采用乳液技术和先驱体转化法相结合,利用改性后SiO2颗粒表面的双键引发聚硅氮烷(PSN)原位聚合,得到SiO2/PSN核壳结构微球,经高温裂解过程成功制备SiO2/SiCN核壳陶瓷微球.研究SiO2与PSN原料的质量比、固化时间和热解温度对核壳微球形成过程和形貌的影响,并采用SEM,EDS,TEM,FT-IR,XRD对微球的微观形貌、化学成分及物相进行表征.结果表明:SiO2与PSN质量比为1∶4时,200℃固化4h得到表面颗粒分布均一、包覆完全的SiO2/PSN核壳微球;经800～1200℃热处理后,得到能保持原来形貌的非晶态SiO2/SiCN核壳陶瓷微球;1400℃热解产物发生结晶,生成了SiO2,SiC和Si3 N4晶相.
The SiO2/PSN core-shell microspheres were prepared via an emulsion reaction combined with the polymer-derived ceramics (PDCs) method using polysilazane (PSN) in situ polymerization on the surface of SiO2 modified by silane coupling agents MPS,followed by pyrolysis process to obtain SiO2/SiCN core-shell ceramic microspheres.The effects of raw mass ratio,curing time and pyrolysis temperature on the formation and the morphology of core-shell microspheres were studied.The morphology,chemical composition and phase transformation were characterized by SEM,EDS,TEM,FT-IR and XRD.The results show that after reaction for 4h at 200℃,SiO2 completely coated PSN forms a core-shell microsphere with rough surface when the mass ratio of SiO2 and PSN is 1 ∶ 4;when pyrolysis temperature is at 800-1200℃,amorphous SiO2/SiCN core-shell ceramic microspheres are prepared;at 1400℃,the amorphous phase partially crystallizes to produce SiO2,SiC and Si3N4 phase.
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