液态SiC陶瓷前驱体分子结构与固化热解行为  

Molecular Structure of Liquid SiC Ceramic Precursors and Their Curing and Pyrolysis Behavior

作　　者：荆楚凡 缑新岳 张宗波[1] 李永明[1] 徐彩虹[1,2] JING Chufan;GOU Xinyue;ZHANG Zongbo;LI Yongming;XU Caihong(Key Laboratory of Science and Technology on High-Tech Polymer Materials,Institute of Chemistry,Chinese Academy of Sciences,Beijing 100190,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院化学研究所,中国科学院极端环境高分子材料重点实验室,北京100190 [2]中国科学院大学,北京100049

出　　处：《硅酸盐学报》2024年第9期2780-2788,共9页Journal of The Chinese Ceramic Society

摘　　要：液态超支化聚碳硅烷具有低黏度和高陶瓷产率等优良特性,作为SiC陶瓷前驱体应用潜力巨大,但目前关于其分子结构与性能关系的研究尚不充分。对2类共5种具有不同分子结构和热解产物碳硅比的液态超支化聚碳硅烷的固化、热解特性以及其陶瓷产物的结晶行为进行了研究。结果表明,聚碳硅烷分子结构中侧甲基、乙烯基以及烯丙基的含量共同影响了其固化和热解行为,适量乙烯基/烯丙基可显著提高陶瓷产率和降低固化温度,而甲基含量的增加会导致固化温度升高和热解过程中甲烷释放量增多,使陶瓷产率降低。同时,前驱体的分子结构决定其热解产物的碳硅比,进而影响其结晶行为和抗氧化能力。5种单源前驱体的热解陶瓷产率为75%~89%,所得陶瓷产物(1.15~1.70)均具有良好的高温抗氧化性。Introduction SiC ceramics,known for their lightweight,high strength,high temperature resistance and oxidation resistance,find extensive applications in aerospace,energy and transportation industries.The polymer-derived ceramics(PDC)method is an important method for the preparation of SiC ceramics,employing special polymers as raw materials and converting them into inorganic ceramics via high-temperature pyrolysis.This method offers advantages such as controllable elemental composition,ease of molding,and lower processing temperatures.As one of the most important raw materials in the PDC method,hyperbranched liquid polycarbosilanes,synthesized via the Grignard coupling reaction and the subsequent reduction reaction,are prized for their low viscosity,high ceramic yield,and ease of processing and molding.Therefore,it has been widely used in the fabrication of ceramic matrix composites,coatings and membrane materials.A large number of articles have been published on the synthesis and applications of polycarbosilanes.The molecular structure of SiC polymer precursors not only influences their curing and pyrolysis processes,including weight loss and gas release behavior,but also plays an important role in determining the elemental composition(e.g.,C/Si ratio),crystallization behavior and oxidation resistance.There are many studies conducted to investigate the structure of precursors affecting their curing and pyrolysis properties.However,it is very necessary to investigate the relationship between molecular structures of different types of liquid polycarbosilanes with varying C/Si ratios and their curing,pyrolysis and crystallization behaviors.In this work,the curing and pyrolysis behaviors as well as the crystallization behavior of two major types of liquid hyperbranched polycarbosilanes vinylhydridopolycarbosilane(VHPCS)and allylmethylhydridopolycarbosilane(AMHPCS)with different carbon-to-silicon ratios and molecular structures were comprehensively characterized by a variety of testing methods.The relationship between

关 键 词：液态聚碳硅烷 固化行为 热解行为 抗氧化性能 

分 类 号：TQ127.2[化学工程—无机化工]