Study on electrochemical behavior of 690 alloy with corrosion products in simulated PWR primary water environment

Abstract

Purpose The purpose of this paper is to study the electrochemical behavior of 690 alloy with corrosion products in simulated pressurized water reactor (PWR) primary water environment. Design/methodology/approach This paper opted for a laboratory study using simulation of high temperature and high pressure environment immersion testing. The electrochemical behavior was studied by potentiodynamic polarization, electrochemical impedance spectroscopy, scanning Kelvin probe microscopy (SKP). Moreover, the corrosion products were analyzed by X-ray photoelectron spectroscopy. Findings The results demonstrated that the particle majority in the 690 alloy corrosion products subsequent to high temperature and high pressure immersion testing were mainly oxides of Fe and Ni, which protected the matrix. As the immersion testing duration increased, the corrosion potential of the 690 alloy apparently increased, and the corrosion current density de'creased, while the corrosion resistance Rf increased gradually along with the density. The SKP demonstrated that the EKP increased by nearly 400 mV from −0.42 to −0.03 V following the immersion testing, indicating that the corrosion product film played an apparent protective role on the substrate. Originality/value This paper provides a theoretical basis for the corrosion behavior and inhibition mechanism of 690 alloy in PWR primary water environment.