苯甲酸钠对AM60镁合金在氯化钠溶液中的缓蚀作用

为了改善AM60镁合金的抗腐蚀性能,通过电化学阻抗、极化曲线和浸泡等方法研究了苯甲酸钠(SB)对AM60镁合金在3.5%氯化钠溶液中的缓蚀作用,并考察了温度对缓蚀率的作用规律,借助扫描电镜观察了不同温度和不同SB浓度下镁合金腐蚀后的表面形貌,分析了SB的缓蚀机制。结果表明:SB明显减缓了AM60镁合金的腐蚀速率,当其浓度为0.5 mol·L^-1时,缓蚀率达到75%以上,这主要是因为SB在AM60镁合金表面发生了物理吸附,这种吸附为放热、熵增的自发过程,形成的多分子吸附层隔离了镁合金和腐蚀介质的直接接触。随着SB浓度增加,镁合金腐蚀反应活化能增大,缓蚀率随之而增大。当SB浓度增大到0.7 mol·L^-1以后,由于分子间排斥作用占主导作用,导致缓蚀率没有明显增加,且随着温度从25℃升高到70℃,SB的缓蚀率略有下降。     

麻竹竹叶提取物对铝在HNO_3介质中的缓蚀性能

用失重法、电化学法和扫面电子显微镜(SEM)研究了麻竹(Dendrocalmus latifcorus Munro)竹叶提取物(DLMLE)在1.0 mol/L HNO3溶液中对铝的缓蚀作用。结果表明:DLMLE对铝的缓蚀性能随缓蚀剂浓度的增加而增大,且在铝表面的吸附符合Langmuir吸附等温式,标准吸附Gibbs自由能(ΔG°)表明DLMLE在铝表面的吸附为包含物理吸附和化学吸附的混合吸附。动电位极化曲线表明,DLMLE为混合抑制型缓蚀剂;EIS谱呈半圆容抗弧,添加DLMLE后电荷转移电阻随缓蚀剂浓度的增加而增大。SEM表明DLMLE对铝在HNO3中的腐蚀产生抑制作用。     

离子液体在甲醇/硫酸介质中对Q235钢表面的缓蚀性能

探究硫酸存在时Q235钢在甲醇中的腐蚀行为,以及离子液体1-丁基-3-甲基咪唑氯盐（[Bmim]Cl）对金属表面的缓蚀作用。通过静态失重法、电化学测试、扫描电子显微镜来测定[Bmim]Cl对Q235钢的缓蚀性能。并利用量子化学计算和分子动力学模拟分析[Bmim]Cl分子的缓蚀机理。在甲醇中随着硫酸含量的增加碳钢的腐蚀速率增加。含有59.51 ml 0.05 mol·L^-1 H₂SO₄的甲醇溶液作为腐蚀介质时,随着[Bmim]Cl浓度升高,缓蚀效率逐渐增大,当浓度为0.6 mol·L^-1时,缓蚀效率达到最佳值,为90.63%,且[Bmim]Cl是主要控制阳极反应的混合抑制剂,SEM分析表明在含有缓蚀剂溶液中浸泡后的Q235钢表面相对于未加缓蚀剂更加平整。前线轨道分析和Fukui指数都表明,离子液体在碳钢表面的吸附位点分布在咪唑环上,与Fe发生化学吸附。分子动力学模拟结果表明缓蚀剂分子以阳离子[Bmim]⁺平行吸附于金属表面,阴离子Cl^-扩散在溶液中的方式达到缓蚀的效果。理论计算结果与实验结果一致,即[Bmim]Cl在甲醇/硫酸水溶液中对Q235钢具有很好的缓蚀作用,为新型离子液体缓蚀剂研究应用奠定了基础。     

月桂酸咪唑啉硫酸酯盐缓蚀剂在A3钢表面吸附成膜行为

采用失重法、接触角测试、原子力显微镜和X射线光电子能谱等分析方法研究了实验室自制月桂酸咪唑啉硫酸酯盐缓蚀剂(LIMS)在盐酸溶液中对A3钢的缓蚀吸附行为,同时探讨了LIMS在A3钢表面的成膜行为和作用机理。结果表明,月桂酸咪唑啉硫酸酯盐缓蚀剂LIMS分子可以明显抑制A3钢在盐酸溶液中的腐蚀,随着盐酸溶液中LIMS质量浓度的增加,缓蚀率增加。当LIMS质量浓度为800mg/L时,在298~318K温度范围内缓蚀效果良好,缓蚀率可达90%以上。LIMS可在金属表面形成一层吸附膜,这种吸附膜来源于长链烷基在金属表面形成的疏水薄膜和N、S、O与金属表面的强烈作用,成膜试片表面的接触角随着缓蚀剂质量浓度的增加而增大,接触角可达103.51°,接触角增大,吸附膜作用增强,致密性越好。     

