STUDIES ON CORROSION INHIBITION OF IRON IN AQUEOUS SOLUTIONS

Abstract

Corrosion is the destructive attack of a metal by chemical or electrochemical reaction with its environment. The vast majority of metals occur naturally in the combined state (commonly as oxides or sulphides) They are only won from these ores by a high energy input. Thermodynamically, the return of a metal to the combined state by corrosion ts, therefore, expected to be a spontaneous process. The corrosion products of this reaction may be solid, liquid or gas. Both the physical and chemical natures of the prod ucts are important since they frequently influence the subsequent rate of corrosion. Corrosion is a complex process and its study is still more complex due to various and varying conditions of environment.

The majority of metal-corroding processes taking place in electrolytes are electrochemical in nature. The rate of any given electrochemical corrosion process depends on the rates of two conjugate reactions proceeding at the metal surface, anodic reaction consisting in the transfer of metal ions from the lattice to the solution with an attendant liberation of electrons, and a cathodic reaction consisting in the assimilation by some depolarizer of the electrons liberated during the anodic reaction. Ox + ne ----+Red ( 1.1) Many researches have contributed for the understanding of the Process of corrosion and its prevention