There are many types of protection for carbon steel against corrosion. One of them is the use of cadmium as a coating. The use of cadmium as a protective for carbon steel from corrosion is not because of carelessly, but for specific reasons that cadmium have than other materials. The following describes some of the reasons the use of cadmium as a coating of carbon steel for protection against corrosion.
Cadmium is Powerful and Versatile
Cadmium has several advantages, including powerful and versatile. Cadmium has the physical properties of white and soft. Cadmium is “sacrificial coating” so it can protect the carbon steel overlaid from corrosion attack.
Electroplated cadmium is widely known application in steel plating method. Usually also be combined with an additional chromate coating to improve protection resistance against corrosion, the outermost layer after the addition of chromate will be visible gold in general, some other colors are also available, such as olive drab.
Cadmium vs Zinc vs Nickel Plating Comparison
Indeed, cadmium is the best and no substitute due to its nature. Cadmium is “sacrificial protection”, not sticky, soft and fit combined with aluminum. Replace Cadmium with Zinc may be can be done for protection against corrosion because Zinc is also “Sacrificial protection”, but zinc may be problematic in interaction with the metal.
Most of the hardware in this world use Zinc plated compared with Cadmium plated. This would be fine depending on the level of critical need.
Nickel does not have a sacrificial protection nature on carbon steel. Nickel is only acting as a barrier layer between the media cause corrosion to the carbon steel, so that in case of scratches that damage the layer then carbon steel be corrosive first, even carbon steel will protect Nickel because carbon steel is anodic against Nickel.
One which Cadmium disadvantage is its extremely toxic metal.
Some examples the use of Cadmium Plated metal are cadmium plated screw, cadmium plated sprinf for Pressure Safety Valve (PSV).