How Does Rust Form?

Nov_2015_HowDoesRustWorkRust is one of the worst things that can happen to any car. It is a sneaky condition that can lead to costly and dangerous vehicle issues. Rust is fairly common but can be controlled and, in some cases, prevented. So how does rust form, and what happens to the metal before it turns to a reddish-brown, crumbly mess?

How Is Rust Formed?

Rust is a type of iron oxide that forms as a result of a chemical reaction called “oxidation” in iron. Rust or corrosion is actually the natural process of metal returning to its original state of iron. Oxidation happens when metal is exposed to certain things in the environment. It often occurs due to corrosion in iron and other alloys, including steel.

Once a metal is corroded, it begins to break down gradually. This results in the familiar yellowish-brown, orange or brownish-red flakes. Rusting causes structural and esthetic damage. This makes the affected areas of metal alloy weaker and susceptible to damage. Rust usually consists of iron oxide-hydroxide, or hydrated iron oxides. Its chemical configuration is Fe2O3.

In order for rust to form, there are several factors that come into play. These are:

  • Iron or metal alloy
  • Oxygen
  • Water or any source of moisture

How Does Rust Work?

Damage from rust does not happen overnight. The process that occurs when iron is exposed to a combination of oxygen and moisture happens gradually. To illustrate, here is a step-by-step breakdown:

  1. Water or moisture comes in contact with iron.
  2. Water molecules combine with carbon dioxide found in the air, forming a weak form of carbonic acid, which is an electrolyte.
  3. Iron begins to dissolve.
  4. The water molecules’ hydrogen and oxygen separate. Oxygen combines with the dissolved iron and forms iron oxide. In the process, electrons are freed.
  5. The freed electrons flow through the electrolytes present. This causes corrosion and weakening in the metal.

How Does Rust Form on Cars?

Moisture is ever-present in a real-life environment — in garages, parking areas and especially out on the street. Even the air that people breathe contains moisture, so a car will undergo oxidation even if it is not exposed directly to water.

There are also other factors that could contribute to a car’s rusting even if careful maintenance is done. For example, frequent exposure to water increases the susceptibility of the car to corrosion. Exposure to other materials such as salts and acids can also lead to rusting.

How Can Car Rust Be Controlled?

Rustproofing preserves and protects the surface of the metal by using a specific treatment. Treatments are repeated to create a barrier between the surface of the metal and the environment. Although completely stopping rust on cars forever is scientifically impossible, the process can be delayed and controlled for many years.

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