Repossivation Behavior of Amorphous Ni-P Alloy

A new set of scratching electrode apparatus has been designed to investigate the repassivation behavior of electroless amorphous Ni-P alloy in 3.5% NaCl solution. The results show that the repassivation kinetics obeys the equation, i (t)=-A₁exp (-C₁t) + A₂ exp (-c₂t). In the lower potential, the oxidation of Ni occurs quickly and the stable oxide NiOOH forms on the surface. The oxide film growth follows the ionic conduct mechanism of high electric field. And, in the higher potential, the adsorption process is rapid, and the adsorbed monolayer on the interface makes the bare surface current decrease quickly. The adsorbed anion H₂PO₂^- effectively inhibits the dissolution of Ni site.