The electroplating process is a chemical process which is used to deposit a metal layer or more metal layers on a metal object for purpose of surface treatment. Electroplating process mainly consists of two electrodes, an anode (positively charged) and a cathode (negatively charged). An anode is an object to be plated and a cathode is an inert electrode or normally made up of metal which forms deposition on the anode during the electrochemical process. Both of these two electrodes are immersed into an aqueous metal salt solution containing metal ions called electrolyte. A DC power supply is connected to the electrodes to form a closed circuit and current flows continuously in the closed loop. The current flows into the cathode and oxidizes the metal atoms that the cathode consists of into positive metal ions. The metal ions will be attracted to the cathode under the impact of the electric field and receive electrons from the cathode, that is, metal ions are reduced to the metal atom, to form a metallic deposition on it. Due to the formation of the deposition, the electroplating process is also commonly known as electrodeposition process.
There are various electroplating processes which can be adopted to electroplate metallic objects, such as barrel plating, rack plating, continuous strip plating and line plating. Each plating process possesses its own features and application areas. The function of the plating can be classified into two distinct categories- decorative plating and functional plating. Decorative plating is intentionally used to achieve an aesthetically attractive surface finishing of an object. In contrast, functional plating is mainly used to enhance mechanical or functional properties of a metallic object. Depending on the intended use of the object, the mechanical properties, such as wear resistance, abrasion resistance, anti-corrosion, hardness, electrical conductivity, lower surface friction, etc., can be altered through a suitable electroplating process.
Different base materials can be plated adopting different surface finishings. Common base materials are beryllium copper, brass, copper, nickel, stainless steel, etc. and common surface finishes are gold, silver, electrolytic nickel, hard chrome, etc. Choosing of plating approach, plating metal and object to be plated are contingent on the application. Hence, a definite plating purpose should be clearly understood before starting a plating process otherwise an intended function might not be acquired.