Electrodeposition of Co-Ni and Co-Ni-Cu systems in sulphate-citrate medium

Electrodeposition of Co-Ni and Co-Ni-Cu alloys was performed in a sulphate-citrate medium. Experimental electrodeposition parameters (pH, cobalt(II), nickel(II) and citrate concentrations) were varied in order to analyse their influence on the deposition. Anomalous Co-Ni codeposition occured in the citrate medium. High [Ni(II)]/[Co(II)] ratios (above 5) were suitable for the preparation of homogeneous magnetic Co-rich Co-Ni deposits of hexagonal close-packed (hcp) structure or face centred cubic (fcc) structure as a function of the deposition potential.The presence of very low copper(II) concentrations (<10⁻² mol dm⁻³) in the nickel-cobalt bath makes it possible to incorporate copper in the deposits in amounts ranging from 5 to 60% Cu, although uniform deposits are obtained only for low copper percentages. These ternary deposits are solid solutions with fcc structure and magnetic behaviour both dependent on the deposition potential.     

Electrodeposition of cobalt-nickel alloys from ammoniacal single-complex baths

The electrodeposition of cobalt-nickel alloys has been studied from ammoniacal single-complex baths containing 5–50 CoSo₄·7H₂O, 5–50 NiCl₂·46H₂O, 20–50 g dm^?3 (NH₄)₂SO₄ and 250–350 cm³ dm^?3 NH₄OH (20.5% solution). The effects of the plating current density and the concentrations of the bath constituents on the cathodic polarisation, current efficiency and composition of the alloy were investigated. A wide range of alloy compositions with a current efficiency of 60–80% could be obtained from the main baths examined. The alloy plating system interchanged between the normal and the anomalous types depending upon the plating current density and the concentration of NH⁺₄ ion in the bath. Electron microscopic and X-ray diffraction studies proved that the structure of the electrodeposited alloy was controlled by the alloy composition.     

On the state of W in electrodeposited Ni-W alloys

We have derived an expression for the theoretical dependence of the Ni-W fcc phase lattice parameter on the atomic fraction of W, in a solid solution. This parameter was used to compare the actual quantity of W, in a solid solution of electrodeposited Ni-W alloys, with the value determined by EDX. It has been shown that not all of the W determined by EDX was present as a solute in the Ni-W fcc phase. The incorporation of tungstates prevailed at lower pH, while the presence of citric complexes dominated at higher pH values. This conclusion was based on the XRD phase analysis of electrodeposited alloys that were annealed in hydrogen or argon atmospheres at 1000 °C. The XRD data correlated well with the morphology results obtained via AFM. The incorporation of tungstates or citric complexes seems to be characteristic of the electrodeposited Ni-W alloys.     

Fabrication of cobalt-nickel binary nanowires in a highly ordered alumina template via AC electrodeposition

Cobalt-nickel (Co-Ni) binary alloy nanowires of different compositions were co-deposited in the nanopores of highly ordered anodic aluminum oxide (AAO) templates from a single sulfate bath using alternating current (AC) electrodeposition. AC electrodeposition was accomplished without modifying or removing the barrier layer. Field emission scanning electron microscope was used to study the morphology of templates and alloy nanowires. Energy-dispersive X-ray analysis confirmed the deposition of Co-Ni alloy nanowires in the AAO templates. Average diameter of the alloy nanowires was approximately 40 nm which is equal to the diameter of nanopore. X-ray diffraction analysis showed that the alloy nanowires consisted of both hexagonal close-packed and face-centered cubic phases. Magnetic measurements showed that the easy x-axis of magnetization is parallel to the nanowires with coercivity of approximately 706 Oe. AC electrodeposition is very simple, fast, and is useful for the homogenous deposition of various secondary nanostuctured materials into the nanopores of AAO.     

XRD studies of the phase composition of the electrodeposited copper-rich Cu-Sn alloys

Studies of the phase and chemical compositions as well as of the surface morphology of Cu-Sn alloys electrodeposited in the sulphate solution containing laprol were carried out using the XRD, SEM, and EDX techniques. The multiphase composition—pure copper, the α-CuSn phase and the intermediate hcp phase were determined to be present in the deposits obtained at cathode potentials positive to that of the reversible of the Sn/Sn²⁺electrode. When the content of Sn in the deposit was higher than 12-13 at.%, the β and/or δ phases were determined to be present along with that mentioned above. The deposit obtained at the potentials negative to that of the reversible of the Sn/Sn²⁺ electrode presented the δ phase with low quantities of the pure Cu and α-CuSn phases. The grain size of deposits increased with the cathode potential until it was positive to that of the reversible of the Sn/Sn²⁺ electrode. The presence of Br⁻ ions in the solution hindered the granular electrocrystallization and reduced the Sn proportion in the alloy. It was assumed that underpotential deposition (UPD) of Sn on copper could be responsible for the formation of the multiphase composition and the intermediate hcp phase. It was concluded that the brightness of the studied Cu-Sn coatings was conditioned by the surface morphology.     

