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The cathode catalyst layer in proton exchange membrane (PEM) fuel cells can contain nanometer-sized platinum particles dispersed on a high surface area carbon. In order to assess support stability, samples of carbon-supported catalysts were held at elevated temperatures under dry air conditions. The samples were weighed at regular intervals. These tests showed that the platinum particles were able...
In situ synchrotron X-ray diffraction measurements of single-walled carbon nanotube and C 60 -peapod samples under high pressures up to 13GPa and at high temperature were carried out. Anisotropical shrinkages of their bundle two-dimensional lattices by compression at room temperature were observed. It was found that the lattices recover original forms reversibly upon pressure release. It was...
Micrography and infrared spectroscopy were applied to explore microstructural stabilization of mesophase pitch at oxidation temperatures as low as 130°C. AR mesophase pitch synthesized from naphthalene was drawn to rods and thick filaments with fine fibrous microstructures that coarsen upon carbonization without adequate stabilization. At 270°C, the stabilization front advances rapidly to a depth...
Chemical flaking of graphite has been performed by reacting natural graphite with a strong oxidizing agent, NaClO 3 /HNO 3 . The formed hydrophilic, negatively charged graphite oxide (GO) colloids can be dispersed in water which allows the deposition of thin GO/cationic polymer (poly(diallyldimethylammoniumchloride, PDDA) multilayer films on a glass substrate by wet-chemical self-assembly...
Diesel soot was investigated with electron energy loss spectroscopy (EELS) and near edge X-ray absorption fine structure spectroscopy (NEXAFS). The EELS spectra were obtained in connection with transmission electron microscopy studies, whereas the NEXAFS were obtained from a scanning transmission X-ray microscope (STXM) and from a conventional NEXAFS beamline at two synchrotron facilities. The X-ray...
The fabrication of carbon–carbon composites by injection of low viscosity mesophase pitch through a fiber preform followed by stabilization and carbonization was examined. The fully transformed mesophase MOMP and AR pitches were injected through either soft or rigidized disk preforms 35mm thick and 68mm in diameter. Injection provided good even filling of major flow channels and fiber bundles. Flow-induced...
A novel fabrication method for carbon composites using liquid phase activated sintering at 1400°C in vacuum is described. Specimens for testing were prepared by subjecting mixtures of mesocarbon microbeads (MCMBs), Ti/Ni or Fe/Ni powders, and suitable additives, to aqueous tape casting, and molding the tapes into laminates prior to sintering. After sintering XRD showed that there were some eutectic...
Novel carbon nanotube-NiFe 2 O 4 composite materials have been prepared for the first time by in situ chemical precipitation of metal hydroxides in ethanol in the presence of carbon nanotubes (CNTs) and followed by hydrothermal processing. The obtained composite powders were characterized using XRD, TEM and EDS. The effect of surface oxidation treatment of CNTs on their properties...
The mechanical properties of well-aligned double-walled carbon nanotube (DWNT) strands with diameters of 3–20μm and lengths of ∼10mm were measured using a stress–strain puller. The average tensile strength and Young’s modulus of the tested strands are 1.2GPa and 16GPa, respectively. Deformation and fracture processes of these samples are discussed. The tensile strength and Young’s modulus of an individual...
In the fabrication of carbon–carbon composites by mesophase injection through a fiber preform, it is essential to stabilize the flow-induced microstructure in the flow channels and to prevent relaxation and exudation of the mesophase. Oxidation stabilization studies were conducted on preforms injected with the naphthalene-based AR mesophase pitch. Oxidation mass gain (OMG) curves at 170, 222, and...
To examine whether acid treatment of a non-graphitizing hard carbon influences positively or negatively its electrochemical anodic performance, this study reports the effects of sulfuric acid treatment on the microstructural changes and electrochemical performance of PAN-based hard carbons prepared at various temperatures. It was found that PAN-based hard carbons heat treated at 900°C (TAN9) exhibit...
High resolution XPS analysis of chemical functionalised multi-wall carbon nanotubes (MWCNTs) and single wall carbon nanotubes (SWCNT) was done with ESCA300 (overall instrument resolution of 0.35eV). Information to the degree of functionalisation was ascertained by argon ion bombardment of the samples followed by XPS analysis to detect the functional groups, the percentage atomic concentration of various...
Surface-enhanced Raman scattering (SERS) was used to investigate C 60 self-assembling in solvents like pyrrolidine (Py) and N-methyl-2-pyrrolidinone (NMP) as well as in binary mixtures of o-dichlorobenzene (DCB)/acetonitrile (ACN) and DCB/NMP. For a correct evaluation of the modifications of Raman spectra induced by the C 60 aggregation, we have also presented the variations due to...
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