Towards continuous processes for the synthesis of precursors of amorphous Si/B/N/C ceramics
作者:Markus Weinmann、Matthias Kroschel、Thomas Jäschke、Jürgen Nuss、Martin Jansen、Grigorios Kolios、Aristides Morillo、Carlos Tellaeche、Ulrich Nieken
DOI:10.1039/b716144a
日期:——
The development of a process for the continuous synthesis of Cl3SiNMeBCl2 (DMTA) as a single-source precursor of highly durable Si/B/N/C ceramics is reported. The process is based on a series of gas phase reactions starting from silicon tetrachloride and methylamine. Cl3SiNHMe (TSMA), which is initially formed, is subsequently reacted with BCl3 to yield DMTA as a colorless, highly air-sensitive liquid. Amine hydrochloride byproducts are removed by filtration through ceramic filters. DMTA crystallizes in the monoclinic system, space groupP21/m, with a = 709.96(13) pm, b = 685.61(12) pm, c = 897.28(16) pm, and Z = 2. Polymerization of DMTA by aminolysis in n-hexane at −78 °C releases a polyborosilazane, SiBN2.4C2.5H8.8, which upon thermolysis releases amorphous SiBN2.3C1.7 ceramic in 56% yield. The latter resists thermal degradation by crystallization in Ar atmosphere up to at least 1700 °C.
本报告介绍了一种连续合成 Cl3SiNMeBCl2 (DMTA) 的工艺,它是一种高耐久性 Si/B/N/C 陶瓷的单一来源前体。该工艺基于从四氯化硅和甲胺开始的一系列气相反应。最初形成的 Cl3SiNHMe(TSMA)随后与 BCl3 反应,生成无色、对空气高度敏感的液体 DMTA。胺盐酸盐副产物通过陶瓷过滤器过滤去除。DMTA 结晶为单斜晶系,空间群为 P21/m,a=709.96(13)pm,b=685.61(12)pm,c=897.28(16)pm,Z=2。DMTA 在 -78 °C 的正己烷中通过氨解发生聚合反应,生成聚硼硅氮烷 SiBN2.4C2.5H8.8,热解后生成无定形的 SiBN2.3C1.7 陶瓷,产率为 56%。后者在氩气环境中可通过结晶抗热降解,温度至少可达 1700 °C。