Why does iron rust?

Iron is a metal that is very susceptible to rust. Most of the iron objects displayed in the museum are rusty. The vegetable knife, if left unused for several months, will rust. Every year around the world, millions of tons of steel turn into rusty iron.

Iron rust is not only due to the chemical activity of iron but also due to external conditions. Water is a condition that causes iron to rust. Chemists have proven that if iron is left in an atmosphere without water, it will not rust even after many years. However, water alone will not cause iron to rust. But if you put the piece of iron in a pot and boil it with distilled water in a closed vessel, the iron will not rust. The reason is that only when water and oxygen act at the same time, iron will rust. In addition, carbon dioxide dissolved in water also causes iron to rust. The composition of rust is very complex, mainly including iron oxide, iron hydroxide, iron carbonate…

Why does iron rust?
A completely rusted piece of iron will increase in volume about 8 times.

Rust is both porous and soft like a sponge. A completely rusted piece of iron will increase in volume about 8 times. A piece of rusty iron with a sponge-like state will easily absorb water and quickly disintegrate.

There are also many factors that make iron susceptible to rust: such as salts dissolved in water, the surface of iron objects is not clean, roughness, carbon content in steel ….

Many measures have been devised to prevent steel from rusting . The most common method is to coat iron and steel objects with a set of painted and plated “coats” that are simple measures to prevent rust. On iron bridges for trains, people are often painted, in hot air pipes, people are coated with aluminum powder, on containers they are tin-plated, corrugated iron sheets are galvanized …

The most radical measure to prevent iron from rusting is to give iron a “durable core” , which is to add other metals to make stainless steel alloys. The type of inert, stainless alloy steel is because people have added nickel and chromium to the iron to make stainless steel.