Corrosion is a natural process that gradually deteriorates materials, particularly metals, due to chemical reactions with their environment. Left unchecked, corrosion can lead to structural failures, safety risks, and costly repairs. Understanding what causes corrosion and how to prevent it is essential for industries ranging from construction and manufacturing to marine and aerospace engineering.
Corrosion is a chemical or electrochemical reaction between a metal and its environment that leads to its deterioration. The most common form is rust, which occurs when iron or steel reacts with oxygen and moisture, forming iron oxide. However, corrosion can affect a wide range of materials and take many forms, from surface discolouration to deep structural damage.
Several factors contribute to corrosion, and in many cases, multiple causes interact to accelerate metal degradation.
The environment plays a major role in corrosion rates. Some of the most common environmental contributors include:
Corrosion is often driven by electrochemical processes, particularly when different metals come into contact in the presence of an electrolyte (such as water or saltwater). This leads to galvanic corrosion, where the less noble metal corrodes faster. Common examples include:
Extreme temperatures and fluctuating thermal conditions can accelerate corrosion by expanding and contracting materials, leading to stress fractures and micro-cracks. High temperatures also speed up chemical reactions, making metals more susceptible to oxidation.
Some types of bacteria can produce acidic or corrosive by-products that accelerate metal degradation. This is known as microbiologically influenced corrosion (MIC) and is especially problematic in water treatment plants, oil pipelines, and underground infrastructure. Bacteria that produce hydrogen sulphide, for example, can cause severe corrosion in steel structures.
Although corrosion is a natural process, there are several ways to slow it down or prevent it altogether. Proper prevention methods can extend the lifespan of equipment, improve safety, and reduce maintenance costs.
Applying a protective coating creates a barrier between the metal and its environment, reducing exposure to moisture, oxygen, and chemicals. Common protective coatings include:
Cathodic protection is an electrochemical technique used to prevent corrosion in pipelines, ships, and underground tanks. It works by using a sacrificial anode (a more reactive metal) that corrodes instead of the protected structure. There are two main types:
The selection of materials can significantly impact corrosion resistance. Some metals and alloys naturally withstand corrosion better than others:
Minimising exposure to corrosive environments can slow down the corrosion process. Some effective measures include:
Routine inspections can help identify early signs of corrosion before they cause major damage. A proactive maintenance strategy should include:
Corrosion inhibitors are chemicals that slow down the corrosion process by forming a protective layer on the metal’s surface. These are commonly used in:
Corrosion testing is essential for identifying potential issues early and ensuring preventive measures are effective. Using specialised corrosion testers, businesses can monitor corrosion rates, assess the condition of protective coatings, and evaluate material durability under various environmental conditions. Regular testing helps detect problems before they cause significant damage, allowing for timely interventions that extend the lifespan of equipment and infrastructure.
Corrosion is an unavoidable challenge in many industries, but with the right prevention strategies, its impact can be minimised. Protective coatings, cathodic protection, material selection, and regular maintenance are all effective ways to combat corrosion. By taking a proactive approach, businesses can reduce costs, improve safety, and extend the lifespan of critical infrastructure.