Controlling the shear thinning property of calcium silicate melts by addition of Si3N4

Calcium silicate melts at high temperature are valuable as a lubricant for continuous casting of steel. They are limited by the contradictory situation in that high viscosity is required under low shear rate whereas low viscosity is needed under high shear rate. To resolve such problem, we conducted...

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Bibliographic Details
Published in:Journal of non-crystalline solids 2015-09, Vol.423-424, p.45-49
Main Authors: Shin, Seung-Ho, Cho, Jung-Wook, Kim, Seon-Hyo
Format: Article
Language:English
Subjects:
Additives
Calcium silicate
Calcium silicates
Continuous casting
Degree of polymerization
Melts
Nitrogen
Shear rate
Shear thinning
Silicon nitride
Steels
Viscosity
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Summary:Calcium silicate melts at high temperature are valuable as a lubricant for continuous casting of steel. They are limited by the contradictory situation in that high viscosity is required under low shear rate whereas low viscosity is needed under high shear rate. To resolve such problem, we conducted a rheological study to generate a strong shear thinning behavior of a calcium silicate melts which is an ideal thermal property for continuous casting of steel. We found that a small amount of silicon nitride leads to a strong shear thinning property, allowing a high viscosity at low shear rate without significant changes in the viscosity at higher shear rates. Such trend is completely opposite to the one previously suggested with a borate additive. This improvement of the shear thinning property arises because each additive enables these calcium silicate melts to have a shear thinning favorable structure in thoroughly different manner. •Addition of Si3N4 enhances shear thinning property of calcium silicate melts.•The strongest shear thinning property is achieved at 1wt.% of Si3N4 addition.•Si3N4 addition causes selective increase in viscosity at lower shear rate.
ISSN:0022-3093
1873-4812
DOI:10.1016/j.jnoncrysol.2015.04.043