How Does Rust Spread?

How Does Rust Spread?
••• Wikimedia Commons

What Rust Is

In order to understand how rust works and spreads, you first have to understand what rust is. "Rust" is the common name for what is scientifically known as iron oxide, a form of corrosion that occurs when iron (or one of its alloys, such as steel) reacts with oxygen and there is water (or heavy air moisture) present.

Other metals have oxidation processes as well, but they do so differently and the result is not commonly considered rust. Copper corrosion is green (and accounts for the color of the Statue of Liberty) while aluminum corrosion spreads extremely slowly.

The Molecular Process of Spreading

The process of metal corrosion is an electrochemical process. It happens on a molecular level as electrons transfer from iron molecules to the surrounding oxygen molecules, changing the makeup of the iron and turning it into rust. This is happening to iron all the time. In fact, it is impossible to find a piece of iron without at least some oxide present within it. However, the rate of rusting is usually slight and slow but is accelerated by water, especially if the water has a high concentration of electrolytes (substances in the water that help electrons move).This is why the presence of salt causes rust to spread more quickly.

Spreading

Rust does not spread through contact like a biological infection. Instead, the process of iron oxidization occurs independently based on the conditions surrounding a particular piece of metal. This means that if one part of the piece is exposed to water, oxygen, and electrolytes but the rust of the piece is kept clean and dry, the protected metal will not rest at the rate of the wet metal.

Iron alloys will have different corrosion rates based on their makeup.

How Prevention Works

Steel is commonly protected from rusting through a process known as galvanization. In this process, the steel will be dipped with a coating of zinc, which protects the steel by reacting with water molecules. If the zinc coating on a piece of galvanized steel is scratched or scraped away, the exposed area will be vulnerable to rusting.

Related Articles

How to Rust a Penny
What Causes a Nail to Rust?
How Does Salt Water Rust Metals?
What Chemicals Rust Metal Rapidly?
What Does It Tell You if Iron Has an Atomic Number...
The Effects of Oxidation on Copper
How to Write the Balanced Chemical Reaction for the...
Tips for Getting Rust Off & Repainting Wrought Iron...
What Is Zinc Alloy?
Alodine Vs. Anodizing
Corrosion & Chemical Changes in Aluminum Metal
Why Does Copper Change Colors Over Time?
Why Does Citric Acid Clean Pennies?
Why Does My Arm Turn Green With Copper Bracelet?
Zinc Plating Process
The Effects of Saltwater on Metals
Why Do Pennies Change Color?
How to Prevent Rust With Coatings
Types of Metals That Attract Magnets