Abstract

Hybrid Carbon-Silicon Carbide (C-SiC) nano-fibers were fabricated while using a mixture of polyacrylonitrile (PAN) and silicon (Si) nanoparticles as precursors. The microstructure of the material was examined using X-ray diffraction and Raman spectroscopy as a function of processing temperature and holding time. A complete transformation of Si to SiC occurred at 1250 °C. However, for heat treatments below 1000 °C, three distinct phases, including Si, C, and SiC were present. The effect of microstructural changes, due to the heat treatment, on oxidation resistance was determined using thermogravimetric analysis (TGA). Furthermore, the char yield showed exponential growth with increasing the carbonization temperature from 850 °C to 1250 °C. The holding times at higher temperatures showed a significant increase in thermal properties because of SiC grain growth. At longer holding times, the SiC phase has the function of bothcoating and reinforcing phase. Such structural changes were related to fibers mechanical properties. The tensile strength was the highest for fiber carbonized fibers at 850 °C, while the modulus increased monotonically with increasing carbonization temperature.

Highlights

  • Carbon fibers (CFs) are fibers consisting of about 90% carbon elements with high strength (3–7 GPa) and modulus (200–500 GPa) [1,2,3,4]

  • The results showed that carbon nano-fibers (CNFs) began to react with oxygen at 400 ◦ C

  • The heat treatment temperatures and holding times played a key role in changing the microstructure and the resulting thermal and mechanical properties

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Summary

Introduction

Carbon fibers (CFs) are fibers consisting of about 90% carbon elements with high strength (3–7 GPa) and modulus (200–500 GPa) [1,2,3,4]. They display good thermo-chemical stability in nonoxidative environments. Polyacrylonitrile (PAN)-based carbon materials have light weight and high mechanical properties. Yuanjian et al [1] investigated the effect of oxidative environment on mechanical properties of two types of PAN-based CFs, namely CF-A (carbonized at 1350 ◦ C) and CF-B (carbonized at 1450 ◦ C). The tensile strength of fiber decreased significantly, but the modulus was found to remain constant

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