Investigation of inhibiting properties of self-assembled films of 4-aminothiophenol on copper in 3.5% NaCl

A self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) was formed on copper surface which was characterized using cyclic voltammetry, Fourier transform infrared spectroscopy, and Raman spectroscopic techniques. The surface morphology of the monolayer was examined by scanning electron microscopy. The anticorrosive property of the SAM was investigated using electrochemical impedance spectroscopy and polarization studies. The electrochemical measurements showed that the inhibition efficiency increased with the immersion time of copper in ethanolic solution of 4-ATP in 3.5% NaCl. The significant corrosion protection efficiency of SAM could be due to the compact and dense monolayer on metallic surfaces.     

Surface protection of copper in aerated 3.5% sodium chloride solutions by 3-amino-5-mercapto-1,2,4-triazole as a copper corrosion inhibitor

Surface protection of copper in aerated 3.5% NaCl solutions by 3-amino-5-mercapto-1,2,4-triazole (AMTA) has been reported. The study has been carried out using weight loss, pH, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and chronoamperometric (CA) measurements along with scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) investigations. Weight-loss data indicated that the dissolution rate and the pH of the solution decreased to a minimum after 24 days of copper immersion due to the inhibitive action of AMTA. PDP, CA, and EIS measurements showed that AMTA decreased the corrosion rates and increased the polarization resistance and inhibition efficiency. This effect was increased with increasing AMTA concentration as well as the immersion time of the copper electrode to 50 h before measurements. SEM micrograph and EDS analysis proved that the inhibition of copper corrosion takes place due to adsorption of AMTA onto the surface. These results together confirmed that AMTA is a good mixed-type inhibitor and the inhibition of copper corrosion is achieved by strong adsorption of AMTA molecules.     

3-氨基-5-巯基-1,2,4-三唑的制备

以价廉易得的原料硫氰酸铵经两步合成了3-氨基-5-巯基-1,2,4-三唑,而且收率高于文献.并对三种硫氰酸盐合成2,5-联二硫脲进行了对比,结果表明,在相同条件下,以硫氰酸铵为最好.     

Self-assembled 1-octadecyl-1H-1,2,4-triazole films on copper for corrosion protection

A film of 1-octadecyl-1H-1,2,4-triazole (OTA) was formed on a fresh copper surface by self-assembly technique. The optimum concentration of OTA and immersion time for the formation of a protective OTA film have been established using electrochemical impedance spectroscopy (EIS). These are (i) 15 mM concentration of OTA in methanol and (ii) immersion period of 48 h. X-ray photoelectron spectroscopy (XPS), reflection absorption FTIR spectroscopy, atomic force microscopy (AFM), and contact angle measurements have been used to characterize the OTA film on copper surface. The efficiency of OTA film to protect copper from corrosion in aqueous NaCl environment has been investigated using EIS, potentiodynamic polarization studies, cyclic voltammetry and weight-loss studies. All these studies showed that the OTA film affords excellent protection against corrosion of copper.     

Electropolymerisation de monomere 3-amino-1,2,4-triazole sur une electrode de cuivre et effet du polymere sur la corrosion de l'electrode en milieu NaCl 3%

Résumé L'electropolymérisation d'un nouveau polymére a partir de 3-amino-triazole (ATA) est réalisée. L'électrolyte support était de L'eau distillée avec un mélange de méthanol et de KOH. Le microscope électronique à balayage (MEB), la voltammétrie cyclique et le chronoampérométrie ont été utilisées pour caractériser le nouveau polymere. Ces mêmes techniques ont été employees pour étudier la nature du mécanisme d'inhibition de la corrosion du cuivre en milieu NaCl 3% par suite de la formation du polymere. L'électropolymérisation in situ du monomére donne lieu à un polymère isolant. Le traitement thermique du polymère améliore son homogénéité et son adhérence à l'électrode. Un mécanisme de la formation du poly-ATA est proposé. La formation du polymere aboutit à une diminution des courants cathodique et anodique. Les vitesses des réactions de réduction de l'óxygène et de dissolution du cuivre ont été remarquablement diminuées.

