Effect of Sonochemical Treatment Modes on the Electrodeposition of Cu–Sn Alloy from Oxalic Acid Electrolyte

Methods of scanning electron microscopy, potentiodynamic polarization, and X-ray diffraction analysis were used to study the kinetic features of the electrodeposition process of the copper–tin alloy from an oxalic acid electrolyte and analyze the structure, composition, and luster of coatings formed under sonochemical treatment conditions at varied power of the ultrasonic field and current load. The ultrasonic treatment with power of 8–40 W dm^–3 makes it possible to 2–8 times intensify the cathodic process and obtain coatings containing 10–15 wt % tin with luster of 20–40%. The specific content of tin in a coating being formed is nearly independent of the ultrasound power and grows with increasing the cathodic current density.     

Effect of aluminium content on the coating structure and dross formation in the hot‐dip galvanizing process

Hot dipping of steel in aluminium–zinc baths of varying composition (5–90% Al) has been undertaken with the aim of elucidating the mechanism of coating formation. On the basis of these experiments, it has been possible to define a range of aluminium content over which there is a change from a normal galvanizing process to a typical aluminizing process. Alternatively, the coating structure and properties were markedly affected by the aluminium content of the dipping bath. The kinetics of such coatings acquires the character of the activation energy E_a. The effect of various silicon levels as an inhibitor to iron dissolution during hot dipping at different aluminium percentages was studied. The structure of dross formation in 55 wt.% Al–Zn was identified. The adverse effect of heavy accumulation of dross in the dipping pot on the coating structure also was shown. Copyright © 2003 John Wiley & Sons, Ltd.     

Corrosion mechanism of pure aluminium in aqueous alkaline solution

The corrosion of pure aluminium in alkaline solution has been explored using an open circuit potential transient, potentiodynamic polarization experiment and a.c. impedance spectroscopy. The steady-state value of the open circuit potential (E _ocp ^ss ) of pure aluminium in alkaline solution was observed to decrease with increasing rotation rate of the specimen, which is ascribed to the enhanced anodic reaction. The extent of anodic polarization for the aluminium dissolution reaction on pure aluminium at E _ocp ^ss was found to be greater than that of cathodic polarization for the water reduction reaction. This indicates that the rate of corrosion of pure aluminium is mainly determined by the anodic reaction in alkaline solution. Based upon the experimental results, a corrosion mechanism for pure aluminium has been proposed in the presence of the native surface oxide film in alkaline solution, involving consecutive oxide film formation and dissolution, and simultaneous water reduction.     

Electrochemical and computational studies of an expired vilazodone Drug as environmentally safe corrosion inhibitor for aluminum in chloride medium

Through using chemical and electrochemical methods, the theoretical and experimental investigation of the expired vilazodone drug's ability to prevent corrosion on aluminium (Al) in a corrosive medium of HCl (1 M) has been examined. Weighing tests (WL), electrochemical (impedance spectroscopy (EIS), potentiodynamic polarization (PDP)), atomic force microscopy (AFM), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) tests at 25 °C have all been used to investigate Vilazodone's capability to prevent corrosion of Al in 1 M HCl in the concentration in the range of 25–150 ppm. The corrosion inhibition effect of the investigate Vilazodone's against Al in acid environment was investigated weight loss and electrochemical methods. The highest % inhibition efficiency (%IE) was 95% resulted from weight loss technique at the highest concentration for inhibitor. According to the PDP data, this examined vilazodone function as a mixed-type inhibitor, impacting both the anodic and cathodic reactions. The inhibitors covered the active points of the metal surface, according to electrochemical impedance spectroscopy (EIS), to prevent corrosion. It was discovered that the inhibitor adsorption on the Al surface obeyed the Langmuir adsorption isothermal model. AFM, SEM, and FTIR surface examinations proved the inhibitor had a significant protective effect against Al dissolution in 1 M HCl. The outcomes from chemical and electrochemical methods are relatively consistent. Vilazodone acted as an effective corrosion inhibitor, according to all of the experimental data.     

