Oxidation Studies of SiAlON/MgAlON Ceramics with Fe2O3 and CaO Impurities, Part II: Phase Evolution
2013 (English)In: Metallurgical and materials transactions. B, process metallurgy and materials processing science, ISSN 1073-5615, E-ISSN 1543-1916, Vol. 44, no 1, 220-232 p.Article in journal (Refereed) Published
The oxidation behavior of composite SiAlON/MgAlON phases, synthesized from the leaching residue after the aqueous treatment of salt cake from aluminum remelting, is compared with the oxidation of corresponding synthetic samples. The samples were subjected to oxidation under air as the oxidant atmosphere in the temperature range of 1373 K to 1773 K (1100 A degrees C to 1500 A degrees C). The phases present were analyzed by scanning electron microscopy (SEM)-electron-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) to arrive at the evolution of the various phases formed during oxidation. From the experimental results, especially by the characterization of the oxidation products, the mechanism of the oxidation reaction was deduced as follows: With the progress of oxidation, the composition of the material being oxidized moved toward the Al2O3-rich corner of MgO-Al2O3-SiO2 and CaO-MgO-Al2O3-SiO2 phase diagrams relevant to the SiAlON/MgAlON composite. At lower temperatures, the addition of Fe2O3 and CaO facilitated the formation of cordierite and anorthite, respectively. With increasing temperature, islands of silicate melt were formed dissolving these oxides, with the liquidus temperature getting lowered as a consequence. The liquid phase formed engulfed the adjacent solid phases providing strong mobility for the cations and enabling the crystal growth. As a result, intermediate products, i.e., cordierite, anorthite, and spinel, which were formed earlier during oxidation, are found to get dissolved in the liquid phase.
Place, publisher, year, edition, pages
2013. Vol. 44, no 1, 220-232 p.
SiMgAlON, oxidation, mullite, liquid, crystallizationimpurities, arctan, activation energy, oxidation, SiMgAlON
Metallurgy and Metallic Materials
IdentifiersURN: urn:nbn:se:kth:diva-102261DOI: 10.1007/s11663-012-9758-8ISI: 000314909000025ScopusID: 2-s2.0-84873986908OAI: oai:DiVA.org:kth-102261DiVA: diva2:551829
QC 20130320. Updated from submitted to published.2012-09-122012-09-122013-03-20Bibliographically approved