The effect of trace additions of copper and pretreatment conditions on the filiform corrosion of powder-coated aluminium alloy AA6060

This paper presents a short review of the literature data and the newest studies of filiform corrosion (FFC) testing of profiles extruded using a recycling-friendly AA 6xxx aluminium alloy, with Cu content up to 0.09 wt%. As the pretreatment plays a significant role in avoiding FFC on powder-coated aluminium profiles, the profiles were pretreated and coated at three different production sites. They have been tested at 40°C, 82% RH for 1000 hours (according to modified ISO 4623-2). It was observed that differences in FFC behaviour of the same type of profile coated at different plants were more significant than differences between samples with increasing Cu content. In order to understand the differences between profiles coated at different sites, GDOES analysis of samples was performed, specially focusing on surface enrichment of copper through the pretreatment.     

Analysis of heavy metals in atmospheric particulate by ion chromatography

Cu, Ni, Zn, Co, Fe+2, Mn, Cd, Fe+3 and Pb are easily separated and detected in isocratic mode by ion chromatography with post-column derivatization using a bifunctional ion-exchange column and an eluent formed by oxalic acid (28 mM) and sodium nitrate (250 mM). The separation is optimised by using a suggested sample solution containing a given concentration of chloride. Detection limits were 10-15 ppb for all the metals except for cadmium and lead, for which detection limits of 30 and 60 ppb were found, respectively. The method was tested on an atmospheric particulate certified sample. The measured values were in good agreement with certified values. Real samples of atmospheric particulate from industrial and urban sites were analysed and the results are discussed.     

Study of laser ablation of brass materials using inductively coupled plasma atomic emission spectrometric detection

A XeCl laser and a Q-switched Nd:YAG laser operating at 1064, 532, 355 and 266 nm were used to ablate brass materials with varying concentrations of Zn and Cu. The ablated material was transported to an inductively coupled plasma for further atomization, excitation and ionization with an atomic emission spectrometric detection. A Zn enhancement was observed, which could be suppressed by using a Nd:YAG laser working at 266 nm with fluences higher than 400 J cm⁻² (equivalent to 80 GW cm⁻²). In contrast, a lack of linearity was observed for Cu as a function of the concentration, regardless of the wavelength and the fluence. The Cu problem seemed to occur during the ablation and was related to the structure of the brass material. Lack of linearity was also observed for Zn and other contained elements when samples from different origins were used.     

Simultaneous determination of cobalt, copper and zinc by energy dispersive X-ray fluorescence spectrometry after preconcentration on PAR-loaded ion-exchange resin.

A sensitive method for the preconcentration and determination of trace amounts of Co, Cu and Zn by energy-dispersive X-ray fluorescence spectrometry (EDXRF) has been developed. The method is based on the fact that 4-(2-pyridylazo)-resorcinol (PAR) loaded Dowex anion-exchange resin (PAR-resin) can effectively adsorb Co, Cu and Zn at pH 9.0 to form PAR-metal complexes. The detection limits for Co, Cu and Zn were 1.53, 0.31 and 0.21 ppb, respectively. The precisions for five replicate measurements of the three metals were 3.4, 2.7 and 2.1% RSD, and the calibration curves were linear up to 75 microg with correlation coefficients of 0.9975, 0.9980 and 0.9985, respectively. The method was successfully applied for the simultaneous determination of Co, Cu and Zn in seawater samples at ppb levels.     

