SEM and optical microscopy photographs show that large gas porosity exists among granulas and Si3N4 particles have weak connection with CVI Si3N4, which makes the maximum bending strength of the specimen is 71MPa.

• SEM和光学显微图片表明颗粒团间气孔偏大,Si3N4颗粒和CVI Si3N4之间界面弱结合,导致试样的弯曲强度最高只有71MPa。