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Abstract This paper reports the preparation of Ti microparticles that are angular and spherical in shape through the combustion of a TiO 2 + αCa (where α is moles of Ca) exothermic mixture in an inert atmosphere. The relationship between the combustion parameters and the properties of the resultant Ti particles is discussed with consideration of the effect of Ca concentration. Using excess amounts of Ca in the experiment was effective in modifying the shape of the particles from angular to spherical. The Ti powder was found to be well-dispersed and the diameter of individual particles ranged from 5 µm to 50 µm. Based on the combustion parameters, the activation energy for the redox reaction was calculated as ∼ 138 kJ/mol. This paper discusses the chemistry of the reduction process and highlights the effects of combustion temperature and the amount of liquid calcium on the characteristics of the Ti particles. Graphical abstract The combustion process in TiO 2 + Ca mixture developed a maximum temperature of about 1820 °C and resulted in Ti spherical particles. fx1 [ABSTRACT FROM AUTHOR]

In this study, we examined the effect of potassium perchlorate (KClO 4 ) and magnesium hydroxide (Mg(OH) 2 ) additives on the combustion behavior of a ZrO 2  + 2Mg mixture to produce a fine powder of zirconium metal. The results of thermodynamic analysis and experiments imply that nearly 0.04 mol of KClO 4 is needed to initiate a combustion reaction in the ZrO 2  + 2Mg system. As the amount of KClO 4 increases from 0.04 to 0.1 mol, the combustion temperature increases from 1250 to 1850 °C. This results in formation of fine zirconium powder with a typical particle size of less than 5 µm, and with 1.4–2.2 wt% residual oxygen. Subsequent reduction of particle size to 100–500 nm, and oxygen content to <1.0 wt% was achieved by adding Mg(OH) 2 . The as-prepared Zr powder was mixed with nitrocellulose and printed onto 10–100 µm thin-layers to study their burning stability. The wave propagation in a thin layer was on the order of 0.35–30 cm/s, which is suitable for applications requiring localized power generation. [ABSTRACT FROM AUTHOR]

This study deals with combustion behavior of B 2 O 3 /Mg/NH 4 Cl/C complex systems for the synthesis of amorphous boron (B), boron carbide (B 4 C), and boron nitride (BN) nanostructures. The raw mixtures used in the experiments were prepared on the base of a B 2 O 3 –Mg precursor mixture, which is sufficiently exothermic to maintain a self-propagating regime of the combustion reaction. Thermodynamic analysis of the combustion temperatures and experimental validation indicate that the 1000–1500 °C temperature range is very effective for synthesizing the nanostructures of B, B 4 C, and BN. It was found that B-containing functional nanostructures are mainly spherical nanoparticles (B) or nanosheets (B 4 C, BN). The phase composition and microstructural characteristics of the final products were evaluated based on the combustion temperature and solid/liquid phase changes. [ABSTRACT FROM AUTHOR]