Tomsk Polytechnic University, Tomsk, Russia:

G. G. Andreev, Professor

T. I. Guzeeva, Professor, e-mail: guzeev@mail.tomsknet.ru

Federal University of Educational Development, Moscow, Russia:

O. E. Permyakov, Chief Specialist

Production of uranium hexafluoride by direct fluorination of uranium oxides with elemental fluorine has three main stages: fluorination of uranium oxides with elemental fluorine in a flame reactor, desublimation of uranium hexafluoride, and capture of excess fluoride at a fresh portion of uranium oxide in the catcher device. Necessity to clean the reaction gases is related to their high dustiness after devices for fluorination and capturing and requirements to the purity of uranium hexafluoride. Corrosiveness of these gases containing fluorine, oxygen, hydrogen fluoride and uranium hexafluoride is very high. Traditional filtering materials presenting of copper and nickel meshes, metal-ceramic nickel corrode with high speed at a high temperature of exploitation. New filtering materials based on nickelide of aluminium have been obtained by high-temperature self-extending synthesis. The paper presents the results of research of corrosion kinetics of porous intermetallic compounds of nickel and aluminium in fluorine-oxygen environment. Studies of the corrosion kinetics were performed by the comparative method using standard samples of the metal-ceramic filter made of different compositions of nickel and nickelide of aluminium: Ni₃Al; NiAl; Ni₂Al₃; NiAl₃. The dependences of the degree of corrosion of nickelides of aluminium in fluorine at the temperature of 480–500 ^оС and in oxygen at the temperature of 850–900 ^оС, as well as in hydrogen fluoride at 480–500 ^оС and uranum hexafluoride at 680–700 ^оС are presented. Nickelide of aluminium are found to belong to the first group of stability in fluorine (up to 500 ^оС) and oxygen (up to 900 ^оС). Minimal degree of corrosion under the indicated conditions has NiAl. This is explained by ability of NiAl to maintain the ordered state of the crystal lattice to the melting point (1911 ^оС). The samples of NiAl were tested on corrosion resistance and mechanical strength at the Siberian Chemical Industrial Complex.

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