Oxide and carbide coatings and methods of applying them to graphite crucibles were evaluated on a laboratory scale. The objectives were to find a better crucible and mold coating than magnesia (Mgo), which is currently used in the remelt operation, and a better method of application than brushing. The evaluation consisted of the vacuum-melting of slug uranium charges and derby having different coatings, followed by studies of the appearance of the coatings and the metal quality (impurity levels) of the products. Flame-sprayed magnesium zirconate (MgZro/sub 3/) was determined to be the best coating evaluated. It limited the average carbon pickup ...
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Oxide and carbide coatings and methods of applying them to graphite crucibles were evaluated on a laboratory scale. The objectives were to find a better crucible and mold coating than magnesia (Mgo), which is currently used in the remelt operation, and a better method of application than brushing. The evaluation consisted of the vacuum-melting of slug uranium charges and derby having different coatings, followed by studies of the appearance of the coatings and the metal quality (impurity levels) of the products. Flame-sprayed magnesium zirconate (MgZro/sub 3/) was determined to be the best coating evaluated. It limited the average carbon pickup to 73 ppm for derby uranium charges; with slug uranium, no pickup occurred. The flame-spray method provided a uniform coating thickness and virtually eliminated moisture and volatiles in the coatings. Studies showed that the flamesprayed magnesium zirconate contains a very small amount of volatiles and is not hygroscopic, but that 2500 deg F it is reduced slightly by graphite and co is released. (auth)
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Magoteaux, O.R.; Elston, D.L. & Hall, C.F.LABORATORY EVALUATION OF GRAPHITE CRUCIBLE COATINGS FOR VACUUM MELTING URANIUM,
report,
October 24, 1958;
United States.
(digital.library.unt.edu/ark:/67531/metadc1026597/:
accessed April 19, 2018),
University of North Texas Libraries, Digital Library, digital.library.unt.edu;
crediting UNT Libraries Government Documents Department.