Preparation of Macroporous Aluminium Oxide using Template of Poly(methacrylic acid‐co‐glycidylmethacrylate) Crosslinked with Methylenebisacrylamide

Poly(methacrylic acid‐co‐glycidylmethacrylate), poly(MA‐co‐GMA) samples were prepared by exposure to γ–irradiation, at fixed concentration of methylenebisacrylamide MBA, 0.5% wt/wt as crosslinker while the MA/GMA ratio was varied. FTIR spectra showed bands refer to MA, as well as GMA, indicating the involvement of both in the copolymerization. Al(NO₃)₃.9H₂O as a precursor for the preparation of aluminium oxide was templated as a guest into the crosslinked gels by soaking the gels in a methanol solution. The perturbation of the bands at 3439, 2926, 1635, 1476, 1394, and 1166 cm^?1 after the templation of the guest, provides evidence for the loading of the guest species into the gel. The swelling behavior of the prepared samples found to be dependent on the composition of the gel and the pH. The templation of the aluminium nitrate into the gel was further proved by thermal gravimetric analysis (TGA). Scanning electron microscopy (SEM) was used for investigating the produced oxide particles, which revealed macropores with maximum diameter at MA/GMA, 40∶60 wt/wt (H3) and complete disappearance at 80 wt% of methacrylic acid (H5). X‐ray diffraction (XRD) showed an amorphous structure of the aluminium oxide. Increasing the hydrophilicity of the template leads to an increase in the Lewis acidic sites on the surface of the produced aluminium oxide up to 60 wt% of methacrylic acid (H4) while a further increase was met by a redecrease in the surface acidity (H5).     

Analytical performance of high-voltage neon plasma in glow discharge optical emission spectrometry

In a high-voltage Ne glow discharge plasma (Ne-GDP), calibration factors as well as the limit of determination were compared between atomic resonance lines and singly-ionized lines of copper and aluminium in optical emission spectrometry. These elements have intense ionic lines which are excited by resonance charge-transfer collisions of Ne ions. The ionic lines gave better detection sensitivity in the Ne-GDP, whereas the atomic resonance lines were commonly employed as analytical lines in the other plasma sources such as Ar-GDP and ICP. The limit of determination was 1.3 × 10^–3 mass % for the Cu II 248.58 nm line and 1.0 × 10^–3 mass % Al for the Al II 358.66 nm line at a discharge parameter of 1.60 kV/36 mA.     

Sputtering of aluminium alloys in the grimm glow lamp for emission spectrochemical analysis

The effects of surface roughness, grain size and target thickness on the cathodic sputtering and emission intensities of spectral lines in the Grimm glow lamp have been investigated for samples of aluminium alloys. The intensities of the alloying elements changed with discharge time because the θ phase (Al²Cu) and β phase (Si) are sputtered selectively. The selective sputtering of the θ phase in an Al—8% Cu alloy can be decreased and the intensities can be made constant during discharge by polishing the target surface with coarse sand paper before discharge. When a fine-grained Al—4.9% Cu—7.2% Si alloy sample was used as a target, the intensities remained nearly constant during discharge. The sample preparation for obtaining fine-grained samples involves casting the melt in a metal mould. The thickness of disk samples influences not only the sample temperature but the current, sputtering and intensities. Special attention should be paid to the thickness for the determination of copper in aluminium alloys.     

Effect of the cationic composition of cryolite-alumina melts on the anodic overvoltage

Steady-state polarization of anodes prepared from platinum or glassy carbon is studied in a laboratory cell in a cryolite-alumina melt containing small amounts of potassium and lithium fluorides and various alumina amounts. The surface area of the anodes reaches a few centimeters squared. An insignificant depolarization of the anodic process is discovered following the replacement of a fraction of sodium ions in the electrolyte by potassium ions in an amount of ～3.9 mol % KF (～4.1 wt %) and a noticeable depolarization, following the substitution of K⁺ in an amount of ～7.1 mol % KF (～7.6 wt %). Substituting lithium ions in an amount of ～3.7 mol % LiF (～1.8 wt %) for a fraction of sodium ions leads to an insignificant polarization. A significant effect of a general cryolite ratio on polarization is discovered. A noticeable increase in the anodic polarization is fixed at an alumina concentration equal to 5–5.5 wt %.     

