Let’s discuss the methods of corrosion protection for metals: coatings and cladding
Thread Content
A thin layer of a more corrosion-resistant metal can be used to protect the steel base layer. The common method is electroplating, typically 2 to 3 layers are applied, each with a thickness of only a few dozen micrometers; as a result, pores are inevitably present, and the solution can penetrate these pores, creating a corrosion cell between the plating layer and the underlying layer. If the coating is a precious metal, its potential is higher than that of iron, so it will act as a cathode and accelerate the corrosion of the underlying iron. Therefore, such coatings are not suitable for highly corrosive environments, but can be used in environments such as the atmosphere and water; the slowly formed corrosion products can block the micropores, increasing resistance and thereby granting a certain service life. If inexpensive metals are used, the polarity of the corrosion cell is reversed compared to what was mentioned above, allowing the steel to receive cathodic protection and thus maintain a longer lifespan. In addition to electroplating, hot-dip plating (melting immersion plating), flame spraying, vapor plating, and full-metal sheet cladding are also commonly used. The latter has no micropores, offers superior corrosion resistance and a longer lifespan, but is slightly more expensive.
The main methods for preventing corrosion in metals include plating and coating. A coating is typically applied to the surface of steel by methods such as electroplating or hot-dip plating to form a corrosion-resistant metal film. Electroplated layers are generally thin and contain micropores, which can lead to the formation of corrosion cells; especially when the plating is made of a precious metal, the underlying iron will accelerate corrosion. Relatively speaking, the use of inexpensive metal coatings can provide cathodic protection and extend the service life of steel. The cladding layer is formed by methods such as coating entire metal sheets; since it has no pores, it offers greater corrosion resistance and a longer service life, but at a higher cost. Overall, selecting the appropriate corrosion prevention method requires considering environmental conditions and cost-effectiveness. .