What is electroplating?
Electroplating is an industrial process in which an electric current is applied in a special bath to coat suitable articles with a thin layer of metal. It has been in use since the early 1840's. A familiar example of electroplating is "chrome plating", in which the metal chromium is deposited over the surface of metal and plastic articles. Electroplating occurs in lead-acid battery cells but so slowly, it takes years before it has an effect.
An article to be plated is made the negative electrode in a bath containing a solution of chemical compounds with requisite properties. The positive electrode in the bath is typically made of metal of the type to be plated onto the negative electrode. In practice it requires considerable technical resourcefulness to obtain an evenly-coated electroplating finish.
The diagram below shows an animated schematic representation of an electroplating process at work. For the sake of simplicity, the source of the electric current is a battery. Electric current in a wire circuit consists of a flow of electrons from the negative terminal to the positive terminal of the source of electricity.
The nature of the current changes as it is made to flow through the electroplating bath. Electrons are taken out of metal atoms at the surface of the positive electrode, causing these atoms to be converted into positively charged ions, which promptly become dissolved in the liquid or electrolyte of the bath. Metal ions, being positively charged, are attracted to the negative electrode and are deposited securely onto its surface, receiving electrons from the circuit on the negative side in the process. The ease with which metal atoms can be made to give up electrons on leaving the positive and to receive electrons on arriving at the negative electrode is what makes electroplating possible.