Abstract
SiC coatings were successfully synthesized on NextelTM440 fibers by chemical vapor deposition (CVD) using methyltrichlorosilane as the original SiC source at 1373 K. After deposited, the fibers were fully surrounded by uniform coatings with some bulges. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM) results indicated that the coatings were composed of β-SiC and free carbon. Moreover, thickness control of the coatings could be carried out by adjusting the deposition time. The coating thickness rose exponentially, and the exterior of the coatings became looser as the deposition time increased. The thickness of about 1.5 µm was obtained after depositing for 4 h. The coating thickness was also theoretically calculated, and the result agreed well with the measured thickness. Finally, the related deposition mechanism is discussed and a deposition model is built.
Highlights
SiC ceramic has attracted extensive attention due to its excellent performance, such as appropriate high-temperature strength, relatively high oxidation, corrosion and thermal-shock resistance [1,2,3,4], etc.SiC ceramic can be used in coating materials, especially in fiber-reinforced ceramic matrix composites (FRCMCs) to improve the bond strength between the fiber and matrix
We investigated the deposition mechanism of chemical vapor deposition (CVD) SiC coatings on NextelTM 440 fibers, and thickness control of the coatings was actualized by varying the deposition time
Carbon-rich SiC coatings were synthesized on NextelTM 440 fibers by CVD
Summary
SiC ceramic can be used in coating materials, especially in fiber-reinforced ceramic matrix composites (FRCMCs) to improve the bond strength between the fiber and matrix. Our previous works proved that SiC interphases were suitable for the strength improvement of high-temperature structural and functional materials due to its oxidation tolerance and relatively temperature-stable dielectric characteristics [8,9]. SiC coatings have been successfully deposited by CVD on silicon carbide fibers, carbon fibers, oxide fibers and more [10,11,12]. Most research has focused on the coatings’ effects on microstructure and mechanical properties of those fibers, the strength improvement of the fiber-reinforced ceramic matrix composites, or the degradation mechanism of the coatings [13,14]. Research on the deposition mechanism and thickness control of CVD SiC coatings on oxide fibers is rare
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