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AbstractAbstract
[en] An appropriate technique has been developed for obtaining compact metallic coatings from electrolysis of molten salts. Through the use of this method, it has been possible to produce pure metal deposits which, until now, has been extremely difficult to do. The apparatus used and the main steps of the process such as dehydration of the solvant, degassing of the equipment, and starting of the electrolytic process, are first described. This is followed by a discussion of the deposits of the metals beryllium, uranium, tantalum and tungsten obtained from electrolysis of molten fluorides at temperatures between 600 and 8000C. The metal coatings so obtained are homogeneous and show continuity, their thicknesses varying from a few microns to a millimeter or more. They have been studied by measurements. As potential applications of this new technique, one can mention the growth of diffusion barriers and the production of cathodes for thermoionic emission. The method can also be used for electroforming. An intermetallic diffusion between the deposit and the substrate has been observed in some cases. The advantage of the technique of melt electrolysis in obtaining metal coatings of enhanced thicknesses is illustrated by taking the beryllium-nickel system as an example. It is shown that the thickness obtained is proportional to the square root of growth time and is about 6 to 8 times larger than that obtained by conventional techniques
[fr]
On a mis au point une technique appropriee a la preparation de depots metalliques compacts par electrolyse de sels fondus. Elle permet d'obtenir des revetements de metaux purs jusqu'alors tres difficiles a elaborer dans d'autres milieux. On decrit d'abord l'appareillage et les phases essentielles du procede en montrant l'importance de la deshydratation du solvant, du degazage de l'appareillage et du commencement de l'electrolyse. Ensuite on expose les resultats de la preparation de revetements compacts de beryllium, d'uranium, de tantale et de tungstene en milieu de fluorures fondus entre 600 et 8000C. Les revetements etudies sont sains, homogenes continus et leur epaisseur peut varier de quelques microns a un millimetre ou plus selon leur utilisation. On caracterise ces depots par des examens micrographiques, des analyses chimiques et des mesures physiques. Parmi les exemples d'application, on cite la constitution de barrieres de diffusion, l'elaboration de cathodes pour l'emission thermoionique et la fabrication d'objets par electroformage. Enfin on evoque le phenomene de diffusion intermetallique observe, dans certains cas, entre le depot et le substrat. On met en evidence l'effet benefique de l'electrolyse ignee sur l'epaisseur de la couche de diffusion obtenue en prenant le couple beryllium-nickel comme exemple. Cette epaisseur est proportionnelle a la racine carree du temps et elle est 6 a 8 fois plus importante que celle realisee par un procede classiqueOriginal Title
Etude de revetements metalliques prepares par electrolyse ignee
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Source
Jun 1978; 103 p; These (D. Univ.).
Record Type
Report
Literature Type
Thesis/Dissertation
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