ELECTROPLATING: PROCESSES, APPLICATIONS AND EXAMPLES - CHEMISTRY - 2025

The plating is a technique used in metal electrodeposition coating an electrode to create on this surface with different characteristics to those of the metal in its pure state. Plating and dipping processes are also used in electroplating, which do not involve the use of an electrical current.

Electroplating, a technique used in electroplating, consists of an electrochemical process that is used to create a metallic coating on a conductive surface, by precipitation of metal cations present in an aqueous solution.

Apparatus used in 1882 for electroplating

Although electroplating has been applied for many years, in its beginnings it was used mainly for decorative purposes, until from the First and Second World War, it began to be used as a technology in the electronics industry, in metallurgy, in electrochemistry, and in many other fields.

What is electroplating?

As previously described, electroplating consists of modifying the characteristics of the surface of certain materials through the accumulation of metals on it by deposition.

In this way, the properties are modified by the formation of a layer or coating on the material, using the same principle of electrolytic cells, where the surface to be galvanized functions as the cathodic part of the circuit, while the anode is constituted by the metal that will be electrodeposited on the piece.

Both the anode and the cathode are immersed in a solution that is composed of one or more dissolved metal salts, as well as some ionic species that contribute to the flow of electric current.

When a power source is connected, the circuit is completed and two different processes occur at the anode and at the cathode, which are found in the solution called electrolyte.

On the one hand, the anode receives the flow of current and produces the oxidation of the metallic species of which it is constituted, helping them to dissolve in the electrolyte.

On the other hand, in the cathode there is the reduction of the metal ions that have dissolved in the interface formed between the cathode and the electrolyte, so that they can "spread" towards the cathode.

Processes related to electroplating

Sweep electrodeposition

It is a technique closely related to electroplating, in which specific areas and even entire objects are coated using a brush saturated with the coating solution.

This brush is made of stainless steel and covered in an absorbent cloth, which keeps the coating solution inside and prevents direct contact with the material being coated. It is soaked in the solution and is applied evenly on the material.

Impulse electrodeposition

This method is a simple alteration to the concept of electrodeposition, and consists of rapidly varying the current or potential between two different values, resulting in a chain of pulses that have the same polarity, duration and amplitude, and that they are divided by a current whose value is equal to zero.

If the width or amplitude of the pulse is modified while using this procedure, the thickness and even the composition of the coating layer that is deposited can also be altered.

Electrochemical deposition

In a similar way, electrochemical deposition is normally used to conduct metal oxides and for the accumulation of metals on certain surfaces due to the advantages it presents, such as its low cost in relation to other techniques or that it does not require high processing temperatures.

It is widely used in the synthesis of relatively compact and uniform coatings of certain structures based on a model, and also to obtain higher rates of metal deposition, among other applications.

Strike

There is a process called strike that is based on the use of a sediment with special characteristics for coating, in order to produce a fairly thin coating that adheres well to the substrate and has high quality.

This technique offers a good base for subsequent coatings and, in turn, can be combined with other methods to obtain a better result.

Electroplating Applications

A large number of applications are known for this electrodeposition process. We will describe the most outstanding ones below:

- Increase in thickness in objects or pieces with insufficient dimensions for certain functions in the industry.

- Strengthening of properties such as the hardness or resistance of certain metals through successive coatings.

- Manufacture of parts by electroforming (method for the creation of metal parts by the accumulation of metals on specific patterns).

- Reproduction of decorative elements by electrochemical techniques using different metals.

- Protection of various materials by coating their surface with protective films made of metal alloys.

Examples

In daily life there are several uses of electroplating, one of the most common being the production of coins (which are forged with zinc) with copper coating to protect them from corrosion.

Another example that can often be observed is the coating of iron pieces with zinc films, to prevent them from being oxidized when exposed to oxygen present in the air.

In the case of ornamental elements, there is the coating of jewelry with precious metals such as gold or silver, as well as others that are more difficult to achieve depending on the desired purpose.

Finally, in addition to the existence of many other examples of the use of this useful technique, there is nickel plating (coating with nickel) of steel objects in order to enhance their anticorrosive capabilities.

References

1. Wikipedia. (sf). Electroplating. Recovered from en.wikipedia.org
2. Panda, H. (2017). Handbook on Electroplating with Manufacture of Electrochemicals. Recovered from books.google.co.ve
3. Kanani, N. (2004). Electroplating: Basic Principles, Processes and Practice. Recovered from books.google.co.ve
4. Watt, A. and Philip, A. (2005). Electroplating and Electrorefining of Metals. Recovered from books.google.co.ve
5. Schlesinger, M. and Paunovic, M. (2011). Modern Electroplating. Recovered from books.google.co.ve