When oxidized, metals and alloys lose their numerous valuable properties. They become weaker and less elastic and their thermal and electrical conductivities decrease.

    Once started, corrosion never stops half-way. Slowly but surely the "brown devil" will completely demolish the metallic article.

    A few oxygen molecules hit the surface of the metal. The first few molecules of oxide are formed. What is called an oxide film appears. It is quite loose and the metal atoms pass through it like through a sieve only to become oxidized immediately in their turn. 

    Also, oxygen molecules pass through the pores of the film into the depths of the metal where they continue their destructive mission.
In a more aggressive chemical environment corrosion proceeds more rapidly.

    Chlorine, fluorine, sulphur dioxide and hydrogen sulphide are no less dangerous enemies to metals. When a metal corrodes under the action of gases, chemists call the phenomenon gas corrosion.

    And what about various solutions? They are also terrible enemies of metals. For example, ordinary sea water. Huge ocean liners must from time to time be docked for general overhaul, to have the corroded platings of their bottoms and sides replaced.

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