Stabilization of Cu/ZnO Based Catalysts by Nickel Additive in Methanol Decomposition

A series of Cu/Zn based catalysts with and without Ni, prepared by the co-precipitation method, has been studied for methanol decomposition. CO and H2 are the major products. The Cu/Zn catalysts show a low initial activity and a poor stability. The formation of the CuZn alloys was observed in the deactivated Cu/Zn catalysts which were used for methanol decomposition at 250 . When small amounts of Ni were added in the catalyst, the Cu/Zn/Ni(molar ratio 5/4/ x) catalysts showed a high activity at a low temperature. The activity and the stability of the catalyst depend on the nickel content. The activity of the Cu/Zn/Ni catalysts was maintained at a. relatively stable value of 78% conversion of methanol with 95% selectivity of H2, 93% selectivity of CO, and a more than 70% yield of hydrogen was obtained at 250 C when x >1. The stability of the Cu/Zn/Ni (molar ratio 5/4/x) catalysts showed the maximum (ca 88%) when x=1. The stabilization effect of nickel on the Cu/Zn based catalysts may lead to the increasin     

Simultaneous Determination of Copper(II), Lead(II) and Zinc(II) at Bismuth Film Electrode by Multivariate Calibration

In this work, simultaneous determination of Cu(II), Pb(II) and Zn(II) ions at low concentration levels (ppb) by square wave anodic stripping voltammetry on a Bi(III) film electrode plated in situ at a glassy carbon electrode (GCE) is described. A chemometric approach was used to overcome the overlapping peaks of Cu(II) and Bi(III), the competition of the electrodeposited Cu and Bi for the surface of the GCE and the formation of Cu‐Zn intermetallic compounds. The construction of the multivariate calibration models, based on partial least squares regression, allowed the simultaneous determination of Cu (in the concentration range 8.0 to 20.1 ppb), Pb (2.0 to 30.0 ppb) and Zn (29.7 to 90.4 ppb) with most of the prediction errors obtained in the external validation set for the three models lower than 16, 11 and 26 %, respectively. Finally, this method was used for the determination of these trace metal ions in surface river water samples with satisfactory results [errors below 10, 5 and 32 % for Cu(II), Pb(II) and Zn(II), respectively].     

Internal structure, hygroscopic and reactive properties of mixed sodium methanesulfonate-sodium chloride particles

Internal structures, hygroscopic properties and heterogeneous reactivity of mixed CH(3)SO(3)Na/NaCl particles were investigated using a combination of computer modeling and experimental approaches. Surfactant properties of CH(3)SO(3)(-) ions and their surface accumulation in wet, deliquesced particles were assessed using molecular dynamics (MD) simulations and surface tension measurements. Internal structures of dry CH(3)SO(3)Na/NaCl particles were investigated using scanning electron microscopy (SEM) assisted with X-ray microanalysis mapping, and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The combination of these techniques shows that dry CH(3)SO(3)Na/NaCl particles are composed of a NaCl core surrounded by a CH(3)SO(3)Na shell. Hygroscopic growth, deliquescence and efflorescence phase transitions of mixed CH(3)SO(3)Na/NaCl particles were determined and compared to those of pure NaCl particles. These results indicate that particles undergo a two step deliquescence transition: first at ～69% relative humidity (RH) the CH(3)SO(3)Na shell takes up water, and then at ～75% RH the NaCl core deliquesces. Reactive uptake coefficients for the particle-HNO(3) heterogeneous reaction were determined at different CH(3)SO(3)Na/NaCl mixing ratios and RH. The net reaction probability decreased notably with increasing CH(3)SO(3)Na and at lower RH.     

In-situ investigations on the SILAR-growth of ZnS films as studied by tapping mode atomic force microscopy

Tapping mode atomic force microscopy (TM-AFM) has been successfully used for in-situ imaging of the deposition of ZnS films with the successive ionic layer adsorption and reaction (SILAR) method. The films were deposited in-situ using the commercial TM-AFM liquid cell as a flow-through reactor. The potential of TM-AFM has been used to study the growth of ZnS on different substrates up to 50 SILAR cycles. Reactants and rinsing water were alternately exchanged in the cell by a computer controlled valve system. In comparison to earlier work performed with the conventional AFM operated in contact mode, imaging artefacts introduced by lateral shear forces can be largely eliminated with TM-AFM. On glass the roughness is observed to decrease initially until typical island formation takes place at a larger number of deposition cycles. On mica island formation can be observed right from the beginning of the process and the roughness increases with increasing number of deposition cycles.     

