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Interaction of Yttria with Uranium Fluoride Gases (UF n , n = 4, 6) at High Temperatures
Author(s) -
Erkmen Z. Engin,
Anghaie Samim
Publication year - 1994
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1994.tb09766.x
Subject(s) - corrosion , eutectic system , uranium , materials science , yttria stabilized zirconia , layer (electronics) , fluoride , yttrium , metallurgy , uranium dioxide , uranium hexafluoride , nuclear chemistry , inorganic chemistry , chemistry , oxide , cubic zirconia , ceramic , composite material , microstructure
The corrosion mechanism and microstructural characteristics of yttria (Y 2 O 3 ) exposed to uranium hexafluoride (UF 4 ) and uranium tetrafluoride gases at temperatures above 900°C were investigated. Processed yttria samples were exposed for times ranging from 5 to 40 min. A weight increase was observed after each test exposure. An outer corrosion scale composed of UO 2 and YF 3 , and an inner corrosion layer of YF 3 , were observed following the UF 6 reaction at nearly 1200 K. During the UF 4 exposure, an outer layer containing a liquid mixture of fluoride, oxygen, yttrium, uranium compounds, a secondary reaction layer of UO 2 followed by an inner layer composed of a solution of Y 2 O 3 and YF 3 , possibly in the form of YOF inner layer, were observed. It was found that the corrosion process is controlled by the diffusion which is evidenced by the parabolic growth rate of the secondary layer. After completion of the solidification process, the formation of a eutectic region and dendrites were observed throughout the outer scale. In general, at temperatures above 1173 K, high corrosion rates were observed, and yttria did not appear to be a viable containment material for UF 4 and UF 6 .