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Electroplating is the process of using a weak electric current to bond a metal to an object. The electric current, coupled with the solution, effectively transfers the plating material to the object to be plated and chemically bonds it to the surface. Commonly used plating chemicals include cyanides of the plating metal, phosphates, carbonates, and acids.
In order to initiate the electroplating process, a circuit is set up with an anode made of the metal used for plating. The object to be plated is connected to a cathode. Both objects are then immersed in a liquid solution containing chemicals which oxidize the anode, and with the introduction of an electric current, transfer molecules of the plating material to the object being plated. The electroplating bath usually consists of water and sulfuric acid.
Sulfuric acid is a strong acid with the chemical formula SH2O4. This acid is important to the electroplating process and is the most common plating chemical. It reduces the pH of the bath and also serves as the catalyst for the plating process. Atoms of the plating metal bond with the acid and are then transferred to the object being plated due to the opposite electric charges of the anode and cathode and the electric current passing between them.
Salts of the metal being used for plating are added to the solution. These salts are water soluble, which is essential to the plating process, as the dissolved salts ensure a more even coating of the plating material. Salts are a combination of a metal and chlorine. Almost any metal can bond with chlorine to form a salt. Nickel plating, for example, uses Nickel chloride.
Phosphates, sulfates and carbonates, usually of the plating metal, are also commonly added to the electroplating bath. These plating chemicals help to increase and maintain the electric conductivity of the solution. Increased conductivity improves the efficiency of the plating process.
Plating chemicals also include cyanides of the plating metal as well as other metals, like potassium. These chemicals serve more than one purpose. They increase the conductivity and improve the rate of corrosion of the anode, which leads to better transfer of the plating material to the target object. The addition of cyanides also helps maintain a higher level of dissolved metal ions in the solution, making more of the plating material available to plate the target. Acids like boric acid and hydrochloric acid as well as substances like hydrogen peroxide and sodium hydroxide are also common plating chemicals.
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