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Coatings are used in industries to increase the longevity of systems. Idea is to insulate parts which need protection from hazardous environments. Yet, the lifespan of the coating depends on proper maintenance and upkeep. There are various agents which can damage coatings.
Salt contamination is a common problem which can cause significant damage to coatings. In this article, we will talk about salt contamination on coating performance.
Causes
Salt is a chemical compound made up Sodium (Na) and Chlorine (Cl). By it’s nature, salt is very corrosive which is not ideal for coating performance. For salt contamination to occur, there needs to be build up of salt on the coated surface. This build up can occur due to various reasons.
Environmental Exposure: Salt contamination can occur due to exposure to salt-containing solutions. Exposure to seawater is the most common causes of salt contamination. As an example, the maritime industry is very susceptible to salt contamination.
In addition, industries which use salt-containing chemicals are also at risk.
Finally, one of the least thought of causes of exposure is deicing salts. This type of contamination is prevalent in colder regions.
Poor Surface Preparation: The presence of salt on the surface before coating can result in contamination. Lack of proper cleaning leaves salt particles on the surface to contaminate the coating. Presence of salt decreases the performance of the coating.
Corrosion: Corrosion on metal surfaces can produce salts that can contaminate the coating. This type of contamination is common in industrial settings where metal surfaces are exposed to corrosive environments.
Effects
As mentioned, salt contamination can have significant effects on coated surfaces.
Reduction in Adhesion: Salt contamination can reduce the adhesion of the coating to the surface. Without proper adhesion, coated layer cannot form a bond with the substrate. For this particular reason, reduced adhesion compromises coating performance.
Surface Discoloration: Salt can be very reactive under certain conditions. If reacted with certain chemicals, salt contamination can cause discoloration on the surface. Discoloration poses more threats apart from reducing the visual appeal of the surface. Lack of colouring pigments means less protection against UV radiation, which can be very destructive.
Corrosion Underneath the Coating: Salt contamination can lead to corrosion underneath the coating. This can cause structural damage and reduce the service life of the coated surface. Also, corrosion under the coating is difficult to detect. This difficulty creates and environment for catastrophic system failures.
How to Prevent?
To prevent salt contamination on coated surfaces, the following steps can be taken.
Proper Surface Preparation: The surface must be cleaned before coating to remove any salt particles.
Use of Corrosion-Resistant Coatings: Using corrosion-resistant coatings can reduce the chances of salt contamination.
Monitoring of Environmental Exposure: Monitoring the exposure to salt-containing solutions reduces the chances of salt contamination.
Summary
Salt contamination can cause a significant damage on the performance of coated surfaces. Understanding the causes of salt contamination ensures longevity of coated surfaces. Proper application of preventative measures can help prevent salt contamination.
