铝锌合金的微观结构及抗腐蚀行为研究

Electro-chemical experiment was carded out to test the corrosion rates of aluminium-zinc hot-dip coating. It is shown that 5.3% aluminium-zinc alloy （weight ratio） has superior anti-corrosion property. The determined microstructure has displayed amorphous structure composed of nanometer sized particle of the system. The analysis indicated large negative change of Gibbs energy of 5.3% aluminium-zinc system. Molecular dynamics simulation showed that 5.3% aluminium-zinc system has very different behavior from other systems. A phase transition of this particular system was observed from simulation. The transition temperature was determined around 400 K. The simulation indicated that 5.3% aluminium-zinc system is amorphous over temperature range from 300 to 900 K, supporting the inference from experiments that amorphous solid of aluminium-zinc alloy has special anti-corrosion character.     

A tracer investigation of chromic acid anodizing of aluminium

A tungsten tracer introduced into a sputtering‐deposited aluminium substrate was employed to investigate pore development in anodic films formed at 3 mA cm^?2 in 0.25 M chromic acid electrolyte at 313 K. The anodized specimens were observed by transmission electron microscopy (TEM), with compositions of films determined by Rutherford backscattering spectroscopy (RBS). The anodic films were found to be similar in thickness to that of the aluminium layer consumed during anodizing and revealed the feathered pore morphology that is a characteristic of the electrolyte. The anodizing efficiency was ～45–48%, with tungsten tracer species, in addition to aluminium species, being lost to the electrolyte at the pore base. These findings, together with the relatively uniform distribution of tungsten species within the film, are consistent with field‐assisted dissolution of the alumina playing a major role in the development of pores. The films contrast with those formed in phosphoric and sulphuric acid electrolytes, for which feathering of pores is absent, the tracer distribution is inverted and the film thickness exceeds that of the consumed metal, features indicative of the influence of material flow in pore development. Copyright © 2007 John Wiley & Sons, Ltd.     

Photometric determination of aluminium with alizarin fluorine blue

In order to decide whether Alizarin Fluorine Blue (alizarin complexan, 3-amino-methylalizarin-N,N-diacetic acid) is a suitable reagent for the spectrophotometric determination of aluminium, values of the stability constants for some reactions of this reagent with aluminium(III) and iron(III) have been determined spectrophotometrically in a medium containing 20 % dioxan and 80 % water at ionic strength 0.1. The values of the constants that were determined are log K(Al)(AlHL) = 14.3, log K(2Al)(Al2L) = 25.3 and log K(Fe)(FeHL) = 19.6. These results were employed in the design of a method for the spectrophotometric determination of aluminium in the presence of iron and titanium. The Sandell sensitivity is 0.01 mug/cm(2) and the coefficient of variation for 34 determinations was 0.9 %.     

Determination of aluminium and chromium in slurried baby food samples by electrothermal atomic absorption spectrometry

Electrothermal atomic absorption spectrometry was used to determine aluminium and chromium in different types of baby foods. Samples without previous treatment were introduced into the atomizer as suspensions, which were prepared in a medium containing 0.1% (w/v) Triton X-100 (for chromium) or 10% (v/v) ethanol (for aluminium), 5% (v/v) concentrated hydrogen peroxide, and 0.5% (v/v) concentrated nitric acid. The slurries were homogenized with a potter and introduced directly into the furnace. The presence of nitric acid allowed a substantial amount of analyte to be extracted to the liquid phase. No matrix effect was observed and aqueous standard solutions were used for calibration. The detection limits were 4 and 50 pg for chromium and aluminium, respectively; characteristic masses were 3.8 pg for chromium and 18 pg for aluminium. Reliability of the procedures was checked by statistically comparing the results with those obtained with a previous microwave oven mineralization stage and by analyis of several certified reference materials. Values for the aluminium content ranged between 0.4 and 3.0 microg/g, and for chromium between 0.003 and 0.06 microg/g.     

XPS and TDS study of CO interaction with Pd–AlOx systems

The metal–substrate and metal–metal interactions (MSI, MMI) represent important effects determining the properties of supported catalysts, gas sensors and gettering alloys. We investigated the MSI and MMI effects by the X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) in the case of Pd films deposited on Al₂O₃ and Al substrates. The study shows that the particle-size dependent metal–substrate interaction plays an important role in CO–Pd chemisorption, namely, in the case of “aluminium rich” Pd–aluminium oxide interface. CO chemisorption exhibits a low-temperature desorption feature at 360 K characteristic for Pd–Al and very small Pd particles. The MSI is explained by the formation of a Pd–Al intermetallic interface exhibiting a strong bimetallic Pd–Al interaction.     

Etude dilatometrique de l'anisotropie d'une tole a base d'aluminium obtenue par solidification rapide

Dilatometric study of the anisotropy of an aluminium alloy sheet obtained by rapid solidification. An Al-1.99%Mn-0.80%Mg-0.60%Cr-0.40%Zr-0.13%Fe-0.05%Ti alloy produced by the twin roller melt spinning technique was characterized in terms of thermal stability at low temperature in the range 80–300K. Differences in thermal expansion coefficients in the three directions were evidenced, and revealed the presence of an anisotropy. The differences are mainly due to the nature of the intermetallic phases present in the aluminium matrix. It is important to note the low thermal expansion coefficient obtained along the direction normal to the rolling plane, as compared to those of aluminium alloys prepared by conventional methods.     

