Yoshihisa Suda

Friction and wear properties of graphite/glassy carbon composites

Abstract This paper describes the results of an experimental study of the friction and wear properties of graphite/glassy carbon (G/GC) composites. The frictional tests were performed in ambient air with a pin-on-disk friction apparatus. When the composition of graphite and glassy carbon was changed, the G/GC composite with 34 vol.% graphite content showed the lowest friction coefficient (μ≒0.13) and that with 24 vol.% graphite content showed the lowest specific wear amount (Ws≒2×10−7 mm3/Nm) at this test conditions. Compared with graphite and glassy carbon, G/GC composites showed lower friction coefficients and lower specific wear amounts. Consequently, G/GC composites are expected to be useful as self-lubricating materials.

Stability study of carbon graphite covered quartz crystal

This paper shows the properties and the possibilities of carbon graphite-covered quartz crystal as an organic gas-sensing device. The carbon graphite formed on a side of quartz plate was supported by Pt electrodes. The prepared quartz crystals were heat treated for the enhancement of stability in the temperature range from 100 to 450°C. Impedance analysis of the carbon graphite-covered quartz crystal showed a larger admittance value than that of a lipid coated quartz crystal, which was based on our previous method for detecting gas components. Using the adsorption and desorption responses, the reproducibility and sensitivity are presented for describing the merits of carbon graphite-covered quartz crystal in the detection of organic gas components. The comparison of sensitivity between commercially available alcohol sensor and carbon graphite-covered quartz crystal is provided for a ppm of ethanol injection. These results prove that the carbon graphite-covered quartz crystals are usable as an organic gas sensor and as an analytical device.

Competitive Binding of Catecholamines, Indoleamines, Acetylcholine, and Related Metabolites to Various Glassy Carbon Materials

Abstract We have previously demonstrated the utility of a pre-column containing glassy carbon particles in the determination of acetylcholine and choline by liquid chromatography with electrochemical detection (Ikarashi et al., 1992). Such a pre-column adsorbs neurochemically related catechol and indole derivatives and, thus, prevents interference in the chromatogram for acetylcholine and choline. In the current studies, we report the results of examining three important and related characteristics of this adsorption process. First, the source materials and conditions used in the preparation of the glassy carbon particles substantially affect adsorption of the ‘interfering’ catecholamines, indoleamines, and related metabolites. Second, the primary adsorption sites appear to have a substantial amount of graphite-like, rather than diamond-like, character. Third, the Langmuirian adsorption of the catechol and indole compounds is at least partly competitive, indicating the probable involvement of common adsor...

Effects of graphite content on carbon nitride films prepared by hot carbon filament chemical vapor deposition

Carbon nitride (CNx) thin films were prepared by a hot carbon filament chemical vapor deposition. Several kinds of carbon coils, which are composed of graphite and glassy carbon, were applied as filaments. The carbon coil was heated at about 2073 K in a nitrogen atmosphere of 100 Pa. Effects of the graphite content of the filament on the film microstructure, surface morphology and the nitrogen content in the CNx films were studied by using field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). FE-SEM observations show that the CNx films change from densely columnar to noncolumnar structures with increasing graphite content. AFM observations reveal that the average roughness of the film surface increases with increasing graphite content. It is found from the XPS analysis that the nitrogen content does not depend strongly on the graphite content. The filament with the low graphite content is suitable for preparing CNx films with a den...