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Dubrovnik, Croatia

Joo S.H.,Chungnam National University | Nersisyan H.H.,Chungnam National University | Lee T.H.,Chungnam National University | Cho Y.H.,Hana AMT | And 3 more authors.
Korean Journal of Materials Research | Year: 2015

The self-propagating high temperature synthesis approach was applied to synthesize amorphous boron nanopowders in argon atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in the B2O3 + α Mg system(α = 1.0-8.0) in an argon atmospheres. In this study, the exothermic nature of the B2O3-Mg reaction was investigated using thermodynamic calculations. Experimental study was conducted based on the calculation data and the SHS products consisting of crystalline boron and other compounds were obtained starting with a different initial molar ratio of Mg. It was found that the B2O3 and Mg reaction system produced a high combustion temperature with a rapid combustion reaction. In order to regulate the combustion reaction, NaCl, Na2B4O7 and H3BO3 additives were investigated as diluents. In an experimental study, it was found that all diluents effectively stabilized the reaction regime. The final product of the B2O3 + α Mg system with 0.5 mole Na2B4O7 was identified to be amorphous boron nano-powders(> 100 nm). © Materials Research Society of Korea. Source


Nersisyan H.H.,Chungnam National University | Joo S.H.,Chungnam National University | Yoo B.U.,Chungnam National University | Cho Y.H.,Hana AMT | And 2 more authors.
Combustion and Flame | Year: 2015

A melt-assisted solid flame synthesis approach was applied to synthesize boron nanoparticles in argon gas and air atmospheres. For this purpose, we investigated the characteristics of a thermally induced combustion wave in B2O3 + αMg mixtures (α =1.0-1.5mol) in argon and air atmospheres. Utilizing stoichiometrically insufficient amounts of magnesium ensured that a large portion of molten B2O3 remained in the sample, which reduced the combustion parameters and favored the formation of boron nanoparticles. Under these conditions the combustion temperature and burning velocity were controlled in the range of 1300-1580°C and 0.065-0.18cm/s, respectively, and boron nanoparticles in a ~20-200nm size range were obtained. The characteristics of boron nanoparticles (morphology, purity, specific surface area, oxidation activity, etc.) were analyzed and a reaction pathway leading to boron nanoparticles synthesis was proposed. © 2015 The Combustion Institute. Source

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