Threshold Al KLL Auger spectra of oxidized aluminium foils

Threshold Al KLL Auger electron spectroscopy and K‐edge x‐ray absorption fine structure spectroscopy have been used to examine technical purity (99.5%) aluminium foil before and after chemical treatment that altered the thickness and degree of hydroxylation of the oxidized layer. Comprehensive surface chemical characterization was effected by means of monochromatized Al Kα‐excited photoelectron spectroscopy. Threshold Al KL_{2, 3}L_{2, 3} spectra were obtained for three of the foils investigated and these spectra were in broad agreement with those observed previously for pure Al foil. The relative intensities of the spectral components for two of the foils were clearly consistent with the previously proposed assignment of the resonantly enhanced Auger component, situated between those arising from the metal and Al(III) oxide, to a thin interfacial layer. The threshold Auger spectra from the aluminium foil bearing the thickest and most hydroxylated oxidized layer were not obviously consistent with the interfacial layer model but O K‐edge spectra revealed that this surface layer was fundamentally different from the others and could have had a greater interfacial surface area. Copyright © 2003 John Wiley & Sons, Ltd.     

Chelating agents for human diseases related to aluminium overload

The aim of this review is to give a general view on the current status of the role of aluminium in human health and disease. The main aspects of aluminium metabolism in humans are covered, summarizing the state of knowledge on the absorption, distribution, retention and excretion of aluminium, giving particular emphasis to the main metabolic pathways of this metal ion in different organs. Then the pathological consequences of aluminium overload in man, its role in neurodegenerative diseases and the emerging implication of this metal ions in different pathologies are treated. Finally, the function of different chelators utilized in clinical practice in the therapy of aluminium depending diseases is discussed and the latest studies on aluminium chelators are presented. Some emphasis is given to the parallelism between iron and aluminium chelators, and in particular interesting correlations between structural parameters of these two trivalent metal ions are presented.     

Ammonium aurin tricarboxylate as a reagent in inorganic analysis

Summary Ammonium aurin tricarboxylate produces characteristic colour with various metallic ions. The colour reactions are quite sensitive especially in the case of uranium and thorium besides aluminium and beryllium. The use of the reagent in analysis is suggested.     

How Water and Ion Mobility Affect the NMR Fingerprints of the Hydrated JBW Zeolite: A Combined Computational-Experimental Investigation

An important aspect within zeolite synthesis is to make fully tunable framework materials with controlled aluminium distribution. A major challenge in characterising these zeolites at operating conditions is the presence of water. In this work, we investigate the effect of hydration on the ²⁷Al NMR parameters of the ultracrystalline K,Na-compensated aluminosilicate JBW zeolite using experimental and computational techniques. The JBW framework, with Si/Al ratio of 1, is an ideal benchmark system as a stepping stone towards more complicated zeolites. The presence and mobility of water and extraframework species directly affect NMR fingerprints. Excellent agreement between theoretical and experimental spectra is obtained provided dynamic methods are employed with hydrated structural models. This work shows how NMR is instrumental in characterising aluminium distributions in zeolites at operating conditions.     

Removal of fluoride from fluoride contaminated industrial waste water by electrolysis

Wastewater containing fluoride are generally treated with lime or calcium salt supplemented with aluminium salts. Wastewater generated from different industries does not always behave in the same way due to the presence of interfering contaminants. A number of techniques have been developed and studied for the removal of excessive fluoride. Most of these are based on use of aluminium salt. In alum coagulation the sorption properties of product of hydrolysis of aluminium salts and capacity of fluoride for complex formation plays a very important role. These hydrolysis products of aluminium can be produced by passing direct current through aluminium electrode. The text presented in the paper deals with the various aspect of removal of fluoride by electrolysis using aluminium electrode from fluoride chemical based industrial wastewater.     

Quantitative Sputter Depth Profiling of Silicon- and Aluminium Oxynitride Films

 Silicon- and aluminium oxynitride films have gained attention because of their interesting properties in various fields of technology. The specific properties strongly depend on the concentration of oxygen and nitrogen in the films. For the quantitative analysis of homogeneous silicon- and aluminium oxynitride films, EPMA has been proven a very reliable and precise method of analysis. In order to characterise films with graded composition or interface effects between the film and the substrate it is necessary to use sputter depth profiling techniques such as SIMS, hf-SNMS, AES, or hf-GD-OES. Unfortunately, stoichiometric silicon- and aluminium oxynitride films are insulating and therefore charge compensation has to be applied. For the quantification it was necessary to prepare calibration samples which have been analysed by different bulk analytical techniques such as NRA, RBS and EPMA. With these calibration samples, sensitivity factors have been determined and the functional dependence of the sensitivity factors on the composition has been derived. The advantages and disadvantages of the different sputtering techniques and the applicability of the obtained sensitivity functions for the quantitative depth profiling of silicon- and aluminium oxynitride films are discussed.     

