Electrical and electronic conductivity of CaO-SiO 2 -FeO x slags at various oxygen potentials: Part I. Experimental resu
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THE electrical and electrochemical properties of oxidecontaining melts have been the subject of a number of research studies of both fundamental and practical interest. The earliest of such studies were published in the middle of the twentieth century,[1–4] and increasing attention has been paid to the subject since then. The primary interest in studying the electrical properties of metallurgical slags is their application in the design and optimization of electric melting/smelting processes. The electrical properties of metallurgical melts have also been of particular interest in the electrolytic production of metals. A large number of metals, including aluminum, magnesium, and titanium, have been produced by the electrolysis of molten slags and salts.[5,6] In addition to their importance in industrial processes, the investigations of the electrical properties of slags have played a significant role in developing base knowledge about slags. Such studies were among the primary work through which insights into and an understanding of the structure of liquid oxides were developed. For example, the earliest evidence of the ionic structure of oxide melts resulted from electrical conductance measurements.[3,7–11] Although oxide melts are regarded as ionic solutions, the electrical current in many of theses melts is conducted by both ionic and electronic charge carriers. The semiconduction behavior, or the contribution of electronic carriers in the conductivity of liquid FeO,[12,13] FeO-SiO2,[14,15] FeOCaO,[16] FeO-CaO-SiO2,[17] FeO-MnO-SiO2,[18] FeO-CaOMgO-SiO2,[19] TiO2-BaO,[20,21] PbO-SiO2,[22] and some molten salts,[23,24] has become evident in the last few decades. The relatively high conductance of many transition metal oxide MANSOOR BARATI, former Ph.D. student, McMaster University, is currently with WP HG Engineering, Toronto, Ontario, Canada. KENNETH S. COLEY, Associate Professor, is with Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario, Canada L8S 4L7. Contact e-mail: [email protected] Manuscript submitted June 11, 2005. METALLURGICAL AND MATERIALS TRANSACTIONS B
melts has also been related to the electronic conduction mechanism in such melts. The majority of the technological interest in understanding the electronic properties of slags arises from the fact that, for an efficient electrolysis, the melt must be predominantly an ionic conductor. Knowledge of the electronic conduction in slags can help in the design or selection of the proper slag for electrolysis,[21,25] or can be used in the optimization of furnace operation.[24] From a more fundamental point of view, increasing attention has been paid to the electronic properties of molten slags, due to their significance in some reactions between gas or metal with slag. Some researchers have suggested that the reactions between slag and molten alloys are electrochemical in nature.[26–30] These findings, along with the evidence of the role of electrons in the mass transfer of oxygen through slag,[31,32] suggest
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