Generally, electroplating processes widely used in corrosion and protection include: electroplating method with applied current, deposition method without external current or using internal current or chemical plating, and direct chemical conversion of the surface of the substrate material.
1. Electroplating method of applied current
An electrode is embedded in the electrolyte and current is applied. At this time, there is an electrochemical reaction at the interface between the electrode and the medium. This electrochemical reaction includes the reduction of ions on the cathode surface and the oxidation on the anode surface, both of which are utilized in the electroplating process. And not only can the smaller ions discharge to form the coating, but the larger particles that can make it charged, such as polymer coatings or rubber particles, can also be deposited on the electrode through this method.
2.Electroplating method without external current
The material with different potential is used to contact with the plating piece, and the internal current generated can also be deposited. The replacement reaction or autocatalytic reduction at the interface between the matrix material and the solution makes the ion deposit into the coating, which can eliminate the trouble of applying external current without configuring power supply equipment. However, such methods are inevitably limited by the chemical reaction conditions.
3. Surface conversion
The oxidation or reduction process that occurs when electrons are lost or captured is often used to form a protective film on the surface. This surface treatment means generates reaction products through surface conversion, thus providing many functions of surface facial mask layers. For example, corrosion protection, anti-friction and anti-wear, improving the adhesion of coatings and adhesives, and providing colorless, black or colored decorative coatings.
All the above methods must be completed by ion conversion and electron exchange at the interface. When a charged plasmid migrates in a conductive medium, it actually transfers both charge and mass. The particles after discharge are stacked orderly or disorderly to form the deposition layer we need.
In this way, the relationship between the amount of deposition can be characterized by Faraday’s law. The numerically-like interaction essentially reflects the measurement of the number of reaction particles when crossing both sides of the interface. Strict particle counting makes electroplating a process that is easy to be strictly monitored by parameters and processes. Because of this, combined with flexible application, low cost and easy operation, it has been widely used in industrial production.