SiBCN陶瓷前驱体高温裂解机理  

Pyrolysis Mechanism of SiBCN Polymer Precursor

作　　者：李亚静[1] 张跃[1] 

机构地区：[1]北京航空航天大学材料科学与工程学院,空间材料与服役教育部重点实验室,北京100191

出　　处：《无机材料学报》2014年第3期321-326,共6页Journal of Inorganic Materials

基　　金：国家自然科学基金(51072010;51272009)~~

摘　　要：SiBCN是目前重要的高温非晶材料之一。非晶结构表征是研究非晶材料形成过程的关键。采用固态NMR和FT-IR为主要的研究手段研究聚硅硼碳氮烷的热稳定性和SiBCN陶瓷前驱体高温裂解机理。研究表明,陶瓷化转变过程分为三个阶段,第一阶段是产生引发剂,即聚合物前驱体中的叔碳脱氢转化成季碳自由基;第二阶段是链增长和链终止,季碳自由基首先攻击碳甲基,使甲基脱落生成新的自由基,随着温度的升高,自由基还会攻击硅甲基,生成新的自由基。在生成新的自由基过程中使链增长。当自由基与自由基结合时,链终止;第三阶段是陶瓷化,通过脱氢将已经无机化的中间产物转化成陶瓷,形成无机三维连续非晶网络。第一、二阶段属于有机转变,第三阶段属于无机转变。当转化成陶瓷时,陶瓷内只含有Si、B、C和N四种元素,端基完全脱落。High temperature amorphous materials, mainly in the system of SiBCN, have aroused ever increasing attention. Effective methods should be used to study the structural changes in the process of fabrication. In this paper, the thermal stability of PBSZ and the pyrolysis mechanism of SiBCN polymer precursor were studied by SS-NMR and FT-IR. Polymer-to-ceramic transformation can be divided into three stages as follows. The first stage is the production of initiator in which, the tertiary carbon dehydrogenates to quaternary carbon free radical. The second stage is propagation and termination in which, quaternary carbon free radical attacks methyl group to turn the methyl group into new free radical. With increasing temperature, the free radical attacks Si-CH3 and results in a new free radical. The propagation of the chain occurs when new free radicals are generated, while the termination occurs after the free radicals combination with each other. The third stage is polymer-to-ceramic transformation. Through dehydrogenation, ceramics are produced from the intermediate inorganic products, and amorphous continuous 3D mesh structures are formed. The first and second stages are organic transformations and the third stage is an inorganic transformation. There are four elements in the ceramic, including Si, B, C and N.

关 键 词：MNR FT-IR SiBCN 聚硼硅氮烷 

分 类 号：TB35[一般工业技术—材料科学与工程]