Understanding why metals rust can help prevent unnecessary corrosion. Certain types of metal and the environment they are in can speed up the process considerably.
When selecting building materials it is integral for safety to prolong the life of critical infrastructure. For expensive equipment corrosion can reduce the useable hours of the machine, making it more costly.
This all comes with a heavy financial cost. In North America this is especially true with corrosion costing Canada an estimated 63 Billion dollars a year. Adding insult to injury, corrosion-induced losses are usually greater than the costs of undertaking proper corrosion management practices before the onset of disaster.
Getting to the Root of Corrosion
Given sufficient time, all materials will face degradation. Corrosion can be seen in many types of materials, like polymers and ceramics. Metals, however, are the most common place we see corrosion occurring on a daily basis.
At its core, metallic corrosion is an electrochemical process. When a metal surface comes into contact with water, an electrochemical reaction may begin.
These reactions have two sites that each complete half of a reaction, to form corrosion, and can often be done on the same piece of metal. The first site is called the anode, here a metal will give up electrons (energy) and in doing so, the metal will begin to dissolve. The second site is the cathode, this area takes the extra electrons and uses them to create products on the surface like rust, from the dissolved metal of the anode. These coatings can occur on many metals and are often referred to as oxides, as they are made with oxygen.
Salts also speed up this process significantly. When salt dissolves, it forms a liquid called an electrolyte, which is a conductive medium and speeds up the transfer of electrons. This is why corrosion rates are much higher near the oceans than they are in dryer climates.
Although not corrosion is bad, some oxides help to make metal more resistant to its surroundings. However, when not intended, oxides can ruin the structural integrity of the material. Since oxides have a greater volume than the metal they are made from, they can result in making weaker materials, and building up pressure inside of other objects and causing stress and internal damages.
Culprits of Corrosion
Several factors influence the rate of corrosion:
- Different metals have varying oxidation potentials. Iron is particularly susceptible to corrosion due to its low oxidation potential
- The type and concentration of dissolved ions in the water significantly impact conductivity and corrosion rate. Saltwater, for instance, accelerates corrosion due to the presence of readily available conductive ions
- Higher temperatures generally increase reaction rates, leading to faster corrosion
- The availability of oxygen as the oxidizing agent plays a crucial role. Reduced oxygen levels can slow down the rate of corrosion
How To Fight Corrosion
Rust prevention on steel can involve multiple strategies to disrupt this electrochemical process.
Corrosion experts like our team here at ICE typically begin inspecting equipment and structures meticulously searching for any signs of corrosion.
With the aid of cutting-edge technology, techs then search for “pain points” that jeopardize the longevity of your assets. Next the data is gathered and interpreted. Priority is given to the most degraded areas/assets typically solved by applying the best QA/QC practices.
Typically solutions involve the introduction of cathodic protection combined with chemical inhibitors to protect steel structures. Application of galvanized coating, and thoughtful selection of rust-averse materials such as stainless steel.
Here at ICE, we tailor our intensive scientific approach to your specific needs. We also help train your staff and safety experts how to monitor and solve any future corrosion issues.
