caa a22 4500 475815564 CHVBK 20180406123809.0 cr unu---uuuuu 170329e20001001xx s 000 0 eng 10.1023/A:1004002303181 doi (NATIONALLICENCE)springer-10.1023/A:1004002303181 Evaluation of nickel deposition by electrochemical impedance spectroscopy [Elektronische Daten] [M. Holm, T.J. O'Keefe] Electrochemical impedance spectroscopy was used to characterize the deposition of nickel from unbuffered acid sulfate electrolytes, from which a wide range of deposit morphologies and current efficiencies are possible. The operating parameters were in the range of 40 to 60 g L−1 Ni2+, 40 to 60 °C, and the pH from 2.0 to 3.5. The resulting impedance spectra for nickel deposition at 20 mA cm−2 consisted of one or two characteristic loops whose frequency and capacitance were dependent upon the electrowinning conditions and indicative of the resultant deposit morphology. A single high frequency capacitive loop, on the order of 1 kHz, correlated to good quality deposits which were flat, smooth and ductile. The presence of a low frequency loop, on the order of a few hertz, indicated a degraded deposit morphology which showed localized dark, glassy areas and were cracked, curled and brittle. The second loop may be associated with a diffusion controlled component in the reaction mechanism. Deposits of intermediate quality had impedance spectra consisting of both type loops. No apparent trend between the impedance spectra and the deposit current efficiency was determined, but a correlation with deposit quality was clearly established. Kluwer Academic Publishers, 2000 acid sulphate electrolyte nationallicence deposit morphology nationallicence electrochemical impedance spectroscopy nationallicence nickel deposition nationallicence Holm M. Department of Metallurgical Engineering and Graduate Center for Materials Research, University of Missouri-Rolla, Rolla, 65401, Missouri, USA aut O'Keefe T.J. Department of Metallurgical Engineering and Graduate Center for Materials Research, University of Missouri-Rolla, Rolla, 65401, Missouri, USA aut Journal of Applied Electrochemistry Kluwer Academic Publishers 30/10(2000-10-01), 1125-1132 0021-891X 30:10<1125 2000 30 10800 https://doi.org/10.1023/A:1004002303181 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1004002303181 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Holm M. Department of Metallurgical Engineering and Graduate Center for Materials Research, University of Missouri-Rolla, Rolla, 65401, Missouri, USA aut NATIONALLICENCE 700 1- O'Keefe T.J. Department of Metallurgical Engineering and Graduate Center for Materials Research, University of Missouri-Rolla, Rolla, 65401, Missouri, USA aut NATIONALLICENCE 773 0- Journal of Applied Electrochemistry Kluwer Academic Publishers 30/10(2000-10-01), 1125-1132 0021-891X 30:10<1125 2000 30 10800 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer