期刊
CERAMICS INTERNATIONAL
卷 46, 期 17, 页码 26880-26887出版社
ELSEVIER SCI LTD
DOI: 10.1016/j.ceramint.2020.07.164
关键词
Viscosity; Activation energy; Break temperature; Melt structure; CaO-Al2O3-Based flux
资金
- National Natural Science Foundation of China [51874363, U1760202]
- Natural Science Foundation of Hunan Province [2019JJ40345]
- Hunan Scientific Technology projects [2018RS3022, 2018WK2051]
The CaO-Al2O3-based mold flux is expected during the casting of aluminum containing advanced high strength steels. In this study, the rheological behavior of the CaO-Al2O3-based mold fluxes with different Na2O contents was investigated. The results show that the viscosity in the range of 1423-1573 K reduced sharply when the Na2O content increased from 0 wt % to 10 wt %, but the tendency slowed down with further increasing Na2O from 10 wt % to 15 wt %. The activation energy for viscous flow also decreased from 237.76 +/- 4.88 kJ/mol to 180.37 +/- 7.10 kJ/mol with increasing Na2O. The structure analyses show that the melt networks were mainly constructed by [SiO4](4-)-tetrahedral, [AlO4](5)-tetrahedral and Si-O-Al structural units. These networks were depolymerized with the addition of Na2O since the charge compensation effect from Na+ was relativity weaker comparing with the network breaking effect from O-2(-). In addition, the break temperature of the mold fluxes also decreased from 1406 K to 1198 K due to the more precipitation of low melting point Ca2Al2SiO7, rather than MgAl2O4 in the mold flux, during the cooling cycle.
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