• Carbon letters
• /
• 제16권1호
• /
• pp.51-56
• /
• 2015

Carbonate-type organic electrolytes were prepared using propylene carbonate (PC) and dimethyl carbonate (DMC) as a solvent, quaternary ammonium salts, and by adding different contents of 1-ethyl-3-methyl imidazolium tetrafluoroborate ($EMImBF_4$). Cyclic voltammetry and linear sweep voltammetry were performed to analyze conducting behaviors. The surface characterizations were analyzed by scanning electron microscopy method and X-ray photoelectron spectroscopy. From the experimental results, increasing the $EMImBF_4$ content increased the ionic conductivity and reduced bulk resistance and interfacial resistance. In particular, after adding 15 vol% $EMImBF_4$ in 0.2 M $SBPBF_4$ PC/DMC electrolyte, the organic electrolyte showed superior capacitance and interfacial resistance. However, when $EMImBF_4$ content exceeded 15 vol%, the capacitance was saturated and the voltage range decreased.

• 전기화학회지
• /
• 제15권3호
• /
• pp.190-197
• /
• 2012

비닐에틸렌 카보네이트(VEC: vinyl ethylene carbonate)를 전해질 첨가제로 사용했을 때 하이브리드 커패시터(hybrid capacitors) 전극에서 나타나는 전기화학적 특성변화에 대해서 고찰하였다. 하이브리드 커패시터는 양극은 활성탄(AC : activated carbon) 음극은 리튬티타늄옥사이드(LTO: $Li_4Ti_5O_{12}$)를 사용하였고, 전해질로서는 에틸렌 카보네이트(EC: ethylene carbonate): 디메틸 카보네이트 (DMC: dimethyl carbonate) : 에틸메틸 카보네이트(EMC : ethyl methyl carbonate)를 사용하였고, 염으로 육불화인산리튬($LiPF_6$: lithium hexafluoro phosphate)을 사용하였다. 전극 표면의 산소관능기 그룹을 제거하고, 표면을 환원시킴으로써 전극에 안정성을 향상시킨다고 알려진 VEC의 첨가량에 따른 전기화학적 특성을 평가하였으며, 0.7%(부피비)의 VEC첨가시, 가장 우수한 전기화학적 특성을 얻을 수 있었다. 0.7% 이상 첨가하였을 경우, 오히려 부반응 증가로 전기화학적 성능이 감소하였다. X-ray photoelectron spectrocopy (XPS) 결과로부터 LTO 전극에서 VEC가 첨가되지 않은 전해질에 비해 LiF가 감소한 것을 확인 할 수 있었다. VEC가 첨가되지 않은 전해질은 2500 사이클 후, 43.2 %의 용량 유지를 나타냈지만, 최적화된 VEC 첨가를 통하여 82.7 %의 높은 용량을 유지하는 특성을 가진 하이브리드 커패시터를 얻을 수 있었다.

• 공업화학
• /
• 제18권1호
• /
• pp.64-70
• /
• 2007

분산성이 우수한 carbon-slurry 연료의 제조와 특성 분석을 하였다. Carbon-slurry 연료는 액체연료(Jet A-1)와 탄소 입자 그리고 적당한 첨가제를 혼합하여 얻었다. Carbon-slurry 연료의 분산성은 교반 온도, 탄소 입자의 특성 그리고 첨가제의 양과 종류 등에 따라서 달라진다. 특히 첨가제의 종류가 slurry 연료의 안정성에 가장 중요하였다. 다양한 음이온성, 양이온성, 비이온성 형태의 첨가제를 사용하여 carbon-slurry 연료의 분산성을 분석하였고, 이 결과 나트륨 염의 형태를 가진 음이온성 첨가제를 사용하였을 경우 carbon-slurry 연료의 분산성이 가장 우수하였음을 확인하였다. Carbon-slurry 연료의 분산성은 빛이 투과되는 광도 값을 측정하여 분석하였다.

• 한국분말재료학회지
• /
• 제25권4호
• /
• pp.291-295
• /
• 2018

A conductive additive is prepared by dispersing multi-walled carbon nanotubes (MWCNTs) on Cu powder by mechanical milling and is distributed in epoxy to enhance its electrical conductivity. During milling, the MWCNTs are dispersed and partially embedded on the surface of the Cu powder to provide electrically conductive pathways within the epoxy-based composite. The degree of dispersion of the MWCNTs is controlled by varying the milling medium and the milling time. The MWCNTs are found to be more homogeneously dispersed when solvents (particularly, non-polar solvent, i.e., NMP) are used. MWCNTs gradually disperse on the surface of Cu powder because of the plastic deformation of the ductile Cu powder. However, long-time milling is found to destroy the molecular structure of MWCNTs, instead of effectively dispersing the MWCNTs more uniformly. Thus, the epoxy composite film fabricated in this study exhibits a higher electrical conductivity than 1.1 S/cm.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2005년도 International Meeting on Information Displayvol.II
• /
• pp.1447-1450
• /
• 2005

Carbon nanotube field emission display devices were fabricated using screen printing techniques. The CNT pastes are composed of organic binder, CNT, and additive materials such as glass frit, silver or ITO powders. The change in mixing ratio of various organic binders in CNT paste varied the electron emission characteristics. With increasing the contents of additive materials in CNT paste, turn-on field were increased, leading to decrease in electron emission current. The post-treatment process in this study induced the vertical alignment of carbon nanotubes on glass, resulting in the improvement of electron emission uniformity.

