COMBUSTION SYNTHESIS AND CHARACTERIZATION OF ENERGETIC BORIDES
A. Vorozhtsov, A. Zhukov, M. Ziatdinov
National Research Tomsk State University, Lenin av., 36, 634050, Tomsk, Russia
Borides are advanced materials for use as fuel additives for energetic systems. The potential of use of metal powders (Al, Mg and others) is almost exhausted today. New additives with higher energy characteristics are required. Boron is the best alternative so far. Heat of combustion for boron is almost two times higher than for aluminum. Production technologies for boron and its compounds are well-known and tested. Moreover, boron is non-toxic, occurs in nature in large quantities and produced on an industrial scale.
From the very beginning of the research in the field of combustion synthesis a lot of promising systems from the practical point of view were determined, however, a self-sustaining process was not possible due to their insufficient exothermicity. The first approach was pumping of additional heat by means of pre-heating of initial mix in a resistance furnace. It was the production of intermetallides when the operation of increasing of initial temperature of reaction mix was used for the first time for SHS reactions. The increase of initial temperature of the mix up to 50-500°C made it possible to synthesize aluminides of Ni, Co, Ti, Cr, Mo and other metals in combustion mode. When such furnace SHS technology is used in practice its characteristic advantages such as zero energy consumption, simplicity of equipment and low time consumption are reduced to zero.
The use of potentially high boron exothermicity becomes possible if it is used in the form of metal borides which also have high values of the heat of combustion. It was found that borides of Al and Mg as well as Ti and Zr are the most promising ones.
This paper describes a laboratory technology of production of borides of Al, Ti, Mg etc. including double and mixed compounds. Elemental boron, boron carbide, iron boride were used as boron source. The experimental results of XRD-analysis, TGA and particle size analysis obtained for synthesized powders are given.
Self-propagating high-temperature synthesis is the most suitable method for of development of new energy materials which makes it possible to produce ultrapure product with target chemical and phase composition by means of adjustment of synthesis parameters. Preliminary studies have indicated that it is possible to produce borides with high content of target phase. According to DTA data the degree of oxidation of obtained powders exceeds 95%.
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