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

Abstract

Effect of 2,5-dimercapto-1,3,4-thiadiazole (DMTD) concentration on the electrochemical behaviour of bronze was studied in 30 g L-1 sodium chloride (NaCl) by means of surface analyses and electrochemical techniques. Scanning Electron Microscopy (SEM) was used to observe surface morphology. Raman micro-spectroscopy was carried out to study chemical structure of deposited layers. X-ray photoelectron spectroscopy (XPS) enabled elemental characterization as well as molecular structure investigation. Finally, electrochemical polarization and impedance permitted a thorough study of corrosion protection behaviour reached through the presence of DMTD based organic layers on the surface. Above 1 mM, a fast adsorption of DMTD on copper (Cu) and lead (Pb) allows a thin and blocking film to be formed on bronze surface. DMTD prevents oxide formation at high concentrations and the surface film is mainly composed of Cu I-DMTD and Cu II-DMTD complexes as evidenced by spectroscopic techniques, with a bidentate adsorption at 1 mM and monodentate adsorption at 10 mM.

Small Concentrations of Nacl Help Building Stable Inhibiting Layers from 2,5-Dimercapto-1,3,4-Thiadiazole (Dmtd) on Aa2024-T3

“…Its corrosion inhibition power for AA2024-T3 has been attributed to the formation of Cu-DMTD complexes, which have limited aqueous solubility and are able to reduce the oxygen reduction reactions on Cu-rich intermetallics (IMs) [5,13,21]. This hypothesis is supported by recent works on Cu alloys showing that DMTD forms strong chemical interactions instead of just physical adsorption [22]. On the other hand, reports showing that DMTD's functional groups of pyrrolic N from the azole ring and thiol S from the mercapto anchoring group are responsible for the chemisorption on Ag, Au and Cu [23] suggest that, also in the case of aluminum alloys, the interactions may go beyond the suggested Cu-DMTD complexation at some IMs.…”

Effects of 1-pyrrolidinedithiocarbamate and 2,5-dimercapto-1,3,4-thiadiazole on lead corrosion behavior in chloride medium

“…decanoate) have been proved to provide Pb surface with good corrosion protection through formation of crystalline Pb carboxylate layer which exhibits good passivation properties [15,20,21]. More recently, innoxious dithio compounds such as 1-pyrrolidinedithiocarbamate (PDTC) and 2,5-dimercapto-1,3,4-thiadiazole (DMTD) have been successfully used as corrosion inhibitors on bronze in neutral solution [22,23]. In both cases, organic inhibitors' adsorption on bronze surface led to thick, insulating and protective layer enabling very good corrosion protection.…”