Effect of different anions on pitting corrosion behaviour of Monel-400 in sea water

The effect of different anions such as sulphides, sulphates, thiosulphates and hypochlorite ions on the pitting behaviour of Monel-400 alloy in 3.5% NaCl solution is investigated. The results indicate that E-pit decreases with increasing concentrations of dissolved sulphide and thiosulphate due to loss of alloy passivity, but addition of different concentrations of sulphate, sulphite and hypochlorite ions move E-pit to more noble values. The alloy samples were examined. by scanning electron microscopic (SEM) measurements to identify the morphology of the sample surfaces.