The structure of molten binary silicate systems CaO-SiO 2 and MgO-SiO 2
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is an increasing need for the understanding of various properties of oxides in the molten state. In metallurgical systems, a knowledge of the properties of slags, which are mainly oxide mixtures, is d e s i r a ble because of t h e i r important role in slag-metal reactions. A number of experimental studies have been reported on various properties such as density, viscosity and electrical conductivity, and attempts have been made to describe the structure of s l a g s from such information. T h e r e are some reports on glassy silicates (see for example, Warren, Krutter and Morningster; Biscoe, Druesne and W a r r e n et al, which have been r e f e r r e d to previously.1) However, only a few investigations on molten silicates ~ using X-ray diffraction methods to obtain structural information have been reported. The main p u r p o s e of this work is to provide information about the structure of molten binary silicate systems of CaO-SiO2 and MgO-SiO2 by means of a high temperature X - r a y diffraction technique. I. EXPERIMENTAL The X - r a y diffractometer, monochromator and high temperature chamber used in this work have been described in detail in an e a r l i e r paper.2 The sample preparation, measurements of scattered X - r a y intens i t y , operating procedures and the correction of the observed intensity data were almost identical t o those previously reported.1 Thus, only those modifications which were necessary for the present study are given below. The previously described high temperature cell1 was slightly modified in o r d e r t o operate at temperatures up t o 1800°C. Depending on temperature and slag composition, either Pt-30 pct Rh alloy, Mo or W plate (60 × 15 mm, thickness 0.2 ~ 0.6 mm) was used both as a h e a t e r and sample holder. In addition, a P t or Mo net of 3 mm mesh was placed on the surface of the molten slag sample. This resulted in the spreading of the slag through the mesh and due to surface tension effects creating an approximately flat surface as required for the Bragg-Brentano focusing geometry. YOSHIO WASEDA and J. M . TOGURI are Visiting Professor and Professor, respectively, Department of Metallurgy and Materials Science, University of Toronto, Toronto, Canada, M 5 S 1A4. Manuscript submitted April 1 8 , 1977. METALLURGICAL
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The schematic arrangement of the sample holderheater assembly is shown in Fig. 1. The slag was heated in a sample holder (20 × 12 × 4 mm) which was part of the main heater, and by an additional h e a t e r directed to the top surface of the slag t o insure a uniform sample temperature. The heater-sample holder assembly was enclosed under a purified dry a r g o n atmosphere. The sample temperature was monitored with a W-5 pct Re/W-26 pct Re thermocouple which was located at the bottom of the sample holder. The sample temperature was calibrated by measuring the lattice parameter of P t or Mo powder packed into the mesh of the net and by comparing the change in lattice parameter with the t h e r m a l expansion data of these el
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