Preparation and Properties of Pressureless-Sintered Porous Si 3 N 4 Ceramics

In this paper, the effect of benzoic acid on the porosity, dielectrical and mechanical properties of porous Si3N4 ceramics prepared by pressureless sintering was investigated. The results showed that the addition of benzoic acid improved the porosity and dielectrical properties of Si3N4 remarkably by pressureless sintering at 1700 ℃ for 60 min. The porosity of sample reached 40.79% with 50 wt% benzoic acid addition and the reflectivity of the sample reached −45 dB at around 12 GHz.