The codeposition of Zn-Ni alloys from chloride bath has been studied by means of potentiostatic electrodeposition in the potential range -700 to -1100 mV vs Ag/AgCl, where both normal and anomalous codeposition occurs. Deposition of alloys of different composition, morphology and structure, depending on the cathodic potential, was found. Analysis of the partial current densities showed that the production of nickel rich alloys in the potential range -700 to -900 mV is due to the underpotential reduction of zinc, driven by nickel ion discharge. Morphological and microstructural analyses showed that these alloys have the face-centred-cubic structure of nickel (alpha phase) and that the addition of zinc in the nickel lattice causes internal stresses in the deposits, which are prevalently amorphous. At potentials more negative than -910 mV, corresponding to the equilibrium potential of the zinc rich gamma phase deposition, the rate of deposition of the alpha phase decreases and the further increase in deposit zinc content leads to the formation of the gamma phase, with a decrease in internal stress. In this range of potential, zinc and nickel reduction can occur separately, according to their respective exchange current densities.

Normal and anomalous codeposition of Zn-Ni alloys from chloride bath / Roventi, Gabriella; Fratesi, Romeo; R. A., DELLA GUARDIA; Barucca, Gianni. - In: JOURNAL OF APPLIED ELECTROCHEMISTRY. - ISSN 0021-891X. - 30:(2000), pp. 173-179. [10.1023/A:1003820423207]

Normal and anomalous codeposition of Zn-Ni alloys from chloride bath

ROVENTI, Gabriella;FRATESI, Romeo;BARUCCA, Gianni
2000-01-01

Abstract

The codeposition of Zn-Ni alloys from chloride bath has been studied by means of potentiostatic electrodeposition in the potential range -700 to -1100 mV vs Ag/AgCl, where both normal and anomalous codeposition occurs. Deposition of alloys of different composition, morphology and structure, depending on the cathodic potential, was found. Analysis of the partial current densities showed that the production of nickel rich alloys in the potential range -700 to -900 mV is due to the underpotential reduction of zinc, driven by nickel ion discharge. Morphological and microstructural analyses showed that these alloys have the face-centred-cubic structure of nickel (alpha phase) and that the addition of zinc in the nickel lattice causes internal stresses in the deposits, which are prevalently amorphous. At potentials more negative than -910 mV, corresponding to the equilibrium potential of the zinc rich gamma phase deposition, the rate of deposition of the alpha phase decreases and the further increase in deposit zinc content leads to the formation of the gamma phase, with a decrease in internal stress. In this range of potential, zinc and nickel reduction can occur separately, according to their respective exchange current densities.
2000
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11566/50971
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 87
  • ???jsp.display-item.citation.isi??? 81
social impact