Electroplated cadmium is a corrosion resistant cyanide coating, according to the Chem Processing Inc. Plating 304 stainless steel with cadmium gives the steel a number of advantages over uncoated stainless steel. These benefits include added corrosion resistance, malleability and non-reaction to aluminum. These attributes make it an attractive material for the aerospace industry but environmental concerns over the material's toxicity make it less sought- after than other coatings.
According to the "Engineer's Companion," cadmium is widely used in the aerospace industry for its corrosion resistance. Even though stainless steel has an inherent resistance to corrosion, cadmium increases the resistance making it ideal for aerospace parts that may be hard to monitor for corrosion. Cadmium plating also increases the corrosion resistance of stainless steel in salt environments, such as coastal areas.
Cadmium is a good choice for aircraft production, due to its increased solder-ability, low reactivity to aluminum and low coefficient of fiction. This means that soldering cadmium-plated stainless steel parts to aluminum parts, one of the most common materials in the industry, is relatively easy and inexpensive. Additionally, the fact that it has a low reactivity to aluminum and a low coefficient of friction means routine inspections and removal of the parts produce very little wear. The parts resist corroding in the presence of aluminum.
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The primary concern with coating stainless steels such as the 300 series, with cadmium, is the toxicity of the metals. According to www.chemprocessing.com, cadmium is a known carcinogen and the cyanide coating process creates additional health concerns even in small amounts. Because of this cadmium coating of stainless steel is largely limited to the aerospace industry, despite it having potential performance advantages in other industries.