Experimental and Theoretical Evaluation of Rutin as Eco-Friendly Corrosion Inhibitor for Aluminum 6063 Alloy in Acidic Medium

The corrosion inhibition characteristics of rutin a natural flavonoid glycoside has been studied as an eco-friendly green inhibitor for corrosion control of aluminum alloy AA6063 in 0.5 M HCl medium at a temperature range of 30–60 °C by weight loss method, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) techniques. The inhibition efficiency increased with the increase in concentration of the inhibitor and also with increase in temperature. The surface morphologies of the polished, corroded and inhibited surfaces were scanned using the scanning electron microscope images. The activation parameters like energy of activation, enthalpy of activation and entropy of activation were calculated and analyzed. Thermodynamic parameters for the adsorption of the inhibitor on the metal alloy surface were calculated and analyzed. The inhibitor acted as a mixed inhibitor. The mechanism of adsorption deduced from the variation of inhibition efficiency with temperature as well as kinetic and activation parameters suggests significant chemisorption of the inhibitor on the metal surface. The mechanism of inhibition can partly be attributed to the possible coordination of rutin to form stable aluminum–rutin complex. The maximum inhibition efficiency was found to be 95.1 and 94.45% by PDP and EIS studies, respectively, at 60 °C. Density functional theory calculations under the level B3LYP/6-311G(d) is utilized for the calculation of quantum chemical parameters.     

Nondestructive evaluation of corrosion by fractal geometry

Fractal geometry is finding its application in the nondestructive evaluation (NDE) of corrosion by characterizing the corrosion surface with fractal dimensions. It was found that corrosion surfaces can be well described by multifractals. Two algorithms were used to obtain the fractal dimensions of a corroded aluminum alloy surface, one being box-counting and another being coherent light scattering. Fractal dimensions were related with the damage caused by corrosion and fatigue.     

高压对高功率脉冲磁控放电等离子体注入与沉积氧化钒薄膜的影响

利用高功率脉冲磁控放电等离子体注入与沉积技术制备了氧化钒薄膜,分别采用X射线衍射仪、原子力显微镜、扫描电子显微镜和电化学分析仪研究了不同高压幅值对氧化钒薄膜的相结构、表面形貌、截面形貌以及耐腐蚀性能的影响。结果表明制备的氧化钒薄膜以VO2(-211)相为主,还含有少量的VO2(111)、VO(220)、VO(222)相。不同高压下氧化钒薄膜表面致密、平整,其表面粗糙度仅为几个纳米,显示出良好的表面质量。氧化钒薄膜表现出典型致密的柱状晶生长形貌,且随着高压增加,氧化钒薄膜膜层厚度有所下降。氧化钒薄膜耐腐蚀性能较纯铝基体有较大提高,腐蚀电位提高0.093V,腐蚀电流下降1～2个数量级;当高压为-15kV时,氧化钒薄膜腐蚀电位最高,腐蚀电流最低,表现出最佳的耐蚀性能。     

Nondestructive Evaluation of Corrosion by Fractal Geometry

Abstract

Fractal geometry is finding its application in the nondestructive evaluation (NDE) of corrosion by characterizing the corrosion surface with fractal dimensions. It was found that corrosion surfaces can be well described by multifractals. Two algorithms were used to obtain the fractal dimensions of a corroded aluminum alloy surface, one being box-counting and another being coherent light scattering. Fractal dimensions were related with the damage caused by corrosion and fatigue.     

Surface Protection and Morphological Study of Copper by Green Corrosion Inhibitor: 8QSC in HNO<Subscript>3</Subscript> Medium

The inhibition performance and surface protection of green corrosion inhibitor 8-quinoline sulphonyl chloride (8QSC) on copper (Cu) was evaluated by chemical (weight loss) method in 0.5, 1.0 and 2.0 M HNO₃ solutions and by electrochemical methods such as potentiodynamic polarization (PDP), AC-impedance spectroscopy (AC-IS) and linear polarization resistance in 1.0 M HNO₃ solution at room temperature. Both chemical and electrochemical techniques showed that 8QSC is an efficient green corrosion inhibitor for copper and the efficiency reached 90.4% by weight loss method and 88.4% by AC-IS method at optimum concentration of (300 ppm) 8QSC. The adsorption behavior of 8QSC on copper metal in acid medium obeyed the Langmuir isotherm. The thermodynamic parameters of the adsorption processes were calculated and discussed. AC-IS technique exhibits one capacitive loop, indicating that the corrosion reaction was controlled by charge transfer process. The PDP curves revealed that 8QSC acts as a mixed-type inhibitor. Protective layer of 8QSC on copper surface was examined by SEM, AFM and FT-IR techniques. The experimental results corroborated with results obtained from theoretical DFT studies.     

