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Thermodynamic Stability of Spinel Phase at the Interface Between Alumina Refractory and CaO–CaF 2 –SiO 2 –Al 2 O 3 –MgO–MnO Slags
Author(s) -
Park Jun Seok,
Kim Da Hye,
Park Joo Hyun
Publication year - 2015
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.13570
Subject(s) - spinel , slag (welding) , materials science , phase (matter) , dissolution , precipitation , metallurgy , analytical chemistry (journal) , mineralogy , chemistry , physics , organic chemistry , chromatography , meteorology
The interfacial reaction between alumina refractory and CaO–CaF 2 –SiO 2 –Al 2 O 3 –MgO–MnO slag was observed at 1873 K to estimate the stability of the spinel phase using computational thermodynamics under refining conditions of Mn‐containing steels. The concentration of MnO formed by the slag–steel reaction in the CaO–CaF 2 –SiO 2 –Al 2 O 3 –MgO melts generally increased by decreasing the CaO/SiO 2 ratio of the initial melts. No intermediate compounds were formed at the refractory–slag interface when the initial CaO/SiO 2 ratio was 0.5, whereas CaAl 12 O 19 ( CA 6) and Mg(Mn)Al 2 O 4 (spinel), identified from TEM analysis using EDS mapping and SAED patterns, were observed at the refractory–slag interface when the CaO/SiO 2 ratio was 1.0 or greater. The (at.%Mg)/(at.%Mn) ratio in the spinel solution increased by increasing the CaO/SiO 2 ratio, which originated from the fact that MgO activity continuously increased as the CaO/SiO 2 ratio increased. From thermodynamic analysis considering the equilibrium constant ( K SP ) and activity quotient ( Q SP ) of the spinel formation reaction at the slag–refractory interface and the bulk slag phase, the precipitation–dissolution behavior of the spinel phase was predicted, which exhibited good consistency with the experimental results. Hence, the dissolutive corrosion mechanism of alumina refractory into the CaO–CaF 2 –SiO 2 –Al 2 O 3 –MgO–MnO slag was proposed.