Electrochemical and microscopic investigation on passive behavior of ductile iron in simulated cement-mortar pore solution. (30th September 2017)

• Record Type: Journal Article
• Authors: Sun, Xiang-Hua; Zuo, Xiao-Bao; Yin, Guang-Ji; Jiang, Kai; Tang, Yu-Juan
• Is Part Of: Construction & building materials. Volume 150(2017)
• Page Start: 703
• Page End: 713
• Publication Date: 2017-09-30
• Subjects: Ductile iron -- Passive behavior -- Simulated cement-mortar pore solution -- Electrochemical measurement -- SEM/XPS; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2017.06.042
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Passivation on the surface of ductile iron surface needs a high alkaline solution. Increase of solution alkalinity leads to short passive time and compact passive film. Mechanism of passivation on the surface of ductile iron is revealed by EIS/SEM/XPS. Abstract: The passive behavior of ductile iron in simulated cement-mortar pore (SCMP) solution with different alkalinity was investigated by electrochemical measurements, such as open circuit potential (OCP), Tafel polarization curve (TP), electrochemical impedance spectroscopy (EIS), and microscopic tests, including scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Results show that, with increase in immersion time, the SCMP solution with the high pH value can cause the increase of OCP and capacitive loop of ductile iron surface, a morphology of growing surface film, and the high Fe 2+ /Fe 3+ ratios in its surface Iron-oxide compounds, presenting the formation of passive film on the surface of ductile iron. But in the SCMP solution with low pH value, its OCP, TP curve and EIS show no obvious change, and also produce the corrosion morphology of rust with low Fe 2+ /Fe 3+ ratios, indicating loss of surface protection on the ductile iron.