Electroplating processes commonly used in corrosion and protection include electroplating methods with applied current, deposition methods without or using internal current, or electroless plating, as well as direct chemical conversion of the surface of the substrate material.
1.Electroplating method with applied current
An electrode is built into the electrolyte and a current is applied. At this point, an electrochemical reaction occurs 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. Not only can smaller ions be discharged to form a coating, but larger particles that can make them electrically charged, such as polymer coatings or rubber particles, can also be deposited on the electrode through such methods.
2.Electroplating method without external current
Using materials with different potentials to contact the plated piece can also be deposited through the generated internal current. The replacement reaction or autocatalytic reduction at the interface between the matrix material and the solution allows ion deposition into a coating, which can eliminate the trouble of applying external current without configuring a power supply device. However, such methods are inevitably subject to various limitations of chemical reaction conditions.
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, friction reduction and wear resistance, improving the adhesion of paints and adhesives, and providing colorless, black, or colored decorative film layers.
All the above methods must be completed through the conversion of ions and the exchange of electrons at the interface. When a charged plasmid migrates within a conductive medium, it actually transfers both charge and mass. After discharge, particles accumulate in an orderly or disorderly manner to form the required deposition layer.
In this way, the relationship between the amount of deposition can be characterized by Faraday’s law. Numerically similar interactions essentially reflect the measurement of the number of reactive particles crossing both sides of the interface. Strict particle counting makes electroplating a process that is easy to strictly monitor through parameters and processes. Because of this, coupled with its flexibility, low cost, and ease of operation, it has been widely used in industrial production.