✍ Scribed by C.H. de Minjer
No coin nor oath required. For personal study only.
Abatraat -The potential of an electrode with a nickel-phosphorus surface undergoes a sudden change to more negative values when it is heated in a solution for electroless nickel @atin& containing hypophosphite as reducing agent. This phenomenon is reported in the literature, but no satisfactory explanation has been given. Some factors affecting the temperature, at which the potential shift occurs, were investigated. The results can be explained by assuming a transition from the passive to the active state. This assumption was sustained by impedance measurements. Some implications of these passivation phenomena in processes in which elecctroless nickel is used, are dealt with.
Nickel sheets, 55 x 10 x 1 mm (area 12cm*), were used for potential-temperature and for polarization measurements.
Pairs of nickel rods, diameter 5 mm, length-100 mm were used for impedance measurements. One of the ends was sandpapered and polished.
Sheets and rods were degreased, first with trichloroethylene, then in a Na,PO, .12H,O solution. After rinsing, the electrodes were anodically etched in 2 M sulfuric acid. After rinsing again they were plated with elcctroless nickel-phosphorus in a solution, containing gl-'
📜 SIMILAR VOLUMES