聚酯镀铝膜的湿热老化机理

针对聚酯(PET)镀铝膜在湿热条件下表面腐蚀脱落的现象及其随老化时间的变化规律,分别从物理老化和化学老化角度研究了PET本体膜在湿热条件下的玻璃化转变、熔融行为、特征基团以及相对分子质量的变化。结果表明,PET本体膜物理老化显著,玻璃化转变温度在不同湿热条件下随老化时间出现不同程度的上升;而化学老化,即相对分子质量和特征基团(酯基)的变化并不明显。湿度是影响镀铝层腐蚀脱落的主要原因,而与温度相关的PET本体膜自身老化无关。扫描电镜结果显示,镀铝层腐蚀首先发生在缺陷部位,并形成腐蚀坑。通过光谱分析检测聚酯镀铝膜水热老化后铝离子浓度的变化,进一步证实铝层脱落的主要原因是铝在水热的作用下发生腐蚀。     

包铝层和氧化时间对2E12铝合金硫酸阳极氧化及膜层性能的影响

对保留表面包铝和去除包铝的2E12-T3铝合金采用硫酸阳极氧化处理工艺,研究了包铝层和氧化时间对铝合金阳极氧化行为及膜层耐蚀性的影响。采用扫描电子显微镜观察氧化膜的表面以及截面形貌,应用动电位扫描极化曲线和电化学阻抗谱对膜层的电化学性能进行分析。结果表明:两种铝合金表面均能形成具有防护性能的阳极氧化膜,膜层随氧化时间延长而增厚。富铜的第二相颗粒会使得不带包铝的2E12铝合金氧化膜具有更多孔洞缺陷,甚至出现微裂纹。保留包铝的2E12铝合金表面氧化膜更厚,孔洞缺陷少,耐蚀性更好。阳极氧化30min和45min的2E12铝合金阳极氧化膜具有较低的腐蚀电流和较高的多孔层阻抗,耐蚀性好。     

Surface-enhanced vibrational microspectroscopy of fulvic acid micelles

Micro-Raman spectroscopy, infrared absorption microspectroscopy, and AFM images of nano- or microsized micelles formed by fulvic acid (FA) solutions, prepared at different pHs, and cast on glass slides or gold island films, are reported. FA films cast on gold islands are characterized by surface-enhanced infrared absorption (SEIRA), surface-enhanced infrared reflection absorption, and surface-enhanced Raman scattering (SERS). Based on spectral evidence, it is expected that the chemisorption of FA on gold island films takes place through thiol groups, which become more active as pH increases. The SEIRA spectra of these films show increased peak intensity, as well as improved band resolution. Microspectroscopy SERS studies show that, at pH 5, FA form small aggregates on gold surfaces. At pH 8, FA tends to expand due to electrostatic repulsion, giving rise to a fractal surface composed of different domains. SERS studies of these domains reveal that the most polar molecules are located on the external faces. At pH 11, fractal conformations are even more pronounced and give rise to radial patterned structures. At this pH, the position of fulvic acid molecules in the fractal micelles is the same as observed at pH 8. In this way, SERS can be viewed as a powerful tool for the analysis of the composition, apparent contribution of the surface functional groups of FA films, and the FA building blocks (i.e., catechol, gallic, salicylic, or ftalic acids) in the structures of these materials.     

草酸阳极氧化法制备铝合金氧化膜及其防腐蚀性能

为了改进铝合金的防护性能,扩展铝合金应用范围,需要对铝合金进行表面处理。利用草酸电解液阳极氧化法在2A12铝合金表面制备了一层氧化膜,通过扫描电子显微镜(SEM)、X射线光电子能谱(XPS)、X射线衍射仪(XRD)、原子力显微镜(AFM)等手段分析其表面形貌、组织结构、物相和表面粗糙度。微观表征结果表明,阳极氧化法能使铝基体表面生成非晶态的氧化铝薄膜,并且该薄膜是多孔结构,具有优异的屏蔽作用。利用电化学方法、中性盐雾试验评价了阳极氧化膜的防腐蚀性能,证实了阳极氧化后铝合金的防腐蚀性能优于铝合金基体。     

PAA与PBTCA对CaCO3显微结构的影响

利用扫描电镜(ＳＥＭ)和原子力显微镜(ＡＦＭ)研究了分散剂ＰＡＡ与ＰＢＴＣＡ对ＣａＣＯ _３显微结构的影响．结果表明,与ＰＡＡ相比,ＰＢＴＣＡ对ＣａＣＯ_３的沉积形貌具有更大的影响．ＳＥＭ表明,在两种分散剂的存在下,沉积物的形貌皆发生了变化,随着阻滞影响增大,沉积物晶型畸变程度随之严重,沉积物形貌的分维值也随之增大．ＸＲＤ分析表明,随着阻滞影响增大,ＣａＣＯ_３晶相中球霰石的含量增大．在分散剂存在下,热力学上属亚稳态的文石和球霰石从动力学上被稳定住了．ＡＦＭ研究表明,随着阻滞影响增大,ＣａＣＯ_３晶体表面上台阶间距变大．同时,发现了ＣａＣＯ_３晶体表面台阶的聚并现象并进行了讨论．     