Flow injection-mini-column technique with ICP-AES detection for the isolation and preconcentration of the fast reactive aluminium fraction in waters

A flow injection mini-column system based on short reaction times with 8-hydroxyquinoline (oxine) with ICP-AES detection is described for the isolation and preconcentration of the “fast reactive” or “toxic” aluminium fraction in water samples. Using a 3 s reaction time with oxine (5 × 10^–4 mol/l) at pH 5.0, the “fast reactive” aluminium fraction is shown not to include the non-toxic AlF²⁺ species at low F^–: Al³⁺ molar ratios (0.3 : 1). The complexed aluminium is isolated in a stable and recoverable form on mini-columns of Amberlite XAD-2 (0.3 cm × 5.0 cm, resin particle size range 0.08 mm–0.16 mm)). The retained aluminium is recovered by “back-flushing” the analytical column with 1 mol/l HCl for final element specific detection by ICP-AES. Detection limits (after preconcentration) of 2 μg/l, a linear range of 0–500 μg/l, and possible preconcentration factors of up to 18 times are demonstrated with the present system. Implications for the possible solution of sample stability problems encountered with labile aluminium species analysis and the development of a “field sampling” technique are discussed, where the desired Al fraction is quantitatively retained in a stable form on mini-columns.     

镍铝介金属镀膜之抗坑蚀行为

采用3种原子百分比Ni52Al48,Ni60Al40及Ni70Al30成分的靶材以阴极电弧放电离子被覆技术制备不同组成的Ni＿Al薄膜于AISI1045中碳钢基材表面上,并观察镀膜微结构与成分随靶材成分的变化,评估应用Ni＿Al于抗坑蚀功能方面的可行性.研究结果显示:使用上述3种靶材所获致的镀膜组成依次为Ni62Al38,Ni63Al37及Ni69Al31,镀膜镍含量随靶材镍含量增加而增加.3种镀膜的相组成均以Ni3Al为主,从富镍Ni70Al30靶材所得的镀膜尚含有部分镍相.镀膜具有极强的附着性并反映在镀膜的抗坑蚀性上.在纯水中,所有的Ni＿Al镀膜试片均能提高中碳钢基材的抗坑蚀性,约达10倍.在3.5wt%盐水与3.5wt%盐酸中亦分别有两倍以上的效果.而在这3种测试环境中,3种镀膜试片的坑蚀损失差别均不明显,无法判断镀膜组成对抗坑蚀性的影响.从动电位极化曲线可以看出,镀膜试片均能大幅提高基材在盐酸与盐水溶液中的抗蚀性,然而因坑蚀破坏而形成的孔洞会由于孔蚀而导致腐蚀加剧,造成镀膜试片在腐蚀溶液中之抗坑蚀效果低于电化学量测时所预期的保护效果.     

Electrochemical properties of cathodes made of (La,Sr)(Fe,Co)O3 containing admixtures of nanoparticles of cupric oxide and intended for fuel cells with a solid electrolyte based on ceric oxide

The electric and electrochemical characteristics of cathodes made of La_0.6Sr_0.4Fe_0.8Co_0.2O_3?δ (LSFC) and intended for fuel cells with electrolytes based on ceric oxide are studied. Adding cupric oxide into the LSFC cathode is shown to exert a favorable effect of the properties of the LSFC-CuO/SDC electrode system, where SDC stands for the CeO₂-Sm₂O₃ electrolyte. The effect produced by cupric oxide when added in the form of nanopowder is perceptibly greater than in the case of micropowdered CuO. Adding a mere 0.5 wt % of nanopowdered CuO reduces the LSFC cathode resistance nearly tenfold. The cathode’s adhesion to the electrolyte substantially improves as well, which makes it possible to lower the cathode’s firing temperature by 100°C. The maximum of electrochemical activity is intrinsic to cathodes containing 2 wt % CuO, with the caking temperature of 1000°C. According to a 2011-h life test of the LSFC-SDC composite cathodes containing nanopowdered CuO, temporal stability of their electrochemical characteristics improves with the SDC content. The time dependences of the polarization resistance of cathodes containing 40–50 wt % SDC look like decaying exponential curves. The steady-state polarization resistance, calculated on the basis of this, is equal to 0.1–0.2 ohm cm². At an overvoltage of less than 100 mV, the cathodes may provide for a current density of 0.5–1.0 A cm^?2.     

