Metal-Solution Potentials of Nickel in Foreign Ion Solutions and the Mechanism of Nickel Corrosion

Abstract

Phase boundary potentials of nickel in various aqueous solutions, practically free from nickel ions, have been measured. The nickel-solution potentials in air drift and reach high positive (noble) potentials. The potentials of nickel vs. solution in an inert gas reach stationary values after several hours, depending upon the pH. The final potentials remain negative with respect to the standard hydrogen electrode. The differences of the corresponding potentials in the same solution, in presence of air and in absence of air, range up to half a volt or more. The role played by oxygen in influencing the potentials has an interesting bearing on the initial stages of the corrosion of nickel.

Electrode Potentials in Fused Systems. I. Sodium Hydroxide

“…Probably the solution of surface impurities occurs rapidly only at temperatures higher than the melting point of sodium hydroxide. 6. In Table I are listed the steady-state electrode potentials of the metals studied.…”

“…Virtually no work of this kind has been reported in the literature although several workers have studied foreign ion cells in aqueous solutions. [4][5][6][7][8] The work of MacGillavry and co-workers on the potential of nickel in foreign ion solutions, including aqueous sodium hydroxide, is of interest and will be referred to later. Lux has studied reactions in various melts, particularly on the addition of oxides to a K2SO4-LÍ2SO4 eutectic at 950°.9 He found that gold electrodes could be used to follow the progress of a reaction by measuring the change in potential between a reference and an indicator electrode.…”