Search

Carbon microrods were grown from ethylene using laser-assisted chemical vapor deposition. The precursor pressure and laser power were varied. The internal structure of the carbon rods was characterized by Raman spectroscopy at 514.5 nm using an Ar[sup +] laser. The rods were cast in epoxy resin and polished in order to allow a radial analysis of the cross section. Each spectrum has been analyzed by noting the peak positions and width changes. Intensities of the G and D peaks were compared between spectra and allowed the determination of the crystal size as a function of radius. An analysis of the spectra gave insight in the bonding conditions as well as the growth mechanism of the rods as a function of the experimental parameters. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Carbon fibers were deposited directly from ethylene by laser-assisted chemical vapor deposition. The precursor gas pressures and the incident laser powers were varied. Micro-mechanical testing was carried out using a high-precision micro-manipulator. During three-point bend testing the fibers showed an elastic response, with no residual strain upon unloading, until fracture. The fibers’ strength and Young’s modulus are reported. A model for fiber fracture is proposed based on fiber cross-section analysis. Scanning electron microscopy was used to study the fiber cross-sections and the fiber surface morphology. The mechanical properties are related to the characteristic fiber microstructure investigated by Raman spectroscopy. [Copyright &y& Elsevier]

Carbon microfibers were deposited using laser-assisted chemical vapor deposition at atmospheric and sub-atmospheric pressures. Precursor pressures and incident laser powers were varied. Fibers were cast in acrylic resin and polished to allow nanoindentation of the cross sections. Cross-sectional roughness was examined by optical profilometry. A radial change in mechanical properties was observed. The local elastic modulus (Young’s modulus) and hardness for the edge and core regions are reported. These mechanical properties were investigated with respect to deposition parameters and corresponding fiber microstructure. [ABSTRACT FROM AUTHOR]