Coupling of electrochemical, electrogravimetric and surface analysis techniques to study dithiocarbamate/bronze interactions in chloride media

Abstract

Interaction between ammonium pyrrolidinedithiocarbamate (PDTC) and bronze in 30 g L -1NaCl was investigated at several concentrations between 0.1 and 10 mM by means of various electrochemical and spectroscopic techniques. Electrochemical measurements revealed a fast adsorption process of PDTC on Cu and Pb and the formation of a thick insulating and protective film with a high surface coverage. At high concentrations, PDTC prevents oxides formation. Surface analyses confirm PDTC adsorption on bronze mainly via interaction between sulphur atoms and Cu sites to form Cu I -PDTC complex.

Corrosion protection of bronze using 2,5-dimercapto-1,3,4-thiadiazole as organic inhibitor: spectroscopic and electrochemical investigations

“…This is shown by the EDX results displayed in table 2 and confirming the presence of sulphur within the films formed at these two DMTD concentrations, and only traces of oxides, likely indicating a fast adsorption of DMTD on bronze surface preventing the oxides film formation. Similar results were observed in the case of PDTC adsorption on bronze [18]. It is important to note that, despite their presence in DMTD, the carbon and nitrogen were not analyzed quantitatively.…”

“…After immersion in the solution containing 10 mM DMTD, changes are visible on survey spectrum. Foremost, the nonappearance of Sn and Pb signals proves a substantial coverage of the bronze surface in the presence of DMTD, as previously observed in the case of PDTC [18]. Moreover, as evidenced by the appearance of N and S peaks, and the increased intensity of C peak, the surface electrode is covered by a layer containing species from DMTD compound.…”

“…In the blank test solution, the surface morphology (not shown) is quite similar to that observed in 0.1 mM DMTD (Fig. 1a) revealing a grainy microstructure, basically corresponding to the formation of an oxide film [18]. For higher DMTD concentrations i.e.…”

“…The studied alloy is an industrial bronze (used in aerospace and automotive industries) which composition is given in table 1 and was also used in our previous study [18]. This bronze is an alpha-cored bronze corresponding to the AFNOR norm "CuSn12".…”

“…Dithio compounds were shown to be particularly effective as corrosion inhibitors for Cu among which 1-pyrrolidinedithiocarbamate (PDTC) [16,17] and 2,5-dimercapto-1,3,4-thiadiazole (DMTD) are important examples. In a very recent study dedicated to bronze corrosion inhibition by PDTC [18], we showed that this compound adsorbs on bronze surface, via interactions between sulphur atoms and Cu sites, to form Cu I -PDTC complex. Besides, PDTC adsorption is so fast that it prevents oxides formation.…”