Corrosion inhibition of copper–phosphorus brazing alloys in tetra‐n‐butylammonium bromide aerated aqueous solution by benzotriazole

The corrosion inhibition behavior of benzotriazole (BTA) on a brazing alloy, CuP in the non‐welded and welded conditions in 17 wt% (0.534 mol/L) tetra‐n‐butylammonium bromide (TBAB) aerated aqueous solution was investigated by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy/energy dispersive X‐ray spectroscopy techniques. The experimental results showed that BTA could protect effectively copper alloys in aqueous TBAB solution. The inhibition efficiency of BTA increased with increasing inhibitor concentration from 0.1 to 6 g/L, attaining efficiencies of up to 96% calculated according to different methodologies. Corrosion current densities were lower after the melting process. Galvanic studies showed that copper behaved as the anode when coupled to its alloys. The addition of BTA caused an increase in charge transfer resistance and a decrease in the capacitance of the double layer. Adsorption of BTA in 17 wt% TBAB solution on the copper alloys' surface was found to obey the Langmuir adsorption isotherm.     

The synergistic effect of Na3PO4 and benzotriazole on the inhibition of copper corrosion in tetra‐n‐butylammonium bromide aerated aqueous solution

The effect of Na₃PO₄ and the mixture of benzotriazole (BTA) and Na₃PO₄ (SP) on the corrosion of copper in 17 wt% (0.534 mol/L) tetra‐n‐butylammonium bromide (TBAB) aerated aqueous solution has been investigated by means of weight‐loss test, potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy/energy dispersive X‐ray techniques. The experimental results showed that a dosage of Na₃PO₄ stimulated the copper corrosion, and the corrosion rate increased with increasing Na₃PO₄ concentration, whereas the mixture of BTA and Na₃PO₄ could protect copper in aqueous TBAB solution. The inhibition action of the mixture of BTA and Na₃PO₄ on the corrosion of copper is mainly due to the inhibition of the anodic process of corrosion. The inhibition efficiency of a mixture consisting of 2 g/L BTA and 1 g/L Na₃PO₄ was about 96%. The mixture of BTA and Na₃PO₄ inhibits the corrosion of copper better than BTA by itself, indicating that Na₃PO₄ has a synergistic role with BTA on the corrosion inhibition of copper in TBAB aqueous solution.     

Corrosion study of copper in the presence of benzotriazole and its hydroxy derivative

The inhibitory properties of benzotriazole (BTAH) and its hydroxy derivative, 1‐hydroxy‐benzotriazole (BTAOH) on copper corrosion, were compared in 3% NaCl solution using cyclic voltammetry (CV), immersion tests, profilometry and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDX). CV experiments showed rapid interaction of both inhibitors with a Cu surface, but only at high concentrations. Immersion tests under stationary conditions showed that BTAOH offered corrosion protection only at concentration of 10 mM. Moreover, it was not effective under stirring conditions at any of the concentrations investigated. In contrast, BTAH exhibited good corrosion inhibition ability in all immersion tests. BTAOH, at up to 1 mM, increased the surface roughness of Cu more than 3% NaCl solution alone, but a significant reduction of surface roughening was observed when BTAH was present. Porous cross‐linked acicular structures and star‐like structures were observed using SEM/EDX in the case of BTAOH treatment. When Cu was treated with BTAH, roundish surface structures composed of bent plates with toothed‐like edges, acicular structures and non‐porous few hundred nm thick plates were observed.     

Studies on corrosion inhibition of copper by alkanethiol SAMs prepared in aqueous micellar solution

The character of 1‐dodecanethiol (DT) self‐assembled monolayers (SAMs) formed on copper surface in aqueous micellar solution is investigated by means of contact angle measurement, electrochemical impedance spectroscopy (EIS), and polarization curves. The contact angle measurement shows that the SAMs formed in aqueous micellar solution are oriented and compact. According to the electrochemical measurements, it is found that both the concentration of DT and temperature can significantly affect the property of SAMs. The DT SAMs can prevent the corrosion of copper in chloride‐containing solution effectively because the inhibition efficiency can reach 99.59% at the DT concentration of 10^?2 M . The adsorption of DT in aqueous micellar solution obeys to the Langmuir adsorption isotherm, and the value of the free energy of adsorption calculated indicates that the adsorption of DT molecule is a spontaneous process and a typical of chemical adsorption.     

Kinetics of corrosion inhibition of benzotriazole to copper in 3.5% NaCl

The kinetics of interaction of benzotriazole (BTAH) with the surface of copper were studied using an electrochemical quartz crystal microbalance (EQMB) and electrochemical impedance spectroscopy (EIS). Upon injecting BTAH into the electrolyte, three regions appear in the time response of the microbalance. Region I (at short time scale of few minutes) exhibits rapid linear growth of mass with time. This is attributed to the formation of a Cu(I)BTA film that is several hundred layers thick. Region II reveals adsorption of BTAH at a slower rate, on the inner Cu(I)BTA complex. Region III is a plateau indicating that the BTAH film attains an equilibrium thickness, which increases with the concentration of BTAH. The polarization resistance of the interface changes with time in a similar fashion while the double layer capacitance decreases. The results suggest that the thickness of the physically adsorbed film of BTAH increases with time and BTAH concentration while the thickness of the inner Cu(I)BTA remains constant. Two semicircles were obtained in the impedance spectra corresponding to the complex Cu(I)BTA and the physically adsorbed BTAH.     

