When is corrosion beneficial

Why is Corrosion Protection Important? Coatings reduce repair costs. Exposure to elements and chemical or electrochemical reactions result in the deterioration of the entire exposed surface of a metal. Parts and equipments affected by this type of corrosion often require a complete replacement.

Coatings prevent operating losses. Corroded equipments take time to fix or replace. Website Admin Tuesday, June 27, Definition of Corrosion Corrosion can be defined as the destruction or deterioration of a material because of reaction with its environment. The term can refer to a process or the damage caused by such a process. Important to note In some cases of corrosion, there is no visible deterioration. The effect of the reaction with the environment is to change the properties, often the strength, of the material.

Such forms of corrosion are not common in day-to-day experience but are of great importance to the corrosion engineer. Loss due to purely mechanical forces is known as wear. However, there are cases when corrosion and loss by mechanical forces combine and these are described in these notes. The definition applies to materials other than metals. However, the term is usually applied to metals.

Metallic corrosion is mainly considered in these notes. As long as the paint remains intact, the iron is protected from corrosion.

Other strategies include alloying the iron with other metals. For example, stainless steel is mostly iron with a bit of chromium. The chromium tends to collect near the surface, where it forms an oxide layer that protects the iron.

Zinc-plated or galvanized iron uses a different strategy. Zinc is more easily oxidized than iron because zinc has a lower reduction potential. Since zinc has a lower reduction potential, it is a more active metal. Thus, even if the zinc coating is scratched, the zinc will still oxidize before the iron.

This suggests that this approach should work with other active metals. Another important way to protect metal is to make it the cathode in a galvanic cell. This is cathodic protection and can be used for metals other than just iron. For example, the rusting of underground iron storage tanks and pipes can be prevented or greatly reduced by connecting them to a more active metal such as zinc or magnesium Figure 3.

This is also used to protect the metal parts in water heaters. The more active metals lower reduction potential are called sacrificial anodes because as they get used up as they corrode oxidize at the anode. The metal being protected serves as the cathode, and so does not oxidize corrode. When the anodes are properly monitored and periodically replaced, the useful lifetime of the iron storage tank can be greatly extended.

Corrosion is the degradation of a metal caused by an electrochemical process. Large sums of money are spent each year repairing the effects of, or preventing, corrosion. Some metals, such as aluminum and copper, produce a protective layer when they corrode in air. Crevice Corrosion. Intergranular Corrosion.

Too much humidity or condensation of water vapour on metal surfaces are the primary causes of corrosion. Corrosive gases such as chlorine, hydrogen oxides, ammonia, sulfur oxides, amongst others can result in corrosion of parts of electronic equipment, etc. Corrosion can also occur due to hydrogen and oxygen exposure. Corrosion is the process by which certain materials, metals and non-metals, deteriorate as a result of oxidation.

Rusting is oxidation of iron in the presence of air and moisture. Rusting occurs on surfaces of iron and its alloys. Corrosion requires surface exposure to air or chemicals. How to Prevent Corrosion Use non-corrosive metals, such as stainless steel or aluminium.

Make sure the metal surface stays clean and dry. Use drying agents. Use a coating or barrier product such as grease, oil, paint or carbon fibre coating. Lay a layer of backfill, for example limestone, with underground piping.