Magnetic properties of nanocrystalline iron group thin film alloys electrodeposited from sulfate and chloride baths

Systematic studies of iron group binary (NiCo and CoFe) and ternary (CoNiFe) thin film alloys relating their magnetic properties with film composition, grain size and the corresponding crystal structure were investigated. Anions influence current efficiencies, magnetic properties, surface morphology and phases of electrodeposited films. Higher current efficiencies in chloride baths compared to sulfate baths were observed for CoFe, NiCo and CoNiFe alloys. The higher deposition current efficiencies in chloride baths were attributed to a catalytic effect. Anion types in CoFe and CoNiFe thin film alloys influenced the microstructures and the resulting magnetic properties (coercivity and squareness). The microstructures of NiCo alloys depend on the deposit Co contents rather than anion types. The surface morphologies of CoFe, NiCo and CoNiFe thin films were independent of anion types. CoFe deposits exhibited relatively smooth surface morphology and turned into fine crystallites with increasing solution Fe⁺² concentration. NiCo deposits showed very smooth surface morphology. CoNiFe deposits had the surface morphology of polyhedral crystallites. The deposit Fe content in CoFe electrodeposits linearly increased with increasing solution Fe⁺² concentration for both chloride and sulfate baths. Similar linear behavior of deposit Co contents was observed in NiCo electrodeposits.     

磺基甜菜碱型氟碳表面活性剂在蒙脱土上的吸附性能

针对黏土吸附表面活性剂造成的损耗使得二元复合驱不能具有很好的协同效用,采用比色法研究了磺基甜菜碱型氟碳表面活性剂（FS）在钠基蒙脱土上的吸附性能,并考察了醇、部分水解的聚丙烯酰胺（HPAM）、pH值、温度对FS在钠基蒙脱土上吸附量的影响。结果表明：加入10%(体积)的不同种类的醇时,甲醇、乙醇、异丙醇、正丁醇降低FS在蒙脱土上的吸附,而辛醇、癸醇、乙二醇、丙三醇则增加FS在蒙脱土上的吸附,其中乙醇使FS吸附量降低67.25%,辛醇使FS吸附量增加86.76%;所以分子量相对较小的醇能降低FS相似文献   

Structural and magnetic properties of a stage-2 HoCl3-graphite intercalation compound

A stage-2 HoCl₃-GIC has been synthesized and characterized by XRD experiments and magnetic measurements. EDS and 00l X-ray analyses lead to the chemical formula C_23.8HoCl_3.7.The c-axis repeat distance is 1313 ± 5 pm, and the stacking sequence of intercalated HoCl₃ along the c-axis corresponds to the layer sandwich Cl-Ho-Cl, where the distance between Ho and Cl layers is 157 pm. The HoCl₃ in-plane structure is oblique with lattice parameters a = 689 pm, b = 1177 pm, γ = 149.6° close to those in the pristine crystal. It presents two different micro-domains disorientated with respect to graphene planes by θ₁ = ± 19°. Magnetic studies show that Ho³⁺ ions obey the Curie-Weiss law for both pristine HoCl₃ and stage-2 HoCl₃-GIC. The presence of graphene planes between HoCl₃ intercalated layers leads to an increased Curie-Weiss temperature and to a decrease in the weak antiferromagnetic interactions between Ho³⁺ ions.     

Property modifications of finished textiles by a cationic surfactant

Fabrics made of 100% cotton, 100% polyester and a 50/50 cotton/polyester blend with and without functional finishes were treated in aqueous solutions of the cationic surfactant distearyldimethylammonium bromide (DSDMAB). Finishes chosen were dimethyloldihydroxyethyleneurea (DMDHEU), a durable press finish, and poly(acrylic acid), a soil release finish. Selective sorption of the cationic surfactant by finished and unfinished fabrics was quantified. Cotton takes up much larger amounts of DSDMAB than does polyester. In general, acrylic finished fabrics take up more DSDMAB, while DMDHEU finished fabrics take up smaller amounts of DSDMAB as compared to their unfinished controls. These findings indicate that ionic interaction forces play an important role in the sorption process. In order to investigate this, acid numbers were used as a relative measure of negative sorption sites on fabrics. A direct relationship between DSDMAB sorption and the acid numbers of the fabrics was established. Perceived fabric softness is generally improved by treatments with DSDMAB for all test fabrics. Although cotton fabrics finished with DMDHEU were perceived to be less soft than unfinished cotton, treatment with DSDMAB restored the softness level to that of unfinished cotton. The softness of both cotton and polyester fabrics was greatly lowered by the acrylic finish. The presence of even large amounts of DSDMAB did not restore softness ratings to levels comparable to unfinished controls. Electrical resistivity and electrostatic clinging measurements were used to assess the effectiveness of DSDMAB as an antistatic agent. DSDMAB reduced the electrical resistivities of all test fabrics. However, relative humidity played a much larger role in reducting the electrical resistivity of fabrics. Clinging times were also reduced by DSDMAB treatments. DSDMAB was particularly efficient in reducing the clinging time of polyester. Additional moisture related properties were investigated. The presence of DSDMAB on the test fabrics did not significantly alter moisture regain. The application of DSDMAB from aqueous solutions resulted in lower water retention values of the test fabrics after centrifuging at ag-factor comparable to home washing machines. This leads to energy savings during drying from 10–24%, depending on the fabric and finish type. However, energy savings due to fiber type were more significant than those due to the cationic surfactant treatment.     

