Zinc is a highly corrosion resistant metal and therefore is an ideal coating to use on other types of metals to prevent corrosion. Through zinc plating, highly corrosive metals such as iron can be safely used in a variety of different applications and have a much longer life.
The basic role of zinc plating is to create a skin, or a physical barrier, which limits moisture, chemicals or pollutants in the environment from attacking the surface of the metal. However, zinc can go beyond this, through specific types of plating, to heal or repair scratches and damage even after the plating has been applied.
The Layer
Over time, and after the zinc plating process has been completed, there will be a slight but noticeable gray to white powdery looking layer over the surface of the plated metal. This is a result of a series of chemical reactions between the air and the zinc.
After the zinc plating process, the zinc initially reacts with the oxygen in the air, resulting in the formation of zinc oxide. The oxide then reacts with moisture in the air to form zinc hydroxide. This zinc hydroxide then reacts with carbon dioxide to create the powder. This coating is impermeable by many environmental contaminants but can be dissolved in specific types of acids.
The Processes
There are several different options in zinc plating processes. One of the most common is alkaline zinc plating. This plating provides outstanding protection without any significant amount of change in the size of the part because of the coating process.
Zinc iron plating adds a small amount of fine grain iron to the alkaline electrolyte, creating a uniform distribution of the plate with an extremely even iron coating. The result in a bright, even finish that is blister free.
Another very common option in zinc plating is zinc-nickel. This provides a zinc/nickel alloy coating with a bright finish and excellent adhesion characteristic. This is the best option if high heats are a consideration for the part, and it continues to provide top protection even after thermal shock.
Choosing the right zinc plating process is critical in providing the metal with the protection you need. Working with a company with experiencing in plating is essential for any order, giving you the benefit of their experience with the processes.
At DeKalb Metal Finishing, we have been specializing in the zinc plating processes for over 70 years. To learn more about each option or to contact us visit www.dekalbmetal.com.
