The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The chemical and structural transformations which result from the pyrolisis of Kevlar (poly[p-phenyleneterephthalamide]) fibres in argon, and from subsequent activations to differing levels of burn-off, under differing activation conditions in CO 2 , have been investigated using XPS, SEM and XRD. XPS indicates a marked decrease in surface oxygen after pyrolysis followed by the formation of...
Two iron-carbon composites were prepared from ferrocene-polymer mixtures with resol resin (Fe-RESOL) or epoxy resin (Fe-EPOXY), and they were compared with the previous composite (Fe-PFA) made from a ferrocene-poly(furfuryl alcohol) mixture from structural and the electrochemical viewpoints. The features of the composites were divided into two groups, that is, a group consists of Fe-PFA and Fe-RESOL...
Pore size control of a series of activated carbon fibers was attempted by chemical vapor deposition (CVD) of benzene to clarify the influence of the pore distribution on the development of molecular sieving ability. Weight increase by CVD was found to saturate at a certain level respective to the fiber, reflecting their surface areas. However, when saturation was obtained, the molecular sieving...
Carbon nitride thin films were deposited using an ArF excimer laser to ablate a target of 3,5 diamino 1,2,4 triazole (guanazole) in a reactive atmosphere of ammonia. Films were obtained at room temperature onto crystalline silicon and aluminium substrates. The dependence of the film properties on the ammonia pressure is reported. Films were characterized systematically by profilometry, Fourier Transform...
The structure and microtexture of the 3000°C treated carbon film prepared from a polyimide film Upilex with a thickness of 50 μm (Upilex-3000) were studied by SEM observation and X-ray diffraction measurements. The thickness of Upilex-3000 was 30 μm. Observation of the fracture surface of Upilex-3000 by SEM indicates three kinds of microtextures: (1) skins of 230-300 nm in thickness with well-aligned...
C–SiC–B 4 C composite materials were fabricated from pitch based needle coke, SiC and B 4 C with or without SiC nanoparticulate additive by grinding and then pressureless sintering. Anisothermal and isothermal oxidation tests of the composites obtained were carried out in oxygen flow at temperature increasing continuously from 773 to 1573K. Self-protection behavior of the composites...
The structural components and the internal organization of carbon cathodic deposits fabricated using an arc with the conditions adjusted for the effective production of nanotubes have been characterized by transmission electron microscopy (TEM), high resolution electron microscopy (HREM) and scanning electron microscopy (SEM). Typically, such deposits are columnar structures oriented along the growth...
Activated carbon fiber composites (ACFCs) with the specific surface area of about 1150 m 2 /g were reacted to produce silicon carbide fiber composites with SiO vapor generated from a mixture of Si and SiO 2 at 1673 K under vacuum for various hold times ranging between 10-120 min. Chemical analysis of the converted ACFCs resulting from reaction showed that the products contained 79-90...
A very unusual form of carbon fibers is reported. While preparing vapor grown carbon fiber at temperatures exceeding 1200 o C, formation of nodulated carbon fibers were found in addition to normal vapor grown carbon fibers. The growth temperature was found to be the primary, if not only, factor influencing the formation of nodules and the frequency of occurrence. The formation of such an unusual...
Vapor grown carbon fibers (VGCFs) with a maximum length of 2 cm and a diameter of a few micrometres have been fabricated by a conventional thermal deposition method at 1000 o C using ferric sulfate or ferrous sulfate as catalyst precursors, nitrogen as carrier gas, benzene as the source of carbon and a ceramic tube as substrate. Experiments employed a feeding gas of 27 wt.% benzene vapor and...
High-temperature protection of carbon-carbon (C/C) composites against oxidation by ambient air is a serious problem with no single, universal solution. In this paper, we present the results of a novel laser-induced chemical decomposition (LICD) process used to apply two types of oxidation protection system (OPS) coatings on C/C composites. Silicon carbide and iridium were selected as the candidate...
A rapid high temperature chemical vapor deposition method was employed to grow micro-sized tree-like carbon structures on graphite electrodes. Temperature dependence of the nucleation density of carbon micro trees and the influence of methane partial pressure (carbon source) on the growth rate of carbon trees were systematically investigated. Substrate surface effects such as mechanical polishing...
A new kind of carbon whisker, different from others, has been found by means of high resolution electron microscopy and field emission scanning electron microscopy. Carbon layers are almost perpendicular to the whisker axis and a spiral structure is formed around it. Structure analysis indicates the growth process consists of two stages; firstly, carbon layers stacked in turbostratic manner, and then...
An activated carbon artifact was prepared through mixing, moulding, curing and carbonizing, using polyvinylbutyral resin (PVB) as the binder, dibutyl phthalate (DBP) as a plasticizing agent and isocyanuric acid ester as a cross-linking agent to clarify influential factors on its strength. Preparation conditions such as moulding pressure, temperature and time of curing, carbonization and the amount...
We report the growth of pillar-like cylindrical structures consisting of densely packed and vertically aligned multiwalled carbon nanotubes by exposing Ni-coated oxidized-Si (001) substrates to a xylene-ferrocene mixture. The nanotube pillars have a diameter between 10 and 100 μm, and lengths of several tens of micrometres. Formation of circular microcracks in the film allows ferrocene and xylene...
Epoxy composites based on vapor grown carbon fiber (VGCF) were fabricated and analyzed for room temperature thermophysical properties. An unprecedented high thermal conductivity of 695 W/m K for polymer matrix composites was obtained. The densities of all the composites are lower than 1.5 g/cc. In addition the high value of coefficient of thermal expansion (CTE) of the polymer material was largely...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.