Polyaluminasilazanes with nominal Si/Al molar ratio of 3 were synthesized by reaction of poly (methylvinyl)silazane with aluminum isopropoxide at 90, 100 and 120 ℃, respectively. The structures of theprecursors were characterized by FTIR and NMR. The results indicate that, with the synthesis temperature increasing, the intensities of Al-N FTIR vibration peak (1450 cm-1) and AlON2 (8 ppm) and AlO2N (-1 ppm)groups of 27Al NMR increase. The higher the reaction temperature is, the more the Al-N bonds are. The dehydrocoupling process may be a three-stage reaction process and the structure of polyaluminasilazane synthesized at 120 ℃ is the most complicated one due to the highest synthesis temperature. The pyrolysis processes of the precursors were studied by TG/DTA, FTIR and gas chromatography (GC). The synthesis temperatures have no significant effect on ceramization process and ceramic yield. Based on DTA curve, a further crosslink takes place at 475 ℃ during pyrolysis process. Besides, the released gases during pyrolysis process are identified by GC analysis as oligosilazane, CH4, C2H4, H2 and NH3. According to the XRD and SEM results, the product pyrolyzed at 1 200 ℃ under nitrogen atmosphere is a homogenous amorphous phase.%采用聚甲基乙烯基硅氮烷与异丙醇铝在90、100和120℃下反应分别合成出Si/Al物质的量的比为3的聚铝硅氮烷.利用红外(FTIR)和核磁(NMR)对前驱体结构进行表征.结果表明:Al-N键的红外振动强度(1450 cm-1)和核磁铝谱中的(Al)ON2(8ppm)及AlO2N(-1 ppm)基团的强度随合成温度的增加而增加.反应温度越高,形成的A1-N键就越多.这个脱氢耦合合成过程可能是一个三级反应过程,而在最高温120℃下所合成的聚铝硅氮烷的结构最复杂.前驱体的裂解过程通过耦合热重/差热分析(TG/DTA)、FTIR和气相色谱(GC)进行研究.合成温度对陶瓷化过程和陶瓷产率并没有明显的影响.根据DTA曲线可知,475℃发生进一步的交联.另外,GC数据表明裂解时所释放的气体为低分子量硅氮烷、CH4、C2H4、H2和NH3.根据XRD和SEM可知,1 200℃裂解后产物为均匀的非晶相.
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