Enhancing the thermal shock resistance of alumina-rich magnesium aluminate spinel refractories by an aluminum titanate phase

摘要

In order to enhance the thermal shock resistance of alumina-rich magnesium aluminate (MA) spinel ceramics, aluminum titanate (Al2TiO5) was either mixed as a pre-synthesized powder with the spine] raw material or in situ formed from added alumina and titania during sintering. Thermal shock tests were performed by water quenching from 950 degrees C or 1150 degrees C, subjecting the sintered samples to one or five test cycles. The ceramics were investigated by means of porosity measurements, scanning electron microscopy (SEM), three-point bending tests before and after thermal shock, X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). A temperature of 1550 degrees C was found to be suitable for sintering. The ceramics containing Al2TiO5 exhibited lower porosities, larger grain sizes, lower strengths after sintering, and higher retained strengths after the thermal shock tests than comparison specimens without Al2TiO5. Their improved thermal shock resistance is beneficial for refractory applications. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.