Metal-Solution Potentials of Nickel in Foreign Ion Solutions

Abstract

Metal-solution potentials of nickel in foreign ion solutions were investigated. It was found that nickel may show stationary potentials in potassium hydroxide and phosphate buffer solutions, if oxygen was excluded. The stable potentials were reversible with respect to a change of pH. It was noted that nickel was unable to displace hydrogen from a 0.1 M phosphoric acid solution; nickel dissolved only on admission of air. The possibilities of interpreting the observed potentials are discussed.

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

“…The stationary potentials depend on the concentration of KOH, becoming more negative with increasing KOH concentration. This dependence of nickel potential on concentration of KOH may be explained by preferential adsorption of anions in the boundary layer (1).…”

“…For measurement of the nickel-solution potentials in absence of air, the following procedure was developed and necessary apparatus was constructed for elimination and exclusion of oxygen (1,6). Nickel wire samples were abraded, degreased, and dried.…”

“…A foreign ion system, i.e., a metal in a solution essentially free of its ions, would not be stable unless the metal and the solution do not interact (1), the interiors of the phases remaining unchanged. Since nickel shows marked corrosion resistance in alkaline solutions (2), investigation of foreign ion half cells of nickel appeared promising.…”

“…For these reasons, a vacuum tube electrometer utilizing capacitive input coupling was selected as the null point indicator (1,5). A condenser effectively blocks continuous currents, which might cause irreversible changes in the nature of the foreign ion systems.…”

Electrode Potentials in Fused Systems. I. Sodium Hydroxide

“…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.…”