Porous Silicon Nitride Ceramics Fabricated by Carbothermal Reduction-Reaction Bonding

Porous Si3N4 ceramics with a fibrous interlocking microstructure were synthesized directly by carbothermal reduction between SiO2 and carbon and reaction bonding of Si, in the N2 atmosphere. X-ray diffractometry analysis demonstrated that β-Si3N4 was the major phase. The influences of content and powder size of the Si on the microstructure and properties of the samples were investigated. Scanning electron microscope (SEM) analysis exhibited that rod-like β-Si3N4 grains were formed in the samples prepared by using the fine Si powder. With an increase in the Si content, the porosity decreased, and the flexural strength increased accordingly.