Galvanic Corrosion Behavior of Ductile Iron/H62 Brass in Water Distribution System

Abstract

In order to investigate the galvanic corrosion of the connection between ductile cast iron and H62 brass water pipe in tap water supply network, electrochemical noise (EN), EDS, SEM and other methods were used to investigate the galvanic corrosion current, corrosion morphology and corrosion product composition of ductile cast iron /H62 brass electrode at different temperatures (0 ℃, 25 ℃, 40 ℃) and the specific surface area ratios of anode and cathode (Sc ∶Sa ＝1 ∶1、2 ∶1、4 ∶1) under the condition of simulated acidic industrial atmospheric corrosion.Results showed that when the nodular cast iron/H62 brass electrode was coupled, the nodular cast iron served as the anode, and the galvanic corrosion current density was 3.46 times that of its self-corrosion process.The anode corrosion of couple pair was intensified with the increase of temperature.With the increase of Sc ∶Sa, the galvanic corrosion current density increased.Furthermore, the Ig-t and Eg-t spectra of electrochemical noise revealed that the change in charge when the anode protection film of the electric couple pair was damaged and pitting occurred.Hence, the galvanic effect promoted the occurrence of pitting corrosion in anode ductile iron.

Keywords

• ductile iron； h62 brass； galvanic corrosion； corrosion current； electrochemical noise