Inhibition of pitting corrosion of AISI 304 by organic compounds

摘要

AbstractThe influence of N‐lauroylsarcosine, laurylaminedicarboxylic acid, Na‐dodecylbenzene sulphonate and Na‐laurylsulphate on the pitting corrosion of AISI 304 stainless steel has been studied in 0.1 N NaCl solutions, buffered in the pH range 2.2 to 7.5, at 50°C. The steel pitting potentials have been determined by potentiostatic measurements and by a scratching electrode technique.The potential value at which active pits could be repassivated has been identified. The pitting incubation times have been determined on the steel electrodes prepassivated for different times at 0.5 V/Ag/AgCl in buffer solutions in the absence or in the presence of inhibitors. The overall results confirmed the inhibiting effect of the mentioned substances against the intiation of pitting, just emphasized by the means of potentiodynamic tests.On the contrary, the examined compounds do not show any effect on the pitting propagation.Some more information on the mechanism of action of the mentioned inhibitors are obtained from the incubation time values: in order to explicate their action they must either find sufficiently stable oxide film or can contribute to the stabilization of the passive film during its for