一种新型多孔SiC的制备与性能研究

Preparation and Basic Properties of a New Porous SiC

以滤纸和酚醛树脂为原料,通过模压成型、固化、碳化和渗硅制备出微观结构均匀的多孔碳化硅.碳化的温度固定时,多孔碳的气孔率随酚醛树脂用量的增大而减少,弯曲强度随着酚醛树脂用量的增大而增大.酚醛树脂/滤纸两种成分的质量比固定时,气孔率随着碳化温度的升高而减小,弯曲强度随着碳化温度的升高而增大,从SEM照片可以看出,由滤纸纤维的杂乱排列和碳化时不同的收缩率产生了相互连通不规则的孔,在多孔碳化硅结构中也得以保留.多孔碳化硅的气孔率随着排硅时间的增加而增大,强度和韧性随着排硅时间的增加而减小.在1650℃,并经过30min排Si,较大孔隙中的Si就可以排掉,此时得到的多孔SiC具有较高的强度和韧性.

A new type of porous silicon carbide was fabricated by filter paper-phenolic resin composite through mold-stacking, drying, carbonization and Si infiltration process. When the carbonization temperature is fixed, with the increase of the content of phenolic resin, the open porosity of porous carbon decreases, and the bending strength of porous carbon increases. When the weight ratio of phenolic resin and filter paper is fixed, with the increase of carbonization temperature, the open porosity of porous carbon decreases, and the bending strength of porous carbon increases. SEM observation reveals that the irregular interconnected pores are derived from the disorder arrangement of filter paper microfibers and the different shrinkage ratios between phenolic resin and filter paper during carbonization. Moreover, these pores remain to form SiC. Open porosity of porous silicon carbide increases, and bending strength and fracture toughness decrease with the increase of Si removing time. When the samples are heated up to 1650~C with 30min Si removing, the excess Si in bigger pores is removed, the resulting porous SiC has higher bending strength and fracture toughness.