Evaluation of 2-(salicylideneimino) thiophenol and other Schiff bases as bronze corrosion inhibitors by electrochemical techniques and surface analysis

Abstract

In this research, different Schiff bases were synthesized and tested as bronze corrosion inhibitors in concentrated synthetic acid rain at pH 3.3. Some of them showed good inhibiting effects, as detected by EIS and polarization curve recording. The most efficient inhibitor (2-(salicylideneimino) thiophenol, SITP) was also tested with addition of sodium dihydrogen phosphate (P). P improved the surface film resistance against breakdown phenomena. XPS and SEM investigations showed that SITP and SITP + P significantly hinder decuprification. Moreover, SITP forms a protective layer on bronze, composed of both Cu(I)-SITP complexes and adsorbed inhibitor molecules. Cu(II) phosphates were also detected with P addition.

Corrosion Behavior of Different Brass Alloys for Drinking Water Distribution Systems

“…was used to convert the Y parameters of the CPE elements into the associated capacitances (with R being the corresponding couple resistance) [34][35][36]. The R f -CPE f couple described the dielectric properties of the surface corrosion product film (hf time constant), while R ct -CPE dl provided information about the charge transfer process at the metal/electrolyte interface (MF time constant).…”

Improving the Protectiveness of 3-Mercaptopropyl-Trimethoxysilane Coatings on Bronze by Addition of Oxidic Nano- and Microparticles

“…At this short immersion time, the cathodic reaction of oxygen reduction on bronze was under activation control and rather slow, and then it accelerated after 1 day of immersion, inducing a fast Ecor ennoblement to the breakdown potential and an icor stimulation. After 20 days, the cathodic polarization curve remained close to that obtained at 1 day of immersion, but the anodic currents were lower, likely due to the accumulation of surface corrosion products [39]. Table 3 collects the Ecor and icor values measured during these tests.…”

“…EIS spectra on bare bronze were analyzed in a previous paper [39], and the results are here reported as a reference. Figure 7 shows that after 20 days of immersion, and in general at immersion times longer than 1 h [39], bare bronze (blank) exhibited EIS spectra characterized by three capacitive time constants (τ) in the following frequency ranges (black arrows in Figure 7): 10-10 3 Hz (high-frequency (HF) τ), 10 −1 -10 Hz (at slightly higher frequencies for 20-day immersion; medium-frequency (MF) τ), and at frequencies lower than 10 −1 Hz (low-frequency (LF) τ). Therefore, the EIS spectra were fitted by an equivalent circuit (EC) consisting of three nested R-CPE (Resistance-Constant Phase Element) couples, including [40,41]:…”

Inclusion of 5-Mercapto-1-Phenyl-Tetrazole into β-Cyclodextrin for Entrapment in Silane Coatings: An Improvement in Bronze Corrosion Protection

“…The Ecor values on bare electrodes evolved from −0.100 VSCE after 1 h immersion to about +0.043 VSCE after 20 days (Figure 8b). From previous research [54], it was found that this trend was the consequence of the degradation of the protective surface air-formed oxide film during the first half of the immersion period, which stimulated the cathodic reaction, with a consequent Ecor shift towards nobler values. Then, in the second half of the immersion, the progressive accumulation of surface corrosion products induced a slight inhibition of the anodic process and further consequent Ecor ennoblement.…”