Alkaline zinc-nickel plating is an alloy coating formed by the co-deposition of zinc and nickel ions onto the part surface from an alkaline electrolyte bath. The nickel content in the coating structure is typically kept between 12-15%; this ratio promotes the formation of a gamma-phase crystal structure, giving the coating far greater salt-spray resistance than standard zinc plating (with proper passivation, 500-1000+ hours of neutral salt spray (NSS) resistance can be achieved).
The alkaline (cyanide-free) bath composition carries a lower hydrogen embrittlement risk compared to acid baths and offers superior throwing power (thickness distribution) — particularly important for high-strength steel fasteners and complex-geometry parts. Corrosion resistance can be further enhanced with a post-plating chromate passivation (typically in black or silver/blue tones) and an optional top-coat (sealer) layer.
This high performance makes alkaline zinc-nickel plating the preferred coating method for applications requiring long service life and critical corrosion resistance, such as automotive (brake systems, engine fasteners), wind energy, rail systems, and heavy industrial equipment.
Oil, dirt, and oxide layers on the part surface are removed in an alkaline cleaning bath.
The part is activated in an acid bath to prepare it for plating.
Zinc and nickel ions are co-deposited onto the part surface in an alkaline bath, forming a highly corrosion-resistant alloy layer.
The part is rinsed with treated water to remove residues.
A chromate-based protective layer is applied to increase corrosion resistance. Depending on customer request, blue, transparent and black passivation options are available.
Parts are dried, and coating thickness and appearance are given a final check.
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