Kusuhiro Mukai1 and Tomomi Ishikawa2
1Department of Metallurgy, Kyushu Institute of Technology, Kitakyushu
The pendant drop method has been developed to measure the surface tension of liquid slag in the static and dynamic conditions by controlling the size of the pendant drop with the aid of Pt-Rh (20%) coil in contact with the slag. Surface tension in dynamic condition, that is, during the rapid change of the drop size, shows a tendency to differ from that in the static condition. Surface tension in the static condition and the temperature coefficient of the surface tension were determined for the liquid CaO-SiO2, CaO-Al2O3, and CaO-Al2O3-SiO2 slags in the temperature range from the vicinity of liquidus temperature to 1873 K. SiO2 lowers the surface tension while it raises the temperature coefficient of the surface tension from negative at lower SiO2 contents to positive at higher SiO2 contents of CaO-SiO2 and CaO-Al2O3-SiO2 slags. At constant SiO2 contents of CaO-Al2O3-SiO2 slag, Al2O3 lowers the surface tension except for a narrow range of high SiO2 contents and low Al2O3 contents, while it raises the temperature coefficient of surface tension except for the range of high SiO2 content. The surface tension vs SiO2 content curve shows a tendency to have a hump in the vicinity of wollastonite and gehlenite for the CaO-SiO2 and CaO-Al2O3-SiO2 slags respectively.
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