• Journal of the Korean Ceramic Society
• /
• v.29 no.5
• /
• pp.396-402
• /
• 1992

Carbon solid was prepared from dormant mesophase pitch (DMPP) without using a binder and its properties were characterized. DMPP powder was stabilized with air or nitric acid in pretreatment stage so that it might not soften in later heat ttreatment stage. Optimum sintering properties were obtained from carbon powder with 2.36∼2.38 of C/H atomic ratio and 1.27∼1.40 of C/O atomic ration in air stabilization. In nitric acid stabilization, optimum sintering properties were obtained when 20∼40 vol.% of nitric acid solution was used. Compressive strength increased up to 1200$^{\circ}C$ of heat treatment temperature, and the highest compressive strength and bulk density of carbon solid from DMPP were 3000 kgf/㎤, respectively. The optical properties of carbon solid obtained was fine mosaic structure. Carbon solid after graphitization showed the properties of hard carbon due to stabilization and its shore hardness was 120.

• Resources Recycling
• /
• v.7 no.1
• /
• pp.14-19
• /
• 1998

Tile pl~ysimchemical properties of residual or unburned carbon obtaincd from fly ash were mestigated. The carbon-enrichcd samples were extracted from fly ash by flotalion mcthod. Tnz carbon content and chemical compos~lion of t b recovered carbon sample were analyzed. The ash in the carbon sample was also examined. The unburned carbon characterization included measurement oE sire distibution, sudace area, crystal shuchlre md density.

• The Korean Journal of Ceramics
• /
• v.4 no.3
• /
• pp.240-244
• /
• 1998

The analytical method was developed to calculate efficiency of densifying carbon/carbon (C/C) composites using coal tar pitch as a matrix precursor at each cyle. Three factors were defined in analyzing the densification process: impregnation efficiency, retention efficiency, and overall densification efficiency. The relationships developed were applied to the experimental results for three densification cycles of C/C composites with pitches as an impregnant to evaluate the factors which may depend on the impregnant and on the route of carbonization. The impregnation efficiency increased with the repeated process cycles whereas the retention efficiency decreased irrespective of the impregnant and carbonization route. Carbonization route P+A+G, in which pressure carbonizationl (P) and graphitization (G) were done before after atmospheric pressure carboniztion (A) respectively, using impregnant of high carbon yields was the most effective method in densifying C/C composites.

• Journal of the Korean Ceramic Society
• /
• v.40 no.10
• /
• pp.1021-1026
• /
• 2003

Resin impregnation of carbon materials was affected by surface of carbon materials. The surface of carbon materials with coupling treatment improved comparability and wettability with resin, and that increased impregnation efficiency and properties of carbon materials. As a results of FT-IR, The silanol was coated on carbon surface with one layer. Coupling treatment of carbon materials increased impregnation efficiency, which improved porosity, mechanical strength, density and friction behavior.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.11a
• /
• pp.373-377
• /
• 1996

Carbon materials have become a major interestings of research directed toward the development for anode of lithium batteries of enhanced cell capacity. The purpose of this study is to research and develop poly(p-phenylene)(PPP)-based carbon as a anode of lithium secondary batteries. We have synthesized PPP from benzen by chemical reaction. And then disordered carbon materials were obtained by heat-treating PPP in a nitrogen atmosphere at 40$0^{\circ}C$ to 100$0^{\circ}C$ for 1 hour. The carbon prepared by heat treatment showed a broad x-ray diffraction peak around 2$\theta$=23$^{\circ}$. Electrodes were charged and discharged at a current density of 0.1㎃/$\textrm{cm}^2$. Excellent reversible capacity of 275㎃h/g and 97% of charge/discharge efficiency were observed heat treated PPP-based carbon a $700^{\circ}C$.

