Corrosion inhibition of copper in tetra‐n‐butylammonium bromide aqueous solution by benzotriazole

The corrosion inhibition behavior of benzotriazole (BTA) on copper in 17 wt% tetra‐n‐butylammonium bromide (TBAB) aerated aqueous solution was investigated by weight‐loss tests, potentiodynamic polarization, electrochemical impedance spectroscopy, and scanning electron microscopy/energy dispersive X‐ray spectroscopy. BTA is a good inhibitor in 17 wt% TBAB solution. The inhibition efficiency of BTA increases with increasing inhibitor concentration, attaining efficiencies of up to 90% calculated according to different methodologies. Adsorption of BTA in 17 wt% TBAB solution on the copper 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 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%.     

Dynamic electrochemical impedance spectroscopy and polarization studies to evaluate the inhibition effect of benzotriazole on copper‐manganese‐aluminium alloy in artificial seawater

The effect of benzotriazole (BTA) on the corrosion of a new type copper‐manganese‐aluminium (CMA) alloy in artificial seawater was investigated using dynamic electrochemical impedance spectroscopy (DEIS), linear polarization resistance, and Tafel extrapolation methods. Measurement results obtained from those three methods showed that corrosion rates decreased while BTA concentration increased. This clearly indicates that BTA inhibits the corrosion rate of CMA in artificial seawater. Although there are consistent results obtained from all these three methods, the results of the percent inhibition efficiency, IE (%), values obtained from DEIS method should be calculated from the charge transfer resistance (R_ct) values obtained after 5 h.     

Anti‐tarnish treatment of brass for coinage

The anti‐tarnish film was formed on brass for coinage by 1‐phenyl‐5‐mercaptotetrazole (PMTA), which was studied by accelerated corrosion test (metallic coatings‐thioacetamide corrosion test), polarization curves and electrochemical impedance spectroscopy (EIS) in synthetic sweat solution. The accelerated corrosion test showed that PMTA exhibited better anti‐tarnish performance on brass than that of traditional anti‐tarnish agent benzotriazole (BTA). The polarization measurements showed that PMTA could be classified as a mixed inhibitor for it could restrain both anodic and cathodic reactions. EIS measurements indicated that the inhibition efficiency of PMTA on brass was over 98.4% in synthetic sweat solution. All these results showed that PMTA was an excellent anti‐tarnish agent of the brass for coinage, the optimum treating conditions of which were 0.5 gL^?1, pH = 3, 55°C–85°C, 7 min.     

Effect of nano Al (Scx−1Zrx) precipitates on the mechanical and corrosion behavior of Al‐2.5 Mg alloys

Microanalytical, mechanical, and corrosion studies were undertaken to investigate the effect of nano‐precipitates of Al(Sc_x−1Zr_x) on the mechanical and corrosion characteristics of Al 2.5 alloy containing 0, 0.15, 0.3, 0.6, and 0.9 wt% of Sc with 0.15 wt% Zr. Addition of 0.3% Sc significantly increased the yield strength due to small precipitates sizes (5–19 nm) and the high coherency of the nano‐particles. Largest contributor to the strength was grain boundary strengthening caused by pinning of grain boundary precipitates. The alloys showed a good resistance to corrosion in 3.5 wt% neutral chloride solution. The alloy offered a high passivation tendency because of homogeneous coherent nano Al(Sc_x−1Zr_x) precipitates. The nano precipitates interfaces and homogeneously distributed Al₃Sc precipitates offer a high degree of corrosion resistance to Al 2.5 Mg Sc alloys compared to conventional aluminum alloys, such as Al 6061 and Al6013.     

