RP264 The Metal Eater

 RP264 The Metal Eater

My bike has been sitting outside in the rain for a week now. I know what I' ll find when the sun finally comes out and I can ride again: scratchy red rust.

Rust is a sign of corrosion. Corrosion is the process of a metal breaking down, separating into its different atoms. What was once a solid piece of steel is turned by corrosion into iron oxide and hydroxide. These are the red, spreading stains you can see.

The corrosion that creates rust is a chemical reaction between iron and oxygen. Water acts as a catalyst, the kick start for the reaction, because water helps the oxygen get into the metal particles.

A drop of rain falls on the metal chain on my bike. As soon as the water makes contact with metal, the metal begins to oxidize. The acid dissolves the iron in the metal. As that happens, the water is broken down into its two parts, hydrogen and oxygen. Some of the free oxygen combines with the iron to form the red, fragile iron oxide or hydroxide. If salt is present, the process happens even faster. Salt water helps the chemicals break down and move faster, which is why metal in seawater rusts away so quickly.

The type of rust formed will depend on the conditions. Iron hydroxides are formed by more pure combinations of metal, oxygen, and water. These rusts stick to the surface of the metal, but protect the metal underneath from rusting more. But when other chemicals come into play, the rust formed can be iron oxides. These flake off and blow away, leaving new metal constantly exposed. This destructive type of rust can eat entirely through a piece of steel.

Rust is preventable. The easiest way to keep metal from rusting is to put a barrier between it and the environment. This barrier can be paints, waxes, or oils.

That reminds me: I need to oil my bike!