Effect of Al2O3 + 4SiO2 additives on the sintering behavior and thermal shock resistance of MgO-based ceramics

Abstract

With the purpose of improving the sintering properties and thermal shock resistance of MgO-based ceramics, micron-sized MgO was used as the main raw material and nano-Al2O3 and SiO2 as additives. MgO-based ceramics was prepared by introducing different amounts of Al2O3 and SiO2 (Al2O3 and SiO2 at a molar ratio of 1:4) to MgO, shaped by moulding machine pressure and sintered at air atmospheric. The phase compositions and microstructure of ceramics were characterized by X-ray diffraction and scanning electron  microscopy, respectively. The effect of different content of Al2O3 + 4SiO2 on the sintering properties and thermal shock resistance of MgO-based ceramics was also investigated. The results showed that introducing Al2O3 + 4SiO2 addition greatly improved the sintering properties and thermal shock resistance of  MgO-based ceramics. Magnesium aluminate spinel and forsterite formed by solid reaction leading to the grain boundary migration rate of the periclase phase was hindered, the degree of densification of the specimen was deepen, improving the sintering properties of MgO-based ceramics. Meanwhile, the degree of densification increased with the increasing sintering temperature ranged from 1400 to 1500 °C. Furthermore, thermal shock resistance of the
specimen was improved by microcrack interlinking in the body. Through addition of up to 30 wt. % and 45 wt. % Al2O3 + 4SiO2 to MgO showed that the superior sintering properties and thermal shock resistance, respectively. Ill. 7. Ref. 14. Tab. 1.