Inhibition of Carbon Steel Corrosion in Cooling Water Systems by New Organic Polymers

摘要

This paper presents some attempts of analyzing the corrosive phenomena, which occur in cooling water systems, and relates to the protection of metallic surfaces from corrosion using new organic synthesis inhibitors obtained in microwaves field. Using the microwaves energy new organic polymers were synthesised by radicalic polymerization. The methods employed were potentiodynamic polarization, electrochemical impedance spectroscopy and metallurgical microscopy techniques. The inhibition activity analysis of these new organic polymers was made by assuming that the mechanism of inhibition by organic molecules is chemisorptions on the metallic surface, which leads to formation of a thin adsorption film. We presume that, these new organic polymers inhibit corrosion of carbon steel by a protective mechanism, forming insoluble iron complexes and repairing the porous oxide layers. The addition of these new organic synthesis inhibitors led in all the cases to decreasing of the corrosion rate, this means that the corrosion process was inhibited. The inhibition efficiency increases once with increasing of the inhibitor concentration up to a limit value when the corrosion rate starts to increase again and consequently, the inhibition efficiency starts to decrease slowly. The adsorptions of the organic compounds on the carbon steels surface obeyed Langmuir's isotherm. Using Fourier transform infrared spectroscopy (FT-IR) it was proved the adsorption of organic inhibitors and the formation of corrosion products on the carbon steels surface. The inhibition process was attributed to the formation of the adsorbed film on the metal surface that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface.