Why does corrosion occur?

Corrosion is the degradation of metal when exposed to environmental elements such as water and oxygen.

Steel rusts, copper tarnishes and most metals, unless protected, will eventually return to their natural state.

In nature, the iron in steel is found only when combined with other elements. An example is iron oxide or iron ore. When iron is extracted from the ore and processed into steel it has a natural tendency to return to its original oxide state. It does this through an electrochemical corrosion process called oxidation.

When steel rusts it loses its useful properties, such as strength as well as its attractive appearance.

For steel to rust, the corrosion reaction needs oxygen and water, both of which are found in air. Steel exposed to air will have all of the necessary elements for rust to occur.

Corrosion is an electrochemical process and occurs in what are described as galvanic cells. These galvanic cells are also found in torch batteries and in a similar manner have positive (+) and a negative (-) side.

The galvanic cells that cause corrosion can occur for different reasons.

Dissimilar metals in contact with each other and or differences in the chemical composition within the grains of the metal itself provides the driving force for the galvanic chemical reaction. Different materials have a different “activity” in terms of electrochemical corrosion. When in contact the more active metal will corrode first.

For the galvanic cell to cause corrosion the electrical circuit must be competed. Water provides the path in which the electrical current can flow. This water is called the electrolyte in the reaction. The more “salty” the water, the better it can conduct electricity and the corrosion reaction will be faster. There is often enough water in the air to start rusting to occur. Protecting the metal surface from water will protect the surface from rust.

Oxygen is needed to complete the corrosion reaction. Sealing the surface of the metal from air (and oxygen) will protect the surface from rust.

When a steel surface comes in contact with air and moisture, a large number of small galvanic cells form on the surface and rusting occurs. However, this can be prevented by providing a more “active” material to sacrifice itself to protect the steel, preventing moisture from reaching the steel and or protecting the steel from oxygen.

Why is it important to protect metals?

It is estimated that the annual cost of corrosion for the Australian economy is somewhere between $13 Billion and $32 Billion dollars, however much of this corrosion can be prevented through protection of the metal surfaces.

Corrosion not only shortens the life of structures, plant and equipment, it can lead to catastrophic failures that can affect human life and damage the environment.

Why use Galmet to protect your metal?

Galmet has been developing and supplying metal protection paint for over 50 years.

Our experience and ideals of continual improvement has allowed the company to continue to provide the optimum protective coatings which are also easy to use. This has kept Galmet at the top of the market in both the industrial and consumer segments.

Galmet products provide the security you can trust to protect your metal.

Case Study – Galmet ColdGal

Case Study – Galmet DuraGal