Influence of Mechanical Activation on Synthesis of Compounds

in the B/C - Mg/Al/Ca System

Farit Kh. Urakaev1,2, Vyacheslav S. Shevchenko1 and Vladimir V. Boldyrev2

1Institute of Mineralogy and Petrography, Siberian Division, Russian Academy of Sciences,

prospekt akademika Koptyuga, 3, Novosibirsk, 630090, Russia

2Novosibirsk State University, Pirogova street, 2, Novosibirsk, 630090, Russia

Abstract

The possibility of mechanochemical synthesis and influence of mechanical activation on thermal synthesis of borides and boron carbides of mass-low metals is investigated. The opportunity of mechanochemical synthesis in the mill AGO-2 of such compounds as AlB2 and CaC2B2 is established. Influence of mechanical activation in the mill SPEX 8000 on synthesis of such compound as Mg0.5Al0.5B2 is shown. Mechanical activation also influences on the process of thermal synthesis: compound Mg0.5Al0.5B2 is obtained in the conditions inaccessible to traditional thermal synthesis; formation of compound Mg1-xAlxB2 in literature up to x = 0.4 was established on shifts of reflexes (002) and (110) pure MgB2 aside the large corners; in our case x = 0.5 and as it was necessary to expect shifts of these reflexes exceeds shifts measured in literature only for x £ 0.4.

Features of synthesis in systems containing metal magnesium are considered. The opportunity of application of crystalline boron for mechanochemical synthesis of borides and boron carbides of mass-low metals is established, that it was not represented probable to make in its ceramic synthesis. We revealed also that thermal analysis in conditions of helium results in crystallization almost all activated samples, and the analysis of received X-ray reflexes unambiguously allows to assert that mechanical activation accelerates synthesis of reaction products in the investigated systems in comparison with the traditional methods of its synthesis.