Every year, the metal industry loses millions of dollars through the actions of one simple phenomenon. This is corrosion. Steel and iron companies are heavily affected by the ability of this action and reaction to degrade components and products. To fight against the potential risks to the public from corroding metal components and products, companies turn to the finishing industry. They look to protective coatings to provide their parts and items with what they need to remain intact.
What Is Corrosion?
Corrosion is a reaction that occurs because of different factors. The most common type of corrosion is galvanic corrosion. This results when two metals, each having a different potential (electrochemical charge), are linked together through what is termed a conductive path. The current will flow from the metal that is anodized (positive) to the cathodic (negatively charged) metal. This transfer of ions from the weaker metal to the stronger one is responsible for creating the effect known as galvanic corrosion.
Another type of corrosion is referred to as stress-corrosion cracking (SCC). This results when a metal component or object becomes placed under tensile stress. This stress may result from a process called cold work or from welding and even thermal treatment. If the issue affects the grain boundary, SCC can occur. This leads to the formation of cracks. Corrosion sets in to these cracks further creating problems of stability. When combined with an environment that may increase the problems and capability of stress cracking, the problem becomes severe. In fact, the damage that results from SCC can be irreparable.
Other types of corrosion are:
- General: A major media is water which oxidizes the surface of the metal resulting in a layer of rust. The process is electrochemical in nature
- Localized: This type of corrosion is localized. It only affects a small part of a component
- Caustic Agency: The result of when an impure gas, liquid, or solid erodes the material. One example is hydrogen sulfide
No matter what type, the most effective response will likely be suitable protective coatings.
Protective Coatings: The Response to Corrosion
In order to prevent or inhibit the impact of corrosion, manufacturers turn to protective coatings. In the case of galvanic corrosion, the application of a corrosion resistant coating would do one of two things:
1. Prevent the transfer of ions
2. Stop the conditions that allow it to exist
Some common metal protective coatings are aluminum, cadmium, cobalt-chromium, nickel-chromium and zinc. These may take the form of powder coatings, electroplating or electroless plating.
Protective Coatings
Metal coatings are advantageous for the manufacturer for many reasons. They augment the overall appearance of the exterior. They impede the overall wear-and-tear a component may undergo. They can also increase the overall size of a part. Yet, the main reason for choosing protective coatings is a simple one – to fight off the detrimental effects and serious risk caused by corrosion.
