CAO Zhongmin 1, ZHOU Cunlong 1, 2, WANG Qiang 1, YANG Chao 1
(1. School of Mechanical Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, Shanxi, China; 2. Shanxi Key Laboratory of Metallurgical Equipment Design Theory and Technology, Taiyuan 030024, Shanxi, China)
Abstract: As Si3N4 ceramics are increasingly used in the aerospace, metallurgical and mechanical manufacturing fields, as wear-resistant key components, enhancing their toughness and wear resistance at the same time has become a hot research topic. Si3N4 ceramics with different properties were prepared by introducing different levels of La2O3 and the effects of La2O3 on microstructure, density and mechanical properties of the Si3N4 ceramics were studied. It was showed that the density of theSi3N4 ceramics was increased with increasing content of La2O3 , with maximum of 99.6±0.12%, while the fracture toughness tended to increase and then decrease and the hardness tended to decrease and then increase. When the content of La2O3 reached 4 wt.%, a second reinforce phase La3Si8O4N11 was formed in the Si3N4 ceramics. The Vickers hardness (HV) reached 1590±20 and the fracture toughness reached 5.58±0.11 MPa•m1/2. The wear rate was 2.99×10-4 mm3/N m under frictional wear conditions with a normal load of 30 N, a sliding frequency of 3 Hz and a sliding distance of 4 mm.
Key words: Si3N4 ; La2O3 ; gas pressure sintering; mechanical property; second phase