Preparation and Basic Properties of a New Porous SiC

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 tem- perature 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.More- over,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℃with 30min Si removing,the excess Si in bigger pores is removed,the resulting porous SiC has higher bending strength and fracture toughness.