Corrosion: Definition, Prevention & Protection

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  • 0:04 What is Corrosion?
  • 0:55 Process
  • 1:27 Preventing Corrosion
  • 3:29 Lesson Summary
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Lesson Transcript
Instructor: Julie Zundel

Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

You've seen metals corrode even if you weren't aware of what was happening. This lesson defines corrosion and examines ways to protect metals, thus preventing corrosion.

What is Corrosion?

You're wandering around and you notice an old car. What in the world happened? It's covered in an orange substance that makes it look really bad.

Well, what you're observing is called corrosion, which is the breaking down of a substance, typically a metal, due to reactions that have occurred between the substance and the environment. So, that orange material all over that car is corrosion due to rust, which is a common type of corrosion caused by iron or steel breaking down in the presence of water and air.

Rust makes the metal weaker and can cause problems. Plus, let's face it, it looks pretty terrible! While a rusty car doesn't seem like a huge deal, corrosion actually costs the United States upwards of $276 billion per year! Think of all of the money it takes to rebuild and repair corroded stuff in your world, whether that is a bridge, a building, or a train.


What's happening when something corrodes? Let's focus on metals, since corrosion is most common with them. Naturally, metals are found attached to other elements in compounds. In order to get a pure metal from a compound, energy must be used to refine it.

When this pure, refined metal is placed in the environment, the energy is released - this is corrosion. In other words, the corroded version of the metal is more stable than the pure metal, so, when exposed to things like seawater or oxygen, the pure metal reverts back to its stable form.

Preventing Corrosion

So, how do you prevent corrosion? Let's check out some common ways people avoid corrosion in metals.

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