Cadmium Plating,Cadmium Plating,Cadmium Plating,Cadmium Plating,Cadmium Plating
Electrodeposits of cadmium are used to protect steel and cast iron against corrosion. Because cadmium is anodic to iron,
the underlying ferrous metal is protected at the expense of the cadmium plate even if the cadmium becomes scratched or
nicked, exposing the substrate.
Cadmium is usually applied as a thin coating (less than 25 μm or 1000 μin. thick) intended to withstand atmospheric
corrosion. It is seldom used as an undercoating for other metals, and its resistance to corrosion by most chemicals is low.

Besides having excellent corrosion protective properties, cadmium has many useful engineering properties, including
natural lubricity. When corrosion products are formed on cadmium-electroplated parts, they are not voluminous, and there
is minimal change in dimension. These two properties are responsible for the wide use of cadmium on moving parts or
threaded assemblies.
Cadmium has excellent electrical conductivity and low contact resistance. Noncorrosive fluxes can be used to produce
top-quality soldered sections. Steel that is coated with cadmium can be formed and shaped because of the ductility of the
cadmium. Malleable iron, cast iron, powdered metals, and other hard-to-plate surfaces can be coated with cadmium, and
materials used for adhesives bond very well to cadmium-coated surfaces.
Cadmium is highly toxic, and health, safety, and environmental concerns are driving the reduction or elimination of its
use for many applications. See the section "Toxicity of Cadmium" in this article and the article "Cadmium Elimination" in
this Volume for more information.

Plating Baths
Most cadmium plating is done in cyanide baths, which generally are made by dissolving cadmium oxide in a sodium
cyanide solution. Sodium cyanide provides conductivity and makes the corrosion of the cadmium anodes possible.
Cyanide Baths. Compositions and operating conditions of four cyanide baths are given in Tables 1(a) and 1(b). Note
that for each of these baths a ratio of total sodium cyanide to cadmium metal is indicated; maintenance of the
recommended ratio is important to the operating characteristics of the bath.

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