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Abscheidung und Charakterisierung von Sol-Gel-Aluminiumoxidschichten auf kommerziellen Kraftwerksstählen zum Schutz gegen Korrosion bei Oxyfuel-Verbrennung

  • The objective of the present work was the investigation and demonstration of the potential of sol-gel alumina layers as corrosion protection of commercial power plant steels under oxyfuel conditions. The starting points of this work were modified Yoldas-sols which were developed in the BAM-department 5.6. These sols were suitable for the spin-coating method only. The application of coatings on tubes by spin-coating is impossible. Therefore, the chemical composition of the modified Yoldas-sol had to be adapted to the dip- and spray-coating techniques. Exclusively the sol with the composition s-0.52-6-1.5 with a nitrate/aluminium ratio of 0.52; a solid content of 6 wt.% and a PVP (binder) content of 1.5 wt.% could fulfill the necessary criteria: long-term stability; formation of a dense, crack-free and well adhered layer on polished metal surfaces; as well as high protective abilities against corrosion in H2O-CO2-O2-SO2. The commercial power plant steel X20CrMoV12-1 (X20) and the steelThe objective of the present work was the investigation and demonstration of the potential of sol-gel alumina layers as corrosion protection of commercial power plant steels under oxyfuel conditions. The starting points of this work were modified Yoldas-sols which were developed in the BAM-department 5.6. These sols were suitable for the spin-coating method only. The application of coatings on tubes by spin-coating is impossible. Therefore, the chemical composition of the modified Yoldas-sol had to be adapted to the dip- and spray-coating techniques. Exclusively the sol with the composition s-0.52-6-1.5 with a nitrate/aluminium ratio of 0.52; a solid content of 6 wt.% and a PVP (binder) content of 1.5 wt.% could fulfill the necessary criteria: long-term stability; formation of a dense, crack-free and well adhered layer on polished metal surfaces; as well as high protective abilities against corrosion in H2O-CO2-O2-SO2. The commercial power plant steel X20CrMoV12-1 (X20) and the steel X12Cr13 were successfully coated with the sol s-0.52-6-1.5 by means of the dip-coating method. An at least 400 nm thick alumina layer (δ-Al2O3) is necessary to ensure the corrosion protection of these steels. The corrosion of the coated samples compared to that of the uncoated ones was significantly reduced, even after 1000 h of exposure in a H2O-CO2-O2-SO2 atmosphere at 600°C. Sulfur and carbon were not detected at the substrate surface or beneath the coating. Hence the transport of the flue gas components SO2 and CO2 into as well as through the alumina layer could be hindered. The diffusion of the alloying elements (Cr, Mn, Si) into the alumina layer resulted in the formation of mixed oxides like δ-(Al,Cr)2O3. Formation of such phases considerably contributed to the corrosion protection. The long-term stability of the sol s-0.52-6-1.5 and the high protective abilities of the alumina layer on commercial power plant steels provide a good basis for an industrial application.zeige mehrzeige weniger

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Metadaten
Autor*innen:Wencke Schulz
Dokumenttyp:Dissertation
Veröffentlichungsform:Graue Literatur
Sprache:Deutsch
Jahr der Erstveröffentlichung:2016
Veröffentlichende Institution:Bundesanstalt für Materialforschung und -prüfung (BAM)
Titel verleihende Institution:Freie Universität Berlin, Geowissenschaften
Gutachter*innen:S. Schorr, R. Milke
Datum der Abschlussprüfung:24.09.2015
Verlag:Freie Universität
Verlagsort:Berlin
Erste Seite:0
Letzte Seite:179
DDC-Klassifikation:Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten
Freie Schlagwörter:Alumina; Coating; High-Temperature Corrosion; Oxyfuel; Steel; TEM
DOI:10.17169/refubium-6842
URN:urn:nbn:de:kobv:188-fudissthesis000000102280-0
Verfügbarkeit des Dokuments:Datei für die Öffentlichkeit verfügbar ("Open Access")
Lizenz (Deutsch):License LogoCreative Commons - CC BY-NC - Namensnennung - Nicht kommerziell 4.0 International
Datum der Freischaltung:03.02.2020
Referierte Publikation:Nein
Schriftenreihen ohne Nummerierung:BAM Dissertationen ohne Nummerierung
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