ELECTROCHEMICAL SYNTHESIS OF ULTRAFINE INTERMETALLIC POWDERS BASED ON LANTHANUM AND COBALT FROM CHLORIDE MELTS

The paper studies the combined electroreduction of lanthanum LaCl₆^3–and cobalt CoCl₄^2– chloride complexes in an equimolar KCl–NaCl melt at a tungsten electrode. As it follows from the results of voltampere measurements, potentials of La and Co reduction at a tungsten electrode coated with preliminary reduced cobalt differ by more than 1,0 V. Therefore, the electrochemical synthesis of La and Co intermetallics is possible only in the kinetic regime. The paper develops the method for the high-temperature electrochemical synthesis of lanthanum and cobalt intermetallic powders in halide melts. The paper determines conditions for realization of the combined electroreduction of La³⁺ and Co²⁺ ions, on the basis of which the paper demonstrates the principal possibility of the direct electrochemical synthesis of lanthanum intermetallics. The paper establishes that the electrosynthesis mechanism is determined by electrolysis conditions. Under potentiostatic conditions (when potentials are more negative than potentials for reduction of the more electronegative element – lanthanum) the combined reduction of La and Co takes place, and the synthesis process is determined by the activation energy of the interaction reaction between lanthanum and cobalt at the cathode. In general, the electrosynthesis of La- and Co-based intermetallics is determined by the following interrelating parameters – the composition of the electrolytic bath and the voltage across it. The paper describes the high-temperature electrochemical synthesis of lanthanum- and cobalt-based ultrafine powders of intermetallics кобальта (Сo₃La₂, Сo₇La₂, Co₁₃La) from chloride melts. 

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