Features of the processes  of boride formation during plasma treatment  of titanium-boron-containing raw materials

Metallurgy and Materials

The temperature dependence of the composition of the gaseous and solid products formed, the composition of gaseous compounds thermodesorbed from the surface of titanium diboride, and the morphology of nanoparticles were studied in order to form ideas on the mechanism of boride formation processes occurring during plasma treatment of titanium-boron-containing raw materials. Analysis of the results suggests a possible mechanism for the formation of titanium diboride in the «vapor-melt-crystal» scheme, which includes the condensation of titanium vapor in the form of an aerosol, the boron nano-drop of the melt with borohydrides, and the crystallization of the titanium-boron melt; A generalized hypothetical scheme of boride formation has been compiled, containing 2 zones: a high-temperature (5400–3500 K) for the formation of a reaction mixture in which evaporation of a powdered titanium-boron-containing charge occurs, «gasification» of boron into borohydrides, and a lower-temperature (3500–2000 K), In which condensation of titanium vapor occurs, a significant decrease in the concentration of borohydrides and the formation of titanium diboride.