Journal Article

Formation of TiBsub.2–MgAlsub.2Osub.4 Composites by SHS Metallurgy

Yeh, Chun-Liang, Zheng, Fu-You

2023

Overview

TiB[sub.2]-MgAl[sub.2]O[sub.4] composites were fabricated by combustion synthesis involving metallothermic reduction reactions. Thermite reagents contained Al and Mg as dual reductants and TiO[sub.2] or B[sub.2]O[sub.3] as the oxidant. The reactant mixtures also comprised elemental Ti and boron, as well as a small amount of Al[sub.2]O[sub.3] or MgO to serve as the combustion moderator. Four reaction systems were conducted and all of them were exothermic enough to proceed in the mode of self-propagating high-temperature synthesis (SHS). The reaction based on B[sub.2]O[sub.3]/Al/Mg thermite and diluted with MgO was the most exothermic, while that containing TiO[sub.2]/Al/Mg thermite and Al[sub.2]O[sub.3] as the diluent was the least. Depending on different thermites and diluents, the combustion front temperatures in a range from 1320 to 1720 °C, and combustion wave velocity from 3.9 to 5.7 mm/s were measured. The XRD spectra confirmed in situ formation of TiB[sub.2] and MgAl[sub.2]O[sub.4]. It is believed that MgAl[sub.2]O[sub.4] was synthesized through a combination reaction between Al[sub.2]O[sub.3] and MgO, both of which can be totally or partially produced from the metallothermic reduction of B[sub.2]O[sub.3] or TiO[sub.2]. The microstructure of the TiB[sub.2]-MgAl[sub.2]O[sub.4] composite exhibited fine TiB[sub.2] crystals surrounded by large densified MgAl[sub.2]O[sub.4] grains. This study demonstrated an energy-saving and efficient route for fabricating MgAl[sub.2]O[sub.4]-containing composites.

• Publisher: MDPI AG
• Subject: Combustion