---

The electrochemical polymerization of a new polymer is described. The monomer used was 3-amino-1,2,4-triazole (ATA) and the supporting medium was distilled water/methyl alcohol containing KOH. Scanning electronic microscopy (SEM), cyclic voltammetry and chronoamperometry were used, to characterize the new polymer. The same techniques were also used to study the nature of corrosion inhibition processes caused by the formation of the polymer on copper in NaCl 3%. The in-situ electropolymerization of the monomer gives an insulating polymer. Heat treatment of the polymer improves its homogeneity and adherence to the copper electrode on which it is formed. A mechanism for the formation of the poly-ATA is proposed. The formation of the polymer gives rise to a decrease in both anodic and cathodic currents. The rates of oxygen reduction and copper dissolution reactions are considerably decreased.

     

Enhancing corrosion resistance of aluminum composites in 3.5% NaCl using pigmented epoxy fluoropolymer

The corrosion protection performance of AA6061 T6–10% Al₂O₃ composite, coated with four different fluoropolymer paint systems, were investigated in 3.5% NaCl aqueous solutions under uniform and scratched conditions. A comparison between epoxy-treated clear and pigmented fluoropolymer coatings with newly developed vanadate-based fluoropolymer coatings was performed from corrosion protection, adhesion and durability points of view. The corrosion rates of epoxy-treated clear FLBZ 1074 increased dramatically after less than one month of exposure in 3.5% NaCl aqueous solutions. The addition of iron oxide or titanium oxide as pigments to the fluoropolymer decreased the porosity of epoxy and hence, improved the corrosion resistance. The newly developed vanadate based-clear FLBZ 1074 system showed outstanding corrosion resistance even after two months of immersion in 3.5% NaCl aqueous solutions under scratched coating conditions. The durability of such new coating based on salt spray test results was very promising (>2000 h without any sign of corrosion). The vanadate-pigmented FLBZ 1074 showed a dramatic increase in the corrosion rates. Moreover, the presence of pigments affected negatively the adhesion performance as well as the durability of the coating. A general model has been used to analyze the impedance data in terms of reactions occurring during the interaction of the coated metal with the environment. It was found that the vanadate-treated specimens not only improve the protective power against filiform corrosion as a factor of time, but also maintain the adhesion performance within the acceptable ranges.     

Synthesis,characterization and corrosion protection of poly-4-methyl-3-mercapto-1,2,4-triazole/TiO2 composite on copper

The present work deals with the electrochemical synthesis of poly-4-methyl-3-mercapto-1,2,4-triazole (p-MMTA)/TiO₂ composite on metallic copper to evaluate its corrosion protection. The composite was characterized by FT-IR, cyclic voltammetry, X-ray diffraction and energy dispersive X-ray analysis. The distribution of inorganic particles in the polymeric matrix was evidenced from the scanning electron microscopic studies. The corrosion performance of composite coating was evaluated by electrochemical impedance spectroscopy and Tafel polarization measurements in 3.5 % NaCl medium. The p-MMTA/TiO₂ composite showed an excellent corrosion protection ability, which was evidenced from the results of electrochemical measurements. The enhanced ability could be due to the barrier effect of composite coatings against corrosive species and also due to the synergistic effect between organic polymer and inorganic particles.     

3-氨基-5-邻甲苯基-4H-1,2,4-三唑的合成工艺

[目的]3-氨基-5-邻甲苯基-4H-1,2,4-三唑是具有多种抗菌活性的三唑类抗菌剂。介绍3-氨基-5-邻甲苯基-4H-1,2,4-三唑的合成工艺方法,并对工艺条件进行优化。[方法]以2-甲基苯甲酸和S-甲基异硫脲硫酸盐为原料,分3步反应合成3-氨基-5-邻甲苯基-4H-1,2,4-三唑。[结果]通过实验讨论了不同的物料比、反应时间及反应温度等因素对各步目标产物的产率和纯度的影响,确定出各步反应的最佳合成工艺条件。[结论]该合成工艺操作简便、反应条件温和、收率高、产品纯度高,适合工业化生产。     

Plant derived cationic dye as an effective corrosion inhibitor for 7075 aluminum alloy in 3.5% NaCl solution

The inhibition of the corrosion of 7075 aluminum alloy in 3.5 wt.% NaCl solution by 5,6-dihydro-9,10-dimethoxybenzo[g]-1,3-benzodioxolo[5,6-a]quinolizinium (berberine) has been studied using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electrochemical microscopy (SECM) and scanning electron microscopy (SEM). Inhibition efficiency was found to increase with increasing concentration of berberine. The adsorption of the berberine on the 7075 aluminum alloy surface obeyed the Langmuir adsorption isotherm. The adsorbed film on 7075 aluminum alloy surface containing inhibitor was confirmed by the SEM, and SECM. The results obtained showed that the berberine could serve as an effective inhibitor of the corrosion of 7075 aluminum alloy in 3.5% NaCl.     

