Electroplating which is also known as electrodeposition is a process which passes an electric current via a solution called electrolyte. Electroplating includes two electrodes, an anode (positively charged electrode) and a cathode (negatively charged electrode). The plating metal is connected to the anode and the metal to be plated is connected to the cathode. The electrolyte consists of an aqueous solution containing metal salt in which the metal ions form a deposition on the plated object. These electrodes are immersed in the electrolyte and connected to a power source to form a closed circuit. When a direct current is supplied to the anode, the plating metal will be oxidized to positive ions and dissolves in the electrolyte. On account of its positive charge, the metal ions dissolving in the electrolyte will be attracted by the cathode. The cathode will provide required electrons to neutralize the attracted metal ions on it and form a metallic deposition. Thickness or amount of deposition is directly proportionally to the current provided by the power source.
There are several key factors that will greatly impact the accuracy of the electroplating result include electrolyte and temperature of the reaction bath, anodic or cathodic current density, time of plating and distance between anode and cathode. In addition, Faraday’s laws of electrolysis consist of two principles which are able to give us further insights into the electroplating. Faraday’s first law enunciated that the amount of the substance deposited or liberated at an electrode is directly proportional to the quantity of the electricity that passes. Faraday’s second law enunciated that the mass of a substance deposited or liberated at any one of electrodes when a certain amount of the charge passes through is directly proportional to its electrochemical equivalent.
Selection of the electrolyte also plays a crucial role in achieving a good quality electroplating result. There are different types of electrolyte, acids, bases, metallic salts or molten salts. Bear in mind that factors of selecting a proper electrolyte are corrosion, abrasion, wear resistance, mechanical strength, hardness, and ductility. With the aid of electroplating, mechanical properties and aesthetics of an object can be greatly enhanced. The diversity of electroplating types, such as nickel plating, hard chrome plating, copper plating, silver plating, etc., provides us a wide range of choices according to our application area.
