O.V. Chernova, S.V. Zhykovin.
ABSTRACT
High-tech industrial sectors need materials with unique physical and chemical properties, as well as a low cost of the material itself. As studies show, the use of rare earth metals (REM) as alloying additions to a number of metals makes it possible to obtain alloys required by modern technology. It should be noted that the use of rare earth metals is promising as components of coatings. This paper presents the results of studies of the process of coating with praseodymium on metallic nickel by the method of applying EMF. For this, a short-circuited galvanic cell with a soluble lead-sodium alloy anode was implemented. Sodium was introduced into the alloy by electrolysis to a certain content (10.5 C). During the deposition of coatings, the electrolyte was an equimolar mixture of sodium and potassium chlorides with the addition of praseodymium trichloride 0.5–7 wt % The preparation of intermetallic compounds was carried out in the temperature range 1073–1173 K. The saturation of nickel with praseodymium was carried out for 30 minutes. The dependences of the specific weight gain of nickel samples on the temperature and concentration of praseodymium chloride in the melt were obtained by the gravimetric method. It is shown that the graphical dependences of the sample weight gain on the PrCl3 concentration in the electrolyte are curvilinear, and at a praseodymium chloride concentration of 3–4 wt % go to a horizontal linear section This allows us to assume that at a concentration of 3 wt % and more, the rate of diffusion mass transfer remains practically unchanged. With increasing temperature, the specific weight gain of the samples increases. The presence of a linear dependence of the specific weight gain on temperature suggests that the limiting stage of the saturation process is the delivery of praseodymium ions to the electrode surface. As a result of the studies, a mechanism and technological recommendations for obtaining a coating on nickel from an equimolar NaCl–KCl melt with the addition of praseodymium trichloride by applying an EMF were proposed. To determine the phase composition, the obtained samples were analyzed using an XRD-7000S X-ray powder diffractometer (Japan). The results of the analysis showed the presence of an intermetallic compound of the composition NiPr.
KEYWORDS
chlorides metals, praseodymium, nickel, EMF superposition method, intermetallic compound
DOI: 10.31857/S0235010621060025