Determination of traces of chloride and fluoride in H2SO4, H3PO4 and H3BO3 by in situ analyte distillation-ion chromatography

A simple dual vessel in situ analyte distillation (IAD) system has been developed for suppressed ion chromatographic determination of chloride and fluoride ions in complex matrices. In IAD system, water vapours generated from the outer vessel reacts with sulfuric acid generating heat, thus favouring the quantitative distillation of chloride and fluoride within 30 min on water bath temperature (approximately 80 degrees C). The distilled analytes, as their respective acids in water, were directly injected into an ion-chromatograph. This newly developed method has been applied for analysis of trace impurities in H2SO4, H3PO4 and H3BO3. The detection limits for chloride is 8, 80 and 70ppb (w/w) for H2SO4, H3PO4 and H3BO3, respectively. For fluoride the detection limits are 6 and 60 ppb (w/w) for H2SO4 and H3PO4, respectively. The recovery of spikes for both the analytes ranged between 87 and 100%.     

Comparison Between Different Methods of Analysis of Corrosion Products of Aluminum Brass in Sea Water: Chemical analysis,X-Ray Diffractometry,Auger Spectroscopy

Abstract

The oxidation layer formed on the surface of aluminum brass corroded in sea water at 40° C for 15 days was analysed by using different techniques (chemical analysis after selective dissolution, X-ray diffreactometry and Auger spectroscopy) and was found to be formed by Cu oxychlorides, basic Zn sulfates, Al and Mg Car bonates, Al oxides.

Chemical and diffractometric analyses yield an average value of the composition of the corrosion layer, whose thickness should be greater than 60-80° Å for chemical and than 100 Å for diffraacto metric analysis.

Auger speactroscopy permits the analysis of thin films and of small surface areas, and gives results that agree with those of the other two techniques when the corrosion layer is homogeneous.     

DMFCs用磺化聚醚醚酮/功能化二氧化硅复合质子交换膜

在磺化度(DS)为55.1%的磺化聚醚醚酮(SPEEK)中掺杂功能化二氧化硅(吸湿性SiO2溶胶及带有磺酸基团的二氧化硅(SiOx-S)粒子)制备SPEEK/SiO2和SPEEK/SiOx-S复合质子交换膜.SiO2和SiOx-S的掺杂能有效提高复合膜的抗溶胀、阻醇性能及高温低湿情况下的电导率.纯SPEEK膜在80℃溶胀为52.6%,而SiO2和SiOx-S掺杂量为15%的复合膜在此温度下分别仅有26.2%和27.3%的溶胀.在室温至80℃范围内,SPEEK/SiO2(20 wt%)和SPEEK/SiOx-S(20 wt%)复合膜的甲醇透过系数比Nafion115膜小近2个数量级.在120℃、相对湿度(RH)为40%情况下,SPEEK纯膜的电导率仅为2.6×10-4S.cm-1,SPEEK/SiO2(20 wt%)复合膜约为2.0×10-3S.cm-1,而SPEEK/SiOx-S(20 wt%)复合膜高达1.0×10-2S.cm-1,与Nafion115相当.SPEEK/SiO2(20 wt%)和SPEEK/SiOx-S(20 wt%)2种复合膜的尺寸稳定性较高,膜电极无催化剂与膜分离现象,其DMFCs单电池性能好于SPEEK膜.     

Direct and simultaneous determinations of Zn,Cd, Pb,Cu, Sb and Bi dissolved in sea water by differential pulse anodic stripping voltammetry with a hanging mercury drop electrode

Differential pulse anodic stripping voltammetry with a hanging mercury drop electrode is used for the direct and simultaneous determination of Zn, Cd, Pb, Cu, Sb and Bi at their natural levels in sea water after adjustment to pH 1 and to a 2 M chloride concentration. The optimal instrumental parameters are described. With a plating time of 60 min, the detection limits are about 0.1 ppb for Zn and Cu, 0.01 ppb for Cd and Pb, and 0.05 ppb for Sb and Bi. Relative standard deviations are about 10—15%. Simultaneous determinations of the six metals take about 2 h.     