Structural study of VOx doped aluminium fluoride and aluminium oxide catalysts

The structural properties of vanadium doped aluminium oxyfluorides and aluminium oxides, prepared by a modified sol-gel synthesis route, were thoroughly investigated. The influence of the preparation technique and the calcination temperature on the coordination of vanadium, aluminium and fluorine was analysed by different spectroscopic methods such as Raman, MAS NMR and ESR spectroscopy. In all samples calcined at low temperatures (350 °C), vanadium coexists in two oxidation states V^IV and V^V, with V^IV as dominating species in the vanadium doped aluminium oxyfluorides. In the fluoride containing solids aluminium as well as vanadium are coordinated by fluorine and oxygen. Thermal annealing of 800 °C leads to an extensive reorganisation of the original matrices and to the oxidation of V^IV to V^V in both systems.     

Exploitation of synthetic surfactant vesicles for enhanced fluorescence of metal chelates

The use of synthetic surfactant vesicles as a means for enhancing the photoluminescence of metal chelates is illustrated and a sensitive fluorimetric determination of aluminium with quinolin-8-ol-5-sulphonic acid in vesicles of didodecyldimethylammonium bromide is given. The influence of different variables on the organized aluminium-quinolin-8-ol-5-sulphonic acid reaction is investigated and possible mechanisms of the observed enhancing effects are discussed. The limit of detection is 1 μg l^?1 of aluminium. The optimized fluorimetric method has been successfully applied to the determination of aluminium in tap waters and dialysis fluids.     

预先负载原料法的制备过程对复合分子筛形成的影响

采用预先负载原料法合成了具有核/壳结构的复合分子筛, 并研究了铝源类型和制备过程对反应的影响. 结果表明, 以异丙醇铝为铝源时, 晶化时间较短, 产物中没有SAPO-5晶体, 延长晶化时间可以提高SAPO-5的结晶度. 将负载磷的ZSM-5分别与不同组成的凝胶混合, 经室温陈化后可以明显加快晶化速度. 制备过程中凝胶的水含量和搅拌方式也根据铝源类型的不同有所差别. 当以拟薄水铝石为原料时, 在相同的处理条件下, 产物的结晶度都较高.     

预富集-氢化物发生原子吸收光谱法测定饮料中的痕量铅

原子吸收光谱法测定水样中的痕量元素是应用得最广泛的方法之一[1]。有时需采用多种方法对水样中的痕量元素进行富集。其中一类方法是基于待测元素配合物可以最终定量富集于少量颗粒上,过滤收集这些颗粒,然后制成小体积的、可直接用原子吸收光谱法测定的悬浊液。特定的配位剂分     

In-situ FTIR studies of dimethyl ether adsorption on H-ZSM-5 zeolites

In situ infrared spectra of dimethyl ether adsorbed on two H-ZSM-5 zeolites are reported which are different in both lattice and extraframework aluminium contents. A number of dissociatively adsorbed dimethyl ether species associated respectively with the Bronsted acid sites, the external silanol groups and extraframework aluminium species at different temperatures are identified. In particular, dimethyl ether reacts with non acidic hydroxyl species associated with extraframework aluminium to form the third methoxy species. The distributions of hydrocarbons desorbed from a single pulse of dimethyl ether (1.0 mL) onto these zeolite samples are presented. Propene is the major product, and the yield of hydrocarbons correlates with the concentration of Bronsted acid bound methoxy groups.     

Simultaneous determination of silicon and aluminium in ferrosilicon by instrumental neutron activation analysis with the aid of an Ac-Be isotopic neutron source

A method has been developed for the accurate determination of silicon and aluminium by instrumental neutron activation analysis with the aid of an²²⁷Ac-Be isotopic neutron source. The samples are pellets made of 4.6 g of ferrosilicon and 0.9 g of a pelletizing agent. Each pellet is irradiated twice at two different fast-to-thermal neutron flux ratios. Each irradiation is followed by two integral mode countings. This allows correction for manganese activities and calculation of the fraction of the aluminium activity induced in silicon and aluminium. The method has been tested with laboratory-prepared synthetic samples as well as commercially certified ferrosilicon. For ferrosilicon containing 75% Si, a relative precision of 0.7% for the results of the silicon concentration has been obtained. For aluminium the relative precision varied from 2 to 7% for concentrations of 3.5 to 1.5%.     

Thermal decomposition of sodium aluminium sulphate crystallohydrate

Dynamic TG investigations were carried out to elucidate the mechanism of thermal decomposition of aluminium sodium sulphate crystallohydrate. Shimadzu 31H and MOM Derivatograph X-ray diffraction and other techniques were used to determine data on the decomposition, activation energy, structure and phases in the solid products. Isothermal study in the temperature ranges 883–958 K and 983–1113 K in air or a reducing gas atmosphere revealed different reaction mechanisms. Depending on the experimental conditions, mainly Al₂O₃ can be obtained.