About Rust

Rust that forms on metal is a red iron oxide that occurs when the metal comes into prolonged contact with oxygen. It is part of either water or moisture that is present in the air. When something rusts, it becomes brittle and corroded and in some cases (if it is a machine, in particular) heavy rusting can cause irreversible damage.

Function

Rust occurs when iron or an iron alloy comes into contact with a combination of oxygen and water. Corrosive elements such as sulfur dioxide or sodium cause iron to rust more quickly. When the iron comes into contact with this, it oxidizes and produces iron oxides, which is rusted iron that is extremely brittle. This layer flakes off and fresh iron is exposed, which then rusts and continues to the process until the whole piece of iron has rusted away.

Considerations

Most iron and its alloys can actually stand up very well to pure water or to dry oxygen. Because of this, rust may not be seen at all for a long time if those are the only things that the metal is exposed to. However, it is important to understand that while pure water and oxygen will not cause iron to rust quickly, it will over time. All iron will eventually rust unless it is in a vacuum. However, the time it takes for it to rust can be controlled.

Effects

When water, oxygen or other corrosives are introduced to iron, electrons are shared and it begins to rust. This causes the iron to change and become very brittle. It loses its strength and when this happens in machines or automobiles, it could cause parts to fall apart or to stop working. The metal changes to a reddish-brown or copper color as well, and given enough time holes in the metal will occur, rendering it partially or completely useless.

Warning

One of the most common rust formations that can cause major problems occurs in automobiles. Since there are many parts in the engine and under the floorboards of an automobile made from an iron alloy, rust can form without an owner's knowledge. This is especially true if there has been any heavy rain or flooding that the car has been involved with. Rusting of brakes or engine parts could go unnoticed and continue until the part no longer works, causing the car to breakdown or malfunction. This can happen with heavy machinery as well, though in most cases it is easier to spot rust.

Prevention/Solution

It is possible to prevent rust by using various coatings on metal. For example, it is possible to prevent rust on steel through a process called cluing, where a waterproof coating is added to blue steel. This is only temporary and popularly used on firearms. Zinc is cheap and often used in galvanizing, which is coating iron alloys in something that prevents it from coming into contact with air or water, and thus preventing it from rusting. This is more common with large machines or important parts and is longer lasting than the bluing process.