Electrochemical Noise and Polarization Analyses on Corrosion of Al-Brass Alloy During Erosion-Corrosion

Abstract

It is known that impingement of solid particles on the surface of alloys could cause an increase in corrosion rate during erosion-corrosion. The increase in corrosion rate by erosion could be studied using the common electrochemical technique of polarization. Electrochemical noise method, on the other hand, has been widely used to study the localized corrosion. This technique could provide useful data on the effect of single particle impact on the corrosion rate of materials. In the present paper, both techniques of polarization and electrochemical noise were used to study the corrosion behavior of Al-brass alloy during erosion-corrosion. The erosion-enhanced corrosion rate was calculated and the results obtained from these two techniques were compared. The erosion-corrosion tests were performed at various sand concentrations of 0–30 g/l and different particle sizes. Under sand concentrations lower than 10 g/l, the electrochemical noise technique as a proper method for analysis of localized corrosion showed higher accuracy in measuring the erosion-enhanced corrosion as compared with the polarization method. However, at the concentrated slurries, higher possibility of simultaneous impacts and, therefore, overlapping of the current peaks imposed some limitation for the electrochemical noise method. The polarization and noise analyses revealed that an increase in the particle size resulted in an increase up to 2.8 times in the erosion-enhanced corrosion rate of the alloy.