Thermodynamic Analysis of Perspective AlB12 Synthesis Reactions from Industrially Accessible Oxygen-Free Compounds

Abstract

Reactions of aluminum dodecaboride synthesis from oxygen free industrially available boron compounds by interaction of condensed and gaseous aluminum with boron nitride and carbide were the subject of thermodynamic analysis in this work. It was shown, that both reactions are thermodynamically advantageous at low temperatures rather than at high and the probability of their occurrence rises significantly for gaseous aluminum in comparison with condensed aluminum. Calculated values of Gibbs' free energy and equilibrium constants and the analysis of contributions into them clearly demonstrate the advantages of reaction with boron nitride. The probability of polyphase product composition imposes minimum temperature restrictions on the synthesis; it should be carried out at temperatures above 1000 ℃. Hypothetical mechanisms of reactions between aluminum and boron containing compounds differ by the place of interaction -any place on the surface of each layer of BN and only open surface of B 4 C -and by the transport of reaction participants in the reaction zone. From the results of analysis, we suggest indicative synthesis conditions: vacuum thermal synthesis to provide oxygen free environment and temperature above 1000 ℃ to avoid aluminum diboride formation.

Application of AlB$_{12}$–Al Electric Spark Coatings to Protect Titanium Alloys During Wear Under Fretting Corrosion

“…Its synthesis from Al and BN, developed at the Frantsevich Institute for Materials Science Problems of N.A.S. of Ukraine is more rational and economically efficient than direct one from Al and B [13]. AlB12 has a low density (∼ 2.52 g/cm 3 ) and the particularity of its crystalline structure (icosahedral boric frame) determines its high hardness (22-24 GPa) and infusibility (2070°C) [14].…”

Properties of AlB$_{12}$–Al Electric Spark Coatings on D1 Aluminium Alloy

“…Its synthesis from Al and BN, developed at the Frantsevich Institute for Problems of Materials Science of N.A.S. of Ukraine is more rational and economically efficient than direct one from Al and B [20]. In addition, AlB 12 has a low density (∼2.52 g/cm 3 ) and the particularity of its crystalline structure (icosahedral boric frame) determines its high hardness (22-24 GPa), and refractoriness (2070°C) [21].…”