The corrosion behavior of Ni-P deposits with high phosphorous contents in brine media

The corrosion behavior of Ni-P deposits with the phosphorous contents of 20, 24 and 28 at.% (denoted as Ni-20P, Ni-24P, and Ni-28P, respectively) and annealed in air at different temperatures was systemically compared in a brine medium containing 3 wt.% NaCl. The anticorrosive properties of these Ni-P deposits were further examined in a brine-fog test (using a 5 wt.% NaCl solution) under 37 degreesC for 24 h. In the electrochemical studies, the Ni-28P deposit showed the lowest corrosion rate when it has been annealed between 200 and 300 degreesC. This deposit also exhibited the highest corrosion resistance in the studies of linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). In the brine-fog study, the weight loss of the Ni-P deposits was found to decrease with increasing the phosphorous content. After the brine-fog test, there was no obvious change in morphologies for all Ni-P deposits with the annealing treatment at 300degreesC. (C) 2003 Elsevier Science B.V. All rights reserved.