PCS/VHPCS复相碳化硅先驱体的制备及性质研究

Preparation and Properties of PCS/VHPCS Complex Silicon Carbide Precursors

固态聚碳硅烷和全氢聚碳硅烷是目前研究较多的聚合物碳化硅陶瓷先驱体,在碳化硅陶瓷及其复合材料的制备方面具有广泛应用。制备了由不同比例固态聚碳硅烷(PCS)和乙烯基全氢聚碳硅烷(VHPCS)组成的复相碳化硅陶瓷先驱体,并对先驱体及其裂解产物的理化性质以及结构等进行了研究。研究表明,当PCS引入量低于30 wt.%时,PCS/VHPCS复相先驱体黏度低于200mPa·s;当PCS引入量低于20wt.%时,陶瓷产率可达到80%以上。PCS/VHPCS复相先驱体陶瓷产物为半结晶状β-SiC,晶粒尺寸较小,无明显晶界出现,且元素分布均匀,碳硅比低于PCS衍生陶瓷。

Solid polycarbosilane and perhydropolycarbosilane are the most widely used polymer precursors for the preparation of silicon carbide ceramics and their composites.Complex silicon carbide ceramic precursors with different ratios of solid polycarbosilane(PCS) and vinyl perhydropolycarbosilane(VHPCS) were prepared,while physicochemical properties and structures of the precursors and their pyrolysis products were systematically studied.When the PCS mass fraction is lower than 30 wt.%,the viscosity of the PCS/VHPCS composite precursor is lower than 200 mPa·s.When the PCS mass fraction is lower than 20 wt.%,the ceramic yield can reach more than 80%.The PCS/VHPCS complex precursor derived ceramics are semi-crystalline β-SiC with small grain size,while no obvious grain boundaries were observed.The element distribution is uniform and the carbon-to-silicon ratio is lower than that of PCS-derived ceramics.