十六烷基三甲基溴化铵在盐酸介质中对锌的缓蚀作用

采用失重法研究了3%盐酸介质中十六烷基三甲基溴化铵对金属锌的缓蚀作用。结果表明,该缓蚀剂对锌的腐蚀有良好的抑制作用,且随缓蚀剂质量浓度的增大,缓蚀作用加强。当其质量浓度达到一定值时,缓蚀作用基本保持不变。该物质在锌表面产生单分子层吸附,并且满足Langmuir吸附规律:吸附过程为放热过程;随着温度的升高,吸附能力减弱,缓蚀效率下降。     

在盐酸溶液中[HMIM]BF_4对70高碳钢的缓蚀作用和吸附行为

合成了咪唑类离子液体1-己基-3-甲基咪唑四氟硼酸盐([HMIM]BF_4),采用失重法与电化学方法研究了在1 mol/L HCl溶液中对高碳钢(70钢)的缓蚀性能、吸附行为及缓蚀机理。结果表明,[HMIM]BF_4具有明显的缓蚀作用,属于混合型缓蚀剂,缓蚀效率随着浓度的增加而增大,随着温度升高而下降。该离子液体在碳钢表面的吸附反应为自发放热过程,且该吸附符合Langmuir吸附等温式,属于同时具有物理吸附和化学吸附的混合吸附。     

中性红在盐酸溶液中对冷轧钢的缓蚀作用

用失重法和动电位极化曲线法研究了酸碱指示剂中性红对冷轧钢在1.0～8.0 mol/LHCl溶液中的缓蚀作用.结果表明:中性红对冷轧钢在1.0 moL/L HCl溶液中具有良好的缓蚀作用,为混合抑制型缓蚀剂,且在钢表面的吸附符合校正的Langmuir吸附等温式,缓蚀率随缓蚀剂浓度的增加而增大,但随温度和盐酸浓度的增加而减小.通过吸附理论求出了相应的吸附热力学(吸附自由能△G°,吸附热△H°,吸附熵△S°)和动力学参数(腐蚀速度常数k,腐蚀动力学常数B),并根据这些参数讨论了缓蚀作用机理.     

HCl溶液中吐温-40对热轧碳钢缓蚀作用的研究

剂吐温-40对热轧碳钢在盐酸溶液中的缓蚀行为,从缓蚀剂质量浓度、温度等方面考察其对缓蚀性能的影响。研究结果表明,在HCl溶液中,吐温-40对热轧碳钢具有良好的缓蚀作用,缓蚀效率随缓蚀剂质量浓度的增加而增大,最高达到87.4%。吐温-40在热轧碳钢表面的吸附行为符合Langmuir公式,是伴随着熵减少的自发放热过程。通过Mathur经验公式求出了热轧碳钢的腐蚀反应动力学参数,并讨论了吐温-40的缓蚀机制。     

水葫芦叶提取物对冷轧钢在H_2SO_4溶液中的缓蚀作用

采用失重法研究了水葫芦(Eichhornia Crassipes)叶提取物(ECLE)对冷轧钢在0.1~0.5 mol/L H_2SO_4溶液中的缓蚀性能。结果表明:ECLE对冷轧钢在0.1 mol/L H2SO4溶液中具有良好的缓蚀作用,缓蚀率随缓蚀剂浓度的增加而增大。各温度下的缓蚀率大致排序为:40℃30℃50℃25℃。ECLE在钢表面的吸附符合Langmuir吸附等温式,其吸附过程为含有物理吸附和化学吸附的混合吸附过程。冷轧钢在添加ECLE前、后的H2SO4溶液中的腐蚀速率随酸浓度的变化均符合Mathur经验公式;添加ECLE后腐蚀速率常数降低,但腐蚀反应动力学参数升高。     