苯并三唑和咪唑分子内缓蚀协同作用的研究

通过Ｍａｎｎｉｃｈ反应把苯并三唑和咪唑分子用亚甲基链连接起来,合成１－「１’－咪唑）－甲基」苯并三唑化合物,采用静态挂片法,电化学极化曲线法和电化学阻抗法研究了它对３％ＮａＣｌ溶溶中铜的缓蚀作用,讨论了分内苯并三唑单元和唑唑单元的协同缓蚀作用。     

Impedance and XPS study of benzotriazole films formed on copper, copper-zinc alloys and zinc in chloride solution

The formation of protective layers on copper, zinc and copper-zinc (Cu-10Zn and Cu-40Zn) alloys at open circuit potential in aerated, near neutral 0.5 M NaCl solution containing benzotriazole was studied using electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). Benzotriazole (BTAH), generally known as an inhibitor of copper corrosion, also proved to be an efficient inhibitor for copper-zinc alloys and zinc metal. The surface layers formed on alloys in BTAH-inhibited solution comprised both polymer and oxide components, namely Cu(I)BTA and Zn(II)BTA polymers and Cu₂O and ZnO oxides, as proved by the in-depth profiling of the layers formed. A tentative structural model describing the improved corrosion resistance of Cu, Cu-xZn alloys and Zn in BTAH containing chloride solution is proposed.     

Nanostructured surface pre‐treatment based on self‐assembled molecules for corrosion protection of Alclad 7475‐T761 aluminum alloy

Coatings based on self‐assembled molecules (SAMs) for corrosion protection of aircraft aluminum alloys have been studied to evaluate their potentialities as replacements to yellow chromate conversion coatings (CCC), due to the toxicity of these leading to environmental problems. In this work, the influence of alkane diphosphonates self‐assembling molecules on the corrosion resistance of the AA7475‐T761 cladded with AA7072 was investigated by electrochemical impedance spectroscopy and cathodic and anodic polarization curves, in naturally aerated 0.5 mol/L Na₂SO₄ aqueous solution, with pH adjusted to 4. Corrosion accelerated experiments (salt spray tests) were also carried out to examine the resistance of the SAM treated samples against corrosion. The results suggested that the development of boehmite (aluminum oxide) layer with incorporation of SAM was beneficial to the corrosion resistance of the tested aluminum alloy. Samples surface treated with SAM or aluminum oxide/SAM (without and with subsequent polyester layer) showed better corrosion resistance results than samples with CCC, indicating that this last type of coating containing hexavalent chromium could be replaced by the environmentally friendly pre‐treatment corresponding to boehmite growth followed by incorporation of SAM.     

Adsorbed corrosion inhibitors studied by electron spectroscopy: Benzotriazole on copper and copper alloys

Surface films formed by adsorption of benzotriazole (BTA), on copper and copper alloys have been studied by X-ray photo-electron spectroscopy (XPS). It is found that on both copper and copper-nickel alloys, benzotriazole forms a Cu(I)BTA surface complex. For the copper-nickel alloys the time taken to form the Cu(I)BTA film is dependent on the alloy composition. The Cu(I)BTA films were found to oxidize rapidly to a Cu(II) species on removal from the liquid phase. Surface films formed by BTA on 70 Cu : 30 Zn alloy were found to contain both copper and zinc, the copper again being in the Cu(I) state.A study of the adsorption of BTA on cathodically reduced copper surfaces strongly supports previous suggestions that the presence of Cu₃O facilitates formation of the surface film.     

苯并三唑对碳钢/铜合金电偶腐蚀行为的影响

目的 研究NaCl溶液中苯并三唑(BTA)对碳钢/铜合金电偶腐蚀行为的影响.方法 使用丝束电极(WBE)技术和电化学阻抗谱(EIS)技术研究在未添加和添加BTA的NaCl溶液中,丝束电极表面的电位分布、电流密度分布和电化学阻抗谱演化,同时对比分析碳钢区域与铜合金区域的阻抗谱特征.结果 在未添加BTA的条件下浸泡72 h...     

