A thermodynamic study of Ru-Sn binary alloys
- PDF / 297,656 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 86 Downloads / 319 Views
I.
II.
INTRODUCTION
DURING the course of studies directed toward a better understanding of the high-temperature metallurgical processes for the recovery of palladium, rhodium, and ruthenium, from spent fuel generated at nuclear reactors, it became necessary to know the activities of Ru and Sn in {Ru-Sn} binary alloys at 1573 K. To the best of the authors’ knowledge, such data are not available in the literature. In addition, all liquidus and boundaries for the phase diagram of this system proposed by Masalski et al.[1] are schematic, as given by the broken lines in Figure 1. Activity measurements for {Ru-Sn} binary alloys can be made by employing an electrochemical technique incorporating stabilized zirconia as the solid electrolyte, as done by the present authors for Ag-Sn alloys.[2] In the authors’ previous work,[2] {Ag-Sn} liquid alloys were brought into equilibria with pure SnO2, and the equilibrium oxygen partial pressures were determined by a solid electrolyte cell at temperatures below 1273 K. Keeping this in mind, at the initial stages of this study, electromotive force (emf) measurements were made with a mixture of {Ru-Sn} alloy 1 SnO2. However, as reported by Jacob and Chan[3] and Seetharaman and Staffasson,[4] at temperatures greater than 1373 K, stable cell voltages were not obtainable: chemical potentials of oxygen within the test electrode were significantly affected by the emission of gaseous SnO, which is due to the reaction SnO2 (s) 1 Sn (in alloy) 5 2SnO (g)
[1]
A solution to this problem is, as can be seen from Eq. [1], to lower the activities of SnO2. In this study, a mixture of CaO 1 Ca2SnO4 was employed instead of pure SnO2. The electrochemical cell eventually used in this study can be formulated as (1)Mo/Mo 1 MoO2/ZrO2(CaO)/{Ru-Sn} 1 CaO 1 Ca2SnO4/Mo (2)
RYO KAWABATA, formerly Graduate Student, Department of Energy Science and Engineering, Kyoto University, Kyoto 606, Japan is now with NKK. MUNETAKA MYO-CHIN, Research Associate, is with the Nuclear Fuel Technology Development Division, Power Reactor and Nuclear Fuel Development Corporation, Ibaragi, 319-13 Japan. MASANORI IWASE, Professor, is with the Ferrous Metallurgy Research Group, Department of Energy Science and Technology, Kyoto University, Kyoto 606, Japan. Manuscript submitted April 15, 1996. METALLURGICAL AND MATERIALS TRANSACTIONS B
EXPERIMENTAL ASPECTS
A. Sample Preparations Requisite portions of granular Sn (.99.99 pct) and rectangular ruthenium (99.99 pct) of 60-mm length, 3-mm thickness, and 10-mm width, corresponding to XSn 5 0.45, were heated inside an alumina crucible of 40-mm i.d., 50mm o.d., and 100-mm length in a stream of purified argon first near 1573 K and subsequently near 1773 K, for 7 days. At these temperatures, the rectangular ruthenium was observed inside the crucible, in conforming to the two-phase coexistence of Ru (s) 1 {Ru-Sn} liquid alloys. Samples were then withdrawn from the liquid phase, by using a silica sampling tube of 3-mm i.d., quenched in water and weighed. The solubilities of Ru were thus d
Data Loading...
