LLC “EXPERT-AL”, Saint Petersburg, Russia:

E. S. Gorlanov, Deputy Chief Executive Officer

Saint-Petersburg Mining University, Saint Petersburg, Russia:
V. Yu. Bazhin, Dean of a Faculty of Mineral Raw Material Processing, e-mail: bazhin-alfoil@mail.ru
S. N. Fedorov, Post-Graduate Student of a Chair of Metallurgy

The paper presents and substantiates the technology of carbothermic reduction of titanium and boron oxides in the composition of reaction mixture in TiО₂ – B₂О₃ – C at the temperatures up to 1070 ^оC. The initial components of the reaction mixture were titanium and boron oxides in a hydrated form of metatitanate (H₂TiO₃ = TiO₂·H₂O) and boric (Н₃ВО₃ = 1/2В₂О₃·3/2H₂O) acids which made it possible to use “wet” methods of mixing of reactants to increase the reaction surface, first and foremost the Sol-gel technology. The possibility of a low-temperature synthesis of titanium diboride was substantiated by the theory of increased reactivity of compounds in the transformation period of the crystal lattice during phase transitions. A technology was developed and implemented for transfering of anatase-rutile transformation (ART) of titanium oxide from the temperature interval 600–800 ^оC to the range of 1030–1050 ^оC of a phase formation development in a Ti – B – O – C system. A research was conducted on preparation (doping) of TiO₂ by the Sol-gel technology for modification of an amorphous titanium oxide through fluorine according to the ТiO₂·хН₂О→TiO(OH)_2–xF_x↓→TiO_2–xF_x→α-TiO_2–xF_x scheme. The temperature intervals of anatase-rutile transformation of titanium oxide in different gas environments were determined. It is shown that conducting the process in vacuum and argon stimulates the transition of ART, including doped titanium oxide. On the other hand, a stable state of the doped anatase α-TiO_2–xF_x and the state of ART that enables an active interaction can be preserved in an oxygen-containing atmosphere with a temperature up to 1100 ^оC. The temperature and the atmospheric mode of carbothermic reduction of TiO₂ were specified. A sequential phase formation of TiО₂→TinO_2n–1→TiBО₃→TiC_xO_1–x→TiB₂ was realized in a Ti – B – O – C system at 1030–1050 ^оC, which was recorded by X-ray diffraction (XRD) of the samples after synthesis. The conditions were established for implementation of low-temperature synthesis. They are in compliance with recipes and special modes of the reaction mixture preparation, conditions of heating and cooling of samples in a controlled atmosphere. A mechanism of formation of oxy-carbo-boride phases in each stage of the recovery of the activated titanium oxide is presented for purposes of discussion.

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