先驱体转化法制备Si-B-N-C陶瓷纤维及表征

以聚硼硅氮烷为先驱体, 经熔融纺丝、不熔化处理及氮气中高温热解、烧结得到Si-B-N-C陶瓷纤维. 利用元素分析、FTIR、XRD、高温热重分析等手段对Si-B-N-C纤维的组成、结构以及高温稳定性和抗氧化性等进行了表征. 结果表明, 纤维主要由Si3N4, BN和SiC等相组成, 其室温抗拉强度为2.1 GPa, 弹性模量为230 GPa, 具有很好的非晶稳定性和高温抗氧化性, 惰性气氛中可保持非晶至1700 ℃, 空气中加热至1100 ℃以下时无增重, 在1100-1400 ℃温度范围内增重约3.3％.

Preparation and Characterization of Polymer-derived Si-B-N-C Fibers

Si-B-N-C ceramic fibers were prepared by polymer derived method using precursor polyborosilazane. The composition, structure, high temperature stability and oxidation resistance of the ceramic fibers were investigated. The results indicate that the Si-B-N-C fibers combine several desired properties relevant for an application in fiber-reinforced ceramic composites. The fibers show good mechanical properties with the tensile strength 2.1 GPa and elasticity modulus 230 GPa. The ceramic fibers resist crystallization up to 1700 ℃ and only a mixture of partial crystallized Si3N4, BN and SiC phases is observed when heated to 1850 ℃ in N2 atmosphere. The fibers also show a excellent stability against oxidation, with a weight gain of only 3.3% in flowing air up to 1400 ℃.