This study presents the synthesis and high-temperature evaluation of ultra-light CF/SiC composite fibers fabricated through a SiO–C reaction environment combined with a controlled Chemical Vapor Reaction (CVR) process. Although CVR-based SiC deposition is widely used, the influence of carbon fiber crystallinity on SiC nucleation and coating growth remains insufficiently clarified. To address this gap, SiC coatings were formed at various reaction temperatures, and their microstructural evolution was analyzed to identify material-dependent reaction pathways. FE-SEM, TEM/SAED, XRD, and XPS analyses revealed that higher reaction temperatures promoted the transformation of amorphous Si–O–C intermediates into crystalline β-SiC, while the structural ordering of the carbon fibers governed nucleation density and crystal orientation. At 1500°C, a dense and continuous β-SiC coating approximately 1.3 μm thick was achieved without interfacial defects, indicating coherent CF/SiC bonding. Thermogravimetric analysis demonstrated the superior oxidation resistance of the coated fibers: pristine carbon fibers were fully oxidized by 1400°C, whereas CF/SiC fibers exhibited only ~1% mass loss due to the protective SiC layer. These results establish a clear relationship between carbon-fiber crystallinity, SiC growth behavior, and oxidation protection. The findings provide practical guidelines for designing lightweight, thermally robust CF/SiC composites suitable for aerospace and extreme-temperature applications.

본 연구에서는 SiO–C 반응 환경과 CVR 공정을 이용하여 CF/SiC 복합섬유를 합성하고, 탄소섬유 결정성이 SiC 코팅 형성에 미치는 영향을 규명하였다. 반응 온도 증가에 따라 비정질 Si–O–C 종이 β-SiC로 전환되었으며, 1500°C에서 약 1.3 μm 두께의 치밀한 SiC 층이 형성되었다. 고온 산화 평가 결과, CF/SiC 복합섬유는 약 1%의 중량 손실만을 보여 우수한 산화 저항성을 나타냈다. 본 연구는 탄소섬유 구조와 SiC 성장 간의 상관관계를 제시함으로써 고내열 경량 복합섬유 설계를 위한 기반을 제공한다.

Keywords: 탄화규소코팅(SiC coating), 탄소섬유복합소재(Carbon fiber composites), CVR, 열보호시스템(Thermal protection)