Effect of a time-dependent magnetic field on the corrosion of Ni-Al bronze

Abstract

Nickel-aluminum bronze (NAB) was anodically polarized in a solution of 3.5 wt% NaCl and exposed to a time-dependent magnetic field (TDMF) with an amplitude of 180 mT. The effect of a TDMF on the anodic behavior of NAB has been investigated as a function TDMF frequency (0 Hz to150 Hz) and the anodic polarization potential (−180 mVAg/AgCl to −25 mVAg/AgCl). The results show that the anodic current density at a fixed, anodic potential increases when NAB is exposed to a TDMF. The effect increases with frequency of the TDMF, and is highest for the lowest polarization potentials. At −180 mVAg/AgCl, the current density increased by 800% when the sample was exposed to a TDMF of 150 Hz. The increase in current density is explained in terms of joule heating resulting from the induced eddy currents in the NAB sample. The increased anodic reaction at increasing temperature was documented by recording polarization curves at 20°C, 40°C, and 60°C. The results emphasize a potential limitation of the use of NAB in close proximity to TDMFs in chloride-containing media.