Dense Si3N4 Ceramics Sintered at Low Temperature in Traditional Electric Furnace

Due to its high hardness, high wear resistance and high bending strength, Si3N4 ceramic is widely used in metallurgy, chemical industry, ae-rospace and automotive engines. Hot-pressed sintering and gas pressure sintering are commonly used in the preparation of dense Si3N4 ceramics due to the high strength bonding of Si3N4 which is difficult to be compacted. However, the strict preparation conditions such as high temperature pressure sintering greatly limit the basic research and the industrial application of dense Si3N4 ceramics in many technical fields. Therefore, the preparation of dense Si3N4 ceramics were obtained at lower sintering temperature using traditional air furnace to study the phase changes and microstructures of experimental crucible, Si3N4 powder and sintered sample under the present conditions. The results showed that the decomposition of the Si3N4 caused irregular SiC fiber accumulation on the crucible surface, and much more Si3N4 and a small amount of Si2N2O phase were remained in the buried Si3N4 powder because of the lower oxygen partial pressure. Si2N2O phase were also detected on the surface, but no Si2N2O appeared inside the sintered body. The Si3N4 ceramics sintered at 1 650℃ have the relative density over 98% with uniform microtissue and good performance. © 2022, Materials Review Magazine. All right reserved.