烧结助剂对多孔氮化硅陶瓷的力学性能及介电性能的影响(英文)

EFFECT OF SINTERING AID ON MECHANICAL AND DIELECTRIC PROPERTIES OF POROUS SILICON NITRIDE CERAMICS

通过添加烧结助剂,采用常压烧结工艺制备出不同气孔率(19%～54%)的氮化硅陶瓷。采用Archimedes法、三点弯曲法和Vickers硬度测试法测量了材料的密度、气孔率、抗弯强度及硬度。用X射线衍射及扫描电镜检测了相组成和显微结构。用谐振腔法测试了氮化硅陶瓷在10.2GHz的介电特性。结果表明:材料具有优良的介电性能。随着烧结助剂的减少,样品中气孔率增加,力学性能有所下降,介电常数和介电损耗降低。添加Lu2O3所制备的氮化硅陶瓷的力学性能和介电性能优于添加Eu2O3或Y2O3制备的氮化硅陶瓷。当气孔率高于50%时,多孔氮化硅陶瓷(添加入5%的Y2O3或Lu2O3,或Eu2O3,质量分数)的抗弯强度可达170MPa,介电常数为3.0～3.2,介电损耗为0.0006～0.002。

Silicon nitride ceramics with different porosities from 19% to 54% were produced with the initial silicon nitride powder containing different amounts of added sintering aids. The density, porosity, flexural strength and hardness were tested by the Archimedes method, porosimetry analysis, three-point bending test and Vickers hardness measurement, respectively. The dielectric property of silicon nitride ceramics was measured at 10.2 GHz. The microstructure and phase composition of the silicon nitride ceramies were studied by X-ray diffraction and scanning electron microscopy. The results show that the silicon nitride ceramics have excellent dielectric property. The dielectric constant and loss of the silicon nitride ceramics decrease with the increase of porosity. The mechanical and dielectric properties of the silicon nitride ceramics added with Lu2O3 are better than those added with Eu2O3 or Y2O3. Porous Si3N4 ceramics with porosity above 50% and added with 5% in mass sintering aids, such as Y2O3, Lu2O3 or Eu2O3, were obtained with synergistic properties： a flexural strength of 170 MPa, dielectric constants of 3.0-3.2 and dielectric losses of 0.000 6-0.002.