PAA与PBTCA对CaCO3显微结构的影响

利用扫描电镜（SEM）和原子力显微镜（AFM）研究了分散剂PAA与PBTCA对CaCO3显微结构的影响，结果表明，与PAA相比，PBTCA对CaCO3的沉积形貌具有更大的影响，SEM表明，在两种分散剂存在下，沉积物的形貌皆发生了变化，随着阻滞剂影响增大，沉积物晶型畸变程度随之严重，沉积物的形貌的分维值也随之增大，XRD分析表明，随着阻滞影响增大，CaCO3晶相中球霰石的含量增大，在分散剂存在下，热力学上属亚稳态的文石和球霰石从动力学上被稳定住了，AFM研究表明，随着阻滞影响增大，CaCO3晶体表面上台阶间距变大，同时，发现了CaCO3晶体表面台阶的聚并现象并进行了讨论。     

Thickness-stress relations in aluminum thin films

The physical properties of aluminum thin films depend strongly on their microstructure, which can be characterized using different techniques. In the present work, aluminum thin films—grown with different thickness on silicon substrates—were analyzed by atomic force microscopy (AFM) and grazing incidence x-ray techniques. The AFM was used as a high-resolution profilemeter for measuring edge angles, step heights, surface microstructure, and roughness. The structural properties (such as crystallographic orientation, crystallite size, and phase identification) were analyzed by grazing incidence x-ray diffraction. For small thickness, AFM images show small nucleation sites because of the short time of growth. Grain size grows as the thickness increases, and film morphology seems to be uniform with large grains. The AFM results of as-grown films show a linear increase in roughness along with thickness. Roughness values decrease with aging time after film preparation, until a constant value is observed. All films mainly have (111) orientation, and its intensity grows with film thickness, with respect to the (200) and (220) peaks. As the film thickness increases, the surface stress decreases.     

A green and effective corrosion inhibitor of functionalized carbon dots

In this work, a green and effective corrosion inhibitor of functionalized carbon dots (FCDs) was synthesized by the conjugation of imidazole and citric acid carbon dots (CA-CDs). The corrosion inhibition behavior of FCDs for Q235 steel in 1 M HCl solution was systematically investigated by electrochemical analysis, corrosion morphology and adsorption isotherm. The electrochemical results implied that the as-prepared FCDs inhibitor could effectively suppress the corrosion of Q235 steel in 1 M HCl solution. At the same time, the inhibition efficiency of steel in 1 M HCl solution was more than 90% when the inhibitor concentration exceeded 100 mg/L. This excellent property was attributed to the coverage of adsorption film on the steel surface, which conformed to the Langmuir adsorption model. In addition, the analysis of adsorption isotherm displayed that the adsorption mechanism was the physicochemical interaction at the steel/solution interface.     

Deposition and corrosion behavior of silicate conversion coatings on aluminum alloy 2024

Potassium silicate was deposited on AA2024 aluminum alloy as environmentally friendly conversion coatings and its corrosion behavior were examined by means of electrochemical impedance spectroscopy, potentiodynamic polarization and surfaces techniques. Potentiodynamic polarization curves show significant decrease in corrosion current density of silicate coated aluminum in NaCl solution. The corrosion resistance was increased with increasing silicate concentration of coating baths. The results indicated that the coating applied from 3 molar silicate baths is more uniform and continuous. The X‐ray diffraction (XRD) and energy discharge spectroscopy (EDS) spectra confirm the existence of silicate film on the AA2024 surface. The coating performance was evaluated in acidic and basic NaCl solution and the results show the stability of silicate conversion coating in these solutions.     

Copper nucleation and growth during the corrosion of aluminum alloy 2524 in sodium chloride solutions

Copper clusters, as nodules and micro dendritic masses, were observed to nucleate and grow on Al 2524 surfaces after corrosion immersion experiments for up to 5 days in 0.6 M NaCl solutions; with pH values ranging from 3 to 11. Cu clusters observed by SEM on the corroded surfaces and confirmed by EDX analysis were extracted or stripped from their original sites and examined in detail utilizing TEM and EDX spectrometry. These observations confirm a mechanism contributing to pitting corrosion in copper-rich aluminum alloys involving the plating or cementation of Cu²⁺ from solution as an electrochemical displacement reaction, resulting in nucleation and growth of Cu clusters on the aluminum alloy surface, and causing additional aluminum dissolution and pitting around the Cu deposits.     

