图15 多孔氧化铝陶瓷扫描电镜照片 [ 55 ] Fig. 15 SEM images of porous alumina ceramics, which are prepared by using a 20vol% slurry without glycerol, b 20vol% slurry with glycerol, c 30vol% slurry without glycerol and d 30vol% slurry with glycerol [ 55 ] The direction of fracture parallels to the ice front |