ISIJ International
Online ISSN : 1347-5460
Print ISSN : 0915-1559
ISSN-L : 0915-1559
Regular Article
Structure Analysis of CaO–SiO2–Al2O3–TiO2 Slag by Molecular Dynamics Simulation and FT-IR Spectroscopy
Shengfu ZhangXi ZhangHaijun PengLiangying WenGuibao QiuMeilong HuChenguang Bai
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2014 Volume 54 Issue 4 Pages 734-742

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Abstract

The structure information in the CaO-SiO2-14 mass% Al2O3–TiO2 slag was investigated by the molecular dynamics simulation and the FT-IR spectroscopy at 1773 K. The influence of different additions of TiO2 and varying CaO/TiO2 ratios on the structure was studied to clarify the role of TiO2 in the slag. The results show that there exist three stable units, [SiO4] tetrahedron and [AlO4] tetrahedron as well as [TiO6] octahedron in the CaO-SiO2-14 mass% Al2O3–TiO2 slag. The average coordination numbers, CNSi–Al and CNAl–Al, are all approximately equal to 1 and are barely influenced by additions of TiO2 and varying CaO/TiO2 ratios, which indicates that both the [SiO4] and [AlO4] tetrahedrons are surrounded by only one [AlO4] tetrahedron and some other units. Nevertheless, [AlO4] can be linked by more than one [SiO4] tetrahedron but [SiO4] can only be surrounded by one [AlO4] tetrahedron. The bridging oxygen, classified into Si–O–Si, Al–O–Al and Si–O–Al, is preferentially localized in Si–O–Al. However, it is found a little violation of the so-called Al avoidance principle which states that the Al–O–Al linkage is absent have been obtained with about (less than) 5% Al–O–Al, and the bond of Al–O–Al is hardly affected by TiO2 additions. Replacement of CaO by TiO2 can only result in a slight change of the degree of polymerization, indicating TiO2 has the similar role as CaO to be a basic oxide.

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© 2014 by The Iron and Steel Institute of Japan
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