Finishes / Zinc-nickel plating

Zinc-nickel plating services for steel parts

Zinc-nickel is an electroplated alloy of zinc with about 12 to 15% nickel, finished with a trivalent passivate and often a sealer. On steel it protects the same way zinc does, by corroding first, but it lasts several times longer in salt spray and holds up better at engine bay temperatures.

Buyers specify it on brake and fuel line fittings, hydraulic connectors, fasteners and brackets that see road salt or outdoor exposure. It is also the most common replacement where a drawing still calls for cadmium. Send the drawing with the spec, and we match it with shops that run zinc-nickel on the line type your part needs.

Send an RFQ for this finish What to put on the drawing

Carbon steel substratebase
Zinc-nickel deposit, 12 to 15% Ni8 to 13 µm
Trivalent passivateunder 1 µm
Sealer or topcoat1 to 3 µm

A typical automotive build. The passivate and sealer carry much of the corrosion performance, so name them on the drawing.

Section view, not to scale. Thickness values are typical, not promised.

Typical values

Typical ranges, not promised. The spec on your drawing and the process control of the shop set the real numbers.

Thickness: 5 to 15 µm, 8 to 12 µm is common on automotive parts
Nickel content: 12 to 15% in the deposit (the high-nickel gamma phase)
Passivate colors: Clear (iridescent) or black, trivalent chromium
Topcoat: Optional sealer or topcoat, often with a set friction coefficient for fasteners
Process: Rack for larger parts, barrel for screws, nuts and small stampings
Heat: Keeps its protection at higher service temperature better than plain zinc
Galvanic: Closer to aluminum than zinc or cadmium, so it suits steel parts fastened to aluminum

Specs buyers call out

Put the spec and its type, class or grade on the drawing. Shops quote against it, and approvals narrow the list.

ASTM B841: Electrodeposited zinc-nickel alloy coatingsOne class (Class 1) with chromate conversion types A to E. Thickness and nickel limits are in the full text, so name the edition
AMS 2417: Zinc-nickel alloy plating, aerospaceCommon cadmium replacement on aerospace drawings, usually with bake
ISO 19598: Zinc and zinc alloy plating with Cr(VI)-free treatmentsCoating code sets alloy, thickness, passivate and sealer in one line
OEM specs: Automotive manufacturer standardsName the document and revision. Shops need to be approved to some of them

Base materials

Name the alloy and hardness on the RFQ. Preparation changes with the base metal, and some shops only run one family.

Suits

Carbon and low alloy steel
Sintered steel, sealed first
Hardened steel with relief bake

Needs care

Cast iron (needs a suitable activation)
Leaded free-machining steel
Parts with deep blind holes (rack position matters)

Not typical

Aluminum (possible but rarely offered)
Stainless steel
Copper and brass

Hardened steel over 39 HRC

Electroplated steel over 39 HRC needs a hydrogen embrittlement relief bake soon after plating, before the passivate. Put ASTM B850 or your own bake requirement on the drawing and ask for bake time, temperature and start time on the cert. Springs and high strength fasteners need this every time.

When to specify it, and when to look elsewhere

A good fit for

Steel parts that see road salt, outdoor weather or under-hood heat
Replacing cadmium on an older drawing
Steel fasteners or brackets that touch aluminum
Parts where plain zinc already shows red rust too early

Look elsewhere for

Indoor parts where clear zinc is enough and cheaper
Very high strength fasteners where any hydrogen is a concern: look at zinc flake
Decorative bright parts: nickel-chrome is the usual choice
Tight fit bores that cannot take 10 µm per surface

What to put on the drawing and RFQ

Six lines that decide whether quotes compare. Missing items come back as questions and add days.

Spec and codeASTM B841 with the edition and chromate type, or the ISO 19598 code, or the OEM document and revision.
ThicknessMinimum on significant surfaces, and where it is measured. Recesses always plate thinner.
Passivate and topcoatClear or black, sealer yes or no, and a friction coefficient range for fasteners.
Corrosion testIf your spec requires salt spray, name the test method and hours. The requirement is yours to set.
ThreadsState whether the thread class applies before or after plating. See the thread allowance guide.
BakeHardness of the part and the bake requirement, or a note that no bake is needed.

What moves the price

Shops price by load, lot and labor more than by the chemistry itself.

More per part than plain zinc: alloy bath control and the topcoat
Relief bake adds oven time and about a day of lead time
Rack plating costs more than barrel per part
OEM approved process and test reports add paperwork cost

Plating and coating cost: what drives the price per part

Questions buyers ask

About zinc-nickel plating specifically. For how matching works, see the home page.

How is zinc-nickel different from zinc plating?

Both protect steel by corroding first. Zinc-nickel corrodes much more slowly, so the same thickness lasts several times longer in salt spray testing, and it tolerates higher service temperature. It costs more per part.

Can zinc-nickel replace cadmium?

Often, yes. AMS 2417 zinc-nickel is the most common cadmium replacement on aerospace and defense drawings. Check lubricity, torque and galvanic needs with the drawing owner before switching.

Is black zinc-nickel available?

Yes. A black trivalent passivate over zinc-nickel is common on automotive parts. Black passivates usually need a sealer to keep color and corrosion performance.

Can small fasteners be barrel plated in zinc-nickel?

Yes. Many shops run zinc-nickel in barrels for screws, nuts and clips. State the lot size and part weight so the RFQ goes to shops with the right barrel line.

Does zinc-nickel need a relief bake?

On steel over about 39 HRC, yes, as with any electroplating. Softer steel usually does not, unless your spec requires it.

Get quotes for zinc-nickel plating

Send one RFQ with the drawing, base material, spec and lot size. We match it with up to 3 shops that run this finish on a line that fits your part, and reply within 24 business hours.

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