caa a22 4500 463189930 CHVBK 20180406164905.0 cr unu---uuuuu 170326e20071201xx s 000 0 eng 10.1007/s10973-006-8305-8 doi (NATIONALLICENCE)springer-10.1007/s10973-006-8305-8 Zinc coatings for oxidation protection of ferrous substrates [Elektronische Daten] Part II. Microscopic and oxidation mechanism examination [G. Vourlias, N. Pistofidis, E. Pavlidou, K. Chrissafis] A common phenomenon in the process industries is the oxidation of the exterior surface of steel pipes used in superheated steam or hot oils networks. For their protection different coatings could be used. In the present work the performance of zinc coatings deposited with hot-dip galvanizing, pack cementation and thermal spraying was considered, in order to protect industrial equipment up to 400°C. For that purpose coated carbon steel coupons were exposed at 400°C and their behavior was examined with light microscopy, scanning electron microscopy and X-ray diffraction. Thermogravimetric analysis was also used in order to observe in situ the oxidation phenomena. From this investigation it was deduced that in every coating a scale is formed that is mainly composed of ZnO, while Fe oxides were also detected in galvanized and pack coatings. The growth of this scale took place at the metal/scale interface. Moreover, as far as it regards the kinetics of the oxidation, it was concluded that the increase of the mass of the specimens is a function of the square root of the exposure time, which means that the scale formed is rather protective for the underlying zinc. From the above observation it seems that the behavior of zinc coatings would be excellent at 400°C. However, the presence of the Fe/Zn phases inside the galvanized and pack coatings led to the formation of cracks, which could expose the substrate and thus destabilize the coating. This phenomenon does not take place in the thermal sprayed coatings, where the Fe/Zn phases are absent. Springer Science+Business Media, LLC., 2007 coating materials nationallicence oxidation nationallicence scanning electron microscopy nationallicence thermal analysis nationallicence X-ray diffraction nationallicence zinc nationallicence Vourlias G. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut Pistofidis N. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut Pavlidou E. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut Chrissafis K. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/3(2007-12-01), 777-782 1388-6150 90:3<777 2007 90 10973 https://doi.org/10.1007/s10973-006-8305-8 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-006-8305-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Vourlias G. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut NATIONALLICENCE 700 1- Pistofidis N. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut NATIONALLICENCE 700 1- Pavlidou E. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut NATIONALLICENCE 700 1- Chrissafis K. Physics Department, Aristotle University of Thessaloniki, 54124, Thessaloniki, Greece aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/3(2007-12-01), 777-782 1388-6150 90:3<777 2007 90 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence SWISSBIB 463189930 BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer