摘要 |
HOE 88/F 343 Chlorine-containing silazane polymers, process for their preparation, ceramic materials containing silicon nitride which can be prepared from them, and their preparation The invention relates to novel chlorine-containing silazane polymers, to their preparation, their further processing to ceramic material containing silicon nitride, and this material itself. In order to prepare the chlorine-containing silazane polymers, oligosilazanes of the formula (I) in which a > 0, b 2 0 and n is about 2 to about 12, are reacted with at least one of the chlorosilanes Cl2R4Si-CH2-CH2-SiR4Cl2, Cl3Si-CH2-CH2-SiR5Cl2, R5SiCl3 or R7SiHCl2 at 30.degree.C to 300.degree.C, where, independently of one another, R1 and R2 = H, C1-C6-alkyl or C2-C6-alkenyl, R3, R4, R5, R6 and R7 = C1-C6-alkyl or C2-C6-alkenyl and where if b = 0 the reaction with R7SiHCl2, if R7 = C1-C6-alkyl and none of the other chlorosilanes is present, is to be excluded. The chlorine-containing silazane polymers according to the invention can be converted by reaction with ammonia into polysilazanes, which in their turn can be pyrolysed to form ceramic materials containing silicon nitride.
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