The Inhibitive Action of Castor Seed Oil Toward the Corrosion of Aluminum in Saline Medium

Corrosion of metal is a costly material science problem which originates from the day of metal discovery. Corrosion inhibitor usage is an effective way of addressing metallic corrosion in aggressive environments but continued usage of synthetic chemicals for inhibiting corrosion is indefensible as a result of toxicity of the chemicals to the environmental ecosystem. Eco-friendly corrosion inhibiting alternatives are therefore needed. In view of this, castor seed oil was evaluated as anti-corrosion protection of aluminum surfaces in saline medium using weight loss and potentiodynamic polarization methods at 304 K. The obtained results show that castor seed oil on aluminum in saline medium decreased the corrosion rate at different concentrations studied. Inhibitor efficiency (IE) of 85.19% at 0.5 g/L and 41.16% at 0.1 g/L castor seed oil was obtained after 48 h of immersion, respectively, which indicates the inhibition efficiency of the inhibitor increased with an increase in concentration of inhibitor at the studied temperature. The presence of castor seed oil as corrosion inhibitor shows increased inhibition efficiency, potential value and polarization resistance with decreased current density. The inhibitor is a mixed-type inhibitor that can control both cathodic and anodic corrosion which obeyed Langmuir adsorption isotherms.     

The features of the synthesis of ZnO nanostructures by laser ablation of zinc in water-surfactant solutions

The data of experimental investigation of optical properties of colloidal solution, its composition and morphology of the dispersed phase, resulting from laser ablation of zinc in aqueous solutions of surfactants—sodium dodecyl sulfate (SDS) and dioctil sodium sulfosuccinate (AOT) are presented. It is shown that an optical absorption spectra of the colloids, X-ray spectra and AFM (atomic force microscopy) images solid phase of colloids can trace the dynamics of synthesis ZnO nanostructures from zinc nanoclusters in the size of nanometers to fractal aggregates (FA) up to hundreds of nanometers. Determinants of this process are the average power and duration of irradiation, the frequency of the laser pulses, the colloid aging time, the type and concentration of surfactant in the solution. At the selecting of appropriate regimes of the process, along with zinc oxide other nanoproducts-hydrozincite and organic-inorganic layered composite [(β)-Zn(OH)₂ + SDS] are obtained.     

羧甲基壳聚糖在酸性溶液中对铝的缓蚀作用

羧甲基壳聚糖是一种环境友好的重要衍生物,采用失重及电化学方法（EIS）研究了羧甲基壳聚糖（CM—ehitosan）在1mol／LHCI溶液中对铝（2024）的缓蚀作用。失重和电化学测试均表明,当羧甲基壳聚糖浓度达到200mg／L时缓蚀效率最高,可达88．54％。进一步的拟合计算表明,羧甲基壳聚糖在铝表面的吸附基本遵循修正的Langmuir吸附等温式,并获得上述吸附过程的热力学参数△Go、△Ho和△So。     

Acid Cleaning of Steel Using Arghel Echo Friendly Corrosion Inhibitor

Acid cleaning of mild steel dissolution by 1M sulfuric acid/10 % methanol (test solution) in presence of Arghel herb extract as green inhibitor were monitored by potentiodynamic and electrochemical impedance techniques in the temperature range 30–60^oC. At all temperature, the corrosion rate decreased with increasing inhibitor concentration. Potentiodynamic polarization measurements indicated that the inhibitor has strong effect on the corrosion behavior of the steel and behave as mixed type inhibitor. Impedance results indicate that the charge transfer controls the dissolution mechanism of steel across the phase boundary in the absence and the presence of the inhibitor. The inhibition efficiency obtained from various employed methods is in good agreement. Thermodynamic and activation parameters obtained from this study indicated that the presence of the Arghel increases the activation energy, and the adsorption process of the inhibitor on the metal surface is spontaneous.     

铝化学机械抛光中1,2,4-三唑和苯并三氮唑的缓蚀机制

揭示铝低压力化学机械抛光(CMP)中的弱缓蚀机制是铝CMP研究的关键问题。采用CMP试验,研究了1,2,4-三唑(TAZ)和苯并三氮唑(BTA)对铝表面去除率的影响规律;通过接触角和表面原子力显微镜(AFM)试验,分析了TAZ和BTA薄膜在铝表面的亲水性能,发现由TAZ作用形成的缓蚀薄膜比由BTA形成的缓蚀薄膜更厚,更易渗透与去除。结合摩擦磨损试验和Arrhenius公式,探讨了TAZ和BTA在CMP过程中对铝表面化学反应活化能的影响。结果显示:TAZ的活化能小于BTA,更容易形成弱缓蚀薄膜,机械促进化学作用的效果更明显。