凝胶注模成型制备纳米复合多孔氮化硅陶瓷

采用凝胶注模成型两步法烧结工艺,利用纳米碳粉增强,成功地制备出了具有高强度、结构比较均匀并有较高气孔率的氮化硅多孔陶瓷。借助X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线能谱(EDS)、Archimedes法和三点弯曲法等方法对多孔氮化硅陶瓷的微观结构和基本力学性能进行了研究。结果表明:在适当工艺条件下可制成平均强度>100 MPa、气孔率>60%的多孔氮化硅陶瓷。SEM照片显示气孔是由长柱状β-Si₃N₄晶搭接而成的,气孔分布均匀。XRD图谱显示有SiC生成。发育良好的柱晶结构、均匀的气孔分布以及反应生成的SiC微晶是获得高性能的主要原因。 

PREPARATION OF POROUS Si3N4 NANOCOMPOSITES BY GELCASTING

The porous Si3N4 ceramics with a high strength, uniform structure and a relative high porosity were obtained by adding a little amount of nano carbon in slurry by gelcasting and two step sintering. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Energy dispersive X-ray spectroscopy (EDS), Archimedes and three-point bending methods were employed to characterize and analyze the microstructures and basic mechanical performances of porous Si3N4 ceramics.The results show that the strength of sintered porous Si3N4 ceramics reaches 100 MPa and its porosity is more than 60% under proper technical conditions. SEM shows that the pores are formed by pillar β-Si3N4, and XRD and EDS show that SiC were formed. The pillar β-Si3N4 structure, uniform porous distribution and formative SiC particles are the main reasons for good mechanical performances.