CORROSION AND INHIBITION STUDIES OF COPPER IN AQUEOUS-SOLUTIONS OF FORMIC-ACID AND ACETIC-ACID

Corrosion behaviour of copper has been investigated in different compo sitions of formic acid and acetic acid at 30 degrees C by a potentiost atic method. The maximum corrosion rate was found in 20-40 mol/o formi c acid and in 20 mol/o acetic acid in aqueous solution mixtures. The c orrosion rate depended on the concentration of either acid. Formic aci d is observed to be more corrosive than acetic acid. The metal exhibit ed active-passive behaviour in the concentration range of 30-70mol/o o f HCOOH acid in the solution mixture. A short passivity range of poten tial with a high passivity current density was observed for the metal in the solution mixtures of HCOOH acid while in solution mixtures of a cetic acid the metal exhibited only active dissolution. Some organomet allic compounds, viz. Bu(2)SnCl(2), PhSnCl(3), Ph(2)SnCl(2). Ph(3)SnCl have been subjected to inhibition studies in the aqueous solution mix ture (20 mol/o) of either acid. Among the inhibitors used Ph(3)SnCl fu nctions as a better inhibitor in both acids. A strong interaction betw een the inhibitor and corroding surface of copper is speculated due to adsorption of the inhibitor.