预处理温度对聚碳硅烷粒子炉内成球性的影响

Effects of Pre-heating Temperature for Polycarbosilane on Preparing Capsule with Drop-tower Technique

本文以聚碳硅烷（PCS）为原料,采用炉内成球技术制备直径200~400μm、壁厚3~5μm的SiC空心微球,探讨微球制备的最佳条件,并在此基础上研究不同预处理温度对PCS成球产率及品质的影响。结果表明,炉内载气温度为500℃、He与Ar比例为3∶1时PCS的成球产率较高,且微球的球形度、同心度、表面光洁度均最好。此外,由于预处理过程去除了PCS中的低分子量聚碳硅烷和其他小分子,同时使其聚合度升高,提高了PCS的热稳定性和陶瓷化产率。因此,在最佳炉内成球条件下,PCS的成球率随预处理温度的升高而升高,所得微球的表面粗糙度却随之降低。经350℃预处理后的PCS粒子成球率最高,且微球的球形度和表面质量最佳。

The SiC hollow microspheres with the diameter of 200-400μm and the thickness of 3-5μm were fabricated by drop-tower technique using polycarbosilane（PCS）as raw material,and the best furnace conditions and the effects of pre-heating temperature on preparing capsules were investigated in this paper.The obtained microspheres were characterized to study the relationships between their productivities,qualities and the pre-heating temperatures.The results show that the microspheres fabricated at 500 ℃with 25%Ar and 75%He as the inner furnace gas condition possess the highest capsule productivity,and the best sphericity,concentricity and surface finishment.Furthermore,some of the PCS with low molecular weight and other small molecules were eliminated in the pre-heating treatment process,which could reinforce the polymerizationdegree of PCS and enhance the thermo-stability and ceramic yield of the raw materials.Therefore,the productivity of the microspheres promotes while the surface roughness decreases with the increasing of pre-heating temperature at the best inner furnace condition.Especially,the microspheres prepared with PCS pre-heating at 350 ℃ possess the greatest quality.