips, brackets, etc.) where levels of corrosion resistance greater than standard zinc plating are required. The alkaline zinc-nickel plating process (rather than acid zinc-nickel plating) is preferred for parts supplied to this specification, since it provides better coating ductility, minimal flaking, and higher corrosion resistance. A trivalent chromium passivate will be applied to the zinc-nickel plating. Supplementary sealers/topcoats may be applied, depending on the specified plating class and performance requirements. Plated parts should not come in contact with stressed polyamides 6 or 66, due to the potential for stress cracking in the presence of road salts. The service temperature range of zinc-nickel plated parts is -50 to 120^◦C (-58 to 248^◦F). This coating is not intended for electrical grounding applications- See MPAPS G-23.