双苯并咪唑化合物对碳钢在H2SO4溶液中的缓蚀作用

通过腐蚀失重法、电化学法和扫描电镜等方法研究了双苯并咪唑化合物(BBB)对碳钢在0.25 mol/LH2SO4溶液中的缓蚀行为.结果表明,双苯并咪唑化合物缓蚀性能优异,缓蚀效率随缓蚀剂浓度增大而升高,且为同时抑制碳钢腐蚀阴阳极过程的混合型缓蚀剂.在碳钢表面的吸附符合Langmuir等温吸附规律.     

三唑化合物在1mol/L盐酸中对碳钢的缓蚀作用研究

合成了一种新型三氮唑化合物：1-（3-（4-氟苯基）-4,5-吡唑基-2-（1,2,4-三唑基）乙酮,并通过失重实验、动电位极化、交流阻抗及扫描电镜方法研究了其在1mol／L盐酸溶液中对Q235碳钢的缓蚀效果。结果表明,该三唑化合物在1mol／L盐酸中对Q235碳钢有较好的缓蚀效果,是混合型缓蚀剂,该缓蚀剂在碳钢表面的吸附符合Langmuir等温吸附式。     

热浸镀55Al-Zn-1.6Si合金镀层在NaCl溶液中的腐蚀行为

用盐雾试验和电化学阻抗谱法研究了热浸镀55%Al-Zn-1.6%Si合金镀层和某商用热浸镀锌层在5%NaCl溶液中的腐蚀行为,并用光学显微镜和扫描电镜分析了清除腐蚀产物后镀层表面组织形貌特征.结果表明,热浸镀55%Al-Zn-1.6%Si合金镀层耐盐雾腐蚀性约为商用热浸镀锌层的2.5倍.商用热浸镀锌层腐蚀表现出显著的扩散控制特征,而热浸镀55%Al-Zn-1.6%Si合金镀层腐蚀主要由电极表面电荷转移过程所控制.     

胡萝卜茎叶提取物对碳钢在0.5 mol/L H2SO4溶液中的缓蚀作用

目的研究胡萝卜茎叶提取物(DCSLE)在硫酸介质中对碳钢的腐蚀抑制作用及机理。方法通过超声辅助的手段,用水浸提获得DCSLE,利用红外光谱(FTIR)对其含有的主要官能团进行表征。在25~40℃下,采用失重法、电化学极化和阻抗法(EIS)评价DCSLE在0.5 mol/L H2SO4溶液中对碳钢的缓蚀性能,并讨论了其缓蚀机理。结果DCSLE对碳钢在0.5mol/LH2SO4溶液中的腐蚀具有良好的抑制效果,其缓蚀效率随浓度的增加而增加,随温度的增加而先增加后降低(40℃<25℃<30℃<35℃),35℃下,质量浓度为0.6g/L时,缓蚀效率为92.85%。电化学测试表明,DCSLE是混合型缓蚀剂,但主要是抑制阴极的反应。其缓蚀机理是:DCSLE以物理和化学混合吸附的方式吸附在碳钢表面,形成一层保护膜,从而阻止酸溶液的侵蚀,且吸附遵循Langmuir吸附等温模型。扫描电镜(SEM)观察到加入DCSLE后,碳钢的腐蚀得到了明显控制。结论DCSLE可以有效抑制碳钢在0.5mol/LH2SO4溶液介质中的腐蚀,是一种具有广泛应用前景的天然绿色缓蚀剂。     

热镀锌钢材在稀盐酸中的缓蚀和量子化学研究

通过量子化学计算、质量损失测试、电化学测试和扫描电镜等研究烟酸、吖啶和小檗碱等杂环化合物对热镀锌钢材在盐酸介质中的缓蚀作用.量子化学计算结果表明,3种化合物均具有多个吸附活性中心,且其前线轨道与镀层表面锌原子的前线轨道能够相互作用,因而使得杂环化合物分子可通过在镀层钢材表面形成吸附膜而阻止热镀锌钢材在盐酸介质中的溶解.质量损失和电化学测试结果表明3种化合物在盐酸介质中对热镀锌钢材均具有良好的缓蚀作用,最高缓蚀效率可达99%以上;其中小檗碱的缓蚀效果最好,在浓度为1.0×10.4 mol/L时缓蚀效率就已达到80%以上;3种化合物均通过单分子层化学吸附方式吸附在镀层表面,从而起到保护作用,是热镀锌钢材酸洗过程的环境友好型缓蚀剂.     

