Effects of Hydrogen Peroxide on Corrosion of Stainless Steel (VI)

Abstract

Anodic and cathodic polarization properties of stainless steel in high temperature pure water were measured to understand different responses of electrochemical corrosion potential (ECP) and frequency dependent complex impedance (FDCI) on H₂O₂ and O₂. The findings are summarized as follows:

1.	A Pt temporary reference electrode supported by an external Ag/AgCl reference electrode could be applied for stable measurement of polarization properties.
2.	The cathodic current densities of the specimens exposed to H2O2 were determined by the H2O2 redox current, the anodic current densities were determined mainly by H2O2 oxidation current, and both were determined by [H2O2]. However, both anodic and cathodic current densities of the specimens exposed to O2 were not much influenced by [O2].
3.	ECP was saturated against [H2O2] and this resulted from the compensation of [H2O2] dependences of anodic and cathodic current densities.
4.	Crack growth rate could be expressed as a function of modified ECP, which was designated as the potential on the anodic polarization curve of the specimens exposed to O2 with the same corrosion current density as the net corrosion current density of the specimens exposed to H2O2.

KEYWORDS:

• oxide film
• hydrogen peroxide
• stress corrosion cracking
• electrochemical corrosion potential
• BWR
• anodic polarization
• crack growth rate