Electrochemical impedance study of corrosion of B-1900 alloy in the presence of a solid Na 2SO 4 and a liquid 25 wt.% NaCl–75 wt.% Na 2SO 4 film at 800 °C in air

Abstract

Electrochemical impedance spectroscopy (EIS) technique was employed to study the corrosion of B-1900 alloy at 800 °C in air in the presence of a solid Na 2SO 4 and a molten 25 wt.% NaCl–75 wt.% Na 2SO 4 film, respectively. It was found that the Nyquist plot for the corrosion of the alloy was composed of one capacitive loop. The medium resistance decreased and then increased with experimental time in the presence of the Na 2SO 4 film, while the charge transfer resistance reduced with time, which indicated the change of surface deposit from a solid state to a molten state and the occurrence of fast corrosion. As compared with the solid Na 2SO 4 film, the presence of the molten NaCl–Na 2SO 4 film gives rise to smaller impedance. Impedance model was proposed to explain the corrosion behavior of the alloy.