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The experimental adsorption isotherm of N2molecules on mutually isolated single wall carbon nanotubes at 77 K agreed well with the grand canonical Monte Carlo simulated one. The N2adsorption isotherm had two steps stemming from monolayer formation on the internal surface and filling of the residual space of the internal tube pore. Although all of radial distribution functions of molecules adsorbed on the internal, external, and flat surfaces indicated a hexagonal packing structure, the radial distribution functions were different from each other. In particular, the radial distribution function of the monolayer on the internal surface showed an additional peak because of the markedly curved surface.

Abstract Polyimide (PI)-based composites containing single-wall carbon nanohorn aggregate (NH) were fabricated using the spark plasma sintering (SPS) process. For comparison, composites with carbon nanotube (NT) and traditional graphite (Gr) were also fabricated. The NH was produced using CO2 laser vaporization and a graphite target and the NT was produced by a chemical synthesis method. We evaluated the friction and wear properties of the PI-based composites with a reciprocating friction tester in air using an AISI 304 mating ball. NH drastically decreased the wear of PI-based composites; the specific wear rate of composite with NH of only 5 wt% was of the order of 10-8 mm3/Nm, which was two orders of magnitude less than that of PI alone. The wear reduction ability of NT seemed to be slightly inferior to that of NH, although it was considerably better than that of Gr. NH and NT lowered the friction of composites. The friction coefficient of composite with 10 wt% NH was less than 0.25, although it was slightly higher than that of composite with 10 wt% Gr. There was no clear difference in the friction reduction effect of NH and NT. The further addition of Gr to composites with NH or NT rather deteriorated the antiwear property of composites, although the friction coefficient was slightly reduced. The transferred materials existed on the friction surface of the mating ball, sliding against composites with three types of carbon filler. These transferred materials seemed to correlate with the low friction and wear properties of composites.

Metal nanoparticles play an important role in chemical vapor deposition (CVD) synthesis of carbon nanotubes because nanoparticles not only catalyze the nanotube growth but also determine the structural characteristics of the nanotubes. We report on the synthesis of single-wall carbon nanotubes (SWNTs) on the basis of the gas-phase reaction of colloidal solutions of metal nanoparticles containing Co and Mo. The colloidal solution of the nanoparticles is prepared by a reverse micelle method and injected into a furnace, where the solvent serves as the carbon source while the nanoparticles act as the catalyst. We have found that addition of a small amount of thiophene leads to formation of the SWNTs. The formation mechanism of the SWNTs is discussed by comparing the present CVD and laser-ablation methods.

Yields of SO2formed during H2S removal from N2+ H2S mixture at 800°C in the presence of Fe2O3, Mn-nodule and red mud have been determined. The largest yields were observed for Fe2O3followed by Mn-nodule, whereas no SO2was detected in the presence of red mud. A mechanism for H2S reaction with Fe oxides has been proposed involving the use of the component distribution in the clean gas as well as the Fe sulphides formed during adsorption. X-ray diffraction and Mossbauer spectroscopy have been used to determine the forms of Fe in the solids at the end of adsorption. FeS was the main sulphide which was always accompanied by FeS2.

The thermal decomposition of ammonia in shock waves was studied by means of vacuum ultra-violet absorption spectroscopy, monitoring the concentration of atomic hydrogen. Rate parameters of the initiation reaction, NH3+Ar→NH2+H+Ar (I) and the consecutive reactions, NH3+H→NH2+H2(II) and NH2+H→NH+H2(III) were determined. Under the experimental conditions studied, the profile of the concentration of atomic hydrogen formed by decomposition of ammonia was considered to result from these three reactions and the reaction 2NH→N2+2H (IV)