阳离子型聚氨酯乳液的合成与性能初探

对阳离子水性聚氨酯乳液及其膜性能进行了初步的研究。用N -2 10 ,甲苯二异氰酸酯 (TDI) ,N -甲基二乙醇胺(MDEA)为原料 ,以及丙酮作为溶剂来制备阳离子型水分散聚氨酯。讨论了MDEA的用量和NCO/OH比值对乳液及其膜性能的影响。并进行了红外光谱分析。     

有机添加剂对电沉积Fe-Co-Ni合金的影响

通过测定阴极极化曲线和电沉积试验，研究了有机添加剂对电沉积铁－钴－镍合金的影响。认为含硫有机添加剂通过在电极表面的吸附，促进或延缓金属离子的还原反应，而络合剂则通过选择性络合阳离子，起稳定电解液、调节合金组份的作用。     

On the mitigation of erosion-corrosion of copper by a drag-reducing cationic surfactant in turbulent flow conditions using a rotating cage

Erosion-corrosion is a complex materials degradation mechanism involving the combined effects of mechanical erosion and electrochemical corrosion. It is known to be induced by high shear stresses in strong flows.One way to mitigate this phenomenon is to use additives reducing the turbulent Reynolds stresses. Oleyltrimethyl ammonium cationic surfactant and sodium salicylate as counter-ion known to form thread-like micelles behaving as drag reducers were tested in this work and successfully imaged by using AFM technique.A shear stress mapping in the rotating cage using an electrochemical method was implemented in the absence and in the presence of surfactant, showing drag reduction amounts up to 65%. In a second step, erosion corrosion of Cu in Na₂SO₄ 0.1 M in the presence of small amounts of NaCl (1 mM) was investigated on Cu microelectrodes located at different positions on plastic coupons in the cage. The surfactant effect was found to be beneficial by preventing the removal of the pre-existing oxide films, otherwise observed in the absence of surfactant. Tests performed with benzotriazole known as a good corrosion inhibitor for Cu, could not prevent either the breaking of the oxide film in strong flow conditions.     

Influence of the alloying component on the protective ability of some zinc galvanic coatings

The composition of the corrosion products of pure Zn galvanic coatings as well as of some zinc alloys (Zn-Mn and Zn-Co) after treatment in selected free aerated model media (5% NaCl and 1N Na₂SO₄) is studied and discussed. X-ray diffraction and X-ray photoelectron spectroscopy investigations are used for this purpose. It is concluded that the corrosion products (zinc hydroxide chloride hydrate in 5% NaCl and zinc hydroxide sulfates hydrates in 1N Na₂SO₄) play a very important role for the improved protective ability of the zinc alloys toward the iron substrate, compared to the pure Zn coatings. Another result is that, for a given medium, the corrosion products are one and the same for both alloys independently of the fact that the alloying component is electrically more positive or negative than the zinc. Some suggestions about the models of the appearance of these products and their protective influence are also discussed.     

一种含羧基表面活性剂HDXA界面特性研究

通过系统研究一种含羧基表面活性剂HDXA的界面张力特性,表明在一定条件下,该表面活性剂在0.05%~0.4%的范围内可形成10-3mN/m数量级的超低界面张力,添加剂的加入能使油水界面快速的达到最低界面张力,其中最低界面张力和稳定界面张力值均低于单一表面活性剂体系,活性剂HDXA浓度不同时,最佳添加剂浓度也随之改变。不同活性剂浓度达到最低界面张力及稳态界面张力的时间也不同,随着浓度的增大依次缩短。     

Voltammetric study of the influence of benzotriazole on copper deposition from a sulphuric plating bath

Copper electrodeposition on to a platinum substrate from an acid sulphate plating bath was investigated with and without the additive benzotriazole (BTAH). In voltammetric experiments, the deposition process is shifted to more negative potentials in the presence of BTAH than in its absence from the bath. Moreover, the current density of the deposition process was higher in the presence of this additive than in its absence. With or without the additive, copper deposition showed features of nucleation in the voltammetric curves. Scanning electronic microscopy (SEM) images showed that copper deposits laid down in the presence of BTAH, for any potential and charge density studied, were smoother than in the absence of this additive. X-ray spectra indicated that the electrodeposits produced in the absence or presence of BTAH were composed of a mixture of copper, copper oxide and platinum oxide and also indicated that in the presence of BTAH, the deposit was less crystalline than in its absence.     

