Anything made from iron or steel is a prime target for the destructive forces of corrosion. Corrosion occurs due to a chemical reaction between moisture, the surrounding atmosphere and the atoms that comprise a metal substance. Corrosion is a serious problem that can lead to the premature degradation of bridges, buildings, vehicles, appliances and just anything else that is constructed with metal and other materials.
Red and White Rust: What’s the Difference?
Two common types of corrosion that affect metals are red and white rust. Most people are familiar with the former. Red rust is the formation of ferrous oxide, that reddish-brown material you often see on the body of older cars or an outdoor grill that has been exposed to the elements over time. White rust is actually zinc hydroxide that takes the form of a white, waxy powder that is produced when the zinc that is often used to coat steel products reacts with moisture and air.
Electroplating to Prevent Corrosion
Electroplating is one of the most popular methods employed to achieve corrosion control. Electroplating entails the electrodeposition of a metal onto the surface of a steel or iron product. This metal coating acts as a sacrificial barrier that can slow and even prevent corrosion from forming on the underlying material, which is referred to as the substrate. While zinc is frequently the metal of choice to provide corrosion protection, a zinc-nickel alloy such as the one offered by Sharretts Plating Company tends to produce better long-term results than when coating with zinc alone. In fact, zinc-nickel is a top choice for corrosion protection in the automotive industry.
Electroless plating is an electroplating derivative that does not require the use of an electrical current. Instead, deposition occurs via an autocatalytic chemical reaction. This enables a more uniform coating application and provides enhanced ability to manage coating thickness. Electroless nickel is the most common type of electroless plating technique when superior corrosion protection is required.
The electroless nickel plating bath also typically contains phosphorous. Regulating the amount of phosphorous will have an impact on the electroless nickel coating’s ability to ward off corrosion in specific environments. For instance, a low-phosphorous coating will provide the best corrosion protection in alkaline environments, while a high-phosphorous content is better suited for acidic environments.
Gauging the Level of Corrosion Protection with Salt Spray Testing
Salt spray testing is widely regarded as the most reliable method for measuring the effectiveness of an anti-corrosive coating. In simple terms, salt spray testing entails the steady application of a salt water solution to a coated material to assess how long it takes for rust to appear on the surface.
Contact SPC to learn more about the benefits of employing electroplating and electroless plating for corrosion protection.