Formation mechanism and protective property of corrosion product scale on X70 steel under supercritical CO2 environment. (November 2015)

• Record Type: Journal Article
• Authors: Wei, Liang; Pang, Xiaolu; Liu, Chao; Gao, Kewei
• Is Part Of: Corrosion science. Volume 100(2015)
• Page Start: 404
• Page End: 420
• Publication Date: 2015-11
• Subjects: A. Steel -- B. EIS -- B. SEM -- B. XPS -- C. Acid corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2015.08.016
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Formation mechanism of scale formed at 9.5 MPa differed from that at 1 MPa. Amorphous layer only formed at supercritical CO2 condition. The inner scale formed at 9.5 MPa was more protective than the outer scale. Evolution from amorphous layer to inner FeCO3 scale caused localized corrosion. Corrosion rate decreased in a logarithm trend with the Young's modulus of scale. Abstract: The comparison of corrosion mechanism of X70 steel, as well as the formation mechanism of scale, at between 9.5 and 1 MPa were studied. The outer FeCO3 scale formed at 1 MPa presented better protectiveness than that at 9.5 MPa, while the protectiveness of inner layer was just contrary. Under supercritical CO2 condition, localized corrosion occurred at the transitional stage—the amorphous layer evolved into inner FeCO3 scale. General corrosion rate decreased in a logarithm tendency with the Young's modulus of FeCO3 scale. The fracture toughness of scale at 9.5 MPa was higher than at 1 MPa.