Difference WikiChemistry

Difference Between Rust and Corrosion.

Main Difference

The main difference between Rust and Corrosion is that in Rusting, the red-orange coating is formed on the surface, whereas in Corrosion, oxidation can occur on metals and nonmetals.

Rust vs. Corrosion

Rust is a kind of corrosion. Corrosion is a kind of oxidation. Rust occurs only on metals, especially iron and steel. Both metals and non-metals show corrosion. Rust is the main reason for moisture. The main reason for corrosion is air or the spread of chemicals on the surface. Rusting shows red or orange-colored coating on the surface. Corrosion shows skin burn and destruction of wood surface, etc.

The process of rust is initiated when iron comes in contact with the water and oxygen present in the environment. Corrosion is initiated when the metal or nonmetal came in contact with the chemicals or moisture. Rust is the result of iron oxide. However, corrosion is the result of salts or metal oxide. Rust is category corrosion. Corrosion is also known as deterioration. The process of rust leads to the rusting of an alloy. The process of corrosion leads to degradation. Rust doesn’t protect the metal, and it is flaky. Corrosion is a natural process that makes the metal more stable.

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Rust on iron is also known as oxides on iron. Corrosion is losing of refined metal. For rust, there are some conditions to fulfill, like the presence of moisture or the presence of oxygen. In the case of corrosion, there are no necessary conditions. When metal starts’ rusting, then it is very difficult to control because rust spread fast on the whole metal. Corrosion is prevented by the coating of paints, plating, etc.

Comparison Chart

RustCorrosion
In rust red or orange coating forms on the surface of the ironIn corrosion substance due to chemical, electrochemical or other reactions are become corrode
Occurrence
On iron and steel onlyOn skin, wood, metals, etc.
Reason
Exposure to air and moistureExposure to air or spread of chemicals on the surface
Observed As
The color coating on the surfaceDestruction on surface
Type Of
CorrosionOxidation
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What is Rust?

Rust is a type of coating which is reddish or orange in color and caused on the iron surface due to the moisture in the air. Rust is only a type of corrosion that happens due to the different chemical reactions that occur between the surfaces of metals like iron and steel. By chemical splitting, rust doesn’t appear. But it is possible that by the help of chemical rust start to accelerate between the iron and oxygen molecules by increasing the electrical activity. The process of rust on iron metal is also said to be “metallic oxidation.”

On the surface of the metal, atoms are get oxidized in the presence of water and by oxygen from the air. For instance, during the process of rust on iron ferric (Fe2+) in iron oxidized into ferrous (Fe3+). The rate of rust depends on different factors. Metals like iron and steel both show rust on their surfaces, but stainless steel doesn’t show the rust because of the presence of 10-20% chromium. Chromium acts as a component with oxygen and water, and it acts as a thin film. That’s why this thin film of chromium prevents rusting.

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Processes to Prevent Rust

  • Galvanization: It is a process of zinc coating on iron, which prevents the iron metal from being rust by act as a sacrificial anode.
  • Paints: Coat of paint on the metal is also avoiding the metal for initiation of rust.
  • Electroplating: On the surface of the steel, a thin layer of metal like nickel and chromium is coated to avoid rust.

What is Corrosion?

In the process of corrosion, the deterioration of different substances occurs by taking the place of chemical reactions and other electrochemical reactions on the surface. Corrosion occurs on metal as well as non-metal surfaces. Corrosion affects the surface of the material and also the structure of the material. Rusting is one of the best examples of corrosion.

Corrosion can also occur on the top of the table and skin; these are nonmetal surfaces that become corrosive when some chemicals split on these surfaces and deteriorate them. These strong chemicals are hydrochloride acid (HCl), hydrogen sulphuric acid (H2SO4), and some alkali bases like sodium hydroxide (NaOH) and potassium hydroxide (KOH), etc. Such chemicals that impact a corrosive effect called “corrosive chemicals.” Such chemicals can also cause permanent damages to the surface of the material.

Types of Corrosion

  • Crevice Corrosion: Whenever there is a difference in ionic concentration between any local areas of the metal, a localized form of corrosion known as crevice corrosion can occur.
  • Stress Corrosion Cracking: Stress corrosion cracking refers to the cracking of metal as a result of the corrosive environment and the tensile stress placed on the metal.
  • Intergranular Corrosion: Intergranular corrosion occurs due to the presence of impurities in the grain boundaries that separate the grain formed during the solidification of the metal alloy.
  • Galvanic Corrosion: When there is an electric contact between two metals that are electrochemically dissimilar and are in an electrolytic environment, galvanic corrosion can arise. It refers to the degradation of one of these metals at joint or at a junction.

Key Differences

  1. Rust belongs to the metal only, whereas corrosion belongs to metals, polymers, and ceramics.
  2. Rust is influenced by some chemicals like iron; on the other hand, corrosion is the result of many chemical influences.
  3. Rust is mainly caused by moisture; conversely, corrosion is mainly caused by the chemical.
  4. Rust is a type of corrosion; on the flip side, corrosion is a type of oxidation.
  5. Rust can be only in red or orange-brown, while corrosion can be of any color.
  6. Rust is only caused on iron or metal, although corrosion is caused by non-metal as well as on metal surfaces.
  7. Rust is accelerated by chemicals as compared to corrosion; the chemical is the main reason for corrosion.
  8. Rust is a speedy process compared to corrosion, which is a slow process.
  9. Rust occurs due to a change in the environment. However, Corrosion occurs due to the chemical reaction.
  10. Ruts are just an iron-based alloy; on the other sid,e corrosion is the destruction.

Conclusion

It is concluded that rust does not happen due to chemicals, and corrosion can happen due to chemicals.

Harlon Moss

Harlon currently works as a quality moderator and content writer for Difference Wiki. He graduated from the University of California in 2010 with a degree in Computer Science. Follow him on Twitter @HarlonMoss