H. B. Kushchov, R. A. Kardanova, V. V. Khasanov, I. A. Borukaeva
ABSTRACT
This paper presents the results of high-temperature electrochemical synthesis of powders of holmium intermetallides with metals of the iron triad in chloride melts. The effect of the current density, the composition of the electrolytic bath, the duration of the electrolysis process and the composition of the products obtained are studied. It was found that during electrolysis of a molten mixture of KCl–NaCl containing holmium trichloride (0.5–2.5 mol%) and nickel (cobalt) dichloride (0.1–2.5 mol%), current density 0.5–2.0 A/cm2, temperatures 973–1073 K and the duration of electrolysis to 30–60 min on the tungsten electrode, a cathodic precipitate is formed in the form of a “metal-salt pear”, containing of a mixture of nickel (cobalt) metal phases, HoNi, HoNi5, HoNi3 (HoCo2 intermetallides, HoCo3, HoCo5, Ho2Co17) and metallic holmium. It has been established that at a constant current density (1.2 A/cm2), the content of intermetallic compounds in the cathode deposit increases with an increase in the concentration of the holmium chloride in the melt, as well as the ratio of the concentration of the holmium chloride to the concentration of nickel chloride (cobalt). By regulating the composition of the electrolysis bath and the electrolysis regimes, it is possible to ensure that the cathode sediment consisted only of a mixture of holmium and nickel intermetallides (cobalt).
Electrochemical synthesis of holmium intermetallides with iron was carried out in the galvanostatic regime in a KCl–NaCl–HoCl3 melt. Iron ions were introduced into the melt by anodic dissolution of metallic iron. The results of the phase analysis of the electrolysis products show the principal possibility of obtaining holmium and iron intermetallides. Optimum conditions for the electrosynthesis of holmium intermetallides with metals of the iron triad are determined.
KEYWORDS:
electrochemical synthesis, intermetallic compounds, holmium, nickel, cobalt, iron.