• Tribology and Lubricants
• /
• 제24권5호
• /
• pp.264-268
• /
• 2008

A large number of additives have been used with the efforts of improving the performance of lubricants used along with the development of internal combustion engine. In this study, nano-sized graphite was used as liquid-lubricant additive. In order to disperse graphite into oil, we esterified the nano-carbon manufactured by our company with various types of alcohol. After measuring the anti-wear in accordance with the types of alcohol and added concentration, it has been found that its anti-wear/friction decrease has been improved in case of adding 0.1% of the sample composed with C12/14 mixed alcohol & hexadecanol.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
• /
• pp.917-919
• /
• 2003

The effect of conducting carbon layer on the performance of AC thin film EL display was examined. It was found that incorporation of small amount of carbon nano-tube and conducting additive greatly improve the luminance of the inorganic EL compared to the one with only conducting carbon black.

• 대한기계학회논문집B
• /
• 제29권9호
• /
• pp.979-987
• /
• 2005

Numerical simulations were performed at atmospheric pressure in order to understand the effect of additives on flame speed, flame temperature, radical concentrations, $NO_x$ formation, and heat flux in freely propagating $CH_4-Air$ flames. The additives were both carbon dioxide and hydrogen chloride which had a combination of physical and chemical behavior on hydrocarbon flame. In the flame established with the same mole of methane and additive, hydrogen chloride significantly contributed toward the reduction of flame speed, flame temperature, $NO_x$ formation and heat flux by the chemical effect, whereas carbon dioxide mainly did so by the physical effect. The impact of hydrogen chloride on the decrease of the radical concentration was about $1.4\~3.0$ times as large as that of carbon dioxide. Hydrogen chloride had higher effect on the reduction of $EI_{NO}$ than carbon dioxide because of the chemical effect of hydrogen chloride. The reaction, $OH+HCl{\rightarrow}Cl+H_2O$, played an important role in the heat flux from flames added by hydrogen chloride instead of the reaction, $OH+H_2{\rightarrow}H+H_2O$ which was an important reaction in hydrocarbon flames.

• Carbon letters
• /
• 제27권
• /
• pp.81-89
• /
• 2018

The present study aimed to prepare a novel efficient flame retardant additive for polypropylene. The new flame retardant was prepared by chemical grafting of melamine to graphene oxide with the aid of thionyl chloride. Fourier-transform infrared spectroscopy and thermogravimetric analysis proved that melamine had been successfully grafted to the graphene oxide. The modified graphene oxide was incorporated into polypropylene via solution mixing followed by anti-solvent precipitatio. Homogeneous distribution as well as exfoliation of the nanoplatelets in the polymer matrix was observed using transmission electron microscopy. Thermogravimetric analysis showed a significant improvement in the thermo-oxidative stability of the polymer after incorporating 2 wt% of the modified graphene oxide. The modified graphene oxide also enhanced the limiting oxygen index of the polymer. However, the amount of improvement was not enough for the polymer to be ranked as a self-extinguishing material. Cone calorimetry showed that incorporating 2 wt% of the modified graphene oxide lowered total heat release and the average production rate of carbon monoxide during burning of the polymer by as much as 40 and 35%, respectively. Hence, it was concluded that the new flame retardant can retard burning of the polymer efficiently and profoundly reduce suffocation risk of exposure to burning polymer byproducts.

• 에너지공학
• /
• 제29권3호
• /
• pp.50-56
• /
• 2020

Currently, 3D printing technology is a new revolutionary additive manufacturing process that can be used for making three dimensional solid objects from digital films. In 2019, this 3D printing technology spreading vigorously in production parts (57%), bridge production (39%), tooling, fixtures, jigs (37%), repair, and maintenance (38%). The applications of 3D printing are expanding to the defense, aerospace, medical field, and automobile industry. The raw materials are playing a key role in 3D printing. Various additive materials such as plastics, polymers, resins, steel, and metals are used for 3D printing to create a variety of designs. The main advantage of the green cement for 3D printing is to enhance the mechanical properties, and durability to meet the high-quality material using in construction. There are several advantages with 3D printing is a limited waste generation, eco-friendly process, economy, 20 times faster, and less time-consuming. This research article reveals that the role of green cement as an additive material for 3D printing.