LIU Cong 1，GUO Weiming 1，FU Junyu 2，TONG Wenxin 2，WU Shanghua 1
(1. Guangdong University of Technology, Guangzhou 510006, Guangdong, China; 2. Chaozhou Three-circle (Group) Co.,
Ltd., Chaozhou 515646, Guangdong, China)
Abstract: The Si3N4 ceramics were prepared by hot pressing at 1600 °C and 1800 °C using Al2O3-Y2O3 and MgO-Y2O3 as sintering additives, respectively. With the addition of Al2O3-Y2O3, the Si3N4 ceramics produced at 1800 °C showed remarkable bimodal distribution and excellent comprehensive mechanical properties, and its Vickers hardness, flexural strength and fracture toughness were 15.60 ± 0.27 GPa, 1105.99 ± 68.39 MPa and 7.13 ± 0.37 MPa·m1/2, respectively. However, with the addition of MgO-Y2O3, the Si3N4 ceramics fabricated at 1600 ℃showed higher density, contained whisker-like Si3N4 grains with high aspect ratio, and exhibited excellent integrated mechanical properties, and its Vickers hardness, flexural strength and fracture toughness were 16.53 ± 0.21 GPa, 1166.90 ± 61.73 MPa and 6.74 ± 0.17 MPa·m1/2, respectively. Therefore, in order to obtain Si3N4 ceramics with superior mechanical properties, the corresponding sintering temperature for each sintering aid needs to be considered simultaneously.
Key words: Si3N4 ceramics; sintering aids; sintering temperature; microstructure; mechanical property