3-氨基-5-羧基-1,2,4-三唑席夫碱的合成

含1,2,4-三唑环的席夫碱化合物一般都具有很好的生物活性。为了进一步探讨1,2,4-三唑席夫碱的合成,文中以3-氨基-5-羧基-1,2,4-三唑为原料,与取代芳醛反应,合成了8个3-氨基-5-羧基-1,2,4-三唑类席夫碱化合物。采用的反应条件为:3-氨基-5羧基-1,2,4-三唑与取代芳醛的摩尔比为1∶1,N,N-二甲基甲酰胺(DMF)为溶剂,冰醋酸为催化剂,在回流温度下反应3.5—4.5 h。化合物的结构通过IR,1H NMR和元素分析进行了表征。样品分析结果表明,在红外光谱中,所得目标产物在波数ν=1 600—1 625 cm-1处均出现C N的特征吸收峰;在1H核磁共振中,化学位移δ9附近有CH N的质子的化学位移出现。     

Application of electrochemical noise to evaluate outdoor atmospheric corrosion of copper after relatively short exposure periods

This study focused on the application of electrochemical noise to assess the protection level of corrosion products formed on copper during relatively short exposure time in different outdoor atmospheres. Electrochemical noise, cathodic reduction measurements and gravimetric (mass loss) analysis were applied to copper samples exposed at urban and rural/industrial areas in Cuba for 4 months. Measurements of Electrochemical current noise indicated that the poorest protective corrosion products were formed on samples exposed to atmospheres with high concentration of H₂S which agreed with the corrosion rate determined by mass loss and electrochemical chronopotentiometry (cathodic reduction). The electrochemical noise methodology proposed in this work showed acceptable and reproducible results by using an electrochemical cell in which the electrolyte was formed by a distilled-water wetted cloth in contact with the compounds present on a corroded metallic surface. This methodology indicated that the corrosion protection level of the corrosion products formed on copper is related to the corrosivity of the atmosphere.     

A robust method of enhancement of corrosion inhibitive ability of electrodeposited poly-3-amino-5-mercapto-1,2,4-triazole films over copper surface using graphene oxide

Abstract

A simple and new strategy has been developed to protect metallic copper by forming composite material using graphene oxide (GO) and electropolymerised p-3-amino-5-mercapto-1,2,4-triazole (p-AMTa). The structure and the mechanism of the formation of the polymer and polymer composite were predicted from Fourier Transform Infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopic (XPS) analysis and Energy Dispersive X-ray (EDX) spectroscopy. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies (PDS) were employed to study the corrosion inhibitive action of p-AMTa?+?GO composite in 3.5% NaCl medium. The study revealed that, the copper electrode modified with the carbon based polymeric composite suppressed the anodic dissolution of copper thereby increasing its corrosion resistance.     

5-取代苯氨基-6-叔丁基-1,2,4-三嗪-3-硫酮的合成

合成了一系列新的5-取代苯氨基-6-叔丁基-1,2,4-三嗪-3-硫酮化合物,其结构经元素分析、IR、^1HNMR及MS等确证。实验发现目标化合物可以“一锅法”合成,产率较分步反应有较大提高。     

微波辐射合成5-羧基-3-氨基-1，2，4-三氮唑

本文在微波辐射条件下合成5-羧基-3-氨基-1,2,4-三氮唑,产物结构通过IR,^1H NMR进行了表征。微波反应条件下的反应速度是常规条件下反应速度的66倍,并且产率相当。     

NaCl溶液中铜和A_3钢接触腐蚀的研究

研究了金属铜与A3钢在NaCl溶液中偶接时的接触腐蚀行为。考察了偶接时间、溶液中Cl-浓度、电偶对中阴阳极面积比、实验温度等因素对阳极腐蚀速度的影响。结果表明,腐蚀速度随温度升高、溶液中Cl-浓度的增大、阴阳极面积比的增大而增大;偶接时间为24 h时,腐蚀速度趋于稳定。     

The effect of benzimidazole and zinc acetylacetonate mixture on cathodic disbonding of epoxy coated mild steel

