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Types of Zinc Plating

Metal objects or parts are immersed in zinc salt solution. An electric current is passed through the solution. A thin plating of zinc is adheres to the object. This is known as zinc plating by electrolysis. Zinc plating protects the metal hardware from oxidization. The various types of zinc plating are acid or alkaline nickel plating, tin zinc plating, zinc cobalt plating and zinc iron plating.

  1. Zinc Alloy Plating

    • An alloy is a mixture of two or more metals. The properties of an alloy differ from the properties of constituting metals. This is used to derive benefit from zinc alloy plating. The protection provided by zinc plating on other metals is improved when it is alloyed with a metal more noble than zinc. This provides improved corrosion protection.

    Zinc-Nickel Plating

    • The two types of zinc nickel plating procedures are alkaline zinc nickel plating and acid zinc nickel plating.

      A 10 to 15 percent nickel alloy is maintained for optimum protection. Alkaline zinc nickel plating facilitates uniform nickel plating in both high current and low current areas. The inherent alkaline nature provides protection to the uncoated parts of hardware. The acid zinc nickel plating is more efficient and is a faster process. This leads to uneven nickel coating. Low current areas report a higher nickel deposit.

    Zinc-Iron Plating

    • Zinc-iron plating involves iron deposits of 15 to 25 percent. The plated metal is ductile and weldable, which is essential for further manufacturing. Black chromating is frequently used to enhance its benefits. It is not heat resistant and deteriorates when exposed to heat, making it unsuitable for automotive components.

    Zinc-Cobalt Plating

    • Zinc-cobalt plating is economical compared to zinc-nickel plating, making it a popular choice. The corrosion resistance of this alloy plating is lower than nickel plating but suitable for specific applications. Zinc-cobalt plating is more effective than a zinc plating of the same thickness. The deposits have about 1 percent of cobalt coating, and the thickness may vary between high current density and low current density areas. Yellow and black chromate plating is available.

    Tin-Zinc Plating

    • Tin constitutes 70 to 90 percent of the alloy. Tin-zinc plating uses neutral or acid baths. The deposit is suitable for soldering and is ductile. The corrosion resistance of this alloy is as good as or better than zinc-nickel alloys. Chromating is available in yellow or clear. It is fast replacing cadmium plating and is popular in the electronics industry and fasteners industry.

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