Application of the electrochemical noise method to evaluate the effectiveness of modification of zinc phosphate anticorrosion pigment

A variety of approaches have been proposed to achieve an enhancement regarding inhibitive performance of zinc phosphate (ZP) anticorrosion pigment. This work attempts to study behavior of zinc aluminum polyphosphate (ZAPP) representing modified zinc phosphate pigment through electrochemical techniques along with surface analysis. Analysis of the data obtained from electrochemical noise method revealed superiority of ZAPP compared to ZP. The amplitude of the current noise fluctuation and trend of noise resistance variation as well as shot noise theory suggested precipitation of a protective layer in the presence of ZAPP, restricting access of the aggressive species to the steel surface. X-ray photoelectron spectroscopy (XPS) was employed to analyze the sample surface exposed to 3.5% NaCl solution containing modified pigment extract.