Nicotinic acid as a nontoxic corrosion inhibitor for hot dipped Zn and Zn-Al alloy coatings on steels in diluted hydrochloric acid

The inhibition effect of nicotinic acid for corrosion of hot dipped Zn and Zn-Al alloy coatings in diluted hydrochloric acid was investigated using quantum chemistry analysis, weight loss test, electrochemical measurement, and scanning electronic microscope (SEM) analysis. Quantum chemistry calculation results showed that nicotinic acid possessed planar structure with a number of active centers, and the populations of the Mulliken charge, the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) were found mainly focused around oxygen and nitrogen atoms, and the cyclic of the benzene as well. The results of weight loss test and electrochemical measurement indicated that inhibition efficiency (IE%) increased with inhibitor concentration, and the highest inhibition efficiency was up to 96.7%. The corrosion inhibition of these coatings was discussed in terms of blocking the electrode reaction by adsorption of the molecules at the active centers on the electrode surface. It was found that the adsorption of nicotinic acid on coating surface followed Langmuir adsorption isotherm with single molecular layer, and nicotinic acid adsorbed on the coating surface probably by chemisorption. Nicotinic acid, therefore, can act as a good nontoxic corrosion inhibitor for hot dipped Zn and Zn-Al alloy coatings in diluted hydrochloric acid solution.     

Corrosion inhibition of copper by heterocyclic compounds

The corrosion inhibition of copper in aerated 0.5 M H₂SO₄ solution in presence of two classes of heterocyclic compounds, namely phenylazo-pyrazolones (PAP) or hydroxy quinoline and bromobenzyl-carboxy-1,2,3 triazole (BCT) derivatives was studied. The corrosion parameters were obtained at different inhibitor concentrations and the temperature effect was also investigated. The corrosion rate of copper was determined; using Tafel method and the polarization resistance (R_p) technique. The electrolyte solution was analysed using cyclic voltammetry and UV-visible spectroscopy. The results were compared with that of some prepared Cu-complexes in order to explain the inhibition mechanism. Moreover, the thermodynamic activation parameters of the Cu-corrosion reaction were calculated and discussed in relation to the stability of the protective layer. The inhibition effect was attributed to the adsorption of the dye molecules, the precipitation of Cu-chelates and/or formation of π-complexes at the electrode surface.     

Corrosion behaviour of different hot rolled steels

The oxidation-corrosion behaviour of hot rolled alloys was examined by electrochemical impedance spectroscopy. The corrosion behaviour of the non-oxidised alloys was first determined in order to have a reference behaviour. Then, each alloy was oxidised for 1 and 3 days at 650 °C in air and its corrosion behaviour was also determined. For all the alloys, Fe₂O₃ was formed at the scale-gas interface. However, the Fe₂O₃ crystallographic structures varied as a function of the alloy composition. Differences in the corrosion behaviour are due to the thickness, the microstructure and the porosity of the scale. The new graphite chromium iron alloy (Hi-Cr + C) have an oxidation-corrosion behaviour close to the indefinite chill double paired (ICDP) one and is therefore thought to be a good candidate to replace the ICPD alloy. In the case of the high speed steel (HSS) alloy, the oxidation-corrosion kinetics are too slow to prevent sticking problems. The Co addition decreases the corrosion-oxidation rates for the non-oxidised and oxidised samples but this effect is limited in time.     

木薯淀粉接枝共聚物在HCl溶液中对Al的缓蚀性能研究

采用失重法、开路电位 (OCP)-时间曲线、动电位极化曲线、电化学阻抗谱 (EIS) 和扫描电子显微镜 (SEM) 研究了木薯淀粉接枝共聚物 (CSGC) 在1.0 mol/L HCl溶液中对Al的缓蚀性能。结果表明：CSGC对Al具有良好的缓蚀作用,当用量仅为50 mg/L时缓蚀率可高达90%以上,且在铝表面的吸附符合Langmuir吸附等温式;极化曲线表明CSGC为抑制阴极为主的混合抑制型缓蚀剂;EIS谱在高频区呈容抗弧,在低频区亦出现大段感抗弧,阻抗值随缓蚀剂浓度的增加而增大。SEM表明添加CSGC后Al表面的腐蚀程度会显著降低。     

Corrosion inhibition by anionic surfactants of AA2198 Li-containing aluminium alloy in chloride solutions

This paper evaluates the inhibiting action of some anionic surfactants towards AA2198 corrosion in NaCl solutions; the effect of surfactant concentration in relation to chloride amount was determined.On separate electrodes, polarization curves were recorded after 1, 24 and 168 h immersion in the aggressive media, while EIS technique continuously monitored the alloy corrosion process.In general, these substances stifled both the cathodic and anodic processes and noticeably shifted the pitting potential (breakdown potential, E_BR) in the positive direction. The most efficient compounds were N-lauroylsarcosine sodium salt and sodium dodecyl-benzenesulfonate, able to withstand the effects of 0.1 M Cl⁻.     