叶酸对钢在盐酸中的缓蚀作用

用失重法研究叶酸对冷轧钢在盐酸中的缓蚀作用,根据Ⅰ Sekine的方法,讨论了盐酸介质中叶酸在钢表面的吸附行为。结果表明：叶酸是冷轧钢在盐酸中的有效缓蚀剂,缓蚀效率随着缓蚀剂浓度增加而增大,随着温度升高而降低,叶酸是一种吸附型的缓蚀剂,其在钢表面吸附服从Langmuir吸附等温式。根据P.B.Mathur.的处理方法,得到不加和加缓蚀剂时冷轧钢在盐酸中腐蚀的表观热力学和表观动力学参数;从得到加和不加缓蚀剂的表观动力学参数,也能说明叶酸对钢在盐酸中有较好的缓蚀作用,和实验得到的结果相一致。     

THE EFFECT OF ENVIRONMENTALLY BENIGN FRUIT EXTRACT OF SHAHJAN (MORINGA OLEIFERA) ON THE CORROSION OF MILD STEEL IN HYDROCHLORIC ACID SOLUTION

The inhibition of the corrosion of mild steel in hydrochloric acid solution by the fruit extract of shahjan (Moringa oleifera) was studied using weight loss, electrochemical impedance spectroscopy (EIS), linear polarization, and potentiodynamic polarization techniques (Tafel). Inhibition was found to increase with increasing concentration of the extract. The effect of temperature, immersion time, and acid concentration on the corrosion behavior of mild steel in hydrochloric acid solutions with addition of extract was also studied. The inhibition occurred via adsorption of the inhibitor molecules on the mild steel surface obeying the Langmuir adsorption isotherm. Thermodynamic activation parameters such as activation energy, enthalpy (ΔH*), and entropy (ΔS*) of activation for corrosion process were calculated and discussed. The results obtained show that both chemical and physical adsorption of inhibitor molecules occur simultaneously and the fruit extract of shahjan (Moringa oleifera) could serve as an effective inhibitor of the corrosion of mild steel in hydrochloric acid media.     

The inhibitive action of dimethyltin dichloride towards the corrosion of aluminium in hydrochloric acid and sodium hydroxide solutions

The dissolution of aluminium in hydrochloric acid and sodium hydroxide solutions in the presence of dimethyltin dichloride as corrosion inhibitor has been studied using hydrogen evolution and thermometric methods. The two methods gave consistent results. The higher inhibition efficiency of this compound in acidic than in alkaline media may be due to the less negative potential of aluminium in hydrochloric acid solution, favouring adsorption of the additive. The adsorption of this compound was found to obey Frumkin adsorption isotherm.     

Inhibition by <Emphasis Type="Italic">Jasminum nudiflorum</Emphasis> Lindl. leaves extract of the corrosion of cold rolled steel in hydrochloric acid solution

The inhibition effect of Jasminum nudiflorum Lindl. leaves extract (JNLLE) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) was investigated by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) methods. The results show that JNLLE acts as a very good inhibitor, and the inhibition efficiency increases with the concentration of JNLLE. The adsorption of JNLLE obeys Langmuir adsorption isotherm. Values of inhibition efficiency obtained from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) are in good agreement. Polarization curves show that JNLLE behaves as a mixed-type inhibitor in hydrochloric acid. EIS shows that charge-transfer resistance increase and the capacitance of double layer decreases with the inhibitor concentration, confirming the adsorption process mechanism. The adsorbed film on CRS surface containing JNLLE inhibitor was also measured by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). A probable inhibitive mechanism is proposed from the viewpoint of adsorption theory.     

硫脲基松香咪唑啉季铵盐 对A3碳钢的缓蚀性能研究

合成了硫脲基松香咪唑啉季铵盐,对其结构进行了红外和核磁表征。采用失重法、动电位极化曲线、交流阻抗以及接触角测试分析了目标产物在质量分数为15%HCl溶液中对A3碳钢的缓蚀性能。采用AFM以及XPS测试对产物的吸附膜进行了表征。结果表明：目标产物的缓蚀效率随添加质量分数的增加先增大后减小,当目标产物质量分数增加到占盐酸质量的0.4%时,缓蚀效率最高达到90.78%;此物质是一种阴极控制为主的混合型缓蚀剂;AFM以及XPS结果证实目标产物确实可以在碳钢表面形成缓蚀剂吸附膜。     

