Electroplating involves the application of a thin layer of metal to the surface of an object. This layer of metal is known as the plating layer, and is usually applied using an electric current. Electroplating is used for a variety of applications including decorative, functional and protection purposes. The most commonly used source for the metal layer is a solution, which typically contains molecules of the metal to be plated, an electrolyte and various other additives. The purpose of each of these components will now be discussed.
The metal to be plated is typically supplied to the solution in the form of ions, which are positively charged particles. When a negative current is passed through the solution, these metal ions are attracted to the object to be plated and adhere to the surface due to their electrical charge. The metal ions then form a layer on the surface of the object, resulting in the plating layer.
The electrolyte provides an ionic charge environment that facilitates the movement of the metal ions towards the object to be plated. The most commonly used electrolytes for electroplating are aqueous solutions of various acids, for example sulphuric acid or hydrochloric acid. The electrolyte helps to maintain the electrical charge within the solution, so that the ions of the metal can move towards the object.
Various other additives are added to the electroplating solution. These include wetting agents, buffers, sequestering agents and brighteners. Wetting agents help the metal ions to attach to the object more easily and sequestering agents help to keep the metal ions in the solution by binding to them. Buffers are used to maintain the pH of the solution, and brighteners are added to give the surface of the object a brighter shine.
In addition to these components, electroplating solutions often contain organic compounds such as organic solvents, thickeners and surfactants. These organic compounds help to reduce the surface tension of the plating solution, and thus helps to improve the wetting of the metal ions to the surface of the object. They also help to protect the metal ions from contamination and protect the surface of the object from damage during the electroplating process.
To summarise, each of the components of the electroplating solution serves a necessary purpose. The metal ions are attracted to the surface due to their electrical charge, and the electrolyte helps to facilitate this movement. The various other additives also help to protect the metal ions and the surface of the object, and to give the object a higher quality finish.