Corrosion inhibition of carbon steel in tetra-n-butylammonium bromide aqueous solution by benzotriazole and Na3PO4

The corrosion inhibition behavior of benzotriazole, Na₃PO₄ and their mixture on carbon steel in 20 wt.% (0.628 mol l⁻¹) tetra-n-butylammonium bromide aerated aqueous solution was investigated by weight-loss test, potentiodynamic polarization measurement, electrochemical impedance spectroscopy and scanning electron microscope/energy dispersive X-ray techniques. The inhibition action of BTA or SP or inhibitors mixture on the corrosion of carbon steel is mainly due to the inhibition of anodic process of corrosion. The results revealed that inhibitors mixtures have shown synergistic effects at lower concentration of inhibitors. At 2 g l⁻¹ BTA and 2 g l⁻¹ SP showed optimum enhanced inhibition compared with their individual effects.     

Corrosion inhibition of zinc in tetra-n-butylammonium bromide aerated aqueous solution by benzotriazole and Na3PO4

The effect of benzotriazole (BTA), Na₃PO₄ and their mixture on the corrosion of zinc in 17 wt.% (0.534 mol l⁻¹) tetra-n-butylammonium bromide (TBAB) aerated aqueous solution has been investigated by means of weight-loss test, potentiodynamic polarization test, electrochemical impedance spectroscopy (EIS) and SEM/EDX techniques. The experimental results showed that BTA or Na₃PO₄ or inhibitor mixture could protect zinc in aqueous TBAB solution. The inhibitor combinations led to higher efficiencies compared to those obtained when added individually. An inhibition efficiency of an inhibitor mixture consisting of 0.5 g l⁻¹ BTA and 1 g l⁻¹ Na₃PO₄ was more than 97%.     

Corrosion inhibition of zinc in phosphoric acid solution by 2-mercaptobenzimidazole

The inhibiting action of 2-mercaptobenzimidazole on the corrosion of zinc in phosphoric acid (H₃PO₄) solution has been investigated by weight loss and polarization. The studies reveal that the inhibitor is effective for the inhibition of zinc in H₃PO₄ solution and retards the anodic and cathodic corrosion reactions with emphasis on the former.     

Effect of inhibitors on corrosion behavior of copper—nickel in concentrated lithium bromide solution at high temperature

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Corrosion inhibition of copper by 2,5-dimercapto-1,3,4-thiadiazole monolayer in acidic solution

2,5-Dimercapto-1,3,4-thiadiazole (DMTD) monolayer was self-assembled on the fresh copper surface to form protective monolayer against copper corrosion in acidic solution. Its corrosion inhibition was investigated in 0.5 M HCl by cyclic voltammetry, potentiodynamic polarization and electrochemical impedance spectroscopy methods. The results revealed that the DMTD monolayer inhibited the copper corrosion effectively with the optimum self-assembly time of 10 h and the optimum self-assembly concentration of 7.5 mM. Surface observation was performed using scanning electron microscope, contact angle goniometer and Fourier transform infrared spectrometer. The molecular simulation has been used to simulate the adsorption model of DMTD molecule on Cu(1 1 1) surface.     

Corrosion inhibition of carbon steel in hydrochloric acid solution by fruit peel aqueous extracts

The inhibitive action of the aqueous extracts of fruit peels against corrosion of carbon steel in a 1 M HCl solution was investigated using electrochemical impedance spectroscopy, potentiodynamic polarization curves, weight loss measurements and surface analysis. We analyzed aqueous extracts of mango, orange, passion fruit and cashew peels in different concentrations and found that the extracts act as good corrosion inhibitors for the tested system. The inhibition efficiency increases with increasing extract concentration and decreases with temperature. The adsorption of components of the fruit peel extracts on the surface of the carbon steel follows the Langmuir adsorption isotherm.     

Corrosion inhibition of mild steel in sodium chloride solution by some zinc complexes

The corrosion inhibitive effect of zinc acetate, zinc acetylacetonate and zinc gluconate on the mild steel immersed in 3.5% NaCl solution was evaluated by electrochemical impedance spectroscopy (EIS). The results revealed superiority of zinc gluconate whilst zinc acetate showed inferior corrosion inhibition. The surface of the samples exposed to the inhibited solutions was analyzed using XRD and SEM techniques. The pH measurement of the test solutions before and after corrosion, also before and after addition of Fe⁺² and Fe⁺³ revealed that the superior inhibition of zinc gluconate is related to formation of insoluble corrosion products on the mild steel surface.     

Electrochemical studies on the effect of (2E)‐3‐amino‐2‐phenylazo‐but‐2‐enenitrile and its derivative on the behaviour of copper in nitric acid

The objective of this work is to provide additional insight on the influence of (2E)‐3‐amino‐2‐phenylazo‐but‐2‐enenitrile and its derivative as corrosion inhibitors for copper in 0.5 M HNO₃. Electrochemical techniques (potentiodynamic polarization, polarization resistance and impedance spectroscopy) as well as weight loss measurements have been employed to study the corrosion inhibition. The investigated compounds have shown inhibition efficiency in 0.5 M HNO₃. Inhibition efficiency of these compounds has been found to vary with the concentrations of the compounds. The adsorption of these compounds on the copper surface from the acid solution has been found to obey Langmuir adsorption isotherm. The results revealed that the compounds are mixed type inhibitors. The effect of temperature on the inhibition efficiency was studied.