Methods of the Synthesis of Aluminum Borides from Elemental Substances for Use as High-Energy Materials: A Review
- PDF / 563,116 Bytes
- 7 Pages / 612 x 792 pts (letter) Page_size
- 56 Downloads / 217 Views
NOLOGY OF INORGANIC SUBSTANCES AND MATERIALS
Methods of the Synthesis of Aluminum Borides from Elemental Substances for Use as High-Energy Materials: A Review Sh. L. Guseinova, S. G. Fedorova, *, and P. A. Storozhenkoa aState
Research Institute of Chemistry and Technology of Organoelement Compounds, Moscow, 105118 Russia *e-mail: [email protected] Received May 11, 2018; revised June 4, 2018; accepted June 13, 2019
Abstract—Two methods of the synthesis of aluminum borides are considered, one of which is the calcination of a mixture of Al and B powders at temperatures from 900 to 1500°C and the other is high-temperature selfpropagating synthesis with mechanical preactivation. It is shown that aluminum borides can be synthesized by mechanical activation alone. All these methods give micrometer-sized particles of aluminum borides. The plasma recondensation of an Al–B mixture produces nanodispersed powders of aluminum borides. The activity of the powders with respect to atmospheric oxygen is determined by thermogravimetric analysis. Keywords: aluminum borides, aluminum, boron, mechanical activation, plasma recondensation DOI: 10.1134/S0040579520040089
INTRODUCTION Aluminum borides have unique properties, including high values of hardness, specific strength, melting point, chemical resistance, and thermal and electrical conductivity, as well as a low linear thermal expansion coefficient [1]. It is believed that materials based on aluminum borides can be efficient neutron absorbers and can be used in the nuclear industry [2]. However, of particular interest is the use of aluminum borides as high-energy additives to rocket fuels, explosives, and pyrotechnic materials [3]. In calorific value, aluminum borides are second only to boron. The calorific value of elemental boron is 136980 kJ/L; aluminum borides (AlB2, AlB10, and AlB12), 127975–135905 kJ/L; aluminum, 83760 kJ/L; and organoboron compounds, 50000–56000 kJ/L. For comparison, the calorific value of the superdense hydrocarbon propellant RI-5 developed in the United States is 44600 kJ/L [4]. However, although aluminum diboride and other aluminum borides are considered promising for practical application, they have not yet found wide use, mainly because of the absence of a productionfriendly method for their synthesis [5]. REVIEW OF METHODS OF THE SYNTHESIS OF ALUMINUM BORIDES FROM ELEMENTAL SUBSTANCES The purpose of this work was to review the existing synthesis methods of aluminum borides that give pure aluminum borides or their mixture, which can be used as components with high calorific values for highenergy materials, and also to study the activity of these
aluminum borides with respect to atmospheric oxygen. Aluminum borides are considered an alternative to the most energy-efficient fuel—boron. The main obstacle to the use of boron in high-energy materials is known to be the fact that the combustion of boron is accompanied by the formation of liquid boron oxide around a boron particle, which shields the particle and hinders the access of oxygen to it. Howev
Data Loading...
