Basically corrosion means wearing away of metal in other words Corrosion is the gradual destruction of materials (usually metals) by chemical reaction with their environment.
Metals get corroded because they come from ores and the ores mainly comprises of oxides,flourides or other highly electronegitive elements bound with metal atom.Since metals are positive in charge they combine with them and form stable compounds.
~~>Where as wood is already stable with its carbon and Hydrogen materials and also some oxygen. So,it does not need to corrode.
~~>Metals are formed by reducing these stable compounds to metals.And as Oxygen in the Atmosphere is electronegitive. It has high affinity towards the metals and combines with them wear away as powder,this is called corrosion
eg: Fe2O3 (Hematite) , Fe3O4 (Magnetite) are ores of Iron we need to reduce them to form Iron,And Iron has High Affinity towards Oxygen and Fe2O3 and FeO,This is called rust.Preventive measures can be taken
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