Introduction
Corrosion is a common material occurrence as anything exposed to the atmosphere is almost sure to suffer from it. This type of electrochemical reaction is a phenomenon that refers to the destruction of metals or any other material by oxidation. The rust formation process takes place when a metal is exposed to oxygen and water. This can easily occur in an environment of highly polluted air, such as those found near industrialized areas. As oxygen reacts with the metal, the reaction causes the oxidation of the metal and the formation of rust.
In order to protect metals from rust and oxidation, there are several approaches one can take. One option is the use of surface treatments such as the application of paint, coating or plating to the metal. Another is through the process of passivation, which is the removal or inhibition of corrosion by the formation of an invisible layer of protective material such as chromium, zinc or aluminum on the parts surface. This is a more permanent and cost-effective approach for rust and corrosion protection than for example having to constantly repaint surfaces and/or manually inspect and clean.
One of the most common types of passivation is the process of dunking or pickling and this involves immersing the item in an acidic bath. The most common type of pickling is Dry pickling which is where a dry acid powder is applied to the part. This is the recommended approach in cases where pre-treatment is needed for items such as steel plates.
Another form of rust protection is galvanizing and this process involves covering the metal with a layer of zinc, which forms a thin passive layer that covers the base metal surface, making it more resistant to corrosion. It can also be used to improve the appearance of certain products.
Process of Steel Passivation
Although there are various methods of passivating steel, the most efficient way is by using electrolytic passivation or electro-chemical passivation. This process involves using an electrolyte (water-based solution with a certain combination of additives) to create an electro-chemical reaction that generates a thin protective passive layer on the metal surface.
The first step involves preparing the steel surface before the passivation process. This involves pre-cleaning the steel surface with detergents, which removes any dirt, oil and greases that may be present on the surface. It then requires the metals surface to be free of any oxides, scales, rust or impurities. Irregularities such as scratches on the metal surface should also be removed for it to entirely free of any defects.
Once the metal surface is cleaned and prepped, it is then subjected to the passivation process. This process involves submerging the metal in a bath containing the electrolyte solution. An electrical current is applied to the bath and during this process, an electro-chemical reaction takes place that forms a thin passive layer on the metal surface. This layer acts as a shield against moisture and oxygen and also prevents further corrosion.
Advantages of Steel Passivation
Steel passivation has numerous advantages to offer the industry. It provides a high level of corrosion resistance and enables the metal to be more durable and less prone to fractures and other physical defects. Passivation helps to improve the appearance of the product, reducing the dullness and improving the aesthetics. It helps protect against rust and oxidation and prevents further corrosion by inhibiting the number of active sites present on the metal surface.
Furthermore, it increases the life span of the product and enhances its value as a result. Cost-effectiveness is also an advantage of passivation as it helps to reduce the need for additional maintenance or repainting of the metal and provides a more permanent solution to protecting the metal from rust and corrosion.
Conclusion
Steel passivation is a process that provides an effective way of protecting steel and other metals from corrosion by forming a thin protective passive layer on their surface. This improves the aesthetics of the product and increases its life span by preventing further damage from oxidation and rust. This method also allows for cost-effectiveness as it eliminates the need for additional maintenance or repainting of the metals, providing a more permanent solution for corrosion protection.
