液态聚硅氧烷交联-成型-热解制备复杂形状硅氧碳陶瓷

Fabrication of Macroscopic Complicated-shaped Bulk Silicon Oxycarbide Ceramics from Liquid Polysiloxanes by Crosslink-cast-pyrolysis

采用液相法,以含氢聚硅氧烷和乙烯基环四硅氧烷为前驱体,经注模、交联和热解制备出净成型的硅氧碳陶瓷体,研究了该体系的成型、交联和热解行为,以及高温热解过程中陶瓷结构和组成的转变。研究表明:该体系有很好的成型能力,以不同材质和形状的模具均可成型,经热解可制备出各种形状和尺寸的硅氧碳陶瓷材料;交联体在整个热解过程中均保持完整,可获得不同温度(400～1 000℃)的无开裂的热解体;硅氧碳陶瓷在高温热解过程中通过Si—O和Si—C键重排由无定形的Si—O—C网络转化为含SiC和SiO2纳米晶的陶瓷结构。

： Liquid casting process is used for the fabrication of net-shaped bulk silicon oxycarbide （SiOC） ceramics from polyhydromethylsiloxane and tetravinylcycletetrasiloxane through liquid casting, crosslinking and pyrolysis. The shaping, crosslinking and pyrolysis behavior is studied, and the structure and composition evolution of the SiOC ceramics pyrolyzed at high temperature is also studied. This system shows excellent shaping properties allowing the obtaining of macroscopic complicated-shaped bulk SiOC ceramics using different material and shape molds followed by pyrolysis. The crosslinked bodies remain intact during the pyrolysis process to obtain the crack-free pyrolyzed bodies at different temperatures （400-1 000 ）. The structural analysis suggests that the SiOC ceramic transformed from amorphous Si--O--C network into nanoceramic containing SiC and SiO2 nanocrystals through the rearrangement of Si--O and Si--C bonds at higher pyrolysis temperature.