A study of non-linear calibration graphs for brass with femtosecond laser-induced breakdown spectroscopy

The ablation of brass samples with 170 fs laser pulses was studied by time resolved emission spectroscopy. The intensities of Cu as well as of Zn lines were found to be non-linearly dependent on their concentrations in the samples. This behaviour is explained by changes in the mass ablation rate. Thus, linear dependencies were obtained when the Zn line intensities were normalized to the line intensities of Cu. A simple theoretical model based on compositional differences is presented. The differences in ablation are accounted for using the standard two-temperature diffusion model for short laser pulse ablation and the steady current resistivity as a fundamental parameter describing the compositional changes in a set of brass samples. In principle, it is possible to construct linear calibration curves from the measured Zn and Cu line intensities without internal standardization if the model and energy dependent ablation measurements are taken into account. Inductively coupled plasma mass spectrometry measurements are used to demonstrate this.     

Multilayered Cu–Ti deposition on silicon substrates for chemiresistor applications

Abstract

On the perspective to develop CuO–TiO₂ MOS, multilayered Cu and Ti thin layers were alternatively deposited on silicon wafers using 25?keV Ar?+?ion beam sputtering and, subsequently, oxidized by thermal annealing in air at 400?°C for 24?h. The deposited films have variable ratios of the Cu and Ti % at. One of the main goal is to obtain such multilayers avoiding the presence of Cu–Ti–O compounds. The samples were characterized in terms of composition (by RBS and SIMS analyses) and morphology (by AFM and SEM investigations). In particular, SIMS maps allows to observe the spatial distribution and thickness of each phase of the Cu/Ti multilayers, and further to observe Cu diffusion and mixing with Ti, as well as phase separation of CuO and TiO₂ in the samples. The reasons of this effect represent an open issue that has to investigated, in order to improve the MOS fabrication.     

Investigations of the hygroscopic properties of ammonium sulfate and mixed ammonium sulfate and glutaric acid micro droplets by means of optical levitation and Raman spectroscopy

In the presented work an optical levitation technique performed by means of a focused laser beam, Mie and Raman spectroscopy have been utilized for measuring hygroscopic growth curves and composition of laboratory generated single ammonium sulfate (AS) and internally mixed ammonium sulfate-glutaric acid (GA) droplets in the micrometer range. The generated particles have been found to immediately supersaturate (above 45wt% for AS) at 297 K after capturing in the laser beam. Further increase of the relative humidity (RH) up to 85% does not dilute the droplets under the saturation point. A spontaneous hygroscopic growth takes place at 73.5-78% RH for pure AS. The particle grows with an average factor of 1.62 at the deliquescence relative humidity (DRH). Efflorescence of AS occurs at 43% RH with a corresponding concentration of more than 85wt%. Independent of the mixing ratios in ranges 25/75, 50/50, 75/25% AS/GA mixed particles don't exist as a metastable supersaturated solution droplets in the 35-85% RH range. Instead of growing with increasing relative humidity internally mixed particles build up a solid crystalline layer on the surface. This crystalline phase is not further influenced by ambient relative humidities.     

Capillary electrophoresis of trace metals in highly saline physiological sample matrices

Trace metal ions in highly saline samples such as urine were determined with capillary electrophoresis (CE) without desalting or off-line preconcentration. By mixing with a dye, 4-(2-pyridylazo) resorcinol (PAR), the metal ions were converted into anionic complexes having strong absorbance near 500 nm. A large volume of the metal-PAR complex sample solution injected into a coated capillary was stacked isotachophoretically and separated under a reverse potential. The salt anion (chloride) and PAR in the sample matrix acted as the leading and terminating electrolytes, respectively. In a sample containing a 250 mM NaCl matrix, more than 400-fold enhancement in the absorbance detector response was realized compared to the normal CE injection mode. Combination of the dye complexation and isotachophoretic stacking provided excellent detection limits (S/N = 3) for three trace metal ions in the low ppb range (Fe(2+), 0.7 ppb, Ni(2+), 0.4 ppb; Zn(2+), 1.2 ppb) with absorbance detection. The migration time reproducibility was excellent (relative standard deviations: standard samples < 1%, urine samples approximately 1%). The proposed method is convenient and fast, and the sample analysis can be completed within 20 min.     

