无机材料学报 ›› 2025, Vol. 40 ›› Issue (4): 405-414.DOI: 10.15541/jim20240439 CSTR: 32189.14.10.15541/jim20240439

• 研究论文 • 上一篇    下一篇

烧结条件对制备高结晶近化学计量比SiC纤维的影响

苟燕子1(), 康伟峰1, 王堋人2   

  1. 1.国防科技大学 空天科学学院, 新型陶瓷纤维及其复合材料重点实验室, 长沙 410073
    2.酒泉卫星发射中心, 兰州 732750
  • 收稿日期:2024-10-18 修回日期:2024-11-18 出版日期:2025-04-20 网络出版日期:2024-11-25
  • 作者简介:苟燕子(1984-), 副研究员. E-mail: y.gou2012@hotmail.com
  • 基金资助:
    国家自然科学基金(52272100);湖南省自然科学基金面上项目(2022JJ30662);新型陶瓷纤维及其复合材料重点实验室基金项目(WDZC20215250507);核反应堆技术全国重点实验室(中国核动力研究设计院)基金(KGSW-0324-0301-08)

Influence of Sintering Conditions on Preparation of Nearly Stoichiometric SiC Fibers with Highly Crystalline Microstructure

GOU Yanzi1(), KANG Weifeng1, WANG Pengren2   

  1. 1. Science and Technology on Advanced Ceramic Fibers and Composites Laboratory, College of Aerospace Science and Engineering, National University of Defense Technology, Changsha 410073, China
    2. Jiuquan Satellite Launch Center, Lanzhou 732750, China
  • Received:2024-10-18 Revised:2024-11-18 Published:2025-04-20 Online:2024-11-25
  • About author:GOU Yanzi (1984-), associate professor. E-mail: y.gou2012@hotmail.com
  • Supported by:
    National Natural Science Foundation of China(52272100);Natural Science Foundation of Hunan Province(2022JJ30662);Fund of Science and Technology on Advanced Ceramic Fibers and Composites Laboratory(WDZC20215250507);Fund of National Key Laboratory of Nuclear Reactor Technology of Nuclear Power Institute of China(KGSW-0324-0301-08)

摘要:

细直径连续SiC纤维是先进陶瓷基复合材料的最佳增强纤维之一, 在航空航天和核工业领域具有重要的应用价值, 其中高结晶近化学计量比SiC纤维的耐温性能最好, 但是高温烧结条件对该纤维元素组成与微观结构的影响规律还不清楚。本工作研究了烧结温度和时间对纤维中SiCxOy相分解、晶粒长大以及纤维致密化的影响规律, 发现SiCxOy相分解和纤维的致密化过程均是由表层逐渐向芯部进行, 并且只有在适当的烧结温度(1800 ℃)下, 才能通过生长β-SiC晶粒来弥补SiCxOy相分解产生的孔隙缺陷, 最终实现纤维的致密化。值得注意的是, 过高的烧结温度会造成β-SiC晶粒分解。虽然延长烧结时间有助于消除纤维中的残余氧, 但会使β-SiC晶界处的石墨相变得更加集中, 且纤维芯部产生更多的孔隙缺陷。通过优化条件最终成功制备了致密的高结晶近化学计量比SiC纤维, 其组成为SiC1.04O0.02Al<0.01, 纤维中的β-SiC晶粒均匀分布, 尺寸达到100~200 nm。纤维的拉伸强度和杨氏模量分别为1.88 GPa和373 GPa, 并且密度高达3.1 g/cm3。上述研究结果可以为进一步提升SiC纤维的综合性能奠定坚实的基础。

关键词: SiC纤维, 烧结, 近化学计量比, 密度, 高结晶

Abstract:

Fine-diameter continuous SiC fibers are considered one of the most effective reinforcing fibers for advanced ceramic matrix composites, possessing significant application potential in aerospace and nuclear industries. Among them, near-stoichiometric SiC fibers characterized by a highly crystalline microstructure have garnered considerable attention due to their exceptional high-temperature resistance. However, influence of high-temperature sintering conditions on composition and microstructure of the fibers is still unclear. Here, influences of different sintering temperatures and durations on decomposition of the SiCxOy phase, grain growth and densification of the fibers were systematically investigated. It was found that decomposition of SiCxOy and densification of fibers occur progressively from surface to core. Notably, a specific sintering temperature of 1800 ℃ was identified as optimal, wherein growth of β-SiC grains effectively compensated for the pore defects resulting from the decomposition of SiCxOy phase, thereby achieving fiber densification. Conversely, excessively high sintering temperature might result in decomposition of β-SiC grains. Although extending sintering duration facilitated removal of residual oxygen within the fibers, it could cause accumulation of graphite phases at β-SiC grain boundaries, leading to an increase in pore defects within the fiber core. Finally, near-stoichiometric SiC fibers with highly crystalline microstructure were successfully fabricated through optimization of sintering conditions, possessing a composition of SiC1.04O0.02Al<0.01. The β-SiC grains within the fibers were uniformly distributed with sizes ranging from 100 to 200 nm. The fibers exhibited a tensile strength of 1.88 GPa and a Young’s modulus of 373 GPa, accompanied by a high density of 3.1 g/cm3. The findings of this research provide a robust foundation for further improving comprehensive properties of SiC fibers.

Key words: SiC fiber, sintering, nearly stoichiometric, density, highly crystalline

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