THE FORMATION OF A HIGHLY PROTECTIVE AND PERSISTENT FILM AGAINST IRON CORROSION IN ACID-SOLUTIONS WITH TRIETHYLSTIBINE

Corrosion inhibition effects of triethylstibine were studied on iron in 1 N HClO4, 1 N HCl and 1 N H2SO4 by polarization measurements. A high inhibition efficiency (> 90%) was obtained at an extremely low concentration of the inhibitor (5 x 10(-8) M). A thin adhesive film was formed on the iron surface by an action of the triethylstibine solution. An impedance study on an iron electrode treated with the solution revealed that the film thus formed was protective and persistent against iron corrosion in an acid solution withour inhibitors. The surface film was characterized by FTIR, XPS and EPMA measurements to be composed of adsorbed stibinium ion and an anion on the surface, an outer layer consisting of iron and antimony oxides and an inner layer comprising metallic antimony and iron. The high persistency of the film is attributed to the presence of the inner layer and the high inhibition efficiency to that of outer layers.