Corrosion resistance of painted zinc alloy coated steels

Organic coating in combination with sacrificial metal coating is the most popular method of protecting steel strips against atmospheric corrosion. Experiences over the years have proven that such duplex coating systems are best suited for the coil industry for the long term corrosion protection of steel. The excellent corrosion resistance of such systems has been attributed to the synergy between the cathodic protection provided by the sacrificial coating of zinc alloys and the combined barrier resistance of the metal and organic coatings. Traditionally continuously hot dip zinc-coated steels are used for such applications. However, off late the quest for further extending the longevity of the coil coatings has led to the replacement of the zinc coating with a host of other hot dip zinc–aluminium alloy coatings such as Galvalume^®, Galfan^®, ZAM^®, SuperDyma^®, etc. Each of these metal coatings has its own unique metallurgical features in terms of flexibility, bonding, microstructure and electrochemical characteristics which may significantly influence the performance of the organic coatings applied over it. This paper looks into the various aspects of these features of the hot dip coatings on the corrosion performance of the pre-painted steel strips. For simplicity only polyester paint system, the work horse of the coil industry, is considered.     

Corrosion inhibition of carbon and low alloy steels in sulphuric acid solutions by 2-mercaptopyrimidine derivatives

Several derivatives of 2-mercaptopyrimidine (containing -OH, -SH, -NH₂ or -CH₃ substituents) have been studied as corrosion inhibitors of ARMCO iron and low alloy steels in 1 M sulphuric acid solutions. Tests have been conducted during 6 h in the temperature interval between 60 and 90°C. The trends of the corrosion rates as a function of time have been determined by polarisation resistance measurements and analytical determinations of dissolved iron. 2-mercaptopyrimidine, 2,4-dimercaptopyrimidine and 2-mercap-to-4-methylpyrimidine showed the most satisfactory action, reaching efficiencies of 98% on ARMCO iron at 90°C. The presence of Cr and Mo in the alloys exerted a negative influence on the efficiency of pyrimidine derivatives, by diminishing their action at 90°C. A tentative interpretation of the action mechanisms of the additives has been given on the basis of their molecular characteristics.     

柚子皮提取物对热轧碳钢在HCl 溶液中的缓蚀作用研究

采用加热回流萃取法从柚子皮中提取天然缓蚀剂,并采用失重法和极化曲线法测试了提取物在30 ~50 ℃温度范围内,对热轧碳钢在2 mol/ L HCl 介质中的缓蚀性能。失重法测试结果表明,柚子皮提取物对热轧碳钢有良好的缓蚀作用,缓蚀效率随着温度的升高和缓蚀剂浓度的增加而增大,50 ℃时,最大缓蚀效率达到78. 4%。提取物在热轧碳钢表面的吸附作用符合Langmuir 吸附模型,以物理吸附为主。极化曲线测试结果表明,柚子皮提取物主要抑制热轧碳钢腐蚀反应的阴极过程,属于混合型缓蚀剂。     

Corrosion inhibition of mild steel by plant extract in dilute HCl medium

The inhibition effect of Zenthoxylum alatum plant extract on the corrosion of mild steel in 5% and 15% aqueous hydrochloric acid solution has been investigated by weight loss and electrochemical impedance spectroscopy (EIS). The corrosion inhibition efficiency increases on increasing plant extract concentration till 2400 ppm. The effect of temperature on the corrosion behaviour of mild steel in 5% and 15% HCl with addition of plant extract was studied in the temperature range 50-80 °C. Surface analysis (SEM, XPS and FT-IR) was also carried out to establish the corrosion inhibitive property of this plant extract in HCl solution. Plant extract is able to reduce the corrosion of steel more effectively in 5% HCl than in 15% HCl. The adsorption of this plant extract on the mild steel surface obeys the Langmuir adsorption isotherm.