NaCl and Na2SO4 solution effect on weathering steel visual appearance when the ambient temperature changes cyclically. Issue 1 (1st January 2019)

• Record Type: Journal Article
• Authors: Daukšys, Mindaugas; Bytautaitė, Evelina; Mockienė, Jūratė; Nizevičienė, Dalia
• Other Names: Jiao Pengcheng reviewing-editor.
• Is Part Of: Cogent engineering. Volume 6:Issue 1(2019)
• Publication Date: 2019-01-01
• Subjects: weathering steel -- NaCl and Na2SO4 solution -- visual appearance -- XRD analysis -- EDS analysis; Engineering -- Periodicals; Technology -- Periodicals; Engineering; Technology; Periodicals; 620
• DOI: Https://www.tandfonline.com/doi/10.1080/23311916.2019.1659124
• Languages: English
• ISSNs: 2331-1916

Abstract

Abstract: Visual appearance—colour and texture variation—of weathering steel was compared by testing weathering steel samples in aggressive and non-aggressive conditions, and cyclical changes of ambient temperature. This paper introduces a new method for determining visual appearance of weather-resistant steel in different environmental conditions. Weathering steel samples were tested in H2 O, 3% NaCl and 3% Na2 SO4 solutions under ambient temperature changing from +20°C to −20°C per day. The structure of steel surface viewed under optical microscope revealed corrosion products in all steel samples. X-ray diffraction analysis of corrosion products revealed the presence of oxy-hydroxides, such as lepidocrocite (ɣ-FeO(OH)), goethite (α-FeO(OH)) and magnetite (Fe3 O4 ) in different environment. Optical microscopy images of corroded surfaces had different visual appearance and orange, yellow, sandy, black or anthracite colours, which indicate that the corrosion products primarily contain lepidocrocite (ɣ-FeO(OH)), goethite (α-FeO(OH)) and magnetite (Fe3 O4 ). EDS analysis revealed that the rust of samples kept in 3% NaCl solution had the highest amount of iron ions.