Corrosion behaviour of aluminium in NaOH solutions

The electrode potential and the corrosion rate of aluminium were measured in 0.001–2 M NaOH solutions at 30°C. Up to 0.005 M (pH 11.7) the potential was found to be independent of concentration, whereas the corrosion rate is proportional to the alkali concentration. Hence, the corrosion process is diffusion-controlled. Within the concentration range 0.01–0.5 M (pH 12–13.5), the potential decreases at a gradient of 51 mV pH^?1 and the corrosion rate is almost proportional to the square root of concentration. These results were discussed in the light of the kinetics of the anodic and cathodic reactions. Above 0.5 M, both the potential and corrosion rate increase rapidly with concentration. This was attributed to adsorption of Na⁺ ions, which leads to the formation of active cathodic areas at the expense of the anodic ones.     

Effect of phenyl group on the structure and formation of transitional alumina from Al (OPh)<Subscript>3</Subscript>

The structure of freshly prepared Al(OPh)₃, its decomposition product, the hydrolyzed products and their structural evolution were investigated employing ²⁷Al MAS NMR spectroscopy, PXRD, TGA/DTA/DSC/FTIR techniques. In the ²⁷Al MAS NMR spectrum of the aluminium phenoxide, three signals with the chemical shift at 3.78, 21 and 45 ppm were observed. The chemical shift at 3.78 and 45 ppm revealed the presence of four and sixfold coordinated aluminum. The signal at 21 ppm corresponded to fivefold coordinated aluminium. When the aluminium phenoxide was directly decomposed in air at 600 °C, it resulted in amorphous product as evidenced from the PXRD pattern. The observed signals with chemical shifts at 10.1, 42, 73.6 ppm in the ²⁷Al MAS NMR spectrum indicated the presence of 6, 5 and 4 coordination for the aluminium atoms suggesting disordered transitional γ-alumina to be the product. The hydrolysis studies of Al(OPh)₃ with excess of water at 70 °C yielded bohemite (γ-AlOOH). The alumina obtained after dehydration at 600 °C was X-ray amorphous. The dehydrated product at 600 °C showed the presence of four and six coordinated aluminium atoms in the ²⁷Al MAS NMR spectrum confirming it to be ordered γ-Al₂O₃. Crystalline γ-Al₂O₃ was obtained on further heating at 800 °C.     

Electrochemical behavior of composite cathodes in contact with solid electrolyte La<Subscript>10</Subscript>Ge<Subscript>6</Subscript>O<Subscript>27</Subscript>

The cathodic overvoltage of composite cathodes 50 wt % La_0.8Sr_0.2MnO₃ (LSM) + 50 wt % La₁₀Ge₆O₂₇ (LGO) (further on, LSM-LGO), LSM-SSZ (Zr_0.835Sc_0.165O_2?δ), Ag-Pd-LGO, and Ag-Pd-SSZ in contact with the LGO electrolyte is measured. The temperature dependences of the polarization conductivity and the working-current densities of the same composite cathodes are investigated. The study is performed at 700–900°C. A comparison with the SSZ electrolyte is conducted. The chemical interaction in the LSM-LGO composition is studied. It is demonstrated that the interaction of lanthanum-strontium manganite with lanthanum germanate occurs with the dissolution of the initial phases in one another and with the formation of fresh phases at elevated temperatures. Coefficients of linear thermal expansion of the LGO and SSZ electrolytes and the LSM, LSM-LGO, and LSM-SSZ electrode materials are compared at 40–900°C. Most of the studied electrodes in contact with the LGO electrolyte demonstrate thermomechanical stability and high electrochemical activity.     

Electrochemical Formation of Al-Li Alloys by Codeposition of Al and Li from LiCl-KCl-AlF3 Melts at 853 K

The electrochemical behavior of Al(III) ions was studied in molten LiCl-KCl melts on a molybdenum electrode. Cyclic voltammetry, chronopotentiometry and chronoamperometry were used to explore the deposition mechanism of Al and Li. Cyclic voltammetry expriment indicates that under potential deposition(UPD) of lithium on pre-deposited aluminium led to the formation of liquid Al-Li alloys at 853 K. The diffusion coefficient of Al(III) ions at 853 K in LiCl-KCl-AlF₃(1%, mass fraction) melts was determined to be (2.79±0.05)×10^?5 cm²/s. Chronopotentiograms and chronoamperograms demonstrate that the codeposition of Al(III) and Li(I) ions formed Al-Li alloys at cathodic current densities higher than ?0.28 A/cm² or cathodic potentials more negative than ?2.20 V. X-Ray diffraction(XRD) pattern indicates that Al-Li alloys with different phases formed via galvanostatic electrolysis. Inductively coupled plasma(ICP) analyses of the samples obtained by electrolysis show that lithium and aluminium contents of Al-Li alloys could be controlled by AlF₃ concentration and current intensity.     

