Microstructure of SiC fiber fabricated by two-stage chemical vapor deposition on tungsten filament

Abstract

Continuous silicon carbide (SiC) fiber with a diameter of about 100 μm was fabricated by two-stage chemical vapor deposition on tungsten filament. Microstructure of the fiber was investigated by means of scanning electron microscopy, X-ray diffraction, transmission electron microscopy and Raman spectrometry. The results showed that the fiber consists of tungsten core, a W/SiC interfacial reaction zone with the reaction products of W 5Si 3 and WC, and a predominant β-SiC layer. The W/SiC interface can be described as W/W 5Si 3/WC/SiC. The SiC originates at the surface of the WC with a buffer layer, in which β-SiC crystallites nucleate and grow with their preferred (1 1 1) orientation, exhibiting strong 〈1 1 1〉 fiber texture. Raman spectra revealed that the SiC in the fiber is stoichiometric, which is composed of β-SiC and amorphous SiC. Furthermore, the formation mechanism of W/SiC interfacial reaction zone and structural evolution of SiC are discussed.