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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface & Coatings Technology 63 (1994), S. 97-103 
    ISSN: 0257-8972
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface & Coatings Technology 53 (1992), S. 171-176 
    ISSN: 0257-8972
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 17 (1987), S. 574-582 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Operating conditions for zinc and nickel codeposition from chloride baths were studied in order to obtain alloys containing up to 20% nickel. Satisfactory deposits were produced at 50°C using current densities ranging from 5 to 20 mA cm−2 and nickel to zinc ratios ranging from 6.8 to 37.5%. Under the conditions studied, an empirical relationship was deduced in order to calculate the nickel percentage in the deposit from baths of prefixed composition using a given current density. Deposits having a nickel concentration lower than 11% were found to comprise the δ and γ phases, while at higher nickel concentration (up to 20%), the alloys showed only the γ phase structure, with preferred orientation (442) and (600) and excellent microhardness and corrosion resistance properties.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 27 (1997), S. 1088-1094 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electrodeposition of Zn–Co alloys on iron substrate from chloride baths under galvanostatic and potentiostatic conditions were carried out. Current density, temperature and cobalt percentage in the bath were found to strongly influence the composition of the deposits and their morphology. Changes in potentials, current efficiency and partial current densities were studied. The results show that the shift in potential and in the cobalt percentage of the deposits, for a particular current density during galvanostatic electrodeposition, does not always correspond to the transition from normal to anomalous codeposition. This shift is attributed to zinc ion discharge, which passes from underpotential to thermodynamic conditions. In the range of potentials for the underpotential deposition of zinc, the electrodeposition of zinc–cobalt alloys is discussed, emphasizing the influence of the electrode potential on the composition and microstructure of the deposits.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-8838
    Keywords: alloys ; electroless ; microstructure ; morphology ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy coatings were obtained on an iron substrate from a sulfate bath at various pH values. The effects of changes in bath pH on alloy composition, morphology, microstructure and corrosion resistance were studied. Scanning electron microscopy was performed to observe the morphological change of the deposits with bath pH. Coating crystallinity was investigated by grazing incidence asymmetric Bragg X-ray diffraction and transmission electron microscopy. A transition from an amorphous to polycrystalline structure was observed on increasing the bath alkalinity, and thus decreasing the phosphorus content of the alloys. A single crystalline phase corresponding to face-centred-cubic nickel was identified in the alloys obtained from a strong alkaline solution. An increase in zinc percentage up to 23% in the deposits does not change the f.c.c. nickel crystalline structure. Corrosion potential and polarization resistance measurements indicated that the corrosion resistance of electroless Ni–Zn–P alloys depends strongly on the microstructure and chemical composition. The deposits obtained at pH 9.0–9.5 and with 11.4–12.5% zinc and 11.8–11.2% phosphorous exhibited the best corrosion resistance.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 29 (1999), S. 1171-1176 
    ISSN: 1572-8838
    Keywords: alloys ; cyclic voltammetry ; electrodeposition ; electroless deposition ; nickel ; phosphorus ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Electroless Ni–Zn–P alloy deposition from a sulphate bath, containing sodium hypophosphite as reducer, was investigated. To increase the plating rate, the deposition parameters were optimized. The effect of process parameters (T, pH and [Zn2+]) on the plating rate and deposit composition was examined and it was found that the presence of zinc in the bath has an inhibitory effect on the alloy deposition. As a consequence, the percentage of zinc in the electroless Ni–Zn–P alloys never reaches high values. Using cyclic voltammetry the electrodeposition mechanism of Ni–Zn–P alloys was investigated. It was observed that the zinc deposition inhibits the nickel discharge and, as a consequence, its catalytic activity on hypophosphite oxidation. It was also found that increase in temperature or pH leads to the deposition of nickel rich alloys.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Zinc and zinc-nickel (13% Ni) electrodeposits were passivated by dipping in chromate baths and characterized by scanning electron microscopy. The corrosion behaviour was studied using a.c. electrochemical techniques; electrochemical impedance spectroscopy (EIS) measurements were performed at open circuit and under galvanostatic control during the 24 h immersion time. In sodium chloride solution the zinc-nickel electrodeposits show a better corrosion resistance compared to the pure zinc coatings. During the immersion time, a surface nickel enrichment was observed which, together with the zinc corrosion products, acts as a barrier layer reducing the total corrosion rate. In the same solution the passivation treatment improves the corrosion resistance of the electrodeposits; nevertheless, on zinc substrates, the protection exerted by the chromate film is not, always effective during the immersion time. On the contrary the chromate coating on zinc-nickel substrates induces a remarkable and durable improvement of the corrosion resistance reducing the zinc dissolution almost completely. In the ammonium sulphate solution, the corrosion mechanism is significantly influenced by hydrogen reduction on the zinc-nickel surfaces, and by the production of a local surface acidity which is aggressive for the chromate coatings.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 10 (1980), S. 765-774 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The kinetics of nickel-zinc co-deposition and the effect of nickel on zinc morphology have been studied by means of chemical analysis, X-ray diffraction and SEM observations of cathodic deposits obtained in various experimental conditions, including acid and alkaline baths. It has been shown that nickel ions, even if present in the electrolyte at very low concentrations (1 ppm), do not deposit under mass transport controlled conditions but are dragged by zinc ions whose concentration influences the nickel current. With regard to zinc morphology, it has been observed that nickel reduces the grain size of the zinc crystals formed during the electrodeposition.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 14 (1984), S. 505-510 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract The codeposition of some elements with lead from fluoborate baths has been studied in order to obtain lead alloys with a low concentration of a second metal. The metals considered were As, Bi, Cu, Sb, Se, Sn and Te. The chemical analysis of alloys obtained in various electrolysis conditions permitted an investigation of the kinetic behaviour of the metals codeposited with lead. The results showed that only Bi, Sb, Se and Te attain a limiting value of discharge current density and that the codeposition is regular for all metals. SEM observation of the deposits revealed that Sb and Se have a marked influence on the crystal morphology while the remaining metals induce only minor modifications.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 22 (1992), S. 657-662 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Zinc-nickel alloys were electrodeposited on steel from chloride baths containing NH4Cl using different plating conditions. Current density, temperature and nickel percentage in the baths were found to strongly influence the composition of the deposits and the morphology. At low current densities transition from anomalous to normal codeposition was observed. The changes in potential, current efficiency, composition and morphology which follow the transition were studied. No increase in the partial current of hydrogen reduction was observed at the potential values from which anomalous codeposition begins; this fact, plus the formation of zinc ammonium complexes, seems to exclude the precipitation of zinc hydroxide at the electrode surface. The electrodeposition of zinc-nickel alloys is discussed emphasizing the importance of kinetic parameters and cathodic potentials.
    Type of Medium: Electronic Resource
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