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ALUMINIUM, ALUMINA, CARBON MATERIALS
ArticleName Electrochemical titanium diboride synthesis from cryolite melts on electrolysis process
ArticleAuthor Lysenko A. P., Kirov S. S., Selnitsyn R. S., Nalivayko A. Yu.
ArticleAuthorData

Chair of Non-Ferrous Metals and Gold, Institute of Ecotechnologies and Engineering (National University of Science and Technology “MISiS”), Moscow, Russia:

A. P. Lysenko, Assistant Professor, e-mail: reikis@yandex.ru
S. S. Kirov, Assistant Professor
R. S. Selnitsyn, Post-graduate Student
A. Yu. Nalivayko, Engineer

Abstract

This article gives the research studies on electrolytic synthesis of titanium diboride, which are the logical continuing of further improvements of anode block and furnace bottom construction in aluminium electrolysis unit. Titanium diboride covering on carbon parts enables to lengthen their service life significantly, and removes the substrate surface imperfections. There are presented the results of covering production on titanium diboride substrate by electrolytic method from cryolite alloys (cryolite ratio is 2.3), containing Al2O3, TiO2 and B2O3. Basic possibility of TiB2 covering synthesis on carbon substrate is shown. Application of improved differential thermal method for definition of the start of crystallization of oxide-fluorine melts made possible to build melting diagrams for supercooling prone systems: “cryolite – aluminum oxide”, “cryolite – titanium dioxide” and “cryolite – borum oxide” systems with different cryolite ratio (2.7; 2.5 and 2.3). There was shown the mechanism of dissolution of titanium dioxides and borum oxides in cryolite, running via fluorine-oxide complex formation. Operation mode for electrolysis process was worked out with the temperature of 960 оC, current intensity of 2.17 A, and pole distance of 3–4 cm. The electrolysis process span varied from 1 to 3 hours. Analysis of thermodynamic processes, running in the course of high-temperature titanium diboride synthesis (960–980 оC), was carried out. There was substantiated a choice of reactive mixture for electrochemical production of TiB2 in NaF – AlF3 – Al2O3 – TiO2 – B2O3 system. There were defined the side processes, running in the system, leading to worsening of electrolytic synthesis parameters of titanium diboride. There are given the causes of simultaneous formation of titanium diboride and Al and Ti carbides. Photomicrograms of coating samples were attached together with chemical and phase composition data. General characteristics of covering material on carbon substrate were presented.

keywords Titanium diboride, titanium and aluminium carbides, covering, electrolysis, carbon substrate, melting diagram, fluorineoxide complex, thermodynamics, aluminium electrolysis unit
References

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