Influence of Additives and Hot-Press Sintering on Lipophilicl Properties of Silicon Nitride Ceramics

摘要

Fe_3O_4 and Mo and were added to hot-press sintered Si_3N_4 ceramics to improve their lipophilic and mechanical properties. The bending strength, relative density, hardness and fracture toughness of Si_3N_4 ceramics with addition of Fe_3O_4 and Mo were improved by hot-press sintering compared with samples prepared with the pressureless process. In particular, the bending strength and relative density were improved to about 200% and 104%, respectively. Both the macro- and micro-lipophilicity of Fe_3O_4- and Mo-added ceramics were improved when prepared with the hot-press process, compared with those prepared with the pressureless process. This can be attributed to the addition of Fe_3O_4, and the formation of MoO_3 and Si_2N_2O during hot-press sintering. The lower friction coefficient and high wear resistance of Fe_3O_4- and Mo-added ceramics have been achieved by applying the hot press process. The high wear resistance is considered to be due to the improvement of hardness and fracture toughness, which decreased the loss of particles during the wear test.