MBT、BTA和MBO对铜缓蚀性能的电化学研究

用电化学方法比较研究了２－巯基苯并恶唑（ＭＢＯ），苯并三唑（ＢＴＡ）和２－巯基苯并噻唑（ＭＢＴ）在３％ＮａＣｌ，０．１ｍｏｌ／Ｌ ＨＣｌ和０．５ｍｏｌ／Ｌ ＨＣｌ溶液中对铜的缓蚀性能，在３％ＮａＣｌ溶液中，ＭＢＯ表现出稍优于ＢＴＡ，远高于ＭＢＴ的缓蚀能力；与ＢＴＡ和ＭＢＴ相比，在０．１ｍｏｌ／Ｌ ＨＣｌ和０．５ｍｏｌ／Ｌ ＨＣｌ中，ＭＢＯ对铜的腐蚀有突出的缓蚀效果。     

Inhibition of copper corrosion by modifying cysteine self‐assembled film with alkylamine/alkylacid compounds

Complex self‐assembled monolayers (SAMs) were prepared by modifying the adsorption of cysteine with dodecylacid (DAC) and with dodecylamine (DAM) on copper surfaces. Their protective effects against copper corrosion were investigated by potentiodynamic polarization curves and electrochemical impedance spectroscopy (EIS) in 0.5 M HCl aqueous solution. Results show that SAMs suppress cathodic current densities and shift the corrosion potential toward more negative values. Two types of complex SAMs enhance the anticorrosion effect of cysteine SAMs. PM3 semi‐empirical quantum calculations were used to obtain the quantum chemical parameters. The complex SAMs formed from cysteine and DAM have the higher E_HOMO level and the better protection effect.     

SVET study of the corrosion protection of electrodeposited Zn and Zn‐Co‐Fe alloy coated steels

The scanning vibrating electrode technique (SVET) was applied to study the corrosion resistance of partially coated (Zn and various Zn‐Co‐Fe alloys) and partially exposed steel samples in 10 mM NaCl solution. The sacrificial properties and the protection range decreases with increase in Co content in the alloy. For high Co content in the alloy, the coating becomes more noble to steel and loses its sacrificial protection. The barrier resistance of the coatings increases with the increase in Co content in the alloy coating. Zn‐Co‐Fe alloys with high Co content (i.e., 32 wt% Co and 1 wt% Fe) showed excellent barrier properties due to passivation after dezincification protecting the underlying steel. An intermediate region of compositions can be distinguished in which the coatings provide a good combination of sacrificial and barrier resistance properties and also a reasonable protection range.     

Micro‐electrochemical characterization of galvanic corrosion of TA2/316L composite plate

Galvanic corrosion behavior of TA2/316L composite plate was investigated in the solution of 3.5 wt% NaCl by galvanic potential monitoring, scanning localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating micro‐electrode (SVME) techniques. The results demonstrated that the pitting corrosion resistance of 316L for the galvanic combination sample is lower, and the coupled current density is higher than for the single 316L sample. It indicates that the galvanic action works on the corrosion behavior of the TA2 titanium alloy/316L stainless steel galvanic combination in sodium chloride solution. The galvanic effect width was determined as 1500 µm.     

High temperature oxidation of FeCrAl‐alloys – influence of Al‐concentration on oxide layer characteristics

The superior high temperature oxidation resistance of FeCrAl alloys relies on the formation of a dense and continuous protective aluminium oxide layer on the alloy surface when exposed to high temperatures. Consequently, the aluminium content, i.e. the aluminium concentration at the alloy–oxide layer interface, must exceed a critical level in order to form a protective alumina layer. In the present study the oxidation behaviour of six different FeCrAl alloys with Al concentrations in the range of 1.2–5.0 wt% have been characterised after oxidation at 900 °C for 72 h with respect to oxide layer surface morphology, thickness and composition using scanning electron microscopy, energy dispersive X‐ray spectroscopy and Auger electron spectroscopy. The results show that a minimum of 3.2 wt% Al in the FeCrAl alloy is necessary for the formation of a continuous alumina layer. For Al concentrations in the range of 2.0–3.0 wt% a three‐layered oxide layer is formed, i.e. an oxide layer consisting of an inner alumina‐based layer, an intermediate chromia‐based layer and an outer iron oxide‐based layer. In contrast, the 1.2 wt% Al FeCrAl alloy is not able to form a protective oxide layer inhibiting extensive oxidation.     