Secondary ion mass spectrometry in the characterisation of boron-based ceramics

A secondary ion mass spectrometry (SIMS) study of Zr- and Ti-based borides is reported: ZrB2 ceramic samples (with and without nickel addition) and a TiB2-Ni-B4C/Cu joint were investigated. For Zr-based samples, SIMS measurements show evidence for induced effects by the presence of nickel with regard to oxygen and hydrogen absorption and zirconia formation. In the case of the TiB2-Ni-B4C/Cu joint, the ceramic-metal interface region was analysed and the extent of Cu diffusion into the ceramic material was established. SIMS results were in agreement with previously obtained SEM-EDS data.     

镉基体分离及纯镉中杂质成分的ICP-MS法测定

研究了用阴离子交换树脂分离纯镉中铜、锌、铅、铁的条件，所得优化分离条件为：717型阴离子交换树脂柱，样品溶液为2mol/L HCl溶液；三段淋洗液依次为2mol/L HCl溶液、0．2mol/L HBr 0．25mol/L HNO3的混合酸溶液及3mol/L HNO3溶液。经ICP-MS测定证明，95％以上的镉得到分离，95％以上的铜、锌、铅、铁可以分离测定，有效地降低了ICP-MS测定纯镉中铜、锌、铅、铁时镉基体的干扰。     

The Effect of the Compatibilization Route of PA/PO Blends on the Physico-chemical Phenomena Developing Along a Twin-screw Extruder

The effect of the compatibilization method (ex-situ, in-situ, cross linking) on the chemical conversion, morphological and rheological evolution of polyamide/polyolefin blends along a twin screw extruder is investigated. For this purpose, samples were quickly collected from the extruder at specific barrel locations, quenched and subsequently characterized off-line. While significant changes occur very quickly in the melting zone for the ex-situ and in-situ routes, changes of the cross linking system could be detected along all the extruder. Correlations between chemical conversion, particle size and linear viscoelastic response could be established.     

Quantification of copper and zinc species fractions in legume seeds extracts by SEC/ICP-MS: validation and uncertainty estimation

Fractions of Cu and Zn species in legume samples (common white bean, pea, chick pea and lentil seeds and defatted soybean flour) were analysed by on-line hyphenation of size exclusion chromatography and inductively coupled plasma-mass spectrometry. Samples were extracted by 0.02 mol l⁻¹ Tris–HCl buffer solution, pH 7.5. The extraction efficiency lay in the region 60–90 and 60–80% for Cu and Zn, respectively. Quantification of elements in the individual chromatographic fractions was carried out by isotope dilution (ID) and external calibration (EC) techniques. For ID analysis the chromatographic effluent was mixed with the flow of ⁶⁵Cu and ⁶⁸Zn isotope enriched solution and the isotope ratio values ⁶³Cu/⁶⁵Cu and (⁶⁴Zn+⁶⁶Zn)/⁶⁸Zn were measured. In the case of EC technique calibration solutions of elements were injected to the flow of mobile phase by the second injector. Prior entering detector the effluent was mixed with the flow of internal standard solution (In, 50 μg l⁻¹). Both methods have similar precision, however the behaviour of both studied elements was not the same. The chromatographic analysis itself was the main source of variability in the case of Cu. For Zn species analysis, the extraction process and the manipulation with the extract, played the significant role too. It was probably caused by lower stability of the present zinc chelates. The total amounts of Zn found in all chromatographic fractions represented 85–95% of Zn in sampled extract whereas those of Cu approached 100%. In case of small peaks the results of ID and EC were not the same. The EC results were lower then ID results. The great deal of results uncertainty accounts for the precision.