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

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.

1. Elektroliz zagushchennykh suspenziy glinozema kak sposob sovershenstvovaniya protsessa Eru–Kholla. Chast I. Evolyutsiya tekhnologii elektroliticheskogo sposoba polucheniya alyuminiya (Electrolysis of condensed suspensions of alumina as a method of improvement of Hall-Héroult process. Part I. Evolution of technology of electrolytic method of aluminium obtaining). Journal of Siberian Federal University. Engineering & Technologies 2. 2008. No. 1. pp. 135–154.
2. Radionov E. Yu., Bogdanov Yu. V., Knizhnik A. V. et al. Primenenie predvaritelno obozhzhennykh anodov s pazami v alyuminievykh elektrolizerakh dlya uluchsheniya ikh tekhnikoekonomicheskikh pokazateley (Application of preliminary burned anodes with grooves in aluminium electrolyzers for improvement of their technical-economic indices). Alyuminiy Sibiri — Siberian Aluminium. 2007. pp. 41–42.
3. Lysenko A. P., Selnitsyn R. S. Elektrolizer dlya proizvodstva alyuminiya (Electrolyzer for aluminium production). Patent RF, No. 2485216. June 20, 2013. Bulletin No. 17.
4. Lysenko A. P., Kirov S. S., Selnitsyn R. S. et al. Tsvetnye Metally — Non-ferrous metals. 2013. No. 9. pp. 114–117.
5. Devyatkin S. V. Vysokotemperaturnyy elektrokhimicheskiy sintez boridov perekhodnykh metallov iz ionnykh rasplavov : dissertatsiya ... kandidata tekhnicheskikh nauk (High-temperature electrochemical synthesis of borides of transition metals from ion melts : Dissertation of Candidate of Engineering Sciences). Kiev, 2002. 111 p.
6. Moskvitin V. I., Nikolaev I. V., Fomin B. A. Metallurgiya legkikh metallov (Metallurgy of light metals). Moscow : Intermet Engineering, 2005.
7. Grigorev V. G., Zelberg B. I., Knizhnik A. V. et al. Tsvetnye Metally — Non-ferrous metals. 2009. No. 2. pp. 47–50.
8. Vetyukov M. M., Tsyplakov A. M., Shkolnikov S. N. Elektrometallurgiya alyuminiya i magniya (Electrometallurgy of aluminium and magnesium). Moscow : Metallurgiya, 1987. 319 p.