Electrochemical behavior of mild steel in the presence of zinc acetylacetonate (Zn(acac)₂) and benzimidazole (BIMIDA) was evaluated by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution and compared to zinc phosphate (ZP) pigment and zinc potassium chromate (ZPC) pigment extracts. Results showed superior performance of Zn(acac)₂ and BIMIDA mixture (ZBM) compared to ZP pigment, while it introduced inferior inhibitive action compared to ZPC pigment. The epoxy coatings were formulated with ZBM as anticorrosive additive, ZP and ZPC pigments. The disbonding rate of coated steel follows the order: Blank > ZP > ZBM > ZPC. EIS results showed a complex film could be formed at the hole area for the coatings formulated with ZP, ZBM and ZPC. It is concluded that the stronger the complex film on the surface, the lesser the cathodic disbonding rate would be.     

A novel hybrid composite coating of poly-3-amino-5-mercapto-1,2,4-triazole/TiO<Subscript>2</Subscript> on copper for corrosion protection

Poly-3-amino-5-mercapto-1,2,4-triazole/TiO₂ (p-AMTA/TiO₂) composite was effectively synthesized over the copper surface by cyclic voltammetric technique and used as a protective coating against corrosion. The resulting polymeric composite was characterized using Fourier transform infrared spectroscopy. The presence of TiO₂ particles in the polymer matrix was substantiated from X-ray diffraction pattern and energy-dispersive X-ray spectrum. The uniform dispersion of TiO₂ particles in the polymeric matrix was confirmed by the scanning electron microscope images. The protective effect of composite coating was evaluated by electrochemical impedance spectroscopy and potentiodynamic polarization methods in 3.5 % NaCl medium. Impedance measurements showed that charge transfer resistance (R _ct) values increased for polymeric composites which suggested the enhanced corrosion protection of copper. Further, the decrease in corrosion current density (i _corr) values and shifting of corrosion potential (E_corr) toward the cathodic direction confirmed the anticorrosive behavior of the polymeric composite. The reason for the higher protection of polymeric composite may be due to the well-dispersed TiO₂ particles in the polymer matrix exhibiting the enhanced barrier properties to protect copper surface from corrosion. The defects in the coatings can be reduced by embedded TiO₂ particles in the pores of the polymeric films to enhance the corrosion protection, consequently.     

The role of cuprous ion as corrosion inhibitor for copper in a chloride medium

A disconnected Al or Zn strip was found to possess corrosion-inhibition effect on copper in a chloride solution. Original assumption of a pseudo-cathodic protection mechanism was later experimentally proved to be unfounded. A chemical reason was proposed to explain the phenomena.     

Cathodic behaviour of some 5-nitrophenyl-1,2-dithiole-3-thiones and 5-nitrophenyl-1,2-dithiole-3-ones

The electrochemical behaviour of 5-(nitrophenyl)-1,2-dithiole-3-thiones and 5-(nitrophenyl)-1,2-dithiole-3-ones was studied by cyclic voltammetry in DMF. The standard reduction potentials of 5-(p-nitrophenyl)-dithiolethione and 5-(p-nitrophenyl)-dithiolone entered into a linear correlation involving standard reduction potentials of substituted nitrobenzenes and known electronic constants of several substituents. This correlation allowed the determination of the electronic effects of [3-thioxo-1,2-dithiole]-5-yl and [3-oxo-1,2-diothiole]-5-yl groups which were, respectively, σ_p⁻=1.14 and σ_p⁻=0.86, comparable with those of nitro or cyano substituents.     

5–硝基–3–三硝甲基–1H–1,2,4–三唑的合成与性能研究

以氨基胍碳酸氢盐与丙二酸为原料,经缩合–环化反应、重氮化–取代反应和硝化反应合成出5–硝基–3–三硝甲基–1H–1,2,4–三唑。用红外光谱、核磁共振、元素分析对其结构进行了表征。确定了最佳硝化反应体系:5–硝基–1H–1,2,4–三唑–3–乙酸为硝化反应前体,硝硫混酸(V(w为的98%浓硫酸)∶V(发烟硝酸)=1.2∶1)为硝化剂。采用密度泛函理论(DFT)中B3LYP方法在6–31G(d,p)基组水平下对5–硝基–3–三硝甲基–1H–1,2,4–三唑进行了全构型优化,并在优化构型基础上进行了自然键轨道(NBO)分析。差示扫描量热法(DSC)分析结果表明,10℃/min升温速率下,5–硝基–3–三硝甲基–1H–1,2,4–三唑的分解温度为135℃。