If you leave a piece of iron in a damp place for a period of time, it will form a layer of rust, just like someone has painted a reddish paint on it.

So, what is rust? Why does steel rust? Rust is an oxide of iron, which is formed when iron combines with oxides dissolved in water. This means that if there is no water vapor in the air, or no water at all, or no dissolved oxygen in the water, rust will not form.

When a drop of rain falls on the shiny iron surface, it will remain clean for a short time. However, before long, iron and oxygen in the water began to combine to form iron oxide, which is rust. Water drops will turn red and rust will be suspended in water. When the water droplets evaporate, rust will remain on the surface, forming a reddish rust layer.

Once rust is formed, it will spread even in dry air. This is because rough rust is easy to condense water vapor in the air, and water vapor absorbs water vapor and stores it, which is why it is much easier to prevent iron from rusting than to prevent rust from expanding.

Because steel products often need to be stored for a long time, preventing rust has become an important issue. Sometimes, people have to paint or stick plastic films on these items to prevent them from rusting. However, if it is necessary to keep the inside of the retired warship from rusting, what should I do? Relevant departments in some countries have solved this problem with dehumidifiers. To be exact, these machines can exhaust the wet air in the cabin and replace it with dry air, so that the iron will not rust.

Ordinary steel gradually changes color in humid air, and a reddish-brown substance is generated on the surface. This phenomenon is called rust of steel. Its essence is that iron reacts with oxygen and water vapor in the air to generate hydrates of various oxides of iron. The composition of rust is complex, so Fe2O3 is usually used simply. XH2O stands for. Rust is a fragile and porous substance, which can't protect the iron in the inner layer from corrosion, so over time, steel products may rust into a pile of useless waste products. It is particularly serious that steel will soon rust in water vapor containing acid gas and chlorine gas, or when it comes into contact with electrolyte solution. According to statistics, tens of millions of tons of steel have become rust in every country in the world, and the losses caused by the destruction of steel products, such as production stoppage, product quality decline, environmental pollution, harm to human health and even serious accidents, are incalculable. Therefore, the rust prevention of steel has important economic and social significance.