ABSTRACT Porous SiC ceramics were prepared based on precursor conversion method using liquid hyperbranched polycarbosilane (LHBPCS) as the preceramic polymer and expandable microsphere (EMS) as the pore foaming agent. By optimising the content of free radical initiator, the cross-linking process of LHBPCS is synchronised with the foaming process of EMS. The addition of EMS had no serious effect on the cross-linking reaction mechanism and rate of LHBPCS, and the cross-linking of LHBPCS did not significantly confine the foaming of EMS. After 1000°C pyrolysis, EMS decomposed, but its spherical shape with sizes of 20–30 μm homogeneously embedded in the pyrolysed LHBPCS. As a result, a highly porous SiC foam with density of 0.211 g cm–3 and porosity of 91.2% was obtained and its thermal conductivity at room temperature was as low as 0.05 W (m K)–1. In addition, with increasing test temperature, its thermal conductivity increased slowly, indicating a good thermal insulation property.

中文翻译：

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陶瓷前驱体转化制备高多孔碳化硅及其隔热性能评价

【摘要】：以液态超支化聚碳硅烷(LHBPCS)为陶瓷前驱体聚合物,可膨胀微球(EMS)为孔隙发泡剂,采用前驱体转化法制备了多孔碳化硅陶瓷。通过优化自由基引发剂的含量，使LHBPCS的交联过程与EMS的发泡过程同步。EMS的加入对LHBPCS的交联反应机理和速率没有明显影响，LHBPCS的交联没有明显限制EMS的发泡。在 1000°C 热解后，EMS 分解，但其大小为 20-30 μm 的球形均匀嵌入到热解的 LHBPCS 中。结果，获得了密度为 0.211 g cm-3 和孔隙率为 91.2% 的高孔隙率 SiC 泡沫，其室温热导率低至 0.05 W (m K)-1。