Abstract

The inhibition of the corrosion of carbon steel in sea water by diethylene triamine pentamethylene phosphonic acid (DTPMP) and Ni2+ has
been investigated using weight loss and electrochemical measurements. The results show that 70% inhibition efficiency is achieved with
binary system consisting of 250 ppm of DTPMP and 50 ppm of Ni2+.Polarization curves indicate that the system functioned as a cathodic
inhibitor. AC impedance spectra reveal that a protective film is formed on the metal surface. The protective film has been analysed by FTIR
spectra. The surface morphology and the roughness of the metal surface have been analysed by atomic force microscopy.

Key words: corrosion inhibition; carbon steel; electrochemical techniques; atomic force microscopy; diethylenetriamine pentamethylenephosphonic acid