Hyperbaric Laser Chemical Vapor Deposition of Titanium Carbide Fibers

Laser chemical vapor deposition (LCVD) is a technique in which material in the vapor phase can be deposited into a solid phase structure, such as a fiber, under the focus of a laser. This study reports on the deposition of titanium carbide (TiC) through LCVD. A system for the growth of TiC fibers at hyperbaric conditions was developed with subsequent fibers grown at 2 bar. The growth of the TiC fibers was done under three different laser intensities and under three different gas compositions of titanium tetrachloride (TiCl4), ethylene (C2H4), and hydrogen (H2). The combination of gas composition and laser intensity facilitated hollow fibers (or tubes) to hierarchical fibers of a distinct carbon-rich core with a titanium-rich outer shell. These fibers were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The control of the tube-to-carbon rich core is explained by the Soret effect, which is where lighter weight molecules partition to the warmer regions of a reaction region.