DU Daming, BAI Xiaobo, SONG Jieguang

(School of Mechanical and Materials Engineering, Jiujiang University, Jiujiang, Jiangxi 332005, China)

Abstract:Si3N4 ceramics containing Y2O3 and La2O3 complex rare-earth oxides were fabricated by pressureless sintering, and their mechanical properties, phase composition and microstructure were studied by universal material testing machine,microhardness meter, X -ray diffractometer and scanning electron microscope. The results show with the increase of sintering additives, the density of Si3N4 ceramics increased at 1650℃, but increased first and then decreased at 1700℃ and at 1750℃. When 8% Y2O3-La2O3 was used as the sintering additive, the flexural strength and the fracture toughness of the sample sintered at 1700°C reached 960MPa and 7.5MPaom1/2, and Si3N4 ceramics was made of rod-like β-Si3N4 grains.

Key words:rare-earths oxides; Si3N4; mechanical property; microstructure