Abstract

The corrosion inhibition effect of carbon steel in sea water by 2-carboxyethylphosphonic acid (2-CEPA) and Ni2+ has been investigated
using weight loss method and cyclic voltammetry. The results show that 73% inhibition efficiency is achieved with binary system
consisting of 250 ppm of 2-CEPA and 50 ppm of Ni2+. Surface evaluation technique like FTIR is used to determine the nature of the
protective film formed on the metal surface. The protective film consists of Fe2+ – 2-CEPA complex, Ni2+ – 2-CEPA complex and Ni(OH)2.
Cyclic voltammetry study reveals that the protective film is more compact and stable even in 3.5% NaCl environment.

Key words: corrosion inhibition; carbon steel; sea water; cyclic voltammetry; FTIR