Zinc-nickel plating is usually applied where specifiers want the highest performance with the lowest deposit thickness. By specifying zinc-nickel, components can resist more than 1000 hours neutral salt spray (ISO 9227 & ASTM B117) with no effect on the dimensional tolerance of threaded components. Components typically plated with zinc-nickel include:
- Automotive – Fluid transfer tubes which can be deformed into their required shape after plating
- Automotive – Fasteners, particularly in areas of high corrosion (underhood, chassis joints)
- Electronic – Connectors, as a direct replacement for cadmium to provide corrosion resistance and high electrical conductivity
- Aerospace and defense – Joining components in contact with aluminum.
The preferred alloy composition for zinc-nickel plating is 12 – 15% nickel, with the remainder being zinc. This alloy gives exceptional sacrificial corrosion resistance and can be readily passivated. To achieve this alloy, zinc-nickel is usually plated from an alkaline electrolyte. For some applications, including the plating of brake castings, acid zinc-nickel can be used.
Advantages of MacDermid Enthone zinc-nickel plating processes:
- Excellent corrosion resistance
- Good alloy distribution
- Excellent deposit distribution (alkaline)
- Compatible for TriPass hexavalent-chromium free passivates
- Compatible with TriPass 7000 series cobalt-free passivates
- Friction properties can be modified with Torque 'N' Tension fluids
- Specified and approved by many automobile manufacturers
Enviralloy Sprint is suitable for both rack and barrel zinc-nickel plating applications that require 12 -15% nickel alloy coverage. These deposits meet demanding automotive specifications for extended resistance to corrosion. This process is recommended for applications requiring high yield productivity and maximum corrosion resistance.
The as-plated deposit is a uniform silver-grey, which can be further enhanced by passivation with PERMAPASS™ ULTRA IV and sealing with ENSEAL XD40. Where a black finish is required, passivating with TriPass ELV 5700 and sealing with TRIDIP will give a uniform, iridescent-free, deep black finish.