Corrosion Resistances of Steel Pipe Coated with Two Types of Enamel by Two Coating Processes

Journal Article · Mon Oct 15 04:00:00 EDT 2018 · Journal of Materials Engineering and Performance

DOI:https://doi.org/10.1007/S11665-018-3656-4· OSTI ID:22863238

Fan, Liang ^[1]; Tang, Fujian ^[2]; Chen, Genda ^[1]; Reis, Signo T. ^[3]; Koenigstein, Mike L. ^[4]

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1. Missouri University of Science and Technology, Department of Civil, Architectural, and Environmental Engineering (United States)
2. Dalian University of Technology, State Key Laboratory of Coastal and Offshore Engineering, School of Civil Engineering (China)
3. Missouri University of Science and Technology, Department of Materials Science and Engineering (United States)
4. Roesch Inc., Pro-Perma Engineered Coatings (United States)

The corrosion behaviors of uncoated, enamel-coated, and epoxy-coated steel samples were evaluated in 3.5 wt.% NaCl solution with open-circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization tests. Two types of enamel (powder and slurry) were coated on steel samples in electrostatic and wet spraying processes, respectively. Twelve 25 mm × 25 mm steel samples were cut from an API 5L X65 pipe of 323.850 mm in outer diameter and 9.525 mm in wall thickness. They were divided into four groups of three identical samples. Each group represents one of the four conditions: uncoated, powder enamel-coated, slurry enamel-coated and epoxy-coated. Scanning electron microscopy images revealed that the powder and slurry enamel coatings were approximately 180 and 235 µm thick, respectively. The powder enamel coating has fewer but larger isolated pores than the slurry enamel coating. Electrochemical tests consistently indicated that the powder and slurry enamel coatings provided slightly better and worse corrosion protection to the coated steel samples, respectively, than the epoxy coating. The charge transfer resistances of all the coated samples are approximately 10{sup 8} times larger than that of the uncoated samples. All the coated samples were unlikely corroded within 2 h of immersion.

• OSTI ID: 22863238
• Journal Information: Journal of Materials Engineering and Performance, Journal Name: Journal of Materials Engineering and Performance Journal Issue: 10 Vol. 27; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CORROSION
CORROSION PROTECTION
CORROSION RESISTANCE
ELECTROCHEMISTRY
ENAMELS
IMPEDANCE
POLARIZATION
SCANNING ELECTRON MICROSCOPY
SLURRIES
SPECTROSCOPY
STEELS
SURFACE COATING
THICKNESS