Zinc-Nickel Plating
Zinc-nickel plating is a zinc alloy coating containing about 12–15% nickel that gives several times the corrosion life of plain zinc, often 720 hours or more to red rust in salt spray. It is the standard high-performance finish for automotive fasteners, brake and fuel-system parts.
What it is
The coating is electroplated from an alkaline or acid bath that co-deposits zinc and nickel. The nickel makes the coating corrode much more slowly while still protecting the steel sacrificially.
Like zinc, it is finished with a passivation, usually trivalent clear or black, and often a sealer. It also holds up better than plain zinc at elevated temperatures, which suits parts near engines and brakes.
Typical applications
- Automotive fasteners and brackets
- Brake, fuel-line and hydraulic components
- Agricultural and construction equipment parts
- Outdoor electrical and telecom hardware
- Replacement for cadmium in some aerospace and defence parts
Suitable materials
- Carbon and alloy steels
- Cast iron
- High-strength steels (with hydrogen-embrittlement relief)
Points to consider
- It costs more than plain zinc; use it where the extra corrosion life is needed.
- Many automotive customers call up their own OEM specification; share it so the right process and tests are used.
- High-strength parts still need baking to relieve hydrogen embrittlement.
- Black passivation plus sealer gives a durable black finish without paint.
Frequently asked questions
Why is zinc-nickel better than zinc plating?
The nickel alloy corrodes far more slowly, so the same thickness lasts several times longer in salt spray. It also resists heat better than plain zinc.
Is zinc-nickel plating RoHS compliant?
Yes, when trivalent passivation is used, which is standard today.
Can zinc-nickel replace cadmium plating?
In many applications, yes. Zinc-nickel is one of the main cadmium replacements, though aerospace parts must follow the specific approved specification.