原位反应结合多孔Si3N4陶瓷的制备及其介电性能

Preparation and Dielectric Properties of In Situ Reaction Bonded Porous Si_3N_4 Ceramics

以氮化硅(Si_3N_4)和氧化铝(Al_2O_3)为起始原料,利用原位反应结合技术制备Si_3N_4多孔陶瓷.研究烧结温度和保温时间对Si_3N_4多孔陶瓷的微观结构、力学性能以及介电性能的影响.结果表明:烧结温度在1350℃以下,保温时间<4h时,随着烧结温度的升高,保温时间的延长,样品的强度和介电常数增大;但条件超出这个范围,结果刚好相反;物相分析表明多孔陶瓷主要由Si_3N_4和Al_2O_3以及Si_3N_4氧化生成的SiO_2(方石英)组成.所制备的多孔Si_3N_4陶瓷的气孔率范围为25.34%～48.86%,抗弯强度为34.77～127.85MPa,介电常数为3.0～4.6,介电损耗约为0.002.

Porous Si3N4 ceramics were prepared by in situ reaction-bonding technology, using Si3N4 and Al2O3 as starting materials. The effects of sintering temperature and holding time on their porosities, flexural strength, and dielectric properties were studied. The strength and dielectric constants of samples are improved with increasing of sintering temperature and holding time; but the result is reverse in the condition of sintering temperature 〉1350℃ and holding time 〉4h. The phase analyses results indicate that the porous SiaN4 ceramics are mainly composed of α-Si3N4, oxidated SiO2 （cristobalite） and Al2O3. Porous Si3N4 ceramics with porosities from 25.34% to 43,92% and flexural strength from 42.54 to 127.85MPa are obtained. Their dielectric constants are in the range from 3.3 to 4,6 and dielectric loss is about 0.005.