Electroplating is the process of plating a thin layer of other metal or alloy on certain metal surfaces using electrolysis equipment. It has a single metal coating, an alloy coating and a composite coating. The plating layer has protection, decoration and repair functions on the metal surface.
Single metal plating has been more than 170 years old, and 33 metals on the periodic table have been electrodeposited from aqueous solutions. Commonly used are electroplated zinc, nickel, chromium, copper, tin, iron, cobalt, cadmium, lead, gold, silver and other more than 10 kinds. A plating layer formed by simultaneously depositing two or more elements on the cathode is an alloy plating layer. The alloy coating has the structure and properties not possessed by a single metal plating, such as amorphous Ni— P alloy, each of the Sn alloys not on the phase diagram, and has a special decorative appearance, particularly high corrosion resistance and excellent weldability. , magnetic alloy plating, etc.
Composite plating is the process of adding solid particles to a bath to co-deposit with a metal or alloy to form a metal-based surface composite to meet specific application requirements. According to the electrochemical properties between the coating and the base metal, the plating layer can be divided into two types: anodized coating and cathodic coating. Where the potential of the plated metal relative to the base metal is negative, the plating layer is an anode when the micro cell is formed, so it is called an anodized layer, such as a galvanized layer on the steel piece; and the potential of the plated metal relative to the base metal is positive, When the corrosive microbattery is formed, the plating layer is a cathode, so it is called an cathodic coating layer, such as a nickel plating layer and a tin plating layer on steel parts.