Remarkable solvent effect on the structure and electrochemical properties of [M(bipyridyl)3](ClO4)3 (M = Co, Fe and Ru) films

In low dielectric constant media the electrooxidation of bipyridyl complexes of transition divalent metal cations, such us Fe(II), Co(II), and Ru(II) results in the precipitation of microcrystalline film on the electrode surface. In most solvents, the film is reversibly reduced. However, films formed in the presence of acetonitrile are electrochemically inactive over a large potential range. The morphology and crystallographic structure of solid phase formed on the electrode surface during the electrochemical oxidation of bipyridyl complexes of Co(II), Fe(II), and Ru(II) have been investigated by the scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier transformation-IR/horizontal attenuated total reflectance (FT-IR/HATR) spectroscopy and elemental analysis. A correlation between the electrochemical properties and the structure of the film has been found. The electrochemically inactive films of Co(II) and Fe(II) complexes formed in the presence of acetonitrile in solution consist of densely packed column-like crystallites. They exhibit monoclinic symmetry P/2m (no. 10). The other films formed in acetonitrile free solutions, form flower-like aggregates of orthorhombic symmetry Pmmm crystals (no. 47). These films are very porous.     

Preparation and properties of a new type of carbohydrate-based cationic surfactant

A new type of cationic surfactant, 6-O-monoesters of 3-(trimethylammonio)propyl d-glucopyranoside, was prepared in high yield by a simple chemoenzymatic synthesis. Surface-active properties of the compounds were found to be highly dependent on the fatty acyl chain length in the 6-O-position with the dodecanoyl and tetradecanoyl esters exhibiting the highest ability to lower surface tension as well as having the lowest critical micelle concentration values. Furthermore, the dodecanoyl ester had excellent foaming properties. The new surfactants also showed antimicrobial activity. Thus, the most potent compound, the dodecanoyl ester, was able to inhibit growth of both bacterial (Gram-positive as well as Gram-negative) and fungal test strains. The antimicrobial effect was somewhat weaker compared to benzalkonium chloride, one of the most frequently used cationics for topical disinfection. However, compared to benzalkonium chloride, the new cationics exhibit a highly improved compatibility with anionic surfactants, as no precipitation took place even in highly concentrated solutions thereby providing a much more robust antimicrobial system. Finally, the new surfactants are expected to be readily biodegradable because they are carbohydrate ester-based.     

The influence of cationic surfactant CTAB on optical,dielectric and magnetic properties of cobalt ferrite nanoparticles

In the present work, the influence of cationic surfactant CTAB (cetyltrimethylammonium bromide) on size, shape and coalescence behaviour of cobalt ferrite nanoparticles (CFNPs) synthesized via hydrothermal method is reported. Pure CFNPs show no additional peaks, whereas α-Fe₂O₃ phase is observed in CTAB added CFNPs upon annealing. FT-IR analysis confirms the formation of M − O vibrational bands (metal -oxygen) at tetrahedral A-site and octahedral B-site for both samples. SEM observations reveal less agglomeration and smaller particle size for surfactant added CFNPs. Raman spectral study confirms the formation of cubic spinel structure and Raman active modes of CTAB added CFNPs. UV–Vis spectra indicate a decrease in the energy band gap with annealing. The dielectric constant of surfactant added CFNPs decreases with increasing applied frequencies for both real and imaginary, but ac conductivity increases with increasing frequencies. Two sextet patterns of Fe³⁺ trivalent ions from tetrahedral and octahedral sites are observed in Mössbauer spectra. VSM study indicate the ferrimagnetic nature of CTAB added CFNPs. The electrochemical analysis reveals the pseudocapacitive nature of working electrode prepared by CTAB added CFNPs.     

一种季铵盐阳离子表面活性剂的合成与性质

以氯丙烯与N,N-二甲基十二烷基胺(DTA)为原料合成了季铵盐阳离子表面活性剂十二烷基二甲基烯丙基氯化铵(DADAC);研究了原料配比、反应温度、反应时间和溶剂等因素对生成物DADAC收率的影响,通过红外光谱、元素分析确定其化学结构。较佳反应条件为:n(氯丙烯)∶n(DTA)=3∶1,无水乙醇为溶剂,50℃下反应24 h,DADAC收率为93.76%。最后测定了产物的表面性能,得到25℃下,DADAC的cmc为5.76 mmol/L,在cmc时的γ=34.2 mN/m,Krafft点<0℃。