Determination of aluminium contents in selected food samples by instrumental neutron activation analysis

Food and food products are the main sources of Aluminium entering the human body. In order to know aluminium contents in food and food products, selected 26 samples from local market were analyzed by instrumental neutron activation analysis (INAA) using reactor neutrons and high resolution gamma-ray spectrometry. INAA using 1,779 keV γ-ray of ²⁸Al (2.24 min) was used for aluminium concentrations in the range of 33–529 mg kg^?1. Two NIST standard reference materials (SRMs) and two IAEA reference materials (RMs) were analyzed by INAA for quantification of aluminium as a part of method validation.     

Instrumentally simple flow detector for the determination of traces of electroluminescent compounds in aqueous solutions

A flow detector based on the observation of the cathodic electroluminescence at an oxide-covered aluminium electrode is described. The detector responds only to electroluminescent compounds in aqueous eluents, and additional selectivity can be achieved by making use of optical filters for wavelength discrimination. The optimum detection conditions were determined by using the cathodic electroluminescence induced by a polynuclear aromatic hydrocarbon in micellar solutions as the model electroluminescence. This instrumentally simple detector can be used to determine electroluminescent compounds in a wide concentration range with good precision. For instance, its detection limit, dynamic range and precision (i.e., relative standard deviation for 20 successive measurements of 1 × 10^?7 M samples) for the determination of micelle-encapsulated 9,10-diphenylanthracene were found to be 1 × 10^?8 M, four orders of magnitude and 7%, respectively.     

Simultaneous flow-injection determination of aluminium and zinc using LED photometric detection

A flow photometer with a multi-LED detector was applied to the simultaneous determination of aluminium and zinc with microcomputer control of photometric measurements and data processing. Xylenol Orange is the photometric reagent and the reaction is carried out in acetate buffer. Calibration graphs are linear for both metals in the concentration ranges 0.2–25 μg ml^?1 (Al) and 0.2–30 μg ml^?1 (Zn). Both elements can be determined for Al to Zn ratios varying from 0.01 to 100 with r.s.d. 1.1 and 1.4%, respectively. The method developed was applied to the determination of Al and Zn in alloys.     

Determination of aluminium in blood plasma or serum by electrothermal atomic absorption spectrometry

A carbon-furnace atomic absorption method is used to determine aluminium in blood serum or plasma, diluted (1 + 2) with purified water prior to injection (20 μl) into the furnace. Procedures are described to reduce contamination during sample collection, storage and preparation of samples. A study of the interferences of inorganic ions shows that the temperature programme developed minimises these, allowing the use of aqueous standards for calibration. Ashing at 1400°C, prior to atomisation, also removes non-specific background effects, and optical correction is not required. A sample throughput of 50 duplicate analyses per day is possible and the precision (between batch) at 24 μg Al l^-1 was 11.2% (n = 10) and at 340 μg Al l^-1 was 6.3% (n = 18). Down to 4 μg Al l^-1 can be determined. Reference values for a healthy population were 4.1–20 μg Al l^-1 (mean 10.2).     

Synthesis of terpyridine ligands and their complexation with Zn2+ and Ru2+ for optoelectronic applications

A series of soluble conjugated ligands TT , FT , PT , and NT that contained terpyridyl terminal units were synthesized by Heck coupling. These ligands absorbed at 341–434 nm and emitted blue–green light, with maximum at 440–522 nm and photoluminescence quantum yields of 0.15–0.71 in solution. The double‐layer electroluminescent devices with the configuration of ITO/PEDOT/ligand FT , PT , or NT /Ca/Al exhibited a brightness of 43–63 cd/m². These ligands were further reacted with zinc(II) and ruthenium(II) ions and subsequent anion exchange to afford linear and supramolecular complexes. The photophysics of these complexes were investigated. A significant redshift of the emission maximum of the Zn complexes relative to the corresponding ligands was observed. The Ru complexes were used to fabricate photovoltaic devices with the structure ITO/PEDOT/Ru complex/P3HT:PCBM (1:1 wt/wt)/Ca/Al. The power conversion efficiency of these polymer–fullerene bulk heterojunction photovoltaic devices was up to 0.71%. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7702–7712, 2008