• Progress in Superconductivity and Cryogenics
• /
• v.24 no.4
• /
• pp.55-58
• /
• 2022

Carbon-based doping to MgB₂ superconductor is the simplest approach to enhance the critical current densities under magnetic fields. Carbon quantum dots is synthesized in this work as a carbon provider to MgB₂ superconductors. Polyvinyl Pyrrolidone is pyrolyzed and dispersed in dimethylfomamide solvent as a dopant to the mixture of Mg and B powders. Doped MgB₂ bulk samples clearly show the decrease of a-axis lattice constant, grain refinements, and broadening of FWHM of diffraction peaks compared to un-doped MgB₂ possibly due to the carbon substitution and/or boron vacancy at the boron site in MgB₂ lattice. Also, high-field J_c for the doped MgB₂ is enhanced significantly with the crossover about 3 T at 5 & 20 K when increasing the doping of carbon quantum dots.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.3
• /
• pp.571-576
• /
• 2007

In this paper, we have investigated chemical, mechanical and structural properties by changing the content of carbon nanotube, Which is a component part of semiconductive shield in underground power transmission cable. The multi luminescence spectrometer MLA-GOLDS was used to investigate chemical properties of specimens. Also, the density meter EW-200SG was used to investigate the mechanical properties of specimens, and the FE-SEM S-4300 in Hitachi was used for dispersion of CNT(Carbon nanotube). As a result, the cl intensity, which show the effect of oxidation, was decreased by CNT of 1 [wt%], and the density of semiconductive shield materials with CNT and EEA(Ethylene Ethyl Acrylate) is lower than that for commercial semiconductive shield materials. Also, the properties of dispersion showed an increase according to an increase in the ratio of CNT, and the properties were the best at 5 wt%. Therefore, excellent chemical, mechanical and structural properties can be improved with the small amount of CNT.

• Applied Chemistry for Engineering
• /
• v.8 no.1
• /
• pp.16-22
• /
• 1997

When platinum wan impregnated on carbon by methanol, surfactant have an important effect on the stability of platinum colloid. As the increase of amounts of surfactant enhanced the stability of platinum colloid, the particle size of platinum on carbon was diminished. But, after heat treatment, residue of surfactant remained in electrode to decrease current density of oxygen reduction. To remove surfactant, as temperature of heat treatment enhanced, platinum particle was aggromerated and current density was decreased.

• Journal of Electrochemical Science and Technology
• /
• v.3 no.2
• /
• pp.72-79
• /
• 2012

$Li_2MnSiO_4$ was synthesized using the solid-state method under an Ar atmosphere at three different calcination temperatures (900, 950, and $1000^{\circ}C$). The optimization of the carbon coating was also carried out using various molar concentrations of adipic acid as the carbon source. The XRD pattern confirmed that the resulting $Li_2MnSiO_4$ particles exhibited an orthorhombic structure with a $Pmn2_1$ space group. Cyclic voltammetry was utilized to investigate the capacitive behavior of $Li_2MnSiO_4$ along with activated carbon (AC) in a hybrid supercapacitor with a two-electrode cell configuration. The $Li_2MnSiO_4$/AC cell exhibited a high discharge capacitance and energy density of $43.2Fg^{-1}$ and $54Whkg^{-1}$, respectively, at $1.0mAcm^{-2}$. The $Li_2MnSiO_4$/AC hybrid supercapacitor exhibited an excellent cycling stability over 1000 measured cycles with coulombic efficiency over > 99 %. Electrochemical impedance spectroscopy was conducted to corroborate the results that were obtained and described.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.381.2-381.2
• /
• 2014

In this study the amorphous carbon films were deposited by PECVD at the substrate temperature range of 250 to $600^{\circ}C$, and the process conditions of higher and lower precursor flow rate, respectively. The temperature was a main parameter to control the density and mirco-structures of carbon films, and their's properties depended with the process temperatrue are changed by controlling precursor flow rate. The precursor feeding rate affect on the plasma ion density and a deposition reactivity. This change of film properties was obtained the instrinsic stress, FT-IR & Raman analysis, refractive index (RI) and ext. coef. (k) measured by ellipsometer. In the process conditions of lower and higher flow rate of precursor it had a different intrinsic stress as a function of the substrate temperature.