The electrochemical behaviour of Ti‐13Nb‐13Zr alloy in various solutions

The electrochemical behaviour of a near‐β Ti‐13Nb‐13Zr alloy for the application as implants was investigated in various solutions. The electrolytes used were 0.9 wt% NaCl solution, Hanks' solution and a culture medium known as minimum essential medium (MEM) composed of salts, vitamins and amino acids, all at 37 °C. The electrochemical behaviour was investigated by the following electrochemical techniques: open circuit potential measurements as a function of time, electrochemical impedance spectroscopy (EIS) and determination of polarisation curves. The obtained results showed that the Ti alloy was passive in all electrolytes. The EIS results were analysed using an equivalent electrical circuit representing a duplex structure oxide layer, composed of an inner barrier layer, mainly responsible for the alloy corrosion resistance, and an outer and porous layer that has been associated to osteointegration ability. The properties of both layers were dependent on the electrolyte used. The results suggested that the thickest porous layer is formed in the MEM solution whereas the impedance of the barrier layer formed in this solution was the lowest among the electrolytes used. The polarisation curves showed a current increase at potentials around 1300 mV versus saturated calomel electrode (SCE), and this increase was also dependent on the electrolyte used. The highest increase in current density was also associated to the MEM solution suggesting that this is the most aggressive electrolyte to the Ti alloy among the three tested solutions.     

Alloying with copper to reduce metal dusting of nickel

Copper is thought to be noncatalytic to carbon deposition from gas atmospheres, and owing to its extremely low solubility for carbon, inert to the metal dusting reaction. Thus, the addition of copper to nickel, which forms a near perfect solid solution, may be able to suppress or greatly retard the metal dusting of the alloy, without the need for a protective oxide scale on the surface. The dusting behaviour of Ni‐Cu alloys containing up to 50 wt% Cu, along with pure Cu, was investigated in a 68%CO‐31%H₂‐1%H₂O gas mixture (a_C: 19) at 680°C for up to 150 h. Surface analysis showed that two types of carbon deposits, graphite particle clusters and filaments, were observed on pure Ni and Ni‐Cu alloys with Cu contents of up to 5 wt%. Alloys with more than 10 wt% Cu showed very little coking, forming filaments only. SEM and TEM analyses revealed metal particles encapsulated by graphite shells within the graphite particle clusters, and metal particles at filament tips or embedded along their lengths. A kinetic investigation showed that alloy dusting rates decreased significantly with increasing copper levels up to 10 wt%. At copper concentrations of more than 20 wt%, the rate of metal dusting was negligible. Although pure copper is not catalytic to carbon formation, scattered carbon nanotubes were observed on its surface. The effect of copper on alloy dusting rates is attributed to a dilution effect.     

Corrosion behavior of Ti‐xNb‐13Zr alloys in Ringer's solution

Ti‐6Al‐4V alloy has been widely used in restorative surgery due to its high corrosion resistance and biocompatibility. Nevertheless, some studies showed that V and Al release in the organism might induce cytotoxic effects and neurological disorders, which led to the development of V‐free alloys and both V‐ and Al‐free alloys containing Nb, Zr, Ta, or Mo. Among these alloys, Ti‐13Nb‐13Zr alloy is promising due to its better biomechanical compatibility than Ti‐6Al‐4V. In this work, the corrosion behavior of Ti, Ti‐6Al‐4V, and Ti‐xNb‐13Zr alloys (x = 5, 13, and 20) was evaluated in Ringer's solution (pH 7.5) at 37 °C through open‐circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy. Spontaneous passivity was observed for all materials in this medium. Low corrosion current densities (in the order of 10^?7 A/cm²) and high impedance values (in the order of 10⁵ Ωcm² at low frequencies) indicated their high corrosion resistance. EIS results showed that the passivating films were constituted of an outer porous layer (very low resistance) and an inner compact layer (high resistance), the latter providing the corrosion resistance of the materials. There was evidence that the Ti‐xNb‐13Zr alloys were more corrosion resistant than both Ti and Ti‐6Al‐4V in Ringer's solution.     

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.