Enhancing microstructural properties of alumina ceramics via binary sintering aids

• Published in: Journal of Central South University 2021-12, Vol.28 (12), p.3705-3713
• Main Authors: Hu, Yan-jun, Yin, Zi-qiang, Gong, Yu-bo, Yang, Zhi-gang, Yang, Zhan-ping, Liang, Yin-chun, Dong, De-jun, Zhao, Jin-jin
• Format: Article
• Language: English
• Subjects: Engineering; Metallic Materials
• ISSN: 2095-2899; 2227-5223
• DOI: 10.1007/s11771-021-4889-1

Alumina ceramics are widely used in many fields such as cutting tools, laser shock materials, roadbed board and refractory. Herein, Al 2 O 3 ceramics are prepared by a low-cost pressureless sintering technology, using the binary sintering aids of MgO and SiO 2 . The effects of sintering temperature and the ratio of binary sintering aids on the mechanical properties and microstructure of Al 2 O 3 ceramics are investigated. A spinel second phase (MgAl 2 O 4 ) is found out by the analysis of the results of XRD and EDS when MgO and SiO 2 are introduced in the samples. The optimum properties are found when MgO content is 20 wt% based on the total sintering aids and the sintering temperature is 1550 °C. The bending strength and the bulk density reach a maximum value of 314 MPa and 3.73 g/cm 3 , respectively. The addition of appropriate amount of SiO 2 makes the formation of liquid phase sintering and the removal of large pores. Meanwhile, a small amount of magnesium oxide doping has an effect on the grain refinement from the microstructure of the sample. Therefore, it is believed that MgO and SiO 2 are the ideal sintering aids for promoting the densification and property of alumina ceramics.