Ultra-high temperature resistance properties of Si-B-N wave-transparent fibers
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摘要: 以聚硼硅氮烷(PBSZ)为先驱体,经熔融纺丝、不熔化以及在氨气气氛中高温裂解制备了Si-B-N 纤维,然后在高纯氮气保护下加热至超高温。利用元素分析、FTIR、XRD、SEM、力学性能分析和波导法等研究了纤维的耐超高温性能。结果表明:Si-B-N 纤维1 500 ℃退火几乎不失重,在惰性气体中非晶状态可以保持至1 700 ℃,加热到1 850 ℃才形成 Si3N4和BN等结晶相;Si-B-N 纤维的拉伸强度为1.72 GPa,弹性模量为196 GPa,1 500 ℃ 退火Si-B-N纤维的拉伸强度为1.86 GPa,弹性模量为205 GPa,Si-B-N纤维具有很好的耐超高温性能;此外,采用波导法测量,Si-B-N纤维表现出优良的介电性能,测试频率为 8~12 GHz,1 400 ℃退火的Si-B-N纤维平均介电常数和介电损耗角正切值分别为约3.68和0.001 1。
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关键词:
- Si-B-N 陶瓷纤维 /
- 先驱体转化法 /
- 耐超高温 /
- 力学性能 /
- 透波性能
Abstract: Si-B-N fibers were prepared by melt-spinning, curing and pyrolysis under high temperature of a precursor polyborosilazane(PBSZ) under NH3 atmosphere, then the fibers were heated up to ultra-high temperature under purity N2. The ultra-high temperature resistance property of the fibers was researched by elemental analysis, FTIR, XRD, SEM, mechanical properties analysis and wave-guide methods. The results show that the weight of Si-B-N fibers lose little annealed at 1 500 ℃, the fibers can remain amorphous up to 1 700 ℃ in inert atmospheres, and a mixture of Si3N4 and BN crystalline phases are observed upon heating to 1 850 ℃; average tensile strength and average elastic modulus of Si-B-N fibers are 1.72 GPa and 196 GPa at room temperature respectively, and they are 1.86 GPa and 205 GPa annealed at 1 500 ℃, respectively. So the fibers exhibit excellent ultra-high temperature resistance property. In addition, the Si-B-N fibers show good dielectric properties according to the measurement by a wave-guide method, average dielectric constant and dielectric loss tangent of the Si-B-N fibers annealed at 1 400 ℃ are about 3.68 and 0.001 1 in 8-12 GHz, respectively.
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