Corrosion
Iron articles are shiny when new, but get coated with a reddish brown powder when left for some time.
Corrosion process in Iron is commonly known as rusting of iron. Some other metals also get tarnished in this manner. The colour of the coating formed on copper and silver are corrosion.
“When a metal is attacked by substances around it such as moisture, acids, etc., it is said to corrode and this process is called corrosion. “
The black coating on silver and the green coating on copper are other examples of corrosion.
Corrosion causes damage to car bodies, bridges, iron railings, ships and to all objects made of metals, specially those of iron. Corrosion of iron is a serious problem. Every year an enormous amount of money is spent to replace damaged iron.