Precursor gas comparison for the growth of silicon carbide fibers via laser chemical vapor deposition

Laser chemical vapor deposition (LCVD) is a processing technique that can be used to grow fibers. In this study, the relationships between deposited SiC fiber composition, fiber microstructure, and fiber mechanical properties (ambient temperature failure stress in tension) were compared using two different precursor gases - Tetramethylsilane (TMS) and Dimethylsilane (DMS) – using laser chemical vapor deposition (LCVD). Each set of fibers was grown at 2, 4 and 6 bar at a growth rate of 50 um/s. Furthermore, each set of fibers contained a nanocrystalline core. In some cases, the presence of nodular structures were noted, but these features were comprised of nanocrystalline grains. The crystalline structure for both fibers were indexed by X-ray diffraction as the 3C-SiC cubic phase. The fibers were carbon-rich. In general, the TMS fibers had generally higher average stress at failures that were 2280 MPa as compared to the average DMS fibers being 1150 MPa. Considerable spread in the tensile strength at failure was noted for the DMS fibers and is contributed to residual stresses, as they fibers were qualitatively more delicate to handle. A Weibull analysis revealed that the fibers had a low Weibull modulus, which is an indication of a large and unpredictable variation of flaws within the fibers.

Grantor dc:publisher

University of Alabama Libraries

Year dc:date.issued

2020

Author dc:creator

• Matt, Mia Catherine

Advisor dc:contributor.advisor

• Thompson, Gregory B.

Contributors dc:contributor

• Li, Lin
• Allred, Jared

• Materials science

Statement dc:rights

• All rights reserved by the author unless otherwise indicated.

Language dc:language.iso

en_US, English

Dc Identifier Other

u0015_0000001_0003602
Matt_alatus_0004M_14110

OAI identifier oai:identifier

oai:ir.ua.edu:123456789/7001