Self-Propagating High-Temperature Synthesis of MgAl2O4 Spinel

• Published in: Inorganic materials 2020-02, Vol.56 (2), p.142-150
• Main Authors: Radishevskaya, N. I., Nazarova, A. Yu, L’vov, O. V., Kasatskii, N. G., Salamatov, V. G., Saikov, I. V., Kovalev, D. Yu
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Boron; Boron oxides; Chemistry; Chemistry and Materials Science; Flammability; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Liquid phases; Magnesium aluminate; Materials Science; Melting points; Self propagating high temperature synthesis; Spinel; X-ray diffraction
• ISSN: 0020-1685; 1608-3172
• DOI: 10.1134/S0020168520010112

— Magnesium aluminate spinel, MgAl 2 O 4 , has been prepared by self-propagating high-temperature synthesis (SHS) in the MgO–Al 2 O 3 –Mg(NO 3 ) 2 ∙ 6H 2 O–Al–B system. The composition and structure of the synthesis product have been ascertained by X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Using time-resolved X-ray diffraction (TRXRD), we have studied the phase formation process during SHS and identified the key reaction paths. The addition of 2–4 wt % boron has been shown to result in the formation of a liquid phase during the combustion process owing to the formation of a low-melting-point boron oxide, favoring the growth of skeletal spinel crystals 1–10 μm in size. Our results demonstrate that the use of a mixture of aluminum and boron as combustible components of the starting mixture and heating at a rate above 100°C/min allow a material containing more than 95 wt % MgAl 2 O 4 spinel to be obtained.