Carbonaceous Composites Research Articles

Preparation and characterization of carbonaceous material-based hydrogen absorbing composites

Synthesis of hydrogen sorbing composites was attempted by ball milling under hydrogen atmosphere with graphite, carbon black, zirconium metal and ZrMn 2 alloy employed as starting materials. The milling of graphite increased specific surface areas with milling time, but the increase in specific surface area did not monotonously increase the hydrogen capacity. Only zirconium–carbon black composite sorbed more hydrogen than expected for a mere mixture with the same composition. The higher hydrogen capacity on the zirconium–carbon black composite would be due to the specific sites on the carbonaceous material created during the milling. Another effect of the composite formation was stabilization of zirconium and ZrMn 2 , that is, higher temperatures were required to completely dehydrogenate the composites and the ZrMn 2 –carbonaceous composites did not ignite in air.

Preparation and characterization of carbonaceous material-based hydrogen absorbing composites

Synthesis of hydrogen sorbing composites was attempted by ball milling under hydrogen atmosphere with graphite, carbon black, zirconium metal and ZrMn 2 alloy employed as starting materials. The milling of graphite increased specific surface areas with milling time, but the increase in specific surface area did not monotonously increase the hydrogen capacity. Only zirconium–carbon black composite sorbed more hydrogen than expected for a mere mixture with the same composition. The higher hydrogen capacity on the zirconium–carbon black composite would be due to the specific sites on the carbonaceous material created during the milling. Another effect of the composite formation was stabilization of zirconium and ZrMn 2, that is, higher temperatures were required to completely dehydrogenate the composites and the ZrMn 2–carbonaceous composites did not ignite in air.

Structure and UV absorption of QCCs: Carbonaceous dust analogues

“Quenched Carbonaceous Composites (QCCs)” are carbonaceous interstellar dust analogues synthesized in the laboratory from a hydrocarbon plasma. We produced new types of carbonaceous condensates from the ejecta of plasma with mixtures of methane and hydrogen as source gases. We find that QCC with an absorbance peak at 220 nm is composed of onion-like spherules, and QCCs with an absorbance peak at 230–240 nm are composed of polyhedral particles. The onion-like QCC contains aromatic hydrogen bonds, and it shown the 3.3 and 11.4 μm absorption bands. The QCC with an absorbance peak at 230–240 nm is composed of ribbons with bent graphitic layers. This suggests that the carrier of the interstellar 220 nm extinction band might also be an emitter of the interstellar diffuse emission bands.

96/01925 Ceramic coatings for carbonaceous composites from kaolinite

96/01925 Ceramic coatings for carbonaceous composites from kaolinite

Ceramic coatings for carbonaceous composites from kaolinite

Ceramic coatings were prepared on the surface of carbon composites, using a process simpler than the ones presently known. The solid precursor is deposited on the substrate from a suspension, then submitted to heat treatment under controlled atmosphere.Owing to their good thermomechanical properties, β′-SiAlONs have been chosen as the coating agent. They were prepared by a low temperature process using the reduction and nitridation of kaolin under hydrogen/nitrogen (3/1) flow.Deposits of kaolin with an oriented microtexture were obtained by the slow sedimentation of an aqueous kaolin suspension. They were then transformed into β′-SiAlON coatings on C/SiC composites at 1200°C. Whereas the 001 layers of kaolin exhibited an important orientation at the nanometric scale, as revealed by X-ray diffraction, only microtextural orientation was observed for the ceramic coating. These ceramic coatings might be used particularly in a multi-layer protection of carbon against oxidation.

Carbonaceous fibre-reinforced composites: McCullough, F.P., Dick, C.R. and Brewster, S.L. (Dow Chemical Company, Midland, MI, USA) US Pat 4 868 038 (19 September 1989)

Carbonaceous fibre-reinforced composites: McCullough, F.P., Dick, C.R. and Brewster, S.L. (Dow Chemical Company, Midland, MI, USA) US Pat 4 868 038 (19 September 1989)

Chemical, Optical, and Infrared Properties of Quenched Carbonaceous Composites (QCCs)

Quenched carbonaceous composite (QCC) was synthesized by quenching the plasma of methane gas. Chemical properties as well as optical and infrared spectra of the QCC and “oxidized” QCC were measured. Good agreement of the IR spectra of the QCCs to the unidentified infrared (UIR) emission bands was obtained. Correspondence of their features to molecular structures in the QCC was estimated. It is concluded that a “cross-conjugated ketone” structure (CCK) caused the 6.2, 7.7, and 8.6 μm features and “solo” H atoms on carbon are responsible for the 3.3 and 11.3 μm features.

Haemocompatibilily and biological course of carbonaceous composites for cardiovascular devices

A new class of carbonaceous composites has been developed for cardiovascular devices. The aim of the present study, performed in dogs, was to test the immediate blood compatibility of these materials when inserted within the vascular bed. Biocompatibility studies were performed on vascular cylinders (6 mm i.d.) and intra-atrial implants. The specimens were examined sequentially by SEM at 10, 20, 30, 180 s and 10 min after re-establishment of the blood flow. Patency of the vascular cylinders was tested during the second and third postoperative month ay Doppler ultrasound investigations; specimens were examined by light and electron microscopy (scanning and transmission) at 15, 60 and 110 d following implantation. As early as 10 s after re-establishment of the blood flow platelet adhesion and a limited fibrin mesh with few erythrocytes developed on the material. Platelet aggregates were only observed on intravenous implants. Except in the case of the intravenous insert, no thrombosis developed at the contact of intra-arterial or intracardiac implants. After 15 d it was completely covered by a fibrocellular layer (3–5 cells thick) consisting of large myofibroblasts with microfilaments, newly synthesized collagen and elastin. Endothelial-like cells developed and were completed 2 mnth after implantation. However, deposits present inside and outside the fibrocytic cells of the newly developed tissue were observed corresponding to carbon peaks as indicated by wavelength dispersive X-ray microanalysis.

Method for manufacturing fibrous carbonaceous composites having near isotropic properties : Lamdin, F. and Randle, W. W. (USAEC) US Pat 3 718 720 (27 Feb 1973)

Method for manufacturing fibrous carbonaceous composites having near isotropic properties : Lamdin, F. and Randle, W. W. (USAEC) US Pat 3 718 720 (27 Feb 1973)

Fibrous carbonaceous composites and method for manufacturing the same: Trent, P.E. and Miner, J.E. (USAEC) US Pat 3 671 385 (20 Jun 1972)

Fibrous carbonaceous composites and method for manufacturing the same: Trent, P.E. and Miner, J.E. (USAEC) US Pat 3 671 385 (20 Jun 1972)