Muralidharan, V.S. and Veerashanmugamani, M. and Paruthimalkalaignan, G. and Arulraj, I.
(1985)
Mechanism of corrosion of pure nickel in sulphuric acid solutions.
Bulletin of Electrochemistry , 1 (3).
pp. 241-244.
ISSN 0256-1654
Abstract
The anodic behaviour of nickel in acid baths in plating, electrowinning and pickling processes
is of industrial concern. Potentiostatic measurements were carried out to find corrosion rates
in different concentrations of sulphuric acid solutions. To understand the dependence , o, E, f
and I, on solution parameters, a detailed investigation on nickel dissolutjon and hydrogen
evolution has been carried out. In the mechanism of nickel dissolution, the number of
electrons transferred has been identified from the equilibrium potential us concentration of
~ip"lo ts. The anodic and cathodic Tafel slopes, anodic and cathodic reaction orders with
respect to ~iio~ns, 'su lphate ions and pH revealed that the ratedetermining step for
dissolution is
NiOH,,,, . -. NiOH' + e.
The variation of cathodic current densities with the concentration of H' ions, or sulphate ions,
and the value of 135 f 15 mV/ decade for Tafel slope suggest the rate determining step as
H'+e -. H.
The rate of sulphate ions on enhancing the exchange current density of the hydrogen
evolution reaction has been pointed out
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