"Formation of nanocrystalline graphite in polymer-derived SiCN by polym" by Mingxing LI, Laifei CHENG et al.

Article Title

Formation of nanocrystalline graphite in polymer-derived SiCN by polymer infiltration and pyrolysis at a low temperature

Authors

Mingxing LI, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, China
Laifei CHENG, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, China
Fang YE, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, China
Conglin ZHANG, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, China
Jie ZHOU, Science and Technology on Thermostructural Composite Materials Laboratory, Northwestern Polytechnical University, Xi’an 710072, China

Keywords

polymer-derived ceramics (PDCs), silicon carbonitride (SiCN), free carbon, carbonization, dielectric property

Abstract

The microstructure of polymer-derived ceramics (PDCs) was closely related to processing. This study demonstrated that SiCN matrix prepared by polymer infiltration and pyrolysis (PIP) at 900 ℃ inside a Si₃N₄ whisker (Si₃N_4w) preform with submicro-sized pores differed from its powder- consolidated analogue in both the content and structure of free carbon. Chemical analysis showed that PIP process had a higher free carbon yield. Raman spectroscopy and transmission electron microscopy (TEM) observation discovered a higher graphitization degree of free carbon and the existence of nanocrystalline graphite in SiCN matrix. Dielectric properties of Si₃N_4w/SiCN composites were greatly enhanced when volume fraction of SiCN matrix reached 24.5% due to dielectric percolation caused by highly-lossy free carbon. Reconsolidation of hydrocarbon released during pyrolysis by gas-state carbonization in Si₃N₄ whisker preform was supposed to account for the high yield and graphitization degree of free carbon in PIP process.

Recommended Citation

LI, Mingxing; CHENG, Laifei; YE, Fang; ZHANG, Conglin; and ZHOU, Jie (2021) "Formation of nanocrystalline graphite in polymer-derived SiCN by polymer infiltration and pyrolysis at a low temperature," Journal of Advanced Ceramics: Vol. 10: Iss. 6, Article 2.
DOI: https://doi.org/10.1007/s40145-021-0501-2
Available at: https://dc.tsinghuajournals.com/journal-of-advanced-ceramics/vol10/iss6/2

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