Cadmium Plating and Cadmium Electroplating

Cadmium Plating is known to have the highest reliability standards when it comes to coating. The process is commonly used in making critical fasteners for several years now. It is also used in providing corrosion resistance to very thin coating. 

 

Why Use Cadmium?

 

Cadmium is used for plating due to its lubricity and low co-efficient of friction. Cadmium Plating is used to assist on tightening a fastener at a minimal torque. Furthermore, such metal is used one electronic assembly due to its low electrical contact resistance. Cadmium is also used along with aluminum assemblies in order to minimize its susceptibility to galvanic corrosion. The chemical element is used in close tolerance assemblies since it will not lead to the formation of voluminous corrosion products. If necessary, cadmium can also be soldered, especially for assembly purposes. In some instances, Cadmium Electroplating is used. The process is similar to plating, except that it makes use of an electrical current during the process of plating. 

 

Uses of Cadmium Plating

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Due to its exceptional properties, Cadmium is the most commonly used metal as plating for fasteners. They can be plated at a low embrittling coating or something that imparts a significant hydrogen embrittlement. The baking times to relieve the hydrogen embrittlement could take a few hours up to a hundred hours. The Cadmium metal is either dull or bright, but is known to have a luster and an appearance as plated or as chromated. Cadmium Plating can come in the form of columnar or laminar, emanating from the basis metal. The metal can be possibly plated at 0.5, which is low current density cadmium or at 10, which is at high current density. 

 

Process of Plating 

 

Cadmium can be plated without the need for any kind of supplemental treatment, though it still exhibits metallic luster. In some instances, Cadmium is plated and treated with supplemental chromate that has a clear, green, yellow and black shade. Cadmium can also be possibly plated and be conversion coated with the zinc phosphate coating and will leave a surface that has a light gray shade. Furthermore, Cadmium can be applied through a vacuum, thus, it is called vacuum cadmium. In the case of Cadmium Electroplating, the process would require using electrical current. Sometimes, heating the Cadmium is required, often done on a filament until such time that it condenses and evaporates on some parts that are exposed on a vacuum chamber. Since the process would take place on a vacuum, hydrogen embrittlement could happen. The process is known as peen plating and is used to mechanically apply the Cadmium metal.

 

During Cadmium Plating, the cathode efficiency could become a factor which is seldom considered to be part of the process of plating. The new solutions have a higher efficiency, which is more than 90 percent. Sometimes, used solutions can lose its efficiency as time goes by, depending on the formulation of chemicals. Environmentally induced embrittlement if hydrogen is actually considered as a delayed failure mechanism for fasteners, on a service which should be considered whenever substitutes to cadmium are to be considered and this applies to both Cadmium Electroplating and Plating.