活性填料控制的先驱体裂解陶瓷的尺寸变化

DIMENSIONAL CHANGE MODELS FOR ACTIVE FILLER-CONTROLLED PRECERAMIC POLYMER PYROLYSIS

对单一先驱体、先驱体／惰性填料、先驱体／活性填料体系裂解陶瓷的尺寸变化进行了模型分析，从理论上分析了活性填料体积分数与裂解陶瓷体积收缩率和线收缩率之间的关系．揭示了活性填料的临界体积分数与活性填料反应的产率、反应前后的密度比之间的相关性．以聚碳硅烷先驱体为例、预测了在下同反应情况下，常见活性填料的临界体积分数．增加活性填料体积分数．可降低陶瓷产物的体积收缩率和气孔率．

The dimensional change models were developed for conversion of preceramic polymer-filler systems into ceramic bulks during pyrolysis, such as pure preceramic polymer, polymer containing an inert filler phase, polymer containing an active filler phase, and polymer containing inert filler and active filler phases. The relationships between the volume fraction of the active filler in the starting mixture and the volume shrinkage and linear shrinkage of the resulting ceramics were abstractly investigated. Therefore, the relationship between the critical volume fraction of the active filler and the mass change of active filler during reaction pyrolysis and density ratio of the active filler to filler reaction product were found. As to polycarbosilane precursor, the critical volume fractions of some potential active fillers were also predicted according to different reactions. The volume shrinkage and the porosity of the pyrolysis product decreased with increasing the volume fraction of the active filler by the models.