Definition - What does Cadmium Plating mean?
Cadmium plating is a type of coating process that offers technical benefits such as outstanding corrosion resistance, even in high-salt and low-thickness environments. Cadmium is the byproduct of the production of zinc, and it was only in 1920s that cadmium plating was recognized as a form of protective coating.
Cadmium plating is also known as cad plating.
Corrosionpedia explains Cadmium Plating
Cadmium can be similar to zinc plating in many ways and applications. The usual chromates that are applied include:
Cadmium is highly toxic, so it should not be utilized on surfaces intended for direct contact with food. It's mostly used in aerospace and harsh environments and is considered superior protection when it comes to brackish and aquatic applications.
Cad plating offers many advantages, including:
- Low levels of galvanic corrosion when in contact with elements like aluminum
- Corrosion resistance in aquatic settings
- Extraordinary white luster identical to that of silver plating
- Exemplary lubricity
- Promotes low levels of electrical resistance
- Complete rust prevention
- Even ductile deposit
- Can be soldered like tin
It can be applied in several ways, but the most common is through electroplating. In this process, cadmium goes through electrodeposition onto the metal from a solution rich in electrolytes and cadmium salts in vats or barrels. Such electrolyte solutions are closely based on a cyanine alkaline system. Other types of solutions such as fluoroborates based systems can be used, but these may produce results lacking in covering power, throwing power and brightness.
Other methods include mechanical cadmium plating, which makes use of mechanical energy to set down coatings on the components. This type of application is perfect for components such as clips and fasteners that are adequately small to undergo plating within a barrel.
Lastly, cad plating can also be achieved through ion or vacuum deposition, where cadmium is heated inside a vacuum until vaporization is achieved. This is followed by the condensation of cadmium atoms that will form a thin film of quality coating.