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CHARACTERISTICS OF PRECURSOR CERAMIC FIBER UNDER SEVERE ENVIRONMENTS

恶劣环境下原质陶瓷纤维的特性

基本信息

批准号：
05650642
负责人：
OKAMURA Kiyohito
金额：
$ 1.34万
依托单位：
UNIVERSITY OF OSAKA PREFECTURE
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

项目摘要

Precursor ceramic fibers have been produced from inorganic polymers as the precursor. Its process is melt-spinning of precursor polymer, curing and heat treatment. The fibers are amorphous and continuous fine fibers, and they have heat resistance and high tensile strength. The fibers have been expected as the reinforcement of ceramic matrix composites. The fibers contain large quantities of oxygen (more than 10wt%) coming from fiber-precessing of the oxidation-curing, but low-oxygen-type fibers (less than 1wt%) have been recently developed by curing with radiation crosslink. In this research work, mechanical properties, oxidation mechanism and high-temperature pyrolytic mechanism of the precursor fibers have been studied under the severe invironments of inert and oxidation atmosphere at temperatures of 1300ﾟ-1800ﾟC,using high-temperature furnace prepared by the GRANT-IN-AID FOR SCIENTIFIC RESEARCH (C).Precursor ceramic fibers with lower oxygen contents were pyrolyzed more slowly when h … More eated in an Ar atmosphere, and SiO and CO gases evolution of the fibers due to the high temperature pyrolysis were suppressed, significantly retaining their original high strength in the comparison with that of high oxygen-contained fibers. The fibers heat-treated in a N_2 atmosphere at temperatures below 1500ﾟC have higher strength and Young's modulus than that treated in an Ar, because of a formation of the nitride layr on fiber surface.On the other hand, the oxidation rate of the fibers followed the contracting-disc formula for diffusion control. The oxidation is considered to be controlled by the gaseous diffusion through the micropores in the silica film. The oxide film formed on the fiber surface suppressed high-temperature pyrolysis and provide considerable high-temperature strength. When the low-oxygen-types fibers were coated with more thin oxide layr in thickness, the hyrolysis of the fibers was suppressed significantly. The crystl structure in the core of the fibers changed from amorphous to beta-SiC microcrystallines. The tensile strength and Young's modulus were fairly improved by coating thin oxide layrs.These above research results are considered to be very effective for the development of precursor ceramic fibers and the the fibers reinforced ceramic matrix composites. Less

以无机聚合物为前驱体制备陶瓷纤维前驱体。其工艺是先将前驱体聚合物熔融纺丝，然后进行固化和热处理。该纤维是无定形的连续细纤维，并且它们具有耐热性和高拉伸强度。纤维有望成为陶瓷基复合材料的增强体。纤维中含有大量的氧（大于10wt%），氧来自于氧化-固化的纤维加工过程，而低氧型纤维（小于1wt%）则是近年来通过辐射交联而开发出来的。本文利用C型高温炉在1300 ~ 1800 ℃的惰性和氧化性气氛中研究了先驱体纤维的力学性能、氧化机理和高温热解机理。氧含量低的先驱体陶瓷纤维在1300 ~ 1800 ℃的高温下热解较慢，氧含量高的先驱体陶瓷纤维在1300 ~ 1800 ℃的高温下热解较慢，氧含量低的先驱体陶瓷纤维在1300 ~ 1800 ℃的高温下热解较慢，氧含量高的先驱体陶瓷纤维在1300 ~ 1800 ℃的高温下热解较慢，氧含量低的先驱体陶瓷纤维在1300 ~ 1800 ℃的高温下热解较慢。 ...更多信息在Ar气氛中加热，并且由于高温热解而导致的纤维的SiO和CO气体的释放被抑制，与高含氧纤维相比，显著地保持了它们原有的高强度。在1500 ℃以下的N_2气氛中热处理的纤维，由于在纤维表面形成了氮化物层，其强度和杨氏模量比在Ar气氛中热处理的纤维高，另一方面，纤维的氧化速率遵循控制扩散的收缩圆盘公式。氧化被认为是控制通过二氧化硅膜中的微孔的气体扩散。在纤维表面形成的氧化膜抑制了高温热解，并提供了相当大的高温强度。在低氧型纤维上涂覆较薄的氧化物层，纤维的水解得到明显抑制。纤维芯部的晶体结构由非晶转变为β-SiC微晶。通过在陶瓷纤维表面涂覆氧化物薄膜，可以显著提高陶瓷纤维的拉伸强度和弹性模量，这些研究结果对先驱体陶瓷纤维及其增强陶瓷基复合材料的开发具有重要意义。少