天然缓蚀剂对碳钢在盐酸液中缓蚀性能的研究

分别用浸泡水解法、加热回流法从油菜籽中提取天然缓蚀剂,研究各种方法的提取物在室温下酸性介质中对A3钢的缓蚀性能。实验结果表明,两种方法所得植物缓蚀剂均属于阴极抑制为主的混合型缓蚀剂,其中直接浸泡法提取的缓蚀剂因为氨基酸含量最高,因此缓蚀效果最好,缓蚀率最高可达91.91%。     

The application of electrochemical impedance techniques to aluminium corrosion in acidic chloride solution

Electrochemical impedance techniques are applied to the study of aluminium corrosion in hydrochloric acid solution in the passive region. Impedance spectra are obtained in stationary solution and in solution moving due to electrode rotation. The form of the spectra shows the importance of multistep dissolution, ionic migration through the oxide layer, relaxation effects and the influence of chloride ion.     

镧(Ⅲ)离子和非离子表面活性剂对铝的缓蚀协合效应

用失重法研究了在盐酸介质中 ,稀土镧 ( )离子对铝腐蚀速度的影响以及L a3 和非离子表面活性剂聚乙二醇辛基苯基醚 ( OP)对铝的缓蚀协合效应 ,发现L a3 对铝有较强的增蚀作用 ,而 La3 和 OP则表现出显著的缓蚀协合作用     

Humic Acid from Livestock Dung: Ecofriendly Corrosion Inhibitor for 3SR Aluminum Alloy in Alkaline Medium

Humic acids (HAs) extracted from cow, goat, and poultry dung were studied. Extraction was performed by treating the source materials with acid hydrolysis using hydrochloric acid (HCl) before alkaline extraction with sodium hydroxide (NaOH). Yields of 3.33, 2.67, and 1.28% dry weight were obtained from cow, goat, and poultry dung respectively. The extracted humic acids were characterized using Fourier transform-infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopy techniques. The results obtained were in good agreement with commercial HA (Sigma-Aldrich). The humic acid extracted from cow dung was used to evaluate its corrosion inhibition potential for alkaline-induced corrosion of 3SR aluminum alloy using weight loss and electrochemical (potentiodynamic polarization) techniques at 30°–60°C. Results obtained show that the humic acid functions as an excellent corrosion inhibitor for aluminum alloy in 0.1 M NaOH solution. Corrosion inhibition efficiency increased with increase in humic acid concentration but decreased with rise in temperature. Results from potentiodynamic polarization measurements show that the HA behaved mostly as a mixed-type inhibitor. Adsorption of the humic acid was found to obey the Langmuir adsorption isotherm at all concentrations and temperatures studied. The mechanism of physical adsorption has been proposed based on the trend of inhibition efficiency with temperature. The proposed mechanism was also corroborated by kinetic and thermodynamic parameters obtained.     

Corrosion protection of aluminium in acidic chloride solutions with nontoxic inhibitors

Corrosion kinetics of 99.6% aluminium covered by a thin spontaneously formed oxide film in hydrochloric acid solution with and without the presence of substituted N-aryl pyrroles was studied using electrochemical impedance spectroscopy and quasi steady-state polarization. Measurements were performed on a rotating disc electrode in an argon-deaerated solution in the temperature range 20 to 50°C. The addition of inhibitor considerably increases overvoltage of the cathodic process (HER) and shifts Ecorr to negative potential values. The activation energy of the hydrogen evolution reaction was Ea=50±5kJmol–1 and was not affected by the presence of inhibitor. The inhibitory action occurs by -bonding between the adsorbed inhibitor molecules and the electrode surface. The electrode coverage follows the Langmuir adsorption isotherm with an adsorption equilibrium constant K=1.1–2.64×105dm3mol–1. The adsorption of organic compound prevents the adsorption of chloride ions and slow down the rate of corrosion.     

The study of aluminium corrosion in acidic solution with nontoxic inhibitors

The inhibitory activity of some substituted N-arylpyrroles on aluminium corrosion in hydrochloric acid was studied in relation to inhibitor concentration, using potentiodynamic and impedance spectroscopy techniques. All investigated compounds were found to act as cathodic-type inhibitors and inhibition was ascribed to the adsorption of inhibitor onto the electrode surface. The inhibiting efficiency of the additives depended on the inductive power of the groups attached to the benzene and/or pyrrole ring. The carbaldehyde group showed better inhibiting power due to additional condensation on the electrode surface. The impedance results analysed in terms of the polarization resistance showed that the EIS technique can be successfully applied in the determination of corrosion resistance in systems where the corrosion kinetics are not simple.