Anodic dissolution of Ni in 1 N H2SO4 studied by dynamic impedance measurements

✍ Scribed by H.G. Feller; H.-J. Rätzer-Scheibe; W. Wendt

• Publisher: Elsevier Science
• Year: 1972
• Tongue: English
• Weight: 579 KB
• Volume: 17
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(72)85020-5

✦ Synopsis

The anodic dissolution of 99.999 %Ni in 1 N H,SO, has been studied by dynamic impedance measurements using a lock-in-amplifier. The method allows the simultaneous dynamic recording of 1/V and impedance curves. The capacitance/potential curve shows two distinct maxima in the transpassive region at about 1400 mV(nhe). In this region the I/Y curve displays only a monotonic increase of I with V. The potential range at which the two C, maxima occur has &n studied as a function of the velocity of the potential change (0.1 V/h < dV/dr < 20 V/h) and of pH (O-3 < pH < 5.3). The results lead to the conclusion that the first maximum at less noble potential is due to a subsequent oxidation of the passive layer and the second maximum is due to an irreversible adsorption reaction. R&sum&-Etude de la dissolution anodique de Ni & 99.999% darts H.SO, 1 N par des mesures d'im-p&lance dynamique. La methode d&c&e permet les enregistrements dynamiques simultanb des courbes I/ Vet d'imp&lance. La courbe capacitance/potential manifeste deux maxima distincts dans la region transpassive a environ 1400 mV(